Electric load and drive unit for a fitness machine

Abstract

Disclosed is an electric load and drive unit (1) for a fitness machine, comprising: a drive shaft (51), a rotor shaft (11) configured to transmit motion from an electric motor (302) to a gearbox, the rotor shaft (11) being coaxially arranged with the drive shaft (51) and extending through a centre of the gearbox to transmit motion directly from the motor to the gearbox, the gearbox operatively arranged between the drive shaft (51) and the rotor shaft (11) for providing resistance control; wherein the gearbox is configured as one of a single-stage cycloidal gearbox, a Harmonic Pin Ring (HPR) type gearbox, and a Harmonic Drive type gearbox.

Description

[0001] ELECTRIC LOAD AND DRIVE UNIT FOR A FITNESS MACHINE

[0002] The present application generally relates to an electric load and drive unit for a fitness machine, and more particularly to the technical field of electric power transmission and control systems for fitness machines.

[0003] Reference is made to the earlier patent applications DE102024118511 .2 of 01 July 2024, EP25165815.9 of 25 March 2025, and EP25186451.8 of 30 June 2025, the priorities of which are herewith claimed, and the contents of which are herein incorporated by reference.

[0004] DE202024101102U1 discloses a gym-based electricity generation system integrating exercise equipment with kinetic energy conversion, using a dual-shaft mechanism and adaptive resistance control to enhance energy output. The focus is on energy harvesting and user feedback .

[0005] DE202023102964U1 describes an electric bicycle system with a switchable drive and resistance mode, allowing the user to generate resistance and energy during stationary use, with multi-stage resistance control and energy storage.

[0006] DE202012001860U1 relates to a muscle training device with a motor and S-shaped force sensor, providing electronic resistance control and feedback for exercise equipment. The system relies on conventional force sensors.

[0007] EP3274059B1 discloses a driving system for rehabilitation machines, enabling controlled rotation about two perpendicular axes with integrated force / torque sensors for feedback. The system is designed for rehabilitation and is relatively bulky, focusing on multi-axis control. EP3263189B1 describes a cycling simulation device with a flywheel, remote-controlled braking, and torque / position sensors for real-time feedback and training quality assessment.

[0008] EP2203142B1 relates to an arm therapy system with multiple drives and exoskeletal modules, providing anatomically correct movement and force feedback for rehabilitation. The system is complex, designed for medical therapy.

[0009] US2024 / 0122778A1 discloses an exoskeleton for upper limb rehabilitation, featuring multiple joints and actuators to assist shoulder and elbow movement, with a focus on anatomical alignment and user comfort. The system is primarily intended for medical rehabilitation.

[0010] US10278881 B1 describes devices and methods for assisting pronation and supination, using mechanical lever systems and force application mechanisms, primarily for orthotic or therapeutic use.

[0011] US20090149783A1 discloses a cooperative arm therapy system with multiple drives and rotation modules, enabling guided movement and force feedback for rehabilitation. The focus is on exoskeletal guidance and multi-axis control.

[0012] CN110101546A presents a wearable, portable upper limb rehabilitation robot using flexible cable drives and modular training sections for the wrist and elbow, aimed at lightweight, mobile rehabilitation.

[0013] This application addresses the problem of providing resistance control in electric load and drive units for fitness machines. This and other objects are solved by the subject matter of the independent claims. Further improvements are given by the dependent claims.

[0014] The application provides solutions for achieving resistance control through the use of a single-stage cycloidal gearbox, as well as alternative gearbox configurations such as Harmonic Pin ring-type (HPR) or Harmonic Drive type gearboxes. The application also addresses the problem of measuring torsion in the drive shaft by incorporating a torque sensor system with a flexible PCB and an energy harvesting unit. Additionally, the application provides solutions for integrating sensors to measure performance metrics and providing feedback to the user based on the measured metrics, while dynamically adjusting the resistance level.

[0015] The present invention offers a modular drive unit that is tailored for use in fitness equipment. It integrates a high-resolution, contactless torque sensor with a cycloidal gearbox, enabling resistance control in real time while also supporting feedback to the user during exercise. This approach supports responsive operation across a range of training intensities.

[0016] The present invention includes a torque sensor which is embedded using a flexible printed circuit board and operates without contact.

[0017] The present invention supports stable performance under prolonged and repetitive use.

[0018] The present invention offers a more compact, integrated design with a cycloidal gearbox and wireless torque sensor, tailored for fitness machines and capable of providing precise, real-time resistance adjustment and feedback.

[0019] The present invention offers a special lubrication that addresses wear in both rolling and plain bearings, with materials selected for sustained performance under oscillatory, low- speed, and high-load conditions. This supports longer intervals between maintenance and reliability across extended training cycles. The present invention allows the drive unit to be used in new machines or incorporated into existing setups with minimal adaptation effort. Its construction also allows for customization and replacement of components, supporting flexible use across various exercise applications.

[0020] Embodiments of the invention are associated with various advantages and / or technical effects.

[0021] There is disclosed an electric load and drive unit for a fitness machine, comprising: a single-stage cycloidal gearbox for providing resistance control, the gearbox comprising: a rotor shaft configured to transmit motion from a motor to the gearbox, a first eccentric cam mounted on the rotor shaft for driving a first cycloidal gearwheel, an optional second eccentric cam mounted on the rotor shaft for driving an optional second cycloidal gearwheel, the second eccentric cam being offset by degrees relative to the first eccentric cam, a plurality of toothing pins inserted into cylindrical pockets of an outer gearwheel, the first and, if present, the second cycloidal gearwheels configured to mesh with an inner toothing of an outer gearwheel, wherein the electric load and drive unit further comprises a drive shaft that is connected with the first and, if present, with the second cycloidal gearwheels, the drive shaft being provided as a hollow structure that carries an adapter shaft, with a friction bearing and an adapter toothing being provided, for transmitting torque from the adapter shaft over the drive shaft to the first cycloidal gearwheel and, if present, to the second cycloidal gearwheel of the cycloidal gearbox.

[0022] The inclusion of a single-stage cycloidal gearbox allows for resistance control, which can be finely tuned to meet the specific workout intensity requirements of users.

[0023] The hollow structure of the drive shaft, which accommodates an adapter shaft with a friction bearing and adapter toothing, facilitates efficient torque transmission and reduces the overall weight of the unit, contributing to a more compact and lightweight design.

[0024] The electric load and drive unit provides resistance control through the use of a single- stage cycloidal gearbox, allowing for accurate and customizable workout intensity. The inclusion of an optional second eccentric cam in the gearbox provides additional resistance options, allowing users to further tailor their workout experience.

[0025] The drive shaft of the unit is designed as a hollow structure with a friction bearing and adapter toothing, enabling efficient torque transmission to the cycloidal gearwheels.

[0026] The unit can be equipped with a gearbox configured as an HPR-type or Harmonic Drive type, offering alternative gearbox options to suit different fitness machine requirements.

[0027] The torque sensor system integrated into the unit measures torsion in the drive shaft, providing performance metrics and enabling dynamic adjustment of resistance levels based on user feedback.

[0028] In a development, the unit further comprises a gearbox including a drive disc carrying multiple drive pins, and drive rollers mounted on the drive pins for transmitting rotational movement.

[0029] The drive disc with multiple drive pins and mounted drive rollers ensures smooth and consistent transmission of rotational movement, which can lead to a more natural and comfortable exercise experience for the user. This configuration minimizes mechanical play and reduces the risk of slippage, thereby increasing the reliability and longevity of the gearbox within the fitness machine. The use of drive rollers on the drive pins can potentially reduce noise during operation, making the fitness machine more suitable for use in noise-sensitive environments.

[0030] In a development, the unit further comprises a gearbox being configured as an HPR-type instead of a cycloidal gearbox. Configuring the gearbox as an HPR-type provides high power density and efficiency, which is beneficial for fitness machines that require sustained output and durability during intense workouts. The HPR-type gearbox design can offer improved gear meshing and reduced backlash, leading to a better user experience. The robustness of an HPR-type gearbox results in lower maintenance requirements and costs over the lifespan of the fitness machine, providing economic benefits to both manufacturers and end-users. In a development, the unit further comprises a gearbox being configured as a Harmonic Drive type gearbox instead of a cycloidal gearbox. A Harmonic Drive type gearbox offers high gear reduction ratios in a compact form factor.

[0031] The inherent low backlash and high positional accuracy of Harmonic Drive gearboxes contribute to control of resistance levels, allowing for fine-tuning of exercise intensity. The smooth operation and low wear characteristics of Harmonic Drive gearboxes can lead to quieter operation and enhanced durability, improving the overall quality and user satisfaction with the fitness machine.

[0032] There is disclosed an electric load and drive unit for a fitness machine, comprising: a drive shaft, a rotor shaft, a torque sensor system configured to measure torsion in the drive shaft, the torque sensor system comprising: a sensor assembly that measures torsion in the drive shaft, an inductive power transfer (IPT) system comprising a supply coil and a receiver coil configured to provide electrical power to the torque sensor system independently of the stator’s electromagnetic field, an optical transmission system that includes LEDs for transmitting torsion data from the torque sensor system, a first rotor bearing positioned on one side of the rotor shaft, a second rotor bearing positioned on the other side of the rotor shaft, wherein the first rotor bearing and the second rotor bearing are provided between the rotor shaft and the drive shaft, wherein the torque sensor system further comprises: a strain gauge pad and a connection strip, the connection strip carrying at least one transmission LED and the receiver coil, the connection strip extending from an area between the first rotor bearing and the second rotor bearing through a transfer pocket forming an axial channel in the outer surface of the drive shaft, to an area where light signals emitted by the at least one LED are received by a corresponding at least one light receiver element and where the receiver coil is positioned to receive power from the supply coil. The use of an inductive power transfer system with a supply coil and receiver coil in the electric load and drive unit enables a stable and reliable power supply to the torque sensor system, allowing continuous operation of the sensor and optical data transmission without the need for physical power cables or reliance on the stator’s electromagnetic field.

[0033] Positioning the first and second rotor bearings between the rotor shaft and the drive shaft provides enhanced support and alignment, which can lead to improved mechanical efficiency and reduced wear on the components, extending the service life of the unit.

[0034] In a development, the strain gauge pad may be secured to the connection strip by an adhesive. This allows the strain gauge pad and the connection strip to be connected with the PCB as a single unit, thereby reducing risks of misalignment of the components.

[0035] In a development of the electric load and drive unit, the strain gauge pad and the connection strip are provided as a single piece flexible PCB, the single piece flexible PCB further comprising the receiver coil and a strain gauge conductor trace structured in a metal layer of the PCB.

[0036] Providing the strain gauge pad, connection strip, and receiver coil as a single piece flexible PCB simplifies assembly, reduces the number of interconnections, and enhances the reliability and robustness of the torque sensor system.

[0037] In a development, the unit further comprises an area of the drive shaft between the first rotor bearing and the second rotor bearing acting as a load cell for measuring the torque transmitted by the drive shaft. The integration of a load cell within the drive shaft area between the first and second rotor bearings allows for monitoring of torque, enabling proactive maintenance and reducing the likelihood of unexpected mechanical failures. This configuration simplifies the system design by eliminating the need for additional torque measuring devices, thereby reducing the overall weight and complexity of the unit. The load cell's proximity to the rotor bearings ensures high accuracy in torque measurement, which is critical for applications requiring control of power transmission. The inclusion of a torque sensor system enhances the operational efficiency of the unit by providing immediate feedback on torque output, allowing for fine-tuning of the system to achieve enhanced performance. The torque sensor system provides critical data that can be used for adaptive control strategies, improving the dynamic response of the system to varying load conditions.

[0038] In a development, the unit further comprises a lubricant comprising anti-wear additives for applications involving low speeds and high loads. The use of a lubricant with anti-wear additives specifically formulated for low-speed, high-load applications significantly reduces the rate of wear on moving parts, prolonging the operational lifespan of the unit. The lubricant can help maintain consistent performance under extreme conditions, ensuring that the unit functions effectively even with intermittent movement that has been found to increase stress on mechanical components. The enhanced protection provided by the anti-wear additives reduces maintenance requirements and associated costs by reducing the frequency of lubricant replacement and component servicing.

[0039] In a development, the unit further comprises at least one special lubricant being selected from specific types, known for their high performance in supporting back-and-forth movements of the drive shaft, facilitating smooth operation even in the absence of complete revolutions. The use of high-performance lubricants ensures consistent and smooth operation of the drive shaft, which can improve the overall user experience by reducing noise and vibration during use. The at least one special lubricant facilitates the efficient transfer of power within the drive mechanism, potentially leading to energy savings and improved mechanical efficiency in applications where complete revolutions are not consistently maintained.

[0040] In a development, the at least one special lubricant is based on mineral oil and barium complex soap and has a kinematic viscosity of 220 mm2 / s at 40 °C up to 19 mm2 / s at 100 °C like e.g. STABURAGS NBU of Kluber Lubrication, Munich / DE.

[0041] The use of this special lubricant ensures reliable lubrication and wear protection for components subjected to slow, oscillating, or incomplete rotational movements, thereby extending service life, reducing maintenance requirements, and maintaining smooth, quiet operation even under high load and intermittent movement conditions. In another development, the at least one special lubricant is based on synthetic hydrocarbon oil and calcium soap and has a kinematic viscosity of 50 mm2 / s at 40 °C like e.g. Kluberfood NH1 94-51 of Kluber Lubrication, Munich / DE.

[0042] The use of this special lubricant provides beneficial capillary action for continuous lubrication of plain bearing gaps, thereby preventing fretting corrosion and ensuring longterm, low-maintenance operation of gearbox components even under demanding conditions.

[0043] In a further development, the unit comprises a first special lubricant based on mineral oil and barium complex soap and a second special lubricant based on synthetic hydrocarbon oil and calcium soap, each being selected and applied to different bearing points or components of the unit.

[0044] This allows for selecting and applying each lubricant according to the specific tribological requirements of the respective bearing points or components. Consequently, the unit achieves enhanced wear protection, improved corrosion resistance, reduced maintenance needs, and increased operational reliability and efficiency across its entire drive system.

[0045] There is disclosed an electric load and drive unit for a fitness machine, comprising: a drive shaft, a rotor shaft, a torque sensor system configured to measure torsion in the drive shaft, the torque sensor system comprising: a sensor assembly that measures torsion in the drive shaft, an optical transmission system that includes LEDs for transmitting torsion data from the torque sensor system, a first rotor bearing positioned on one side of the rotor shaft, a second rotor bearing positioned on the other side of the rotor shaft, wherein the first rotor bearing and the second rotor bearing are provided between the rotor shaft and the drive shaft, wherein the torque sensor system further comprises: a PCB that includes a strain gauge pad and a connection strip, the connection strip carrying at least one transmission LED, extending from the area between the first rotor bearing and the second rotor bearing through a transfer pocket forming an axial channel in the outer surface of the drive shaft, to an area where light signals emitted by the at least one LED are received by a corresponding at least one light receiver element.

[0046] This configuration enables reliable, contactless optical transmission of torque measurement data from the rotating drive shaft to stationary electronics, thereby eliminating the risk of signal degradation and mechanical wear associated with slip rings or wired connections in conventional systems.

[0047] In a development, the strain gauge pad may be secured to the connection strip by an adhesive layer. This allows the strain gauge pad and the connection strip to be connected with the PCB as a single unit, thereby reducing the risk of misalignment of the components and facilitating a simple manufacturing process.

[0048] In a development, the unit comprises an energy harvesting unit that harvests electrical energy from the stator’s electric field to power the torque sensor system.

[0049] The torque sensor system with an energy harvesting unit and optical transmission system enables wireless and battery-free operation, reducing the need for frequent maintenance and battery replacement.

[0050] In a development, the PCB of the torque sensor system of the unit comprises a single piece flexible PCB that includes the strain gauge pad and the connection strip, the strain gauge pad and the connection strip being provided as a single piece flexible PCB with the energy harvesting coil and the strain gauge conductor trace structured in a metal layer of the PCB. Therein, the connection strip carries the at least one transmission LED and the energy harvesting coil, extending from the area between the first rotor bearing and the second rotor bearing through the transfer pocket forming the axial channel in the outer surface of the drive shaft, to the area where light signals emitted by the at least one LED are received by the light receiver elements and where the energy harvesting coil is exposed to the electromagnetic field of the stator

[0051] The use of a single piece flexible PCB for the strain gauge pad and connection strip simplifies the assembly process and enhances the reliability of the torque sensor system by minimizing the number of interconnections. Positioning the first and second rotor bearings between the rotor shaft and the drive shaft provides optimal support and alignment, which can lead to improved mechanical efficiency and reduced wear on the components, extending the service life of the unit.

[0052] In a development, the unit further comprises an area of the drive shaft between the first rotor bearing and the second rotor bearing acting as a load cell for measuring the torque transmitted by the drive shaft. The integration of a load cell within the drive shaft area between the first and second rotor bearings allows for monitoring of torque, enabling proactive maintenance and reducing the likelihood of unexpected mechanical failures. This configuration simplifies the system design by eliminating the need for additional torque measuring devices, thereby reducing the overall weight and complexity of the unit. The load cell's proximity to the rotor bearings ensures high accuracy in torque measurement, which is critical for applications requiring control of power transmission.

[0053] The inclusion of a torque sensor system enhances the operational efficiency of the unit by providing immediate feedback on torque output, allowing for fine-tuning of the system to achieve optimal performance. The torque sensor system provides critical data that can be used for adaptive control strategies, improving the dynamic response of the system to varying load conditions.

[0054] In a development, the unit further comprises an energy harvesting coil interacting inductively with an electromagnetic field of a stator of the electric load and drive unit to generate electric power for the torque sensor system during operation of the electric load and drive unit, rotational movement.

[0055] The energy harvesting coil removes the need for a power supply cable for the torque sensor system. That way the drive shaft can continuously rotate without being limited by the length of such a power supply cable, and still provide a torque measurement. In a development, the unit further comprises a lubricant comprising anti-wear additives for applications involving low speeds and high loads. The use of a lubricant with anti-wear additives specifically formulated for low-speed, high-load applications significantly reduces the rate of wear on moving parts, prolonging the operational lifespan of the unit. The lubricant can help maintain consistent performance under extreme conditions, ensuring that the unit functions effectively even with intermittent movement that has been found to increase stress on mechanical components. The enhanced protection provided by the anti-wear additives minimizes maintenance requirements and associated costs by reducing the frequency of lubricant replacement and component servicing.

[0056] In a development, the unit further comprises at least one special lubricant being selected from specific types, known for their high performance in supporting back-and-forth movements of the drive shaft, facilitating smooth operation even in the absence of complete revolutions. The use of high-performance lubricants ensures consistent and smooth operation of the drive shaft, which can improve the overall user experience by minimizing noise and vibration during use. The at least one special lubricant facilitates the efficient transfer of power within the drive mechanism, potentially leading to energy savings and improved mechanical efficiency in applications where complete revolutions are not consistently maintained.

[0057] In a development, the at least one special lubricant is based on mineral oil and barium complex soap and has a kinematic viscosity of 220 mm2 / s at 40 °C up to 19 mm2 / s at 100 °C like e.g. STABURAGS NBU of Kluber Lubrication, Munich / DE.

[0058] The use of this special lubricant ensures reliable lubrication and wear protection for components subjected to slow, oscillating, or incomplete rotational movements, thereby extending service life, reducing maintenance requirements, and maintaining smooth, quiet operation even under high load and intermittent movement conditions.

[0059] In another development, the at least one special lubricant is based on synthetic hydrocarbon oil and calcium soap and has a kinematic viscosity of 50 mm2 / s at 40 °C like e.g. Kluberfood NH1 94-51 of Kluber Lubrication, Munich / DE. The use of this special lubricant provides beneficial capillary action for continuous lubrication of plain bearing gaps, thereby preventing fretting corrosion and ensuring longterm, low-maintenance operation of gearbox components even under demanding conditions.

[0060] In a further development, the unit comprises a first special lubricant based on mineral oil and barium complex soap and a second special lubricant based on synthetic hydrocarbon oil and calcium soap, each being selected and applied to different bearing points or components of the unit.

[0061] This allows for selecting and applying each lubricant according to the specific tribological requirements of the respective bearing points or components. Consequently, the unit achieves enhanced wear protection, improved corrosion resistance, reduced maintenance needs, and increased operational reliability and efficiency across its entire drive system.

[0062] There is disclosed a fitness machine, comprising: an electric load and drive unit according to a mechanical interface for connecting the drive unit to user-operated elements such as cranks, levers, or wheels. The mechanical interface allows for versatile connectivity with various user-operated elements, making the electric load and drive unit adaptable to a wide range of fitness machines and exercise modalities.

[0063] The integration of an electric load and drive unit within the fitness machine enables control of resistance levels, allowing for customized workout experiences tailored to the user's fitness goals and capabilities. The design of the fitness machine with an electric load and drive unit promotes a compact assembly, which can reduce the overall footprint of the machine and facilitate its inclusion in space-constrained environments.

[0064] There is disclosed a method of using a fitness machine for guided training of a user, the fitness machine comprising an electric load and drive unit with a single-stage gearbox with a rotationally symmetric configuration, the method comprising: initializing the fitness machine and setting a desired resistance level through the motor control unit, using the electric load and drive unit to provide adjustable resistance during exercise by driving the gearbox via the eccentric cams, measuring performance metrics using integrated sensors, providing feedback to the user based on the measured performance metrics, adjusting the resistance dynamically based on the feedback and user input.

[0065] The method of using the fitness machine with a single-stage gearbox and eccentric cams allows for fine-tuned adjustments of resistance, providing a highly responsive exercise environment that can adapt to the user's instantaneous performance and effort. Performance metrics captured by integrated sensors enable the user to monitor their progress and maintain motivation through immediate feedback, potentially leading to more effective and goal-oriented workouts. Dynamic resistance adjustment based on feedback and user input ensures that the exercise intensity remains optimal throughout the workout session, which can enhance training efficiency and reduce the risk of injury due to overexertion or improper resistance levels.

[0066] According to another aspect, there is disclosed:

[0067] An electric load and drive unit for a fitness machine, comprising: a drive shaft, a rotor shaft configured to transmit motion from an electric motor to a gearbox, the rotor shaft being coaxially arranged with the drive shaft and extending through a centre of the gearbox to transmit motion directly from the motor to the gearbox, the gearbox operatively arranged between the drive shaft and the rotor shaft for providing resistance control; wherein the gearbox is configured as one of a single-stage cycloidal gearbox, a Harmonic Pin Ring type gearbox, and a Harmonic Drive type gearbox.

[0068] The motor may be positioned adjacent to the cycloidal gearbox, with a stator and a rotor arranged such that rotational output from the rotor shaft is directly coupled to the input of the cycloidal gearbox. The drive shaft may be supported by a tapered roller bearing at one end and a counter bearing at the opposite end, the bearings being arranged to enable smooth rotational movement and to absorb both radial and axial forces during operation.

[0069] The drive shaft may be provided as a hollow structure that carries an adapter shaft, with a friction bearing and an adapter toothing being provided for transmitting torque from the adapter shaft over the drive shaft to the gearbox.

[0070] The gearbox may be configured as a single-stage cycloidal gearbox comprising at least one eccentric cam provided on the rotor shaft, at least one first cycloidal gearwheel driven by a corresponding eccentric cam and meshing with toothing pins of an outer gearwheel, and a drive shaft operatively connected to the cycloidal gearwheel.

[0071] The gearbox may comprise a first eccentric cam and a second eccentric cam provided on the rotor shaft, and a first cycloidal gearwheel and a second cycloidal gearwheel each driven by a respective eccentric cam.

[0072] The electric load and drive unit may comprise a torque sensor system arranged on the drive shaft such that at least parts of it rotate together with the drive shaft, the torque sensor system being configured to measure torsion in the drive shaft, the torque sensor system comprising: a sensor assembly mounted on the drive shaft for detecting torsional deformation, the sensor assembly comprising: a strain gauge pad for sensing strain resulting from applied torque.

[0073] The electric load and drive unit may comprise an inductive power transfer system comprising a supply coil and a receiver coil and being configured to provide electrical power to the torque sensor system.

[0074] The receiver coil may be arranged on a PCB that extends into a rotating region of the drive shaft to supply power to the torque sensor system.

[0075] The supply coil may be arranged on a motor control board and is fixed relative to a central housing part of the electric load and drive unit. The electric load and drive unit may comprise an optical transmission system configured to wirelessly transmit torque data, the optical transmission system comprising: at least one transmission LED for sending torque data, mounted on the drive shaft; and at least one light receiver element for receiving torque data, arranged stationary relative to the drive shaft on a stationary structure, and electrically connected to a motor control board for further processing of the received torque data.

[0076] The at least one transmission LED, the strain gauge pad, and the receiver coil may be electrically connected to a flexible PCB affixed to the drive shaft and extending along the drive shaft.

[0077] The drive shaft may extend through a shaft opening formed in the stationary structure; a plurality of transmission LEDs may be provided, distributed circumferentially around the drive shaft (51 ); and a corresponding plurality of light receiver elements may be arranged around a perimeter of the shaft opening so as to receive optical signals transmitted from the transmission LEDs on the rotating drive shaft through the shaft opening.

[0078] The optical transmission system may be configured to transmit modulated signals representing the measured torsion, the modulation being effected by a voltage-controlled oscillator or a microcontroller unit on the drive shaft.

[0079] The electric load and drive unit may comprise an encoder system comprising: an encoder disc mounted on the rotor shaft or on the drive shaft, the encoder disc having a plurality of conductive segments arranged circumferentially for encoding rotational position; and at least one static sensor element in fixed relationship to a housing of the unit, the static sensor element being arranged to detect the passage of the conductive segments of the encoder disc and to generate a signal indicative of the angular position and / or speed of the rotor shaft or, respectively, the drive shaft.

[0080] According to another aspect, there is disclosed:

[0081] An electric load and drive unit for a fitness machine, comprising: a single-stage cycloidal gearbox, a rotor shaft that is configured to transmit motion from an electric motor to the gearbox, a first eccentric cam provided on the rotor shaft for driving a first cycloidal gearwheel, a second eccentric cam provided on the rotor shaft for driving a second cycloidal gearwheel, the second eccentric cam being offset by 180 degrees relative to the first eccentric cam, a plurality of toothing pins inserted into cylindrical pockets of an outer gearwheel, the first cycloidal gearwheel and the second cycloidal gearwheel configured to mesh with an inner toothing of an outer gearwheel and to interact with the toothing pins to transmit forces, a drive shaft that is connected with the first and with the second cycloidal gearwheels, the drive shaft being provided as a hollow structure that carries an adapter shaft, with a friction bearing and an adapter toothing being provided, for transmitting torque from the adapter shaft over the drive shaft to the first cycloidal gearwheel and to the second cycloidal gearwheel of the cycloidal gearbox, wherein the drive shaft further comprises a drive disc carrying multiple drive pins, and drive rollers being mounted on the drive pins for transmitting rotational movement, a torque sensor system configured to measure torsion in the drive shaft, the torque sensor system comprising a sensor assembly that measures torsion in the drive shaft between the inner adapter toothing and the drive disc, an energy harvesting unit that harvests electrical energy from the stator’s electric field to power the torque sensor system, an optical torque transmission system that includes LEDs for transmitting torsion data cable-free from the torque sensor system, a first rotor bearing positioned on one side of the rotor shaft away from a first eccentric cam and a second eccentric cam, a second rotor bearing positioned on the other side of the rotor shaft, close to the first eccentric cam and the second eccentric cam, wherein the first rotor bearing and the second rotor bearing are provided between the inner side of the hollow rotor shaft and the outer side of the drive shaft, wherein the torque sensor system further comprises a single piece flexible PCB that includes a strain gauge pad and a connection strip, the strain gauge pad and the connection strip being provided as a single piece flexible PCB with the energy harvesting coil and the strain gauge conductor trace structured in a metal layer of the PCB, the connection strip carrying a transmission LED and the energy harvesting coil, extending from the area between the first rotor bearing and the second rotor bearing through a transfer pocket forming an axial channel in the outer surface of the drive shaft, and through a shaft opening of a motor control board to an area where light signals emitted by the LED are received by light receiver elements and where the energy harvesting coil is exposed to the electromagnetic field of the stator, wherein the torque sensor system further comprises a voltage-controlled oscillator configured to modulate the data from the strain gauge pad for optical transmission, wherein the torque sensor system further comprises a reception LED configured to receive the transmitted data and convert it into an electrical signal representing the measured torsion.

[0082] According to another aspect, there is disclosed:

[0083] A fitness machine, comprising an electric load and drive unit as defined above, a mechanical interface for connecting the drive unit to user-operated elements such as cranks, levers, or wheels.

[0084] According to another aspect, there is disclosed:

[0085] A method of using a fitness machine for guided training of a user, the fitness machine comprising an electric load and drive unit an electric load and drive unit as defined above, the method comprising: initializing the fitness machine and setting a desired power or resistance level through the motor control unit, using the electric load and drive unit to provide adjustable power or resistance during exercise by driving the gearbox via the eccentric cams, measuring real-time performance metrics using integrated sensors, providing real-time feedback to the user based on the measured performance metrics, adjusting the resistance dynamically based on the feedback and user input.

[0086] Itemized lists

[0087] The disclosure further comprises the following embodiments in the form of itemized lists. Explanations in brackets are intended to be optional and can be read together with other parts of the text or left away when reading and interpreting the embodiments.

[0088] The first itemized list relates to a single-stage cycloidal gearbox for resistance control.

[0089] The features of the first itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0090] Itemized list 1

[0091] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising a single- stage cycloidal gearbox for providing resistance control, the gearbox comprising a rotor shaft (11 ) configured to transmit motion from a motor to the gearbox, at least one eccentric cam (12, 13) provided on the rotor shaft (11 ), at least one first cycloidal gearwheel (16, 17) driven by a corresponding eccentric cam (12, 13) and meshing with toothing pins (19) of an outer gearwheel (18), and a drive shaft (51 ) operatively connected to the cycloidal gearwheel (16, 17).

[0092] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the gearbox comprises a first eccentric cam (12) and a second eccentric cam (13) provided on the rotor shaft (11 ), [the second eccentric cam (13) being offset by 180 degrees relative to the first eccentric cam (12),] and a first cycloidal gearwheel (16) and a second cycloidal gearwheel (17) each driven by a respective eccentric cam (12, 13).

[0093] Item 3. The electric load and drive unit (1 ) according to any one of items 1 or 2, wherein the toothing pins (19) of the outer gearwheel (18) are configured to interact with a corresponding cycloidal structure (160, 170) of the at least one cycloidal gearwheel (16, 17) to transmit forces [, wherein the toothing pins (19) are defined in a continuous cycloidal inner toothing arranged at an outer perimeter of the outer gearwheel (18)].

[0094] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the gearbox comprises a drive disc (24) carrying multiple drive pins (25), and drive rollers (26) mounted on the drive pins (25) for transmitting rotational movement. Item 5. The electric load and drive unit (1 ) according to item 4, wherein each of the drive pins (25) and drive rollers (26) extend into a corresponding cylindrical receiving structure (161 , 172) of the at least one cycloidal gearwheel (16, 17) [, the receiving structures (161 , 172) being formed as cylindrical holes in the respective cycloidal gearwheel (16), (17)].

[0095] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 5, wherein the drive shaft (51 ) is supported by a tapered roller bearing (52) at one end and a counter bearing (53) at the opposite end, the bearings being arranged to enable smooth rotational movement and to absorb both radial and axial forces during operation.

[0096] Item 7. The electric load and drive unit (1 ) according to any one of items 1 to 6, wherein the rotor shaft (11 ) is arranged coaxially with the drive shaft (51 ) and extends through a centre of the cycloidal gearbox to transmit motion directly from the motor to the gearbox.

[0097] Item 8. The electric load and drive unit (1 ) according to any one of items 1 to 7, wherein the motor is positioned adjacent to the cycloidal gearbox, with the stator (42) and rotor (41 ) arranged such that rotational output from the rotor shaft (11 ) is directly coupled to the input of the cycloidal gearbox.

[0098] Item 9. The electric load and drive unit (1 ) according to any one of items 1 to 8, wherein the motor, cycloidal gearbox, and drive shaft (51 ) are integrated within a common housing (141 ).

[0099] Item 10. The electric load and drive unit (1 ) according to any one of items 1 to 9, wherein the drive shaft (51 ) is provided as a hollow structure that carries an adapter shaft (28), with a friction bearing (29) and an adapter toothing (30, 31 ) being provided for transmitting torque from the adapter shaft (28) over the drive shaft (51 ) to the at least one cycloidal gearwheel (16, 17). The second itemized list relates to alternative gearbox configurations. The features of the second itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0100] Itemized list 2

[0101] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ) configured to transmit motion from an electric motor to a gearbox (18, 303), a gearbox (18, 303) operatively arranged between the drive shaft (51 ) and the rotor shaft (11 ) for providing resistance control.

[0102] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the drive shaft (51 ) is provided as a hollow structure that carries an adapter shaft (28), with a friction bearing (29) and an adapter toothing (30, 31 ) being provided, for transmitting torque from the adapter shaft (28) over the drive shaft (51 ) to the gearbox (18, 303).

[0103] Item 3. The electric load and drive unit (1 ) according to item 1 or item, wherein the gearbox (18, 303) is configured as a single-stage cycloidal gearbox.

[0104] Item 4. The electric load and drive unit (1 ) according to item 1 or item 2, wherein the gearbox (18, 303) is configured as a Harmonic Pin Ring (HPR) type gearbox.

[0105] Item 5. The electric load and drive unit (1 ) according to item 1 or item 2, wherein the gearbox (18, 303) is configured as a Harmonic Drive type gearbox. The third itemized list relates to a torque sensor system provided on the drive shaft in a rotatable way. The features of the third itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0106] Itemized list 3

[0107] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), a torque sensor system (71 ) arranged on the drive shaft (51 ) such that at least parts of it rotate together with the drive shaft (51 ), the torque sensor system (71 ) being configured to measure torsion in the drive shaft (51 ), the torque sensor system (71 ) comprising: a sensor assembly mounted on the drive shaft (51 ) for detecting torsional deformation, the sensor assembly comprising:

[0108] - a strain gauge pad (81 ) affixed to the drive shaft (51 ) for sensing strain resulting from applied torque,

[0109] - a connection strip (82) extending along the drive shaft (51 ) and electrically connected to the strain gauge pad (81 ).

[0110] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the torque sensor system (71 ) is integrated with the drive shaft (51 ) in a manner that allows the entire sensor assembly, including the strain gauge pad (81 ) and connection strip (82), to rotate in unison with the drive shaft (51 ) during operation.

[0111] Item 3. The electric load and drive unit (1 ) according to item 1 or item 2, wherein the strain gauge pad (81 ) is secured to the connection strip (82) by an adhesive, allowing the strain gauge pad (81 ) and the connection strip (82) to be connected with the PCB as a single unit, thereby reducing risks of misalignment of the components. Item 4. The electric load and drive unit (1 ) according to one of items 1 to item 3, wherein the strain gauge pad (81 ) and the connection strip (82) are provided as a single piece flexible PCB, the single piece flexible PCB further comprising the receiver coil and a strain gauge conductor trace structured in a metal layer of the PCB.

[0112] The fourth itemized list relates to an inductive power transfer system (IPT) for powering a rotating torque sensor system. The features of the fourth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0113] Itemized list 4

[0114] Item A. An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), a torque sensor system (71 ) arranged on the drive shaft (51 ) and configured to measure torsion in the drive shaft (51 ), an energy harvesting coil (83) configured to interact inductively with an electromagnetic field of a stator (42) of the electric load and drive unit (1 ) to generate electric power for the torque sensor system (71 ) during operation of the electric load and drive unit (1 ), thereby enabling the torque sensor system (71 ) to operate without a physical power supply cable.

[0115] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), a torque sensor system (71 ) arranged on the drive shaft (51 ) and configured to measure torsion in the drive shaft (51 ), an inductive power transfer (IPT) system comprising a supply coil and a receiver coil (83) and being configured to provide electrical power to the torque sensor system (71 ) [independently of the stator’s electromagnetic field, thereby enabling a stable and reliable power supply to the torque sensor system (71 ) without the need for a physical power supply cable or energy harvesting from the stator].

[0116] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the supply coil is arranged on a control or encoder board.

[0117] Item 3. The electric load and drive unit (1 ) according to item 2, wherein the supply coil is arranged on the motor control board (60) and is fixed relative to the central housing part (141 ).

[0118] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to item 3, wherein the receiver coil (83) is arranged on a fixed PCB connected to a flexible PCB that extends into a rotating region of the drive shaft (51 ) to supply power to the torque sensor system (71 ).

[0119] Item 5. The electric load and drive unit (1 ) according to any of the preceding items, wherein the receiver coil (83) is electrically connected to the flexible PCB, the flexible PCB carrying at least one strain gauge pad (81 ) and at least one connection strip (82) for the torque sensor system (71 ).

[0120] Item 6. The electric load and drive unit (1 ) according to item 5, wherein the flexible PCB is structured as a single piece and comprises a strain gauge conductor trace in a metal layer, the receiver coil (83), and at least one transmission LED (79) for optical data transmission.

[0121] Item 7. The electric load and drive unit (1 ) according to item 6, wherein the connection strip (82) of the flexible PCB extends from an area between a first rotor bearing (54) and a second rotor bearing (55) through a transfer pocket (58) forming an axial channel in the outer surface of the drive shaft (51 ), to an area where the receiver coil (83) is positioned to receive power from the supply coil.

[0122] Item 8. The electric load and drive unit (1 ) according to any of the preceding items, wherein the inductive power transfer system is configured to provide continuous electrical power to the torque sensor system (71 ) during both static and dynamic operation of the electric load and drive unit (1 ).

[0123] The fifth itemized list relates to an optical transmission system for wireless transmission of torque data from the rotating drive shaft. The features of the fifth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0124] Itemized list 5

[0125] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), an optical transmission system comprising at least one transmission LED (79) mounted on the drive shaft (51 ) and at least one light receiver element (73) arranged stationary relative to the drive shaft (51 ) on a stationary structure, preferably on a motor control board (60), the optical transmission system being configured to wirelessly transmit torque data from the rotating drive shaft (51 ) to the stationary light receiver element (73). Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the at least one transmission LED (79) is arranged on a flexible PCB (82) extending along the drive shaft (51 ).

[0126] Item 3. The electric load and drive unit (1 ) according to item 2, wherein the flexible PCB (82) comprises a strain gauge pad (81 ) affixed to the drive shaft (51) and electrically connected to the at least one transmission LED (79), the strain gauge pad (81 ) being configured to sense torsional deformation of the drive shaft (51 ).

[0127] Item 4. The electric load and drive unit (1 ) according to one of items 1 to 3, wherein a plurality of transmission LEDs (79) are provided, distributed circumferentially around the drive shaft (51 ), and a corresponding plurality of light receiver elements (73) are arranged on the stationary structure.

[0128] Item 5. The electric load and drive unit (1 ) according to item 4, wherein the drive shaft (51 ) extends through a shaft opening (63) formed in the stationary structure.

[0129] Item 6. The electric load and drive unit (1 ) according to item 5, wherein the plurality of light receiver elements (73) is arranged around the perimeter of the shaft opening (63) so as to receive optical signals transmitted from the transmission LEDs (79) on the rotating drive shaft (51) through the shaft opening (63).

[0130] Item 7. The electric load and drive unit (1 ) according to any of items 1 to 6, wherein the optical transmission system is configured to transmit modulated signals representing the measured torsion, the modulation being effected by a voltage-controlled oscillator (78) or a microcontroller unit (MCU) on the drive shaft (51 ). Item 8. The electric load and drive unit (1 ) according to any one of items 1 to 7, wherein the light receiver elements (73) are electrically connected to a motor control board (60) for further processing of the received torque data.

[0131] The sixth itemized list relates to a voltage-controlled oscillator (VCO) for signal modulation of torque data. The features of the sixth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0132] Itemized list 6

[0133] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a torque sensor system (71 ) configured to measure torsion in the drive shaft (51 ), the torque sensor system (71 ) comprising a voltage-controlled oscillator (VCO) (78) configured to modulate the signal representing the measured torsion for optical transmission.

[0134] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the VCO (78) is configured to modulate a measuring signal of the torque sensor system (71 ) such that the modulation frequency of the transmitted optical signal represents the torsion measured by the torque sensor system (71 ).

[0135] Item 3. The electric load and drive unit (1 ) according to item 3, wherein the torque sensor system comprises a strain gauge pad (81 ) affixed to the drive shaft (51 ) and the VCO (78) is configured to modulate a voltage drop across the strain gauge pad (81 ) such that the modulation frequency of the transmitted optical signal represents the torsion measured by the strain gauge pad (81).

[0136] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 4, wherein the torque sensor system (71 ) further comprises at least one transmission LED (79) arranged on the drive shaft (51 ), the at least one transmission LED (79) being configured to emit light modulated by the VCO (78) for wireless transmission of the torsion data.

[0137] Item 5. The electric load and drive unit (1 ) according to item 5, wherein the torque sensor system (71 ) further comprises at least one light receiver element (73) arranged stationary relative to the drive shaft (51 ), the at least one light receiver element (73) being configured to receive the modulated optical signal and convert it into an electrical signal representing the measured torsion.

[0138] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 6, wherein the VCO (78) is mounted on a flexible PCB (82) that also carries the strain gauge pad (81 ) and the at least one transmission LED (79).

[0139] Item 7. The electric load and drive unit (1 ) according to any one of items 1 to 7, wherein the torque sensor system (71 ) is configured to provide a resolution of at least 0.01 Nm in the measurement and transmission of torsion data.

[0140] The seventh itemized list relates to the drive shaft functioning as a load cell for torque measurement. The features of the seventh itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims. Itemized list 7

[0141] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), and a first rotor bearing (54) and a second rotor bearing (55) positioned between the rotor shaft (11 ) and the drive shaft (51 ), wherein an area of the drive shaft (51 ) between the first rotor bearing (54) and the second rotor bearing (55) is configured to function as a load cell for measuring the torque transmitted by the drive shaft (51 ).

[0142] Item 2. The electric load and drive unit (1 ) according to item 1 , comprising a torque sensor system (71 ) configured to measure torsion in the area of the drive shaft (51 ) between the first rotor bearing (54) and the second rotor bearing (55).

[0143] Item 3. The electric load and drive unit (1 ) according to item 2, wherein the torque sensor system (71 ) comprises a voltage-controlled oscillator (VCO) (78) configured to modulate the signal representing the measured torsion for optical transmission.

[0144] Item 4. The electric load and drive unit (1 ) according to item 3, wherein the VCO (78) is configured to modulate a measuring signal of the torque sensor system (71 ) such that the modulation frequency of the transmitted optical signal represents the torsion measured by the torque sensor system (71 ).

[0145] Item 5. The electric load and drive unit (1 ) according to item 4, wherein the torque sensor system (71 ) comprises a strain gauge pad (81 ) affixed to the drive shaft (51 ) and the VCO (78) is configured to modulate a voltage drop across the strain gauge pad (81 ) such that the modulation frequency of the transmitted optical signal represents the torsion measured by the strain gauge pad (81).

[0146] Item 6. The electric load and drive unit (1 ) according to any one of items 3 to 5, wherein the torque sensor system (71 ) further comprises at least one transmission LED (79) arranged on the drive shaft (51 ), the at least one transmission LED (79) being configured to emit light modulated by the VCO (78) for wireless transmission of the torsion data.

[0147] Item 7. The electric load and drive unit (1 ) according to item 6, wherein the torque sensor system (71 ) further comprises at least one light receiver element (73) arranged stationary relative to the drive shaft (51 ), the at least one light receiver element (73) being configured to receive the modulated optical signal and convert it into an electrical signal representing the measured torsion.

[0148] Item 8. The electric load and drive unit (1 ) according to any one of items 3 to 7, wherein the VCO (78) is mounted on a flexible PCB (82) that also carries the strain gauge pad (81 ) and the at least one transmission LED (79).

[0149] Item 9. The electric load and drive unit (1 ) according to any one of items 3 to 8, wherein the torque sensor system (71 ) is configured to provide a resolution of at least 0.01 Nm in the measurement and transmission of torsion data.

[0150] Item 10. The electric load and drive unit (1 ) according to any one of items 1 to 9, wherein the drive shaft (51 ) is provided as a hollow structure that carries an adapter shaft (28), with a friction bearing (29) and an adapter toothing being provided, for transmitting torque from the adapter shaft (28) over the drive shaft (51 ). Item 11 . The electric load and drive unit (1 ) according to any one of items 1 to 10, wherein the area of the drive shaft (51 ) functioning as a load cell is located between an inner adapter toothing (30) and a drive disc (24).

[0151] The eighth itemized list relates to tapered roller bearings and a counter bearing for stability. The features of the eighth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0152] Itemized list 8

[0153] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), and a first rotor bearing (54) and a second rotor bearing (55) positioned between the rotor shaft (11 ) and the drive shaft (51 ), wherein the unit comprises a tapered roller bearing (52) and a counter bearing (53) positioned between the drive shaft (51 ) and a housing of the electric load and drive unit (1 ) to support the drive shaft (51 ) and enable rotational movement.

[0154] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the tapered roller bearing (52) is arranged at one end of the drive shaft (51 ) and the counter bearing (53) is arranged at the opposite end of the drive shaft (51 ), forming an angular contact bearing pair configured in an "0" or "X" arrangement. Item 3. The electric load and drive unit (1 ) according to item 1 or item 2, wherein the tapered roller bearing (52) and the counter bearing (53) are arranged to absorb both radial and axial forces acting on the drive shaft (51 ) during operation.

[0155] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein a first eccentric cam (12) and a second eccentric cam (13) are provided on the rotor shaft (11 ), the first rotor bearing (54) being positioned on one side of the rotor shaft (11 ) away from the first eccentric cam (12) and the second eccentric cam (13), and the second rotor bearing (55) being positioned on the other side of the rotor shaft (11 ), close to the first eccentric cam (12) and the second eccentric cam (13).

[0156] Item 5. The electric load and drive unit (1 ) according to to any one of items 1 to 4, wherein the second rotor bearing (55) is provided as a double rolling bearing or as two single rolling bearings.

[0157] The ninth itemized list relates to a shock absorber mechanism for limiting movement of the output shaft. The features of the ninth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0158] Itemized list 9

[0159] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: an output shaft or adapter shaft (28) arranged to connect an actuation lever or user- operated element of the fitness machine with a gearbox of the unit, and a shock absorber mechanism configured to limit the rotational movement of the output shaft or adapter shaft (28), the shock absorber mechanism comprising: at least one shock absorber (101 ) fixed relative to the unit, and a stopper arm (103) connected to the output shaft or adapter shaft (28), the stopper arm (103) configured to interact with the at least one shock absorber (101 ) at at least one end position of a permitted rotational range of the output shaft or adapter shaft (28) to at least locally compress the shock absorber (101 ) to absorb impact and restrict further movement.

[0160] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the at least one shock absorber (101 ) is at least partially arranged within or held by a stopper block

[0161] (102) that is fixed relative to the unit (1 ) to protrude parallel to the output shaft or adapter shaft (28).

[0162] Item 3. The electric load and drive unit (1 ) according to item 2, wherein the stopper block (102) is formed as a flat cap that holds the shock absorber (101 ) between the flat cap and a housing of the unit, and wherein the stopper block (102) is fixed to the housing by a cylindrical connecting member [for example by a threaded bolt or by a screw].

[0163] Item 4. The electric load and drive unit (1 ) according to item 3, wherein the stopper arm

[0164] (103) is shaped as a disc oriented perpendicular to the output shaft or adapter shaft (28).

[0165] Item 5. The electric load and drive unit (1 ) according to any one of items 1 to 4, wherein the stopper arm (103) comprises a slot (104) configured to guide the interaction between the stopper arm (103) and the stopper block (102) containing the shock absorber (101 ).

[0166] Item 6. The electric load and drive unit (1 ) according to item 5, wherein the slot (104) of the stopper arm (103) is shaped to follow a circular curve around the output shaft or adapter shaft (28), the curve being oriented in a plane perpendicular to the output shaft or adapter shaft (28).

[0167] Item 7. The electric load and drive unit (1 ) according to any one of items 5 and 6, wherein the stopper block (102) extends into the slot (104) of the stopper arm (103).

[0168] Item 8. The electric load and drive unit (1 ) according to any one of items 1 to 7, wherein the shock absorber (101 ) is made from a rubber-like deformable plastic and the stopper block (102) is made from a rigid material.

[0169] Item 9. The electric load and drive unit (1 ) according to any one of items 1 to 8, wherein the shock absorber mechanism is integrated into the gearbox cover (142) of the unit.

[0170] Item 10. The electric load and drive unit (1 ) according to any one of items 1 to 9, wherein the shock absorber mechanism is configured to prevent mechanical overload of a user of the fitness machine by limiting the maximum rotational displacement of the output shaft or adapter shaft (28).

[0171] Item 11 . A fitness machine comprising an electric load and drive unit (1 ) according to any one of items 1 to 10.

[0172] The tenth itemized list relates to a special lubricant for high-load, low-speed use. The features of the tenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims. Itemized list 10

[0173] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising at least one special lubricant (111 ) configured for use in at least one bearing or plain bearing of the unit (1 ), the at least one special lubricant (111 ) being selected and applied to provide reliable lubrication and wear protection under conditions of intermittent movement and high loads.

[0174] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the at least one special lubricant (111 ) comprises anti-wear additives for applications involving low speeds and high loads.

[0175] Item 3. The electric load and drive unit (1 ) according to item 1 or item 2, wherein the at least one special lubricant (111 ) is selected from lubricants known for their high performance in supporting back-and-forth movements of the drive shaft (51 )[, facilitating smooth operation even in the absence of complete revolutions].

[0176] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the at least one special lubricant (111 ) is based on mineral oil and barium complex soap and has a kinematic viscosity of 220 mm2 / s at 40 °C up to 19 mm2 / s at 100 °C.

[0177] Item 5. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the at least one special lubricant (111 ) is based on synthetic hydrocarbon oil and calcium soap and has a kinematic viscosity of 50 mm2 / s at 40 °C.

[0178] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 5, wherein the at least one special lubricant (111 ) is configured to provide capillary action for continuous lubrication of plain bearing gaps, thereby preventing fretting corrosion and ensuring long-term, low-maintenance operation of gearbox components.

[0179] Item 7. The electric load and drive unit (1 ) according to any one of items 1 to 6, wherein a first special lubricant (111 ) based on mineral oil and barium complex soap, with a kinematic viscosity of 220 mm2 / s at 40 °C up to 19 mm2 / s at 100 °C, is applied to at least one tapered roller bearing (52), and a second special lubricant (111 ) based on synthetic hydrocarbon oil and calcium soap, with a kinematic viscosity of 50 mm2 / s at 40 °C, is applied to at least one plain bearing or bushing of a gearbox of the unit (1 ).

[0180] Item 8. The electric load and drive unit (1 ) according to any one of items 1 to 7, wherein the at least one special lubricant (111 ) is selected and applied according to the specific tribological requirements of the respective bearing points or components of the unit (1 ).

[0181] The eleventh itemized list relates to an encoder system for motion tracking. The features of the eleventh itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0182] Itemized list 11

[0183] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), and an encoder system (43) configured for motion tracking of a rotating component of the drive shaft (51 ) or the rotor shaft (11 ).

[0184] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the encoder system (43) comprises an encoder disc (43) mounted on the rotor shaft (11 ) or on the drive shaft (51 ), the encoder disc (43) having a plurality of conductive segments (450) arranged circumferentially for encoding rotational position.

[0185] Item 3. The electric load and drive unit (1 ) according to item 2, wherein the encoder system (43) further comprises at least one static sensor element in fixed relationship to a housing of the unit (1), the sensor element being arranged to detect the passage of the conductive segments (450) of the encoder disc (43) and to generate a signal indicative of the angular position and / or speed of the rotor shaft (11 ) or, respectively, the drive shaft (51 ).

[0186] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the encoder system (43) is electrically connected to a motor control board (60) that is part of the unit (1 ) for processing the motion tracking data.

[0187] Item 5. The electric load and drive unit (1 ) according to any one of items 1 to 4, wherein the encoder system (43) is configured to provide real-time feedback of rotational position, speed, or direction to the motor control unit (61) for closed-loop control of the fitness machine.

[0188] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 5, wherein the drive shaft (51 ) and the rotor shaft (11 ) are arranged in a coaxial and overlapping relationship along the central axis (45) of the unit (1 ), and the encoder system (43) is arranged coaxially with the central axis (45).

[0189] Item 7. The electric load and drive unit (1 ) according to any one of items 1 to 6, wherein the encoder system (43) is configured to operate in conjunction with a torque sensor system (71 ) to enable combined measurement of position, speed, and torque. Item 8. A fitness machine comprising an electric load and drive unit (1 ) according to any one of items 1 to 7, wherein the encoder system (43) is used to monitor and record user-driven motion during exercise.

[0190] Item 9. A method of operating a fitness machine comprising an electric load and drive unit (1 ) according to any one of items 1 to 7, the method comprising tracking the rotational position or speed of a shaft using the encoder system (43) and adjusting resistance or feedback to the user based on the tracked motion.

[0191] The twelfth itemized list relates to an energy recovery system using bidirectional power factor corrector (PFC) to eliminate the need for a brake chopper. The features of the twelfth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0192] Itemized list 12

[0193] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising an energy recovery system (91 ) with a bidirectional power factor corrector (PFC) (204) configured to enable both the supply of electrical energy from an AC power network (209) to a DC link and the return of electrical energy generated by a motor / generator drive unit (203) to the AC power network (209)[, thereby eliminating the need for a brake chopper (92)].

[0194] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the bidirectional PFC (204) is arranged between the AC power network (209) and DC link capacitors (202) of the electric load and drive unit (1 ). Item 3. The electric load and drive unit (1 ) according to item 2, wherein the motor / generator drive unit (203) is connected to the DC link capacitors (202) and is configured to operate in both motoring and generating modes.

[0195] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the energy recovery system (91 ) is configured to feed electrical energy generated during user-driven operation of the fitness machine back into the AC power network (209) via the bidirectional PFC (204).

[0196] Item 5. The electric load and drive unit (1 ) according to any one of items 1 to 4, wherein the energy recovery system (91 ) further comprises a 24V display supply (201 ) powered from the DC link capacitors (202).

[0197] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 5, wherein the energy recovery system (91 ) is configured such that, in the absence of a brake chopper (92), excess electrical energy is not dissipated as heat but is instead exported to the AC power network (209).

[0198] Item 7. A fitness machine comprising an electric load and drive unit (1 ) according to any one of items 1 to 6.

[0199] Item 8. A gym plant comprising a plurality of fitness machines according to item 7, each connected in parallel to a power network (209) via AC socket outlets (205) and AC plugs (206), wherein each fitness machine comprises an energy recovery system (91 ) with a bidirectional PFC (204) for energy exchange with the power network (209). The thirteenth itemized list relates to user performance feedback for dynamic resistance control. The features of the thirteenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0200] Itemized list 13

[0201] Item 1. A fitness machine (200), comprising: an electric load and drive unit (1 ) configured to provide adjustable resistance during exercise, a torque sensor system (71 ) arranged to measure torsion in a drive shaft (51 ) of the electric load and drive unit (1 ), an encoder system (43) configured to track the rotational position or speed of the drive shaft (51 ) or a rotor shaft (11 ), a motor control unit (61 ) configured to process sensor data and dynamically adjust the resistance provided by the electric load and drive unit (1 ), a display unit (400) configured to provide real-time feedback to a user based on measured performance metrics, wherein the fitness machine (200) is configured to measure user performance, provide feedback to the user, and dynamically adjust resistance in response to the measured performance and / or user input.

[0202] Item 2. The fitness machine (200) according to item 1 , wherein the torque sensor system (71 ) comprises a strain gauge pad (81 ) affixed to the drive shaft (51 ), a connection strip (82) electrically connected to the strain gauge pad (81 ), and a printed circuit board (PCB) carrying the strain gauge pad (81 ) and the connection strip (82). Item 3. The fitness machine (200) according to item 2, further comprising an inductive power transfer (IPT) system configured to provide electrical power to the torque sensor system (71 ), the inductive power transfer system comprising a supply coil arranged on a control or encoder board and a receiver coil (83) arranged on the PCB of the torque sensor system (71 ), the supply coil and receiver coil (83) being configured to enable wireless power transfer to the torque sensor system (71 ) independently of the stator’s electromagnetic field.

[0203] Item 4. The fitness machine (200) according to any one of items 1 to 3, wherein the torque sensor system (71 ) further comprises at least one transmission LED (79) for optical data transmission, at least one light receiver element (73) arranged to receive optical signals from the at least one transmission LED (79), and a voltage-controlled oscillator (VCO) (78) or microcontroller unit (MCU) configured to modulate or digitise the sensor data for transmission.

[0204] Item 5. The fitness machine (200) according to any one of items 1 to 4, wherein the encoder system (43) is configured to provide real-time tracking of the rotational position and / or speed of the drive shaft (51 ) or rotor shaft (11 ).

[0205] Item 6. The fitness machine (200) according to any one of items 1 to 5, wherein the motor control unit (61 ) is configured to interface with the display unit (400) and to control the resistance of the electric load and drive unit (1 ) based on the measured performance metrics and user input.

[0206] Item 7. The fitness machine (200) according to any one of items 1 to 6, further comprising a mechanical interface including a lever arm (404) and a roller pad (405) for transferring user-applied force to the electric load and drive unit (1 ). The fourteenth itemized list relates to an electric load and drive unit comprising a bidirectional DC-DC converter. The features of the fourteenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0207] Itemized list 14

[0208] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ), a DC link, a bi-directional DC-DC converter (66) operatively connected to the DC link and configured to transfer electrical energy in both directions between the DC link and at least one secondary DC domain.

[0209] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the bi-directional DC-DC converter (66) is configured to transfer energy between the DC link and an energy storage device selected from a battery or a supercapacitor.

[0210] Item 3. The electric load and drive unit (1 ) according to item 2, wherein the bi-directional DC-DC converter (66) is configured to operate in a charging mode, in which energy generated by the drive unit (1 ) is stored in the energy storage device, and in a discharging mode, in which energy from the energy storage device is supplied to the DC link.

[0211] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the bi-directional DC-DC converter (66) comprises: at least one power semiconductor switch, at least one inductor, at least one capacitor, a gate driver, a controller, and current and voltage sensors for feedback control.

[0212] Item 5. The electric load and drive unit (1 ) according to any one of items 1 to 4, further comprising a motor control unit (61 ) configured to control the operation of the bidirectional DC-DC converter (66) in response to operational parameters of the fitness machine.

[0213] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 5, wherein the bi-directional DC-DC converter (66) is configured to transfer energy between the DC link and a shared DC bus for energy exchange with at least one further electric load and drive unit (1 ) of a further fitness machine.

[0214] Item 7. The electric load and drive unit (1 ) according to any one of items 1 to 6, further comprising a bidirectional PFC (204) operatively connected to the DC link and configured to transfer energy between the DC link and an AC power network (209).

[0215] Item 8. A fitness machine (200) comprising an electric load and drive unit (1 ) according to any one of items 1 to 7.

[0216] Item 9. A gym plant comprising a plurality of fitness machines (200) according to item 8, each comprising a bi-directional DC-DC converter (66) and being connected to a shared DC bus and / or an AC power network (209).

[0217] The fifteenth itemized list relates to gearbox usage across different fitness equipment types. The features of the fifteenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0218] Itemized list 15

[0219] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a gearbox (18, 303) operatively arranged between a drive shaft (51 ) and a rotor shaft (11 ), the gearbox (18, 303) being configured for resistance control and being adaptable for use across a plurality of different fitness equipment types, wherein the electric load and drive unit (1 ) further comprises a mechanical interface for coupling the drive shaft (51 ) to a user-operated element selected from the group consisting of cranks, levers, wheels, or other actuation members.

[0220] Item 2. The electric load and drive unit (1 ) according to item 1 , wherein the gearbox (18, 303) is selected from the group consisting of a single-stage cycloidal gearbox, a Harmonic Pin Ring (HPR) type gearbox, and a Harmonic Drive type gearbox.

[0221] Item 3. The electric load and drive unit (1 ) according to item 1 or item 2, wherein the mechanical interface comprises an adapter shaft (28) configured to be interchangeably mounted to the drive shaft (51 ) to accommodate different kinematic requirements of various fitness equipment types.

[0222] Item 4. The electric load and drive unit (1 ) according to any one of items 1 to 3, wherein the adapter shaft (28) is provided in a plurality of forms, each form being dimensioned and shaped for coupling to a specific user-operated element associated with a particular fitness machine, such that the electric load and drive unit (1 ) is modularly adaptable to leg training, upper body training, torso training, or other exercise modalities. Item 5. The electric load and drive unit (1 ) according to any one of items 1 to 4, wherein the unit further comprises a torque sensor system (71 ) configured to measure torsion in the drive shaft (51 ), and a motor control unit (61 ) configured to dynamically adjust resistance based on the measured torsion and the specific requirements of the connected fitness equipment type.

[0223] Item 6. The electric load and drive unit (1 ) according to any one of items 1 to 5, wherein the unit is provided with a housing (141 ) and a gearbox cover (142) configured to accommodate the interchangeable adapter shaft (28) and to provide mounting points for integration into different fitness machine frames (401 ).

[0224] The sixteenth itemized list relates to power distribution with bidirectional control. The features of the sixteenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0225] Itemized list 16

[0226] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a DC link, a bidirectional power factor corrector (PFC) (204) operatively connected between the DC link and an AC power network (209), wherein the bidirectional PFC (204) is configured to enable both the supply of electrical energy from the AC power network (209) to the DC link and the return of electrical energy from the DC link to the AC power network (209), wherein the electric load and drive unit (1 ) is configured for power distribution with bidirectional control.

[0227] Item 2. The electric load and drive unit (1 ) according to item 1 , further comprising a motor / generator drive unit (203) operatively connected to the DC link and configured to operate in both motoring and generating modes. Item 3. The electric load and drive unit (1 ) according to item 1 or item 2, further comprising DC link capacitors (202) arranged to buffer electrical energy between the bidirectional PFC (204) and the motor / generator drive unit (203).

[0228] Item 4. The electric load and drive unit (1 ) according to any one of the preceding items, wherein the bidirectional PFC (204) is configured to operate under the control of a motor control unit (61 ) to manage the direction and magnitude of power flow in response to operational parameters.

[0229] Item 5. The electric load and drive unit (1 ) according to any one of the preceding items, wherein the unit is configured to export electrical energy generated during user-driven operation of the fitness machine to the AC power network (209).

[0230] Item 6. The electric load and drive unit (1 ) according to any one of the preceding items, wherein the unit is configured to import electrical energy from the AC power network (209) to supply power to the DC link for operation of the fitness machine.

[0231] Item 7. The electric load and drive unit (1 ) according to any one of the preceding items, wherein the bidirectional PFC (204) is configured to maintain a predetermined power factor at the interface with the AC power network (209) during both import and export of electrical energy.

[0232] Item 8. A gym plant comprising a plurality of fitness machines, each comprising an electric load and drive unit (1 ) according to any one of the preceding items, each electric load and drive unit (1 ) being connected in parallel to the AC power network (209) via AC socket outlets (205) and AC plugs (206), such that each unit is capable of both drawing power from and supplying power to the AC power network (209).

[0233] Item 9. The gym plant according to item 8, wherein each electric load and drive unit (1 ) is configured to communicate with a central control system to coordinate power distribution and energy recovery across the gym plant.

[0234] Item 10. The electric load and drive unit (1 ) according to any one of the preceding items, wherein the bidirectional PFC (204) comprises a full-bridge converter topology with controllable semiconductor switches configured to operate in both rectification and inversion modes.

[0235] Item 11 . The electric load and drive unit (1 ) according to any one of the preceding items, wherein the bidirectional PFC (204) is controlled by a digital controller configured to monitor AC and DC voltages and currents and to dynamically adjust the switching of the semiconductor switches to determine the direction and magnitude of power flow.

[0236] Item 12. The electric load and drive unit (1 ) according to any one of the preceding items, wherein the bidirectional PFC (204) is configured to synchronise the phase and frequency of the output current with the AC power network (209) during export of electrical energy, thereby ensuring compliant and stable grid interaction.

[0237] The seventeenth itemized list relates to an energy recovery network of a gym plant with several fitness machines. The features of the seventeenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0238] Itemized list 17 Item 1 . A gym plant comprising a plurality of fitness machines (200), each fitness machine (200) comprising an electric load and drive unit (1 ) configured to operate in both motoring and generating modes.

[0239] Item 2. The gym plant according to item 1 , wherein each electric load and drive unit (1 ) comprises a motor / generator drive unit (203), a bidirectional power factor corrector (PFC) (204), and DC link capacitors (202) for buffering electrical energy.

[0240] Item 3. The gym plant according to any one of items 1 or 2, wherein each fitness machine (200) is connected in parallel to a power network (209) via standard AC socket outlets (205), AC plugs (206), and power cables (207).

[0241] Item 4. The gym plant according to any one of items 2 or 3, wherein the bidirectional PFC (204) of each electric load and drive unit (1 ) is configured to enable both the supply of electrical energy from the AC power network (209) to the DC link and the return of electrical energy generated by the motor / generator drive unit (203) to the AC power network (209).

[0242] Item 5. The gym plant according to any one of items 2 to 4, wherein the energy generated by user-driven operation of the fitness machines (200) is fed back into the AC power network (209) via the bidirectional PFC (204), thereby enabling energy recovery and reducing energy waste.

[0243] Item 6. The gym plant according to any one of items 2 to 5, wherein each electric load and drive unit (1 ) further comprises a 24V display supply (201 ) powered from the DC link capacitors (202) for operating user interface and control electronics. Item 7. The gym plant according to any one of items 3 to 6, wherein the connection of each fitness machine (200) to the power network (209) is modular, allowing individual machines to be connected or disconnected without affecting the operation of the remaining machines.

[0244] Item 8. The gym plant according to any one of items 3 to 7, wherein the energy recovery network is configured such that no special hardware is required on the grid side, and each fitness machine (200) is adapted to be plugged directly into a standard AC socket outlet (205) of the public grid.

[0245] Item 9. The gym plant according to any one of items 4 to 8, wherein the bidirectional PFC (204) of each electric load and drive unit (1 ) is configured to maintain a predetermined power factor and to synchronise the phase and frequency of exported current with the AC power network (209) during energy recovery operation.

[0246] Item 10. The gym plant according to any one of items 1 to 9, wherein the energy recovery network enables the collective energy generated by multiple fitness machines (200) to be reused within the facility or exported to the public grid.

[0247] The eighteenth itemized list relates to a data network for monitoring and recording individual training positions. The features of the eighteenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0248] Itemized list 18

[0249] Item 1 . A gym plant comprising a data network configured for monitoring and recording individual training positions, the gym plant comprising a plurality of fitness machines (200), each fitness machine (200) comprising an electric load and drive unit (1 ), at least one sensor system for detecting user activity, and a communication interface for transmitting data to the data network.

[0250] Item 2. The gym plant according to item 1 , wherein the at least one sensor system comprises a torque sensor system (71 ) and / or an encoder system (43) for detecting at least one of torque, position, speed, or direction of a drive shaft (51 ) or rotor shaft (11 ) of the electric load and drive unit (1 ).

[0251] Item 3. The gym plant according to any one of items 1 or 2, wherein the communication interface of each fitness machine (200) is configured for wired or wireless data transmission to a central server or cloud-based data storage.

[0252] Item 4. The gym plant according to any one of items 1 to 3, wherein the data network is configured to associate recorded training data with individual users based on user identification input at each fitness machine (200).

[0253] Item 5. The gym plant according to any one of items 1 to 4, wherein the data network is further configured to provide real-time feedback or training analytics to users via a display unit (400) on each fitness machine (200).

[0254] Item 6. The gym plant according to any one of items 1 to 5, wherein the data network is configured to store historical training data for each user and to enable retrieval and analysis of individual training sessions across multiple fitness machines (200).

[0255] The nineteenth itemized list relates to an electric load and drive unit. The features of the nineteenth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims. Itemized list 19

[0256] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a single-stage cycloidal gearbox for providing resistance control, the gearbox comprising: a rotor shaft (11 ) configured to transmit motion from a motor to the gearbox, a first eccentric cam (12) mounted on the rotor shaft (11 ) for driving a first cycloidal gearwheel (16), an optional second eccentric cam (13) mounted on the rotor shaft (11 ) for driving an optional second cycloidal gearwheel (17), the second eccentric cam (13) being offset by 180 degrees relative to the first eccentric cam (12), a plurality of toothing pins (19) inserted into cylindrical pockets (21 ) of an outer gearwheel, the first and, if present, the second cycloidal gearwheels configured to mesh with an inner toothing of an outer gearwheel

[0257] [and interact with the toothing pins (19) to transmit forces, wherein the gearbox provides resistance control for the fitness machine], wherein the electric load and drive unit (1 ) further comprises a drive shaft (51 ) that is connected with the first and, if present, with the second cycloidal gearwheels, the drive shaft (51 ) being provided as a hollow structure that carries an adapter shaft (28), with a friction bearing (29) and an adapter toothing being provided, for transmitting torque from the adapter shaft (28) over the drive shaft (51 ) to the first cycloidal gearwheel (16) and, if present, to the second cycloidal gearwheel (17) of the cycloidal gearbox.

[0258] Item 2. The electric load and drive unit (1 ) of item 1 , wherein the gearbox includes a drive disc (24) carrying multiple drive pins (25), and drive rollers (26) mounted on the drive pins (25) for transmitting rotational movement.

[0259] Item 3. The electric load and drive unit (1 ) of one of the aforementioned items, wherein the gearbox is configured as an H PR-type instead of a cycloidal gearbox. Item 4. The electric load and drive unit (1 ) of one of the aforementioned items, wherein the gearbox is configured as a Harmonic Drive type gearbox instead of a cycloidal gearbox.

[0260] Item 5. An electric load and drive unit (1 ) for a fitness machine, comprising:

[0261] • a drive shaft (51 ),

[0262] • a rotor shaft (11 ),

[0263] • a torque sensor system (71 ) configured to measure torsion in the drive shaft (51 ), the torque sensor system (71 ) comprising: a sensor assembly that measures torsion in the drive shaft (51 )

[0264] [between an inner adapter toothing (30) and a drive disc (24),] an energy harvesting unit that harvests electrical energy from the stator (42)’s electric field to power the torque sensor system (71 ), an optical transmission system that includes LEDs for transmitting torsion data [cable- free] from the torque sensor system (71 ),

[0265] • a first rotor bearing (54) positioned on one side of the rotor shaft (11 )

[0266] [away from a first eccentric cam (12) and a second eccentric cam (13)],

[0267] • a second rotor bearing (55) positioned on the other side of the rotor shaft (11 ) [close to the first eccentric cam (12) and the second eccentric cam (13), the second rotor bearing (55) provided in the form of a double rolling bearing or as two single rolling bearings, a first cam bearing (14) and a second cam bearing (15), that are spaced such that they lie under the first eccentric cam (12) and the second eccentric cam (13), respectively,]

[0268] • wherein the first rotor bearing (54) and the second rotor bearing (55) are provided between the [inner side of the hollow] rotor shaft (11 ) and the [outer side of the] drive shaft (51 ), wherein the torque sensor system (71 ) further comprises:

[0269] • a single piece flexible PCB that includes a strain gauge pad (81 ) and a connection strip (82), the strain gauge pad (81 ) and the connection strip (82) being provided as a single piece flexible PCB with the energy harvesting coil (83) and the strain gauge conductor trace structured in a metal layer of the PCB,

[0270] • the connection strip (82) carrying a transmission LED (79) and the energy harvesting coil (83), extending from the area between the first rotor bearing (54) and the second rotor bearing (55) through a transfer pocket (58) forming an axial channel in the outer surface of the drive shaft (51 ),

[0271] [and through a shaft opening (63) of a motor control board (60)] to an area where light signals emitted by the LED are received by light receiver elements (73) and where the energy harvesting coil (83) is exposed to the electromagnetic field of the stator (42).

[0272] Item 6. The electric load and drive unit (1 ) of item 5, wherein the area of the drive shaft (51 ) between the first rotor bearing (54) and the second rotor bearing (55) acts as a load cell for measuring the torque transmitted by the drive shaft (51 ) [in an area between the inner adapter toothing (30) and the drive disc (24)].

[0273] Item 7. The electric load and drive unit (1 ) of item 5 or of item 6, wherein the torque sensor system (71 ) further comprises a voltage-controlled oscillator (VCO) configured to modulate the data from the strain gauge pad (81 ) for optical transmission, [the modulation frequency of the transmitted light represents the torsion measured by the strain gauges]; or wherein the torque sensor system (71 ) comprises a microcontroller unit (MCU) mounted on a shaft-PCB on the drive shaft (51 ), the MCU being configured to digitise the data from the strain gauge pad (81 ) for optical transmission [thereby enabling interference-resistant and error-checkable optical signal transmission].

[0274] Item 8. The electric load and drive unit (1 ) of one of items 5 to 7, wherein the torque sensor system (71 ) further comprises an optical transmission system with a transmission LED (79) configured to transmit the [modulated] torsion data and a reception LED (80) configured to receive the transmitted data and convert it back into an electrical signal representing the measured torsion.

[0275] Item 9. The electric load and drive unit (1 ) of one of items 5 to 8, wherein the energy harvesting coil (83) interacts inductively with an electromagnetic field of a stator (42) of the electric load and drive unit (1 ) to generate electric power for the torque sensor system (71 ) during operation of the electric load and drive unit (1 ). [the electric power being supplied from outside the rotor shaft (11 ) to the strain gauges within the rotor shaft (11 ) via the connection strip (82).

[0276] Item 10. The electric load and drive unit (1 ) of one of items 5 to 9, wherein the drive shaft (51 ) comprises: • an inner adapter toothing (30) configured to engage with an outer adapter toothing (31 ) of an adapter shaft (28),

[0277] • a drive disc (24) that is connected with a gearbox of the electric load and drive unit (1 ).

[0278] Item 11 . The electric load and drive unit (1 ) of one of items 5 to 10, further comprising a motor control unit (61 ) configured to manage power and energy distribution within the electric load and drive unit (1 ), and to utilize the data from the torque sensor system (71 ) to adjust resistance levels dynamically.

[0279] Item 12. An electric load and drive unit (1 ) for a fitness machine, comprising:

[0280] • a drive shaft (51 ),

[0281] • a rotor shaft (11 ),

[0282] • a rotationally symmetric gearbox between the drive shaft (51 ) and the rotor shaft (11 ),

[0283] • a tapered roller bearing (52) and a counter bearing (53) positioned between the drive shaft (51 ) and a housing of the electric load and drive unit (1 ) to support the drive shaft (51 ) and enable [smooth] rotational movement,

[0284] • [a lubrication system configured to provide lubrication to the tapered roller bearings and the counter bearing (53), comprising a special] lubricant suitable for intermittent movement and high loads.

[0285] Item 13. The electric load and drive unit (1 ) of item 12, wherein the lubricant comprises anti-wear additives for applications involving low speeds and high loads.

[0286] Item 14. The electric load and drive unit (1 ) of item 12 or item 13, wherein the special lubricant (111 ) is selected from specific types, known for their high performance in supporting back-and-forth movements of the drive shaft (51 ), facilitating operation even in the absence of complete revolutions.

[0287] Item 15. A fitness machine, comprising: an electric load and drive unit (1 ) according to one of the aforementioned items, a mechanical interface for connecting the drive unit to user-operated elements such as cranks, levers, or wheels. Item 16. A method of using a fitness machine for guided training of a user, the fitness machine comprising an electric load and drive unit (1 ) with a single-stage gearbox with a rotationally symmetric configuration, the method comprising: initializing the fitness machine and setting a desired resistance level through the motor control unit (61 ), using the electric load and drive unit (1 ) to provide adjustable resistance during exercise by driving the gearbox via the eccentric cams, measuring performance metrics using integrated sensors, providing feedback to the user based on the measured performance metrics, adjusting the resistance dynamically based on the feedback and user input.

[0288] Item 17. The electric load and drive unit (1 ) of one of claims 12-14, wherein the special lubricant (111 ) is based on mineral or synthetic hydrocarbon oil and calcium or barium complex soap.

[0289] Item 18. The electric load and drive unit (1 ) of one of claims 12-14 or 17, wherein the special lubricant (111 ) has a kinematic viscosity of 220 mm2 / s at 40 °C up to 19 mm2 / s at 100 °C, in particular 50 mm2 / s at 40 °C.

[0290] The twentieth itemized list relates to an electric load and drive unit for a fitness machine, to a fitness machine, and to a method of using a fitness machine. The features of the twentieth itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0291] Itemized list 20

[0292] Item 1 . An electric load and drive unit for fitness machines comprising: a. a single-stage cycloidal gearbox with a rotationally symmetric configuration, b. a rotor shaft configured to transmit motion from a motor to the gearbox and vice versa, c. one or more eccentric cams provided on the rotor shaft, d. at least one cycloidal gearwheel driven by a corresponding eccentric cam and meshing with the inner toothing of an outer gearwheel, e. an electromagnetic rotor and stator assembly configured to generate power and / or control resistance through electromagnetic induction, f. a torque sensor configured to measure torsion in a drive shaft.

[0293] Item 2. The electric load and drive unit of item 1 immediately above, wherein the drive shaft includes a drive disc carrying multiple drive pins that transmit rotational movement to the drive shaft.

[0294] Item 3. The electric load and drive unit of item 1 or item 2 immediately above, wherein the drive pins are inserted into drive pin bores in the drive disc and support drive rollers for rolling movement.

[0295] Item 4. The electric load and drive unit of one of the aforementioned items, wherein the outer gearwheel comprises cylindrical pockets housing toothing pins that support toothing rollers [e.g. for rolling movement].

[0296] Item 5. The electric load and drive unit of the aforementioned items immediately above, further comprising a motor control unit connected to the stator, the sensors, a power supply, and an external display.

[0297] Item 6. The electric load and drive unit of the aforementioned items immediately above, wherein the torque sensor comprises a voltage-controlled oscillator (VCO) and at least one transmission LED to optically transmit torque data, and a corresponding at least one light receiver element to receive data from the at least one transmission LED; or wherein the torque sensor comprises a microcontroller unit (MCU) mounted on a shaft- PCB on the drive shaft, the MCU being configured to digitise strain gauge data and to transmit the strain gauge data as a digital data stream via the at least one transmission LED, and a corresponding at least one light receiver element to receive data from the at least one transmission LED [thereby enabling interference-resistant and error-checkable optical signal transmission.]

[0298] Item 7. The electric load and drive unit of the aforementioned items immediately above, wherein the energy recovery system [eliminates the need for a brake chopper by] allowing other consumers to utilize the energy [within an intermediate circuit]. Item 8. Electric load and drive unit according to of the aforementioned items, with an energy recovery system configured to recover energy [for device operation and to reduce heat generation].

[0299] Item 9. The electric load and drive unit of the aforementioned items immediately above, further comprising a shock absorber mechanism made from rubber-like deformable plastic [to prevent hard surface interactions and reduce noise and vibration].

[0300] Item 10. The electric load and drive unit of one of the aforementioned items immediately above, wherein the gearbox includes a special lubricant required due to intermittent movement and high loads.

[0301] Item 11 . The electric load and drive unit of one of the aforementioned items immediately above, wherein the drive shaft is supported by a tapered roller bearing at one end and a counter bearing at the opposite end, forming an angular contact bearing pair configured in an "0" or "X" arrangement.

[0302] Item 12. An electric load and drive unit for a fitness machine, comprising: a drive shaft, a rotor shaft, a torque sensor system configured to measure torsion in the drive shaft, the torque sensor system comprising: a sensor assembly that measures torsion in the drive shaft [between an inner adapter toothing and a drive disc,] a first rotor bearing positioned on one side of the rotor shaft [away from a first eccentric cam and a second eccentric cam], a second rotor bearing positioned on the other side of the rotor shaft [close to the first eccentric cam and the second eccentric cam, the second rotor bearing provided in the form of a double rolling bearing or as two single rolling bearings, a first cam bearing and a second cam bearing, that are spaced such that they lie under the first eccentric cam and the second eccentric cam, respectively,] wherein the first rotor bearing and the second rotor bearing are provided between the [inner side of the hollow] rotor shaft and the [outer side of the] drive shaft, wherein the drive shaft comprises an inner adapter toothing configured to engage with an outer adapter toothing of the adapter shaft, and a drive disc that is connected with a gearbox of the electric load and drive unit, wherein an area of the drive shaft between the outer adapter toothing of the adapter shaft, and the drive disc is provided [as a load cell] for measuring the torque transmitted by the drive shaft [in an area between the inner adapter toothing and the drive disc].

[0303] Item 13. An electric load and drive unit for a fitness machine, comprising: a single-stage rotationally symmetric gearbox, a rotor shaft configured to transmit motion from an electric motor to the gearbox, a plurality of toothing pins inserted into cylindrical pockets of an outer gearwheel, wherein the electric load and drive unit further comprises a drive shaft, the drive shaft being provided as a hollow structure that carries an adapter shaft, with a friction bearing and an adapter toothing being provided, for transmitting torque from the adapter shaft over the drive shaft to the gearbox.

[0304] The twenty-first itemized list relates to an electric load and drive unit for a fitness machine, to a fitness machine, and to a method of using a fitness machine. The features of the twenty- first itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0305] Itemized list 21

[0306] Item 1 :

[0307] An electric load and drive unit for a fitness machine, comprising: a single-stage cycloidal gearbox for providing precise resistance control, the gearbox comprising: a rotor shaft configured to transmit motion from a motor to the gearbox, a first eccentric cam mounted on the rotor shaft for driving a first cycloidal gearwheel, an optional second eccentric cam mounted on the rotor shaft for driving an optional second cycloidal gearwheel, the second eccentric cam being offset by 180 degrees relative to the first eccentric cam, a plurality of toothing pins inserted into cylindrical pockets of an outer gearwheel, the first and, if present, the second cycloidal gearwheels configured to mesh with an inner toothing of an outer gearwheel [and interact with the toothing pins to transmit forces, wherein the gearbox provides precise resistance control for the fitness machine], wherein the electric load and drive unit further comprises a drive shaft that is connected with the first and, if present, with the second cycloidal gearwheels, the drive shaft being provided as a hollow structure that carries an adapter shaft, with a friction bearing and an adapter toothing being provided, for transmitting torque from the adapter shaft over the drive shaft to the first cycloidal gearwheel and, if present, to the second cycloidal gearwheel of the cycloidal gearbox.

[0308] Item 2: The electric load and drive unit of item 1 immediately above, wherein the gearbox includes a drive disc carrying multiple drive pins, and drive rollers mounted on the drive pins for transmitting rotational movement.

[0309] Item 3: The electric load and drive unit of one of the aforementioned items immediately above, wherein the gearbox is configured as an HPR-type instead of a cycloidal gearbox.

[0310] Item 4: The electric load and drive unit of one of the aforementioned items immediately above, wherein the gearbox is configured as a Harmonic Drive type gearbox instead of a cycloidal gearbox.

[0311] Item 5: An electric load and drive unit for a fitness machine, comprising:

[0312] • a drive shaft,

[0313] • a rotor shaft,

[0314] • a torque sensor system configured to measure torsion in the drive shaft, the torque sensor system comprising: o a sensor assembly that measures torsion in the drive shaft [between an inner adapter toothing and a drive disc,] o an energy harvesting unit that harvests electrical energy from the stator’s electric field to power the torque sensor system, o an optical transmission system that includes LEDs for transmitting torsion data [cable-free] from the torque sensor system,

[0315] • a first rotor bearing positioned on one side of the rotor shaft [away from a first eccentric cam and a second eccentric cam],

[0316] • a second rotor bearing positioned on the other side of the rotor shaft [close to the first eccentric cam and the second eccentric cam, the second rotor bearing provided in the form of a double rolling bearing or as two single rolling bearings, a first cam bearing and a second cam bearing, that are spaced such that they lie under the first eccentric cam and the second eccentric cam, respectively,]

[0317] • wherein the first rotor bearing and the second rotor bearing are provided between the [inner side of the hollow] rotor shaft and the [outer side of the] drive shaft. wherein the torque sensor system further comprises:

[0318] • a single piece flexible PCB that includes a strain gauge pad and a connection strip, the strain gauge pad and the connection strip being provided as a single piece flexible PCB with the energy harvesting coil and the strain gauge conductor trace structured in a metal layer of the PCB,

[0319] • the connection strip carrying a transmission LED and the energy harvesting coil, extending from the area between the first rotor bearing and the second rotor bearing through a transfer pocket forming an axial channel in the outer surface of the drive shaft, [and through a shaft opening of a motor control board] to an area where light signals emitted by the LED are received by light receiver elements and where the energy harvesting coil is exposed to the electromagnetic field of the stator.

[0320] Item 6: The electric load and drive unit of item 5 immediately above, wherein the area of the drive shaft between the first rotor bearing and the second rotor bearing acts as a load cell for measuring the torque transmitted by the drive shaft [in an area between the inner adapter toothing and the drive disc].

[0321] Item 7: The electric load and drive unit of item 5 or of item 6 immediately above, wherein the torque sensor system further comprises a voltage-controlled oscillator (VCO) configured to modulate the data from the strain gauge pad for optical transmission [the modulation frequency of the transmitted light represents the torsion measured by the strain gauges]; or wherein the torque sensor system comprises a microcontroller unit (MCU) mounted on a shaft-PCB on the drive shaft, the MCU being configured to digitise the data from the strain gauge pad for optical transmission [thereby enabling interference-resistant and error- checkable optical signal transmission].

[0322] Item 8: The electric load and drive unit of one items 5 to 7 immediately above, wherein the torque sensor system further comprises an optical transmission system with a transmission LED configured to transmit the [modulated] torsion data and a reception LED configured to receive the transmitted data and convert it back into an electrical signal representing the measured torsion.

[0323] Item 9: The electric load and drive unit of one of items 5 to 8 immediately above, wherein the energy harvesting coil interacts inductively with an electromagnetic field of a stator of the electric load and drive unit to generate electric power for the torque sensor system during operation of the electric load and drive unit, [the electric power being supplied from outside the rotor shaft to the strain gauges within the rotor shaft via the connection strip.

[0324] Item 10: The electric load and drive unit of one of items 5 to 9 immediately above, wherein the drive shaft comprises:

[0325] • an inner adapter toothing configured to engage with an outer adapter toothing of an adapter shaft,

[0326] • a drive disc that is connected with a gearbox of the electric load and drive unit.

[0327] Item 11 : The electric load and drive unit of one of items 5 to 10 immediately above, further comprising a motor control unit configured to manage power and energy distribution within the electric load and drive unit, and to utilize the data from the torque sensor system to adjust resistance levels dynamically.

[0328] Item 12: An electric load and drive unit for a fitness machine, comprising:

[0329] • a drive shaft,

[0330] • a rotor shaft,

[0331] • a rotationally symmetric gearbox between the drive shaft and the rotor shaft, • a tapered roller bearing and a counter bearing positioned between the drive shaft and a housing of the electric load and drive unit to support the drive shaft and enable [smooth] rotational movement,

[0332] • [a lubrication system configured to provide lubrication to the tapered roller bearings and the counter bearing, comprising a special] lubricant suitable for intermittent movement and high loads.

[0333] Item 13: The electric load and drive unit of item 12 immediately above, wherein the lubricant comprises anti-wear additives for applications involving low speeds and high loads.

[0334] Item 14: The electric load and drive unit of item 12 or item 13 immediately above, wherein the special lubricant is selected from specific types, known for their high performance in supporting back-and-forth movements of the drive shaft, facilitating smooth operation even in the absence of complete revolutions.

[0335] Item 15: A fitness machine, comprising: an electric load and drive unit according to one of the aforementioned items, a mechanical interface for connecting the drive unit to user-operated elements such as cranks, levers, or wheels.

[0336] Item 16:

[0337] A method of using a fitness machine for guided training of a user, the fitness machine comprising an electric load and drive unit with a single-stage gearbox with a rotationally symmetric configuration, the method comprising: initializing the fitness machine and setting a desired resistance level through the motor control unit, using the electric load and drive unit to provide adjustable resistance during exercise by driving the gearbox via the eccentric cams, measuring real-time performance metrics using integrated sensors, providing real-time feedback to the user based on the measured performance metrics, adjusting the resistance dynamically based on the feedback and user input. The twenty-second itemized list relates to an electric load and drive unit. The features of the twenty-second itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0338] Itemized list 22

[0339] Item 1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a single-stage cycloidal gearbox for providing resistance control, the gearbox comprising: a rotor shaft (11 ) configured to transmit motion from a motor to the gearbox, a first eccentric cam (12) mounted on the rotor shaft (11 ) for driving a first cycloidal gearwheel (16), an optional second eccentric cam (13) mounted on the rotor shaft (11 ) for driving an optional second cycloidal gearwheel (17), the second eccentric cam (13) being offset by 180 degrees relative to the first eccentric cam (12), a plurality of toothing pins (19) of an outer gearwheel, the first and, if present, the second cycloidal gearwheels configured to mesh with an inner toothing of the outer gearwheel [and interact with the toothing pins (19) to transmit forces, wherein the gearbox provides resistance control for the fitness machine], wherein the electric load and drive unit (1 ) further comprises a drive shaft (51 ) that is connected with the first and, if present, with the second cycloidal gearwheels, the drive shaft (51 ) being provided as a hollow structure that carries an adapter shaft (28), with a friction bearing (29) and an adapter toothing being provided, for transmitting torque from the adapter shaft (28) over the drive shaft (51 ) to the first cycloidal gearwheel (16) and, if present, to the second cycloidal gearwheel (17) of the cycloidal gearbox.

[0340] Item 2. The electric load and drive unit (1 ) of item 1 , wherein the gearbox includes a drive disc (24) carrying multiple drive pins (25), and drive rollers (26) mounted on the drive pins (25) for transmitting rotational movement.

[0341] Item 3. The electric load and drive unit (1 ) of any of the preceding items, wherein the toothing pins (19) are statically built into the outer gearwheel, e.g. as internal toothing of the outer gearwheel, wherein in particular the tooth crest is a circular ring section. The twenty-third itemized list relates to an electric load and drive unit. The features of the twenty-third itemized list can be combined with one or more features from any of the other itemized lists in this document, as well as with one or more features of the claims.

[0342] Itemized list 23

[0343] Item 1 . An electric load and drive unit for fitness machines comprising: a. a single-stage cycloidal gearbox with a rotationally symmetric configuration, b. a rotor shaft configured to transmit motion from a motor to the gearbox and vice versa, c. one or more eccentric cams provided on the rotor shaft, d. at least one cycloidal gearwheel driven by a corresponding eccentric cam and meshing with the inner toothing of an outer gearwheel, e. an electromagnetic rotor and stator assembly configured to generate power and / or control resistance through electromagnetic induction, f. a torque sensor configured to measure torsion in a drive shaft, and g. an energy recovery system configured to recover energy e.g. for device operation and to reduce heat generation.

[0344] Item 2. The electric load and drive unit of the aforementioned item, wherein the energy recovery system allows other consumers to utilize the energy e.g. within an intermediate circuit, and / or eliminates the need for a brake chopper.

[0345] Item 3. The electric load and drive unit of one of items 1 -2, wherein the energy recovery system comprises a unidirectional DC-DC-converter.

[0346] Item 4. The electric load and drive unit of item 3, wherein the DC-DC-converter comprises two rectifier switches at the secondary winding.

[0347] Item 5. The electric load and drive unit of item 3, wherein the DC-DC-converter comprises two rectifier switches and two rectifying capacitors at the secondary winding.

[0348] The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. Embodiments of the application will now be described with reference to the attached drawings. Figure 1 shows a perspective view of the overall assembly of the electric load and drive unit of the application,

[0349] Figure 2 shows the electric load and drive unit of Fig. 1 in another perspective view, Figure 3 shows a detailed view of a shock absorber mechanism of the electric load and drive unit of Fig.1 and Fig. 2,

[0350] Figure 4 shows a cross-sectional view of the electric load and drive unit of the application, Figure 5 shows a perspective view of the cycloidal gearwheels of the gearbox of the disclosure,

[0351] Figure 6 shows a further cross-section through an electric load and drive unit of the disclosure,

[0352] Figure 7 shows a perspective view of a detail of the electric load and drive unit of Fig. 6, Figure 8 shows a motor control board of an electric load and drive unit of the disclosure, Figure 9 shows a further perspective view of an electric load and drive unit of the disclosure,

[0353] Figure 10 shows a schematic of the motor control board of Fig. 8,

[0354] Figure 11 shows a perspective view of a detail of the rotor of the electric load and drive unit of the disclosure,

[0355] Figure 12 shows a detailed view of the gearbox of the electric load and drive unit of the disclosure,

[0356] Figure 13 shows the detailed view of the gearbox of Fig. 12, without the rotor,

[0357] Figure 14 shows an encoder disc of an electric load and drive unit of the disclosure, and Figure 15 shows a further detailed perspective view of the electric load and drive unit of the disclosure.

[0358] Fig. 1 shows a perspective view of the overall assembly of the electric load and drive unit 1 of the application.

[0359] The electric load and drive unit 1 is used within a fitness machine. The unit comprises a central housing part 141. Attached to the top surface of the housing are connection cables; the connection cable to the user display and the power supply cable 131 , which provide power to the unit as well as a connection interface for user interaction. An adapter shaft 28 is visible, extending outward. This shaft connects internally to a rotationally symmetric drive mechanism, involving cycloidal gearwheels, a HPR drive, or a harmonic drive.

[0360] A gearbox cover 142, which provides access to the internal gearing mechanisms, and also provides mounting points for securing this unit within the fitness machine. The front of the unit comprises a central axis 45, indicating the output shaft or a point of rotation for transmitting mechanical energy to other elements such as cranks or wheels.

[0361] Additionally, the unit is shown with three reference axes, providing orientation for the figure. The presence of a motor control cover 143 suggests that the unit is designed to be self-contained, with its own control systems for managing the load and performance metrics during use in a fitness setting.

[0362] The overall design implies a compact, robust construction suitable for the dynamic and variable loads experienced by fitness equipment.

[0363] The figures are annotated with coordinate systems, providing a reference for orientation.

[0364] Fig. 2 shows the electric load and drive unit 1 of Fig. 1 in another perspective view.

[0365] The figure illustrates the electric load and drive unit 1 .

[0366] The central housing part 141 acts as the primary enclosure for the internal mechanisms. A gearbox cover 142 is shown positioned on the side of the unit, indicating the location where the internal gearing mechanisms are housed. The motor control cover 143 appears affixed to another side of the unit, designating the area protecting the motor control components. The central axis 45 is visible, representing the central point of rotation or the main drive shaft 51 around which other components would rotate or be driven.

[0367] Fig. 3 shows a detailed view of a shock absorber mechanism of the electric load and drive unit 1 of Fig. 1 and Fig. 2. The perspective view focuses on the adapter shaft 28 and its interaction with shockabsorbing components and limiters. A shock absorber 101 is located within a stopper block 102 which is aligned with a stopper arm 103 comprising a slot for restricting the movement of the system to prevent mechanical overload of a user of the fitness machine that is equipped with the unit. The components are integrated into the structure of the unit, with the gearbox cover 142 partially visible in the Fig. 1. The image also includes a coordinate system with axes labeled x, y, and z, indicating the three-dimensional orientation of the view.

[0368] Fig. 4 shows a cross-sectional view of the electric load and drive unit 1 of the application.

[0369] Visible is the rotor shaft 11 that transmits motion from a motor to a gearbox, which is equipped with a first eccentric cam 12 and a second eccentric cam 13, these being provided on the rotor shaft 11. First cam bearings 14 and second cam bearings 15 are shown in proximity to the first eccentric cam 12 and the second eccentric cam 13. A first cycloidal gearwheel 16 and a second cycloidal gearwheel 17 are in mesh with toothing pins 19 of an outer gearwheel 18, that can be seen in Fig. 5. The gearbox casing includes a motor control cover 143, a central housing part 141 , and a gearbox cover 142.

[0370] As can be seen in Fig. 6, the drive disc 24 holds the drive pins 25 which are attached to the drive rollers 26, facilitating the transmission of rotational motion. The central axis 45 of the machine is depicted, as well as sectional views of the rotor 41 , stator 42, and encoder disc 43.

[0371] Fig. 4 shows the drive shaft 51 being located centrally and supported by bearings at its ends, indicated by the first rotor bearing 54 and the second rotor bearing 55. On the lower part of Fig. 4, stopper elements comprising a stopper block 102 and stopper arm 103 are shown. The unit also includes a tapered roller bearing 52 and a counter bearing 53, with the entire assembly enclosed in the central housing.

[0372] In a development, the tapered roller bearing 52 and the counter bearing 53 are lubricated using a first special lubricant. The first special lubricant may be based on mineral oil and barium complex soap and has a kinematic viscosity of 220 mm2 / s at 40 °C up to 19 mm2 / s at 100 °C like e.g. STABURAGS NBU of Kluber Lubrication, Munich / DE. The reason for this choice is that these tapered bearings operate at low rolling speeds, may be subjected to high axial forces, and do not experience continuous rolling over all bearing surfaces. The rollers move alternately over the same surfaces, which places specific demands on the lubricant. The first special lubricant identified above has been selected by the inventors for its suitability under these conditions.

[0373] The gearbox of the electric load and drive unit 1 further comprises bushings which serve as plain bearings for various rotating or oscillating components within the gear mechanism. While these bushings are not explicitly depicted in Fig. 4, they are used for supporting the relative movement of internal gearbox elements, particularly where rolling bearings are not employed.

[0374] In a development, these gearbox bushings are lubricated using a second special lubricant based on synthetic hydrocarbon oil and calcium soap, such as Kluberfood NH1 94-51 of Kluber Lubrication, Munich / DE, which has a kinematic viscosity of 50 mm2 / s at 40 °C. This lubricant is specifically chosen for its ability to provide continuous capillary lubrication to the fine gaps of the plain bearings, thereby preventing fretting corrosion and ensuring long-term, low-maintenance operation of the gearbox components, even under demanding and intermittent movement conditions.

[0375] The inventors have recognised that the diverse tribological requirements of the different bearing points within the unit 1 cannot be met by a single lubricant. By selecting and applying two distinct lubricants — the first special lubricant designed for the high-load, low- speed, oscillating conditions of the tapered roller bearing 52, and the second special lubricant for the capillary lubrication needs of the gearbox bushings — the inventors have achieved enhanced wear protection, improved corrosion resistance, and increased operational reliability.

[0376] While usually different lubricants are not used together in one single gearbox because of concerns regarding chemical and physical compatibility, the specific combination of a mineral oil and barium complex soap-based grease for the roller bearing 52 and a synthetic hydrocarbon oil and calcium soap-based grease for the bushings results in a drive unit 1 with improved durability and reduced maintenance requirements. A motor control board 60 is visible, including of electronics for controlling the unit's functions. The image includes coordinate axes to provide an orientation within the three- dimensional space.

[0377] Fig. 5 shows a cross-sectional perspective view of the electric load and drive unit 1 . The drive shaft 51 comprises a hollow center, where the adapter shaft 28 is expected to be housed. Surrounding the drive shaft 51 are the first cycloidal gearwheel 16 and the second cycloidal gearwheel 17, which mesh with the inner toothing of the outer gearwheel, creating a cycloidal motion. These gears are driven by the first eccentric cam 12 and the second eccentric cam 13, which are provided on the rotor shaft 11 . The rotor shaft 11 transmits motion from the motor to the gearbox. the first cycloidal gearwheel 16 and the second cycloidal gearwheel 17 engage with toothing pins 19 inserted into cylindrical pockets 21 of the outer gearwheel 18, which is a ring gear. Drive rollers 26 and drive pins 25 are involved in the transmission of motion from the drive disc 24 to support the entire gear mechanism.

[0378] The outer structure is comprised of the gearbox cover 142 and housing bolts 146, which secure the components within the central housing part 141. Spacers 145 ensure the proper alignment and operation of the gear assembly.

[0379] Fig. 6 depicts the electric load and drive unit with the rotor shaft 11 , eccentric cams 12 and 13, and cycloidal gearwheels 16 and 17. Drive pins 25 and drive rollers 26 are part of the drive shaft 51 . The adapter shaft 28 connects to the drive shaft 51 , supported by the friction bearing 29. The first and second rotor bearings 54 and 55 support the rotor shaft 11 . The motor control board 60 connects to the stator 42 and sensors. The gearbox cover 142 and motor control cover 143 protect the internal components. The torque sensor system 71 includes a strain gauge pad 81 and connection strip 82 for measuring torsion.

[0380] Fig. 7 illustrates the electric load and drive unit's components, including the rotor shaft 11 , eccentric cams 12 and 13, and cycloidal gearwheels 16 and 17. Drive pins 25 and drive rollers 26 transmit movement to the drive shaft 51. The adapter shaft 28, friction bearing 29, and inner adapter toothing 30 are shown. The first and second rotor bearings 54 and 55 support the rotor shaft 11 . The motor control board 60 interfaces with the stator 42 and sensors. The gearbox cover 142 and motor control cover 143 protect the assembly. The torque sensor system 71 , with a strain gauge pad 81 and connection strip 82, measures torsion.

[0381] Fig. 8 shows a motor control board 60 of an electric load and drive unit 1 of the disclosure,

[0382] The figure illustrates a perspective view of the motor control board 60 designed to fit within the electric load and drive unit 1 of a fitness machine. The board is shown with multiple electronic elements including an identifiable motor control unit 61 , which plays a critical role in managing the operation of the motor, and a variety of other components involved in processing and power management.

[0383] In the center of the board, there is a shaft opening 63 that allows connection to other parts of the fitness machine's drive system, possibly for alignment with the device's rotor 41 or for encoders that measure rotation. The motor control board 60 is also equipped with an LED system for optical transmission, which could be part of the communication or sensor systems of the machine.

[0384] Surrounding these central comprises are detector coil systems that may be involved in sensing and energy harvesting functions mentioned in the patent claims, particularly relevant to interacting with the stator 42's electromagnetic field for powering a torque sensor system 71 . Adjacent to these coils is a space for the central axis 45, indicating the board's position in relation to the rotating parts of the drive unit.

[0385] Fig. 9 shows a further perspective view of an electric load and drive unit 1 of the disclosure, displaying a cross-sectional view of an electric load and drive unit 1 , which comprises various components of a gearbox and control system designed for use in a fitness machine. The cutaway view shows the arrangement of a rotor shaft 11 , where the first eccentric cam 12 and, optionally, a second eccentric cam 13 are mounted. These cams are used to drive the first and optionally second cycloidal gearwheels. These gearwheels mesh with an outer gearwheel, which incorporates toothing pins 19 inserted into cylindrical pockets 21 . The rotor shaft 11 is linked to a drive shaft 51 , which is provided as a hollow structure designed to transmit torque from the adapter shaft 28, with the help of a friction bearing 29 and adapter toothing. The electric components include a motor control board 60 situated at the top, and connected to or interacting with various internal elements such as an encoder disc 43, stator 42, and others. Additional components such as drive rollers 26, a central axis 45, and rotor 41 bearings are also depicted in this figure.

[0386] Towards the base of the figure, two sections of an outer housing are visible; the central housing part 141 and the gearbox cover 142 are joined by housing bolts.

[0387] Fig. 10 presents an electrical schematic diagram outlining the internal circuitry and connections of a motor control unit 61 and an energy recovery system 91 , which are components of an electric load and drive unit 1 designed for a fitness machine. The diagram comprises various blocks that represent electrical components and their interconnections, such as:

[0388] - A power supply section 67 that includes DC input 64 and AC input 65, along with a DC / DC converter 66 that steps down voltage levels to 380V / 12V and further to 12V / 3. 3V, indicating the conversion of input power to levels suitable for the control unit's operation.

[0389] - The motor control unit (MCU) 61 which acts as the central processing component for controlling motor functions.

[0390] - A brake chopper 92, used to dissipate energy during braking operations to prevent overvoltage conditions.

[0391] - A gate driver 68 and a 2-level Voltage Source Inverter 69 which are used for driving the motor stator 42, indicating the electrical interface to the motor's coils.

[0392] - An STO (Safe Torque Off) 70 input, which acts on the gate drivers of the motor power stage to ensure safe hardware-based torque shutdown.

[0393] - A current sensor 75 and a voltage sensor 76, along with temperature sensors 74 indicated by their respective connections, which monitor the operational parameters of the drive system for protection and control purposes.

[0394] - An energy recovery system 91 and brake chopper 92 block that show how excess energy is managed in the system, with the recovery system possibly incorporating comprises for returning energy back to the power source or storage. - External connection interfaces 84, including CAN / IO and STO signaling.

[0395] - An encoder 86 input categorized under the torque sensor 85, hinting at the feedback mechanism for motor positioning and speed control.

[0396] Additionally, the figure exhibits isolation protocols to ensure that the control electronics are electrically isolated from high-power components for safety and signal integrity.

[0397] Fig. 11 is a perspective partial view of a detail of the rotor 41 of the electric load and drive unit 1 of the disclosure.

[0398] The rotor 41 is disc-shaped and attached around the circumference of the rotor 41 are several magnets 44. The central axis 45 is marked with a dashed line, indicating the central rotation point around which the rotor 41 and attached magnets 44 move. This figure does not depict the entire rotor 41 assembly but provides a close-up view of parts, focusing primarily on a carrier structure of the rotor 41 and magnets 44 attached to it around its circumference. Each pair of magnets forms a V shape, with the point of the V directed towards the rotor’s central axis 45. This arrangement creates a balanced and efficient magnetic field that interacts with the stator windings to produce rotational motion of the rotor 41.

[0399] Fig. 12 shows a further cross-section through an electric load and drive unit 1 of the disclosure.

[0400] The diagram shows an assembly of the electric load and drive unit 1 with a cross-section to display its internal configuration.

[0401] Toothing pins 19 and toothing rollers 20 are inserted into the outer gearwheel 18, which interlock with the first cycloidal gearwheel 16 and the optional second cycloidal gearwheel 17. The rotor shaft 11 transmits motion from the rotor 41 that is surrounded by the stator 42. The rotor 41 with the first eccentric cam 12 and the second eccentric cam 13 drives the corresponding cycloidal gearwheels 16 and 17.

[0402] The electric load and drive unit 1 includes a drive disc 24 - not shown here - carrying multiple drive pins 25 and drive rollers 26 for transmitting rotational movement. The drive shaft 51 is shown as a hollow structure configured with a friction bearing 29 - not shown here - and an adapter shaft 28 which includes the inner adapter toothing 30 and the outer adapter toothing 31. The adapter shaft 28 transmits torque from an external user to the gearbox, via the drive shaft 51 .

[0403] Around the periphery, there is an array of drive pins 25 with drive rollers 26 mounted on them, contributing to the transmission of rotational movement. These drive rollers 26 engage with the gear elements during the operation of the machine. Housing bolts 146 can be seen securing the components within the central housing part 141 of the gearbox.

[0404] Fig. 13: the detailed view of the gearbox of Fig. 12, without the rotor 41 . One can see that the Rotor Shaft 11 drives the First Eccentric Cam 12 and the Second Eccentric Cam 13, though the second cam being optional. These cams drive the First Cycloidal Gearwheel 16 and the Second Cycloidal Gearwheel 17, if present, which interact with the toothing system of the Outer Gearwheel 18.

[0405] The rotor shaft 11 drives both eccentric cams 12 and 13, which in turn drive their respective cycloidal gearwheels 16 and 17 with a 180-degree offset between the cams 12, 13. The toothing pins 19, made with finished or smoothed surfaces by grinding, are inserted into the cylindrical pockets 21 of the outer gearwheel 18. These pins 19 support the toothing rollers 20, which extend beyond the thickness of both cycloidal gearwheels, maintaining continuous contact with both of them at the same time. The cylindrical pockets 21 in the outer gearwheel house and support the toothing rollers 20, transmitting the forces on the rollers into the outer gearwheel 18 and from there into the housing, ensuring efficient load distribution and high precision. The toothing pin disc 25, best seen in Fig. 7, interconnects all toothing pins 19, providing extra stability.

[0406] As one can see in Fig. 13, the overlapping cylindrical holes in the first and second cycloidal gearwheels 16 and 17 form an inner gearwheel 22. The drive rollers 26, mounted on the drive pins 25, contact the inner surfaces of these holes, transmitting rotational movement from the cycloidal gearwheels to the drive disc 24 and the drive shaft 51 . The drive shaft 51 , integrated with the drive disc 24, transmits the reduced speed and increased torque over the adapter shaft 28 to the fitness machine and the user, supported by a tapered roller bearing 52 at one end and a counter bearing 53 at the opposite end, ensuring smooth operation.

[0407] Fig. 14 shows a perspective view of an encoder disc 43, which is part of the sensing and control system in the electric load and drive unit 1 designed for a fitness machine. The encoder disc 43 is circular with an array of conductive segments 450 around its periphery, the segments 450 encoding rotational information. A central axis 45 is the point around which the disc would rotate.

[0408] Fig. 15 is a further detailed perspective view of the electric load and drive unit 1 of the disclosure.

[0409] The rotor shaft 11 is the central rotating component to which other parts are mounted, including the first eccentric cam 12 and the second eccentric cam 13 (not shown in Figure 15), which are driving the cycloidal gearwheels 16, 17, with the second eccentric cam 13 being optional and offset by 180 degrees from the first eccentric cam 12. Attached to the cams 12, 13 are the first and second cam bearings 14, 15 for smooth rotation. The first cycloidal gearwheel 16 and the optional second cycloidal gearwheel 17 engage with the toothing pins 19 inserted into the cylindrical pockets 21 of the outer gearwheel, not visible in this section.

[0410] The drive disc 24 carries multiple drive pins 25, which are linked to drive rollers 26 responsible for transmitting rotational movement. The toothing pin disc 27 is present, and the stator 42 surrounds part of the rotor 41 . The motor control board 60 is seen right next to the stator 42, housing electronic components for controlling the electric motor and sensors. The drive shaft 51 is indicated, which is designed to be hollow, containing an adapter shaft 28 - not shown here - for torque transmission.

[0411] First and second rotor bearings 54, 55; 56, 57 are positioned on either side of the rotor shaft 11

[0412] The assembly of the rotor 41 , as depicted in Figures 11 and 15, involves assembling the rotor 41 arranging the magnets 44. These magnets 44 are positioned in pairs around the circumference of the rotor 11 , forming a V shape with the point of the V directed towards the rotor’s central axis 45. Multiple rotor layers 47 are then mounted onto the rotor sleeve 46. These layers 47 are aligned to ensure that the magnets 44 are correctly positioned and secured.

[0413] The rotor sleeve 46, with the rotor layers 47 and magnets 44, is mounted onto the rotor shaft 11 . The rotor sleeve 46 ensures that all components remain aligned and function as a single unit. The first rotor bearing 54 is installed on one side of the rotor shaft 11 , away from the eccentric cams. The second rotor bearing 55, which can be a double rolling bearing or two single rolling bearings in the form of the first cam bearing 56 and the second cam bearing 57, is installed on the other side of the rotor shaft 11 , close to the first eccentric cam 12 and the second eccentric cam 13. These bearings support the rotor shaft 11 and ensure its rotational movement.

[0414] The encoder disc 43 is then mounted on the rotor shaft 11 .

[0415] Fig. 16 illustrates a mid-mounted bicycle engine 300 incorporating an advanced electric load and drive unit 1. This embodiment showcases a compact design that efficiently integrates a cycloidal gearbox 303 and energy-harvesting features for optimal power transmission and torque control.

[0416] At the core of the assembly is the single-stage cycloidal gearbox 303. The rotor shaft is connected to a motor 302 and features a first eccentric cam 12 and a second eccentric cam 13, the latter offset by 180 degrees relative to the first cam. These eccentric cams drive the first cycloidal gearwheel 16 and the second cycloidal gearwheel 17, which are configured to mesh with the inner toothing of the outer gearwheel 18. The outer gearwheel, also referred to as the ring gear, contains cylindrical pockets 21 that house toothing pins 19, ensuring precise engagement and smooth force transmission. The gearbox is a robust yet efficient mechanism designed to handle dynamic loads, making it useful for a bicycle engine that requires continuous and adaptive resistance control.

[0417] The Drive Disc 24 is a central component that connects the cycloidal gearbox 303 to the drive shaft 51 . Its primary function is to transmit rotational movement generated by the first and second cycloidal gearwheels 16, 17 to the drive shaft. In typical configurations of a cycloidal gearbox, the drive disc holds multiple Drive Pins 25, which act as intermediaries for transmitting torque from the gearwheels. The Drive Rollers 26, which are mounted on the Drive Pins 25, facilitate the smooth transmission of rotational force from the First Cycloidal Gearwheel 16 and Second Cycloidal Gearwheel 17 to the Drive Disc 24. These rollers help minimize friction and wear during the operation of the gearbox and ensure the efficient transfer of torque.

[0418] The entire system is enclosed within a casing 301 . A chain ring adapter 304 connects the assembly to the bicycle’s drivetrain, facilitating effective power transfer to the wheels. The central axis 45 serves as the alignment point for all components, ensuring precise rotational balance and efficient energy transfer throughout the system.

[0419] In an embodiment not shown here, the cycloidal-type gearbox section from the bicycle engine 300 of Fig. 16 is incorporated into the electric load and drive unit 1 shown in Figs. 1 to 15, replacing the cycloid-type gearbox section in this embodiment.

[0420] In particular, the outer gearwheel or ring gear 18 from Fig. 16, which represents a drive for a bicycle, has been replaced with a configuration that incorporates toothing pins 19 and toothing rollers 20. This adjustment enhances force transmission and aligns with the structural and functional demands of the fitness machine’s load and drive unit. The inclusion of these additional components supports balanced load distribution and durability, making the system more suited for applications where controlled resistance and energy conversion are involved.

[0421] In addition, the drive disc 24 in the bicycle application, shown in Fig. 16, has been modified for its use in the embodiment that is not shown here, by integrating drive pins 25 and drive rollers 26. This adaptation refines torque transmission and supports adjustable resistance, which is relevant in guided exercise systems. The addition of these components enhances the interaction between the load and drive unit and the torque sensor system, allowing for precise load control and smooth energy transfer. This configuration supports a fitness machine environment by enabling variations in resistance and bidirectional energy flow.

[0422] Figures 17-20 illustrate a cycloidal gearbox 303 in the embodiment that is not shown here.

[0423] Figs. 17 to 20 provides a detailed perspective of the cycloidal gearbox 303 and its components, which are needed to the functionality of a fitness machine. Each figure highlights specific features and the arrangement of components that contribute to the transmission of rotational motion and torque.

[0424] Fig. 17 illustrates a top-down view of the cycloidal gearbox 303, showcasing the spatial arrangement of the key gear components. Central to this figure are the first cycloidal gearwheel 16 and the second cycloidal gearwheel 17, which interact with the outer gearwheel 18. The outer gearwheel 18, also referred to as the ring gear, encases the cycloidal gearwheels and serves as a stationary reference point for the transmission of torque. Within the inner region of the cycloidal gearwheels, a ball bearing 306 is visible, providing rotational stability and ensuring that the gear assembly operates smoothly. The alignment of the cycloidal gearwheels 16 and 17 within the outer gearwheel 18 ensures torque transfer with less mechanical losses. This figure emphasizes the cycloidal motion achieved by the interaction of these components.

[0425] Fig. 18 presents a cross-sectional view of the cycloidal gearbox 303, offering a detailed look at the internal arrangement of the components. The first cycloidal gearwheel 16 and the second cycloidal gearwheel 17 are shown meshing with the inner toothing 180, which is configured as an inwardly oriented cycloidal structure following a perimeter of the outer gear wheel 18. This interaction facilitates the precise transmission of ferees from the cycloidal gearwheels 16, 17 to the outer gearwheel 18. The ball bearing 306 is depicted in multiple positions, illustrating its role in providing support and reducing friction within the assembly. Additionally, the drive disc 24 is visible, connected to the gear system to transmit rotational motion to the drive shaft 51 . Mounted on the drive disc 24 are the drive rollers 26, which engage with the cycloidal gearwheels to facilitate the smooth transfer of torque. This figure highlights the importance of the cycloidal gearwheels' alignment and the interaction between the toothing pins 19 and the drive rollers 26 in achieving efficient power transmission.

[0426] As shown in Fig. 18, the central axis 45 defines the main rotational axis about which some of the elements of the gear box are symmetrically arranged. The inner toothing 180 of the outer gearwheel 18 is fixed relative to the housing and provides stationary engagement points for a corresponding first cycloidal structure 160 of the first cycloidal gearwheel 16 and a corresponding second cycloidal structure 170 of the second cycloidal gearwheel 17, which engagement points are also referred to as toothing pins 19 in the present disclosure, which may carry toothing rollers 20. In the embodiments shown in Figures 17-19, the toothing pins 19 are defined by a continuous cycloidal inner toothing arranged at an outer perimeter of the outer gearwheel 18.

[0427] The first cycloidal gearwheel 16 and the second cycloidal gearwheel 17 are arranged in parallel, forming a double row configuration. Each cycloidal gearwheel 16, 17 is eccentrically driven by the double eccentric rotor shaft 11 , which imparts a cycloidal motion to the gearwheels 16, 17 via the first 12 and second eccentric cam 13. As the gearwheels 16, 17 rotate, their respective cycloidal structure 160, 170 engages with the toothing pins 19 of the outer gearwheel 18 in a rolling motion, enabling the conversion of high-speed, low-torque input from the rotor into low-speed, high-torque output. The double row arrangement ensures that the forces are distributed symmetrically, reducing localised surface pressure and enhancing the durability and efficiency of the gearbox.

[0428] The drive disc 24 is mechanically coupled to the output side of the gearbox. When torque is input to the rotor shaft 11 , the drive disc 24 is the driven gear in this assembly receiving rotational movement from the cycloidal gearwheels 16, 17. The drive disc 24 carries drive rollers 26, which are mounted on the driving pins 25. These drive rollers 26 are in rolling contact with corresponding cylindrical receiving structures 161 , 172 of the first cycloidal gearwheel 16 and the second cycloidal gearwheel 17, respectively. In the embodiment shown in Figure 18, the drive rollers 26 extend into the receiving structures 161 , 171 , which are formed as cylindrical holes in the respective cycloidal gearwheel 16, 17.

[0429] As the cycloidal gearwheels 16, 17 move, the drive rollers 26 transmit the resulting rotational movement to the drive disc 24, and from there to the output shaft 51 . This arrangement reduces friction and wear, ensuring smooth and efficient torque transfer.

[0430] Fig. 19 provides an exploded view of the cycloidal gearbox 303, clearly presenting the individual components and their arrangement. The outer gearwheel 18, the first cycloidal gearwheel 16, and the second cycloidal gearwheel 17 are shown separately, emphasizing their respective roles in the gearbox's operation. The ball bearing 306 is prominently displayed, illustrating its integration into the gear assembly to support the rotational axis and maintain alignment. The drive disc 24 is positioned at the output side of the gearbox, demonstrating its connection to the cycloidal gearwheels through the drive rollers 26. The toothing pins 19 are also highlighted, showcasing their placement within the outer gearwheel 18 and their function in meshing with the cycloidal gearwheels. This figure provides insight into the modular construction of the gearbox, which facilitates assembly and maintenance.

[0431] Fig. 20 offers a front-facing view of the cycloidal gearbox 303, focusing on the engagement between the first cycloidal gearwheel 16, the second cycloidal gearwheel 17, and the outer gearwheel 18. The toothing pins 19 are depicted in their positions within the cylindrical pockets 21 of the outer gearwheel 18, ensuring a secure and precise connection with the cycloidal gearwheels. The drive rollers 26 are shown in contact with the inner surfaces of the cycloidal gearwheels, highlighting their role in transmitting rotational motion to the drive disc 24. This view emphasizes the relationship between the cycloidal gearwheels and the outer gearwheel.

[0432] The embodiment depicted in Figs. 17 to 20 demonstrates the intricate design and functionality of the cycloidal gearbox 303 within the mid-mounted bicycle engine 300. The first cycloidal gearwheel 16 and the second cycloidal gearwheel 17, driven by the rotor shaft 11 through the eccentric cams, drive the outer gearwheel 18 to achieve torque transmission. The integration of the drive disc 24 and the drive rollers 26 further ensures the transfer of power to the drive shaft 51.

[0433] The transfer of torque from the motor to the adapter shaft 28 is achieved through a precise sequence of mechanical interactions within the gearbox assembly, as illustrated in Figs. 15 to 20.

[0434] The process begins with the motor, which is directly coupled to the rotor shaft 11 . As pointed out in the above, the rotor shaft 11 is provided with the double eccentric arrangement, realised by mounting the first eccentric cam 12 and the second eccentric cam 13 offset by 180 degrees as shown in Fig. 18. As the motor rotates the rotor shaft 11 at high speed and low torque, these eccentric cams 12, 13 impart an eccentric, cycloidal motion to the first cycloidal gearwheel 16 and the second cycloidal gearwheel

[0435] 17, which are arranged in parallel to form the double row configuration, see Figs. 17 and

[0436] 18.

[0437] The cycloidal gearwheels 16, 17 are each provided with the respective first 160 and second 170 cycloidal structure on their respective outer periphery, which engage with the static inner toothing 180 of the outer gearwheel 18. The inner toothing 180 ist fixed relative to the housing and does not rotate, providing stationary engagement points for the cycloidal gearwheels 16, 17, which are also referred to as toothing pins 19 in the present disclosure.

[0438] As the eccentric motion is imparted to the cycloidal gearwheels 16, 17, their cycloidal structures 160, 170 roll along inner toothing of the outer gearwheel 180, converting the high-speed, low-torque input from the rotor shaft 11 into a low-speed, high-torque output. This conversion is achieved by the reduction ratio inherent in the cycloidal gearbox design, which is dependent, among other things, on a ratio between the number of teeth carried by each of the first 16 and second gearwheel 17, and the number of toothing pins 19.

[0439] The rotational movement of the cycloidal gearwheels 16, 17 is then transferred to the drive disc 24, which is positioned at the output side of the gearbox (see Fig. 18). The drive disc 24 is the driven gear in this assembly and is mechanically fixed to the drive shaft 51 .

[0440] The interface between the cycloidal gearwheels and the drive disc 24 is realised by drive rollers 26, which are mounted on drive pins 25 affixed to the drive disc 24 along a circular path around the drive shaft 51 , This arrangement may best be seen in Fig. 19. The drive rollers 26 extend into and are in rolling contact with the receiving structures 161 , 171 of the cycloidal gearwheels 16, 17, which, as mentioned above, are formed as holes in the respective cycloidal gearwheel 16, 17. The receiving structures 161 , 171 are arranged along respective circular paths in the respective cycloidal gearwheels 16, 17, on a radius that corresponds to a radius on which the drive pins 19 are arranged on the drive disc 24. In order to allow for the rolling contact, an outer radius of each of the drive rollers 26 is smaller than a radius of the corresponding receiving structure 161 , 171 , which may best be seen in Figure 20.

[0441] As the cycloidal gearwheels 16, 17 move, the drive rollers 26 transmit the resulting rotational movement to the drive disc 24, ensuring smooth and efficient torque transfer with little friction and wear.

[0442] The drive disc 24, being fixed to the drive shaft 51 , causes the drive shaft 51 to rotate in unison. The drive shaft 51 is provided as a hollow structure, as shown in Figure 16. The drive shaft 51 transmits the output torque directly to the adapter shaft 28, which is inserted into the hollow centre of the drive shaft 51 and coupled via an inner adapter toothing 30 and an outer adapter toothing 31 (see also Fig. 12 for the toothing arrangement).

[0443] The adapter shaft 28 serves as the mechanical interface to the user, allowing the user to apply or receive torque via cranks, levers, or other user-operated elements. The torque generated by the motor and modulated by the gearbox is thus delivered to the user through the adapter shaft 28, enabling precise resistance control and feedback in fitness machine applications.

[0444] In summary, the torque path is as follows:

[0445] Motor —> rotor shaft 11 (with double eccentric cams 12, 13) • Rotor shaft 11 — first and second cycloidal gearwheels 16, 17 (via eccentric motion)

[0446] • Cycloidal gearwheels 16, 17 — > roll along static outer gearwheel 18 (via interaction of first cycloidal structure 160, second cycloidal structure 170, and inner toothing I toothing pins 19 of outer gearwheel 18)

[0447] • Cycloidal gearwheels 16, 17 — > drive rollers 26

[0448] • drive rollers 26 — drive pins 25 of drive disc 24 (driven gear)

[0449] • Drive disc 24 — drive shaft 51 (fixed connection)

[0450] • Drive shaft 51 — adapter shaft 28 (via adapter toothing 30, 31 )

[0451] This arrangement ensures that the high-speed, low-torque output of the motor is efficiently converted and delivered as low-speed, high-torque output to the user. Figures 21-26 show different views of a load and drive unit according to the invention.

[0452] Figs. 21 to 26 depict various views of an electric load and drive unit 1 .

[0453] Fig. 21 shows a perspective view of the electric load and drive unit 1 . The central housing part 141 houses the internal gearbox components. The gearbox cover 142 is attached to one side of the central housing part 141 . The motor control cover 143 is located on the opposite side, providing an enclosure for the motor control system that includes elements such as the motor control board 60 and the motor control unit 61 .

[0454] In Fig. 22, the opposite perspective view of the electric load and drive unit 1 reveals additional structural features. The motor control cover 143 now faces the viewer.

[0455] Fig. 23 provides a frontal view of the electric load and drive unit 1 , focusing on the gearbox cover 142. The intricate pattern of vent-like features on the gearbox cover 142 enhances cooling efficiency, ensuring optimal thermal management during operation. The central opening within the gearbox cover 142 allows for the integration of components such as the rotor shaft 11 or other transmission elements.

[0456] Fig. 24 offers a rear view of the electric load and drive unit 1 , centering on the motor control cover 143. Fig. 25 provides a side view of the electric load and drive unit 1 , highlighting the alignment of the central housing part 141 , the gearbox cover 142, and the motor control cover 143.

[0457] Fig. 26 shows a top view of the electric load and drive unit 1 . The central housing part 141 dominates the view, flanked by the gearbox cover 142 and the motor control cover 143.

[0458] The embodiment shown in Figures 27 to 30 illustrates the integration of an adapter shaft with the electric load and drive unit. This setup demonstrates the adaptability and modularity of the drive system, allowing it to interface with different components or configurations.

[0459] In Fig. 27, the electric load and drive unit 1 is depicted in conjunction with an adapter shaft 28 extending vertically from the unit. The adapter shaft 28 is designed to transmit torque with the output of the drive unit.

[0460] Fig. 28 presents an alternative configuration where the adapter shaft 28 extends horizontally to both sides of the electric load and drive unit 1. This adaptability highlights the modular nature of the system, allowing for diverse implementation scenarios.

[0461] In Fig. 29, the adapter shaft 28 is shown extending in the opposite direction to the configuration in Fig. 27. The figure emphasizes the symmetry and reversible functionality of the drive system, as the adapter shaft 28 can be positioned on either side of the unit.

[0462] Fig. 30 combines both left and right orientations of the adapter shaft 28, similar to the embodiment in Fig. 28.

[0463] Fig. 31 illustrates a front view of a gym machine 200. The machine features a user seat 402 with an ergonomically shaped front pad 403 and grip assemblies 410 graspable by a user in different ways, ensuring user comfort during exercise. A display unit 400 is mounted at the top, providing interactive feedback and workout metrics. A machine frame 401 supports the entire structure, carrying two identical electric load and drive units 1 , which are responsible for generating adjustable resistance and converting mechanical energy into electrical energy. Respective lever arms 404 connect a respective resistance mechanism to the grip assemblies 410, which is positioned to interact with the user's limbs during exercise.

[0464] The force exerted by the user (Fuser), applied horizontally at the grip assemblies 410, is transferred through the lever arms 404 and the machine’s mechanical components to the electric load and drive units 1 . The load and drive units 1 can be any of the embodiments earlier described.

[0465] The dotted line in Fig. 31 indicates the sectional view shown in Fig. 32 and Fig. 33. Figure 32 shows a side view of the fitness machine.

[0466] Fig. 32 illustrates a side view of a gym machine 200, as seen in Fig. 31 , its spatial configuration and functional layout. The electric load and drive unit 1 is centrally integrated within the machine frame 401 .

[0467] The display unit 400 is mounted on an extended support structure, positioned for easy visibility and interaction during exercise. The machine frame 401 supports all mechanical and electrical components, ensuring a rigid and durable structure.

[0468] The angular range of motion 412, which in the current example may equal 45°, is adjustable in a range from 21 ° or lower to 86° or higher, which highlights the adaptability of the machine to different exercise intensities and user preferences. The height of 718 mm, indicating the center of the drive shaft from the floor makes it suitable for a variety of fitness environments.

[0469] This figure also highlights the integration of the electric load and drive unit 1 with the machine's mechanical arm 404, enabling energy transfer from the user's exercise movements to the load and drive system.

[0470] Figure 33 shows details of an alternative fitness machine. Fig. 33 presents a detailed view of a specific mechanical component of a fitness machine which is commonly known as a leg extension machine, focusing on the lever arm 404 and a roller pad 405 that transfers the user-applied force Fuser, which is in the present example directed at a steep angle relative to the vertical direction, to the electric load and drive unit 1. The lever arm 404 features an adjustable lever adjustment 406, with labeled lengths l_Max and l_Min, allowing the machine to cater to users of different sizes and exercise preferences. The roller pad 405 at the end of the arm 404 provides a comfortable interface for the user, ensuring effective force transfer while maintaining user comfort. The mechanical arm assembly is securely connected to the central frame of the machine, enabling stable and controlled motion.

[0471] Figure 34 shows a block diagram illustrating energy recovery in a gym plant with several fitness machines as shown in the Figures before. Fig. 34 illustrates the interaction between multiple gym machines 200 and an overall energy recovery infrastructure. The gym machines 200, labeled as Gym Machine 1 , Gym Machine 2, and Gym Machine N, are connected in parallel to a power network 209 via AC socket outlets 205 and AC plugs 206, forming an integrated network for energy management.

[0472] At the center of Gym Machine 1 , the bidirectional PFC 204 facilitates the conversion and management of electrical energy. The motor / generator drive unit 203 generates electrical energy during user exercise, which is stored temporarily in DC link capacitors 202. The DC link capacitors 202 stabilize the energy flow and store excess energy temporarily, ensuring smooth operation and preventing surges. This energy is further used to power auxiliary components such as the 24V display supply 201 , which provides power for user-facing displays and controls.

[0473] The bidirectional PFC 204 also plays a role in converting the stored DC energy into AC power, making it compatible for transmission back to the power network 209 through power cables 208. The power cables 208 link the gym machines 200 to the power network 209, enabling energy generated by the machines to be reused within the facility or fed back into the larger grid.

[0474] The AC socket outlets 205 and AC plugs 206 provide the modularity and connectivity of the system. They allow individual gym machines 200 to be easily connected or disconnected from the energy recovery network. This modular design ensures flexibility in configuring the gym plant and facilitates maintenance or upgrades without interrupting the operation of the entire system.

[0475] To apply the disclosure, one can use the following concepts. These concepts can be used individually or in combination with two or more others.

[0476] (1 ) One of the concepts of the disclosure is a single-stage cycloidal gearbox design. This gearbox provides resistance control by using components such as the rotor shaft 11 , eccentric cams, cycloidal gearwheels, and toothing pins 19. The design employs two or more cycloidal gearwheels to provide symmetric forces within the gearbox. This configuration reduces individual surface pressure, contact pressure per unit area, seating stress, and bearing pressure within the toothing, thereby improving performance and durability compared to gearboxes with fewer gearwheels. Alternatively, Harmonic Drive gearboxes or Harmonic Pin Ring (HPR) Drives can be used.

[0477] (2) Another conceptual contribution is the torque sensor system 71 , which measures torsion in the drive shaft 51 between an inner adapter toothing 30 and a drive disc 24. The torque sensor system 71 utilizes a single-piece flexible PCB that includes the strain gauge pad 81 and connection strip 82. The energy harvesting coil 83 and strain gauge conductor trace are structured in a metal layer of the PCB, providing a compact and efficient design.

[0478] (3) The disclosure also comprises a concept of an energy harvesting unit that captures electrical energy from the stator 42’s electric field to power the torque sensor system 71 . This eliminates the need for external power cables, enhancing the system's autonomy and reliability.

[0479] (4) To transmit data cable-free from the torque sensor system 71 , the disclosure employs a concept of an optical transmission system. This system includes one or more transmission LEDs, with the emitted light signals received by one or more light receiver elements 73 arranged around the perimeter of the shaft opening 63. This arrangement provides redundancy and reliability in data transmission. Additionally, an optional embodiment with two or more transmission LEDs, preferably six transmission LEDs, arranged 180 degrees apart minimizes energy consumption. (5) A voltage-controlled oscillator (VCO) can be used used to modulate the voltage drop over the strain gauge, which represents another concept, encoding the measured torsion into the light emitted by the transmission LED 79. This method allows for precise transmission of torsion changes with a resolution as low as 0.01 Nm, ensuring accurate and reliable data output.

[0480] (6) The integration of the strain gauge and energy harvesting coil 83 into a single-piece flexible PCB is another optionally available concept. The connection strip 82, carrying the strain gauge pad 81 and energy harvesting coil 83, extends through a transfer pocket 58 in the drive shaft 51 and a shaft opening 63 in the motor control board 60, exposing the coil to the electromagnetic field of the stator 42.

[0481] (7) A bearings configuration concept is designed to support the drive shaft 51 and ensure rotational movement. The first and second rotor 41 bearings are positioned between the rotor shaft 11 and the drive shaft 51 , with the second rotor bearing 55 configured as a double rolling bearing or two single rolling bearings spaced under the eccentric cams. Additionally, tapered roller bearings and a counter bearing 53 can be positioned between the drive shaft 51 and the housing.

[0482] (8) To maintain bearing clearance or play, the gearbox cover 142 and motor control cover 143 can be made from the same materials, for example steel, with spacer sleeves 145 and housing bolts ensuring that the bearing clearance remains constant despite temperature changes. This configuration concept allows the central housing part 141 to be made from aluminum, which improves cooling of the stator 42 and the brake chopper 92 housed within it. The central housing part 141 is designed to accommodate the stator 42 and elastic seals, such as rubber rings, are provided in corresponding grooves to offer temperature tolerances between the central housing part 141 , motor control cover 143, and gearbox cover 142, and to prevent dirt and moisture from entering the unit.

[0483] (9) The area of the drive shaft 51 between the first and second rotor 41 bearings functions as a load cell for measuring torque. In combination with the optical and energy harvesting, this ensures accurate and reliable data transmission. (10) The disclosure also includes an optional brake chopper 92, which can be provided in a brake chopper seating 144 within the central housing part 141. In an alternative concept, the brake chopper 92 is omitted, and the electrical energy generated by the rotor 41 's movement is recuperated and fed back to the ports "DC / DC out" and "24V_ISO," enabling the fitness machine to operate without an external power supply or at least reducing device warming.

[0484] (11 ) The compact and rotationally symmetric design concept of the device allows for short cable paths between the motor control board 60 and other components, with all cables housed internally. Only two external cables are required: one for the user interface and optionally one for the power supply, contributing to a streamlined and efficient design.

[0485] (12) The motor control board 60 (MCB) is capable of controlling the angular position, speed, and torque of the drive shaft 51 , providing precise control over the fitness machine's operation.

[0486] (13) The rotor 41 design can incorporate several pairs of magnets arranged in a V pattern around its circumference. Each pair of magnets forms a V shape, with the point of the V directed towards the rotor 41 ’s central axis 45. This arrangement creates a balanced and efficient magnetic field that interacts with the stator 42 windings to produce rotational motion. Additionally, the rotor 41 can comprise multiple rotor layers 47 mounted onto a hollow cylindrical rotor sleeve 46, which is then mounted onto the rotor shaft 11 .

[0487] (14) To enhance user comfort and reduce operational noise, the disclosure incorporates a shock absorber mechanism. This mechanism prevents hard surface interactions, reducing noise and vibration. It comprises shock absorbers 101 made from rubber-like deformable plastic, a stopper block 102 made from rigid material, a stopper arm 103 that acts against the stopper block 102, and a slotted link that limits movement with shock absorbers 101. Lubrication ensures operation of the roller bearings under intermittent movement and high loads. Lubrication includes a high-viscosity lubricant with anti-wear additives for low-speed, high-load applications. Protection may be sought for combinations of features which are disclosed in the referenced earlier patent applications DE102024118511 .2 of 01 July 2024, EP25165815.9 of 25 March 2025, and and EP25186451 .8 of 30 June 2025, the contents of which are herein incorporated by reference. It is disclosed there how these features combinations contribute to achieving the technical aim of the present application and they are thus comprised in the solution of the technical problem underlying the subject matter of the present application. The features and combinations which are disclosed in the reference documents implicitly belong to the description of the subject matter in the present application and thus to the content of the present application as filed.

[0488] REFERENCE NUMBERS LIST

[0489] I Electric load and drive unit

[0490] I I Rotor Shaft

[0491] 12 First Eccentric Cam

[0492] 13 Second Eccentric Cam

[0493] 14 First Cam Bearing

[0494] 15 Second Cam Bearing

[0495] 16 First Cycloidal Gearwheel

[0496] 17 Second Cycloidal Gearwheel

[0497] 18 Outer Gearwheel (Ring Gear)

[0498] 19 Toothing Pins

[0499] 20 Toothing Rollers

[0500] 21 Cylindrical Pockets

[0501] 22 Inner Gearwheel

[0502] 23 Limiter

[0503] 24 Drive Disc

[0504] 25 Drive Pins

[0505] 26 Drive Rollers

[0506] 27 Toothing Pin Disc

[0507] 28 Adapter Shaft

[0508] 29 Friction Bearing

[0509] 30 Inner Adapter Toothing

[0510] 31 Outer Adapter Toothing

[0511] 41 Rotor

[0512] 42 Stator

[0513] 43 Encoder Disc

[0514] 44 Carrier

[0515] 45 Central Axis

[0516] 46 Coating

[0517] 47 Rotor Layers

[0518] 51 Drive Shaft

[0519] 52 Tapered Roller Bearing

[0520] 53 Counter Bearing 54 First Rotor Bearing

[0521] 55 Second Rotor Bearing

[0522] 58 T ransfer Pocket

[0523] 60 Motor Control Board

[0524] 61 Motor Control Unit

[0525] 62 Detector Coil System

[0526] 63 Shaft Opening

[0527] 64 DC input

[0528] 65 AC input

[0529] 66 DC / DC Converter

[0530] 67 Input Section

[0531] 68 Gate Driver

[0532] 69 2-level Voltage Source Inverter

[0533] 70 Safe Torque Off (STO)

[0534] 71 Torque Sensor System

[0535] 72 LEDs for Optical Transmission

[0536] 73 Light Receiver Elements

[0537] 74 Temperature Sensors

[0538] 75 Current Sensors

[0539] 76 Voltage Sensors

[0540] 77 Optical Torque Transmission System

[0541] 78 VCO (Voltage-Controlled Oscillator)

[0542] 79 Transmission LED

[0543] 80 Reception LED

[0544] 81 Strain Gauge Pad

[0545] 82 Connection Strip

[0546] 83 Energy Harvesting Coil

[0547] 84 External Connection Interfaces

[0548] 85 Torque Sensor

[0549] 86 Encoder

[0550] 91 Energy Recovery System

[0551] 92 Brake Chopper

[0552] 101 Shock Absorbers

[0553] 102 Stopper Block 103 Stopper Arm

[0554] 104 Slot in Stopper Arm

[0555] 111 Special Lubricant

[0556] 121 Connection Cable to User Display

[0557] 131 Power Supply Cable

[0558] 141 Central Housing Part

[0559] 142 Gearbox Cover

[0560] 143 Motor Control Cover

[0561] 144 Brake Chopper Seating

[0562] 145 Spacer Sleeves

[0563] 146 Housing Bolt

[0564] 147 Mounting Hole

[0565] 160 first cycloidal structure

[0566] 161 first receiving structure

[0567] 170 second cycloidal structure

[0568] 171 second receiving structure

[0569] 200 Gym Machine

[0570] 201 24V Display supply

[0571] 202 DC link capacitors

[0572] 203 Motor / Generator drive unit

[0573] 204 Bidirectional PFC (power factor corrector)

[0574] 205 AC socket outlet

[0575] 206 AC plug

[0576] 207 power cable

[0577] 208 power line

[0578] 209 power network

[0579] 300 mid-mounted bicycle engine

[0580] 301 casing

[0581] 302 motor

[0582] 303 gearbox

[0583] 304 chain ring adapter 306 ball bearing

[0584] 400 Display unit

[0585] 401 Machine frame 402 User seat

[0586] 403 Front Pad

[0587] 404 Lever arm

[0588] 405 Roller pad

[0589] 406 Lever adjustment 412 Angular Range of Motion

[0590] 410 Grip Assemblies

[0591] 450 Conductive Segments

Claims

CLAIMS1 . An electric load and drive unit (1 ) for a fitness machine, comprising: a drive shaft (51 ), a rotor shaft (11 ) configured to transmit motion from an electric motor (302) to a gearbox, the rotor shaft (11 ) being coaxially arranged with the drive shaft (51 ) and extending through a centre of the gearbox to transmit motion from the motor to the gearbox, the gearbox operatively arranged between the drive shaft (51 ) and the rotor shaft (11 ); wherein the gearbox is configured as one of a single-stage cycloidal gearbox, a Harmonic Pin Ring (HPR) type gearbox, and a Harmonic Drive type gearbox.

2. The electric load and drive unit (1 ) according to claim 1 , wherein the motor (302) is positioned adjacent to the cycloidal gearbox, with a stator (42) and a rotor (41 ) arranged such that rotational output from the rotor shaft (11 ) is directly coupled to the input of the gearbox.

3. The electric load and drive unit (1 ) according to any one of claims 1 and 2, wherein the drive shaft (51 ) is supported by a tapered roller bearing (52) at one end and a counter bearing (53) at the opposite end.

4. The electric load and drive unit (1 ) according to any one of claims 1 to 3, wherein the drive shaft (51 ) is provided as a hollow structure that carries an adapter shaft (28), with a friction bearing (29) and an adapter toothing (30, 31 ) being provided for transmitting torque from the adapter shaft (28) over the drive shaft (51 ) to the gearbox.

5. The electric load and drive unit (1 ) according to any one of claims 1 to 4, wherein the gearbox is configured as a single-stage cycloidal gearbox comprising at least one eccentric cam (12, 13) provided on the rotor shaft (11 ), at least one first cycloidal gearwheel (16, 17) driven by a corresponding eccentric cam (12, 13) and meshing with toothing pins (19) of an outer gearwheel (18), and a drive shaft (51 ) operatively connected to the cycloidal gearwheel (16, 17).

6. The electric load and drive unit (1 ) according to claim 5, wherein the gearbox comprises a first eccentric cam (12) and a second eccentric cam (13) provided on the rotor shaft (11 ), and a first cycloidal gearwheel (16) and a second cycloidal gearwheel (17) each driven by a respective eccentric cam (12, 13).

7. The electric load and drive unit (1 ) according to any one of claims 1 to 6, comprising a torque sensor system (71 ) arranged on the drive shaft (51 ) such that at least parts of it rotate together with the drive shaft (51 ), the torque sensor system (71 ) being configured to measure torsion in the drive shaft (51 ), the torque sensor system (71 ) comprising: a sensor assembly mounted on the drive shaft (51 ) for detecting torsional deformation, the sensor assembly comprising: a strain gauge pad (81 ) for sensing strain resulting from applied torque.

8. The electric load and drive unit (1 ) according to any one of claims 1 to 7, comprising an inductive power transfer (IPT) system comprising a supply coil and a receiver coil (83) and being configured to provide electrical power to the torque sensor system (71 ).

9. The electric load and drive unit (1 ) according to claim 8, wherein the receiver coil (83) is arranged on a PCB that extends into a rotating region of the drive shaft (51 ) to supply power to the torque sensor system (71 ).

10. The electric load and drive unit (1 ) according to any one of claims 8 and 9, wherein the supply coil is arranged on a motor control board (60) and is fixed relative to a central housing part (141 ) of the electric load and drive unit (1 ).11 . The electric load and drive unit (1 ) according to any one of claims 7 to 10, comprising an optical transmission system configured to wirelessly transmit torque data, the optical transmission system comprising: at least one transmission LED (79) for sending torque data, mounted on the drive shaft (51 ); and at least one light receiver element (73) for receiving torque data, arranged stationary relative to the drive shaft (51 ) on a stationary structure, and electrically connected to a motor control board (60) for further processing of the received torque data.

12. The electric load and drive unit (1 ) according to claim 11 when dependent on claim 8, wherein the at least one transmission LED (79), the strain gauge pad (81 ), and the receiver coil (83) are electrically connected to a flexible PCB (82) affixed to the drive shaft (51 ) and extending along the drive shaft (51).

13. The electric load and drive unit (1 ) according to one of claims 11 and 12, wherein: the drive shaft (51 ) extends through a shaft opening (63) formed in the stationary structure; a plurality of transmission LEDs (79) are provided, distributed circumferentially around the drive shaft (51 ); and a corresponding plurality of light receiver elements (73) are arranged around a perimeter of the shaft opening (63) so as to receive optical signals transmitted from the transmission LEDs (79) on the rotating drive shaft (51 ) through the shaft opening (63).

14. The electric load and drive unit (1 ) according to any of claims 11 to 13, wherein the optical transmission system is configured to transmit modulated signals representing the measured torsion, the modulation being effected by a voltage- controlled oscillator (78) or a microcontroller unit (MCU) on the drive shaft (51 ).

15. Fitness machine with at least one actuator for a human, with an electric load and drive unit (1 ) according to any of claims 1 to 14, wherein the actuator is coupled to the drive shaft.

Images