Method of assembling a slewing ring bearing and a slewing ring bearing

Abstract

A method of assembling a slewing ring bearing, the slewing ring bearing comprising an outer slewing ring, an inner slewing ring configured for fitting within the outer slewing ring, an axial bearing provided between mutually facing surfaces of the outer slewing ring and the inner slewing ring, which surfaces face in an axial direction of the slewing ring bearing, a radial bearing formed between mutually facing lateral surfaces of the outer slewing ring and the inner slewing ring, and bearing balls provided between in the mutually facing lateral surfaces of the radial bearing, wherein the outer slewing ring comprises a first wall part and a second wall part, wherein the first wall part is ring-shaped, and comprises a surface which faces in the axial direction slewing ring bearing, wherein the second wall part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing, wherein an outmost diameter of the inner slewing ring is larger than an inner diameter of the outer slewing ring, and wherein the method comprises the steps of: arranging the inner slewing ring in the outer slewing ring, while providing an axial bearing there between, displacing the inner slewing ring in a radial direction relative to the outer slewing ring, thereby providing an temporarily a loading gap between the inner slewing ring and the outer slewing ring, which loading gap is dimensioned to receive a radial bearing ball, entering a plurality of radial bearing balls through the loading gap into the radial bearing, sliding the inner slewing ring in a radial direction and relative to the outer slewing ring to a concentric position of the outer slewing ring and the inner slewing ring, distributing the radial bearing balls equidistantly in the radial bearing, inserting one or more radial bearing ball for securing an even distribution of the plurality of bearing balls in the radial bearing, and adding an axial bearing seal to the axial bearing and / or a radial bearing seal to the radial bearing.

Description

[0001] METHOD OF ASSEMBLING A SLEWING RING BEARING AND A SLEWING RING BEARING

[0002] The present invention relates to method of assembling a slewing ring bearing. More particularly the invention relates to a method of assembling a slewing ring bearing of the type having an axial bearing and a radial bearing.

[0003] Background of the invention

[0004] Slewing ring bearings, also known as slewing bearings, as such are known from many applications. In general, slewing ring bearings are used for rotation when a device, machine, vehicle or installation has two adjacent structures, which must rotate relative to each other. Slewing ring bearings usually supports heavy load, often on a horizontal plane. However, many are designed to receive high axial, radial and tilting moment load, regardless of the plane of rotation. Equally slewing ring bearings are expected to accommodate for thrust forces in all directions while maintaining the ability to rotate.

[0005] Slewing ring bearings comprises one inner and one outer ring, typically arranged with one or more rows of bearing elements (for example rolling elements, such as balls, cylindrical rollers, conical rollers, etc) arranged between them to decrease friction between the inner and outer ring.

[0006] Slewing ring bearings are hollow, hereby achieving the ability to contain components, such as bearing elements, within, which benefits a great variety of systems. A large diameter further distributes thrust and moment forces on the slewing ring bearing to a larger area, thereby lowering stress on smaller bearing types.

[0007] In general, prior art bearings are either made from

[0008] - multiple outer or inner rings enclosing multiple rows of bearing races and bearing elements and secured to each other by fasteners; or - solid rings known as four-point-contact bearings, which are provided with large radial holes for the purpose of loading rolling elements in between the rings.

[0009] In the latter case, the loading hole weakens the body, and to compensate more material is needed for the rings.

[0010] The French patent application FR372314 discloses a solid outer bearing ring. This disclosure reveals a radial ball bearing with additional axial ball bearing support, intended for rotational shafts. In order to assemble the bearing, the bearing races are very small and thereby weak. Further, it is almost impossible to add a cage to the radial bearing. If FR372314 is required to handle opposite axial thrust, a second outer ring must be added using fasteners, similar to how slewing ring bearings are manufactured today. Further FR372314 is an ordinary bearing, and not a slewing ring bearing.

[0011] DE845927 discloses a slewing ring comprising a solid outer slewing ring. A single row of an axial angular contact bearing is required to handle both axial and radial thrust. Any axial moment thrust is supposed to be received by a waved spring ring, with the primary purpose of keeping the product together and not to facilitate rotation. It is uncertain how the spring element will be installed.

[0012] US 2007 0009191 discloses another bearing assembly. Even if the bearing comprises a solid outer bearing body, this bearing assembly do not accommodate for opposite axial thrust, but only axial and radial thrust. This while illustrating an invention, which does not seem to be able to be assembled, unless the outer metal sleeve is bent inwards as a finishing step of assembly.

[0013] Axial bearings are thrust bearings, which have applied load in an axial direction. Most axial bearings comprise numerous parts, such as rollers / rolli ng elements arranged in a bearing cage between to bearing races. The bearing is installed in a system like a machine. Before installation the components of the bearing are often loose, and the bearing may be taken apart, thus risking contamination and lost components. It is an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, which method makes it simpler to assemble and is therefore more cost efficient to manufacture.

[0014] It is further an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, that allows the bearing ring to be assembled from fewer parts.

[0015] It is also an objective of the invention to provide a slewing ring bearing, which is kept together as a single piece, in a manner which supports the rotation of the bearing.

[0016] It is also an objective of the invention to provide a slewing ring bearing which is capable of receiving considerable axial moment while supporting the rotation of the bearing.

[0017] It is further an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, where the method allows for inserting an increased number of bearing elements.

[0018] It is further an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, where the method allows for inserting larger bearing elements.

[0019] It is a further objective of the invention to provide an axial bearing which is kept together as a single piece, in a manner which supports the rotation of the slewing ring bearing, which is robust and capable of receiving radial thrust, and further being capable of receiving axial moment.

[0020] It is further an object of the invention to increase the variety of options.

[0021] Summary of the invention In a first aspect, the objects of the invention are achieved by a method of assembling a slewing ring bearing, the slewing ring bearing comprising

[0022] - an outer slewing ring,

[0023] - an inner slewing ring configured for fitting within the outer slewing ring,

[0024] - an axial bearing provided between mutually facing surfaces of the outer slewing ring and the inner slewing ring, which surfaces face in an axial direction of the slewing ring bearing;

[0025] - a radial bearing formed between mutually facing lateral surfaces of the outer slewing ring and the inner slewing ring, and

[0026] - radial bearing balls provided between in the mutually facing lateral surfaces of the radial bearing wherein the outer slewing ring comprises a first wall part and a second wall part, wherein the first wall part is ring-shaped, and comprises a surface which faces in the axial direction of the slewing ring bearing, wherein the second wall part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing, wherein an outmost diameter of the inner slewing ring is larger than an inner diameter of the outer slewing ring, wherein the method comprises the steps of:

[0027] - arranging the inner slewing ring in the outer slewing ring, while providing an axial bearing there between,

[0028] - displacing the inner slewing ring in a radial direction relative to the outer slewing ring, thereby providing an temporarily a loading gap between the inner slewing ring and the outer slewing ring, which loading gap is dimensioned to receive a radial bearing ball,

[0029] - entering a plurality of radial bearing balls through the loading gap into the radial bearing,

[0030] - sliding the inner slewing ring in a radial direction and relative to the outer slewing ring o a concentric position of the outer slewing ring and the inner slewing ring,

[0031] - distributing the radial bearing balls equidistantly in the radial bearing, and inserting one or more radial bearing ball distributers for securing an even distribution of the plurality of bearing balls in the radial bearing,

[0032] In an embodiment, the method further comprises adding an axial bearing seal to the axial bearing and / or adding a radial bearing seal to the radial bearing.

[0033] In an embodiment of the method the axial bearing comprises an axial angular contact bearing race provided in one of the outer slewing ring or the inner slewing ring, wherein a recess volume communicating with the axial angular contact bearing race is provided in the one of the outer slewing ring or the inner slewing ring on which the axial angular contact bearing race is provided, and wherein the method comprises the step axially displacing the other one of the outer slewing ring or the inner slewing ring on which the axial angular contact bearing race is provided, and tilting a portion of the radial bearing balls to enter the recess volume.

[0034] In further embodiments of the method, the step of inserting one or more radial bearing ball distributers for securing an even distribution of the plurality of bearing balls in the radial bearing comprises inserting a radial ball bearing cage.

[0035] In an embodiment thereof, the radial ball bearing cage is a crown bearing cage.

[0036] In another aspect, the objects of the invention are achieved by a slewing ring bearing comprising

[0037] - an outer slewing ring,

[0038] - an inner slewing ring configured for fitting within the outer slewing ring,

[0039] - an axial bearing provided between mutually facing surfaces of the outer slewing ring and the inner slewing ring, which surfaces face in an axial direction of the slewing ring bearing,

[0040] - a radial bearing formed between mutually facing lateral surfaces of the outer slewing ring and the inner slewing ring, and

[0041] - bearing balls provided between in the mutually facing lateral surfaces of the radial bearing, wherein the outer slewing ring comprises a first wall part and a second wall part, wherein the first wall part is ring-shaped, and comprises a surface which faces in the axial direction of the slewing ring bearing, wherein the second wall part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing, wherein an outmost diameter of the inner slewing ring is larger than an inner diameter of the outer slewing ring, and wherein the inner slewing ring is configured for fitting within the outer slewing ring such that the inner slewing ring is movable in a radial direction relative to the outer slewing ring, when no radial radial bearing balls are provided between in the mutually facing lateral surfaces of the radial bearing.

[0042] In one embodiment thereof, the axial bearing comprises an axial angular contact bearing race provided in one of the outer slewing ring or the inner slewing ring, wherein a recess volume communicating with the axial angular contact bearing race is provided in the one of the outer slewing ring or the inner slewing ring on which the axial angular contact bearing race is provided.

[0043] In either of the embodiments of either of the aspects of the invention, the axial bearings may comprise

[0044] - plain bearing races, or

[0045] - ball bearings in the combination with a bearing race of the groove-type, or

[0046] - barrel-type rollers with spherical surface on outer axial raceway, or

[0047] - Inverted spherical rollers with spherical surface on inner axial raceway, or

[0048] - ball bearing with inwards recessive area on outer angular axial raceway for axial displacement (tilting of inner race), or

[0049] - ball bearing with outwards recessive area on inner angular axial raceway for axial displacement (tilting of inner race)

[0050] In either of the embodiments of either of the aspects of the invention, the radial bearings may comprise

[0051] - a ball bearing with ball bearing race of the groove-type

[0052] - a ball bearing with angular contact ball bearings races it will be understood that the term ‘bearing race’ may also simply be called ‘race’.

[0053] Further, it will be understood that the term ‘bearing race’ or ‘race’ is sometimes also referred to as ‘bearing raceway’ or simply ‘raceway’.

[0054] In the case of ‘bearing races’ of the type used in ball bearings, the ‘bearing race’ may also be referred to as a ‘ball race’.

[0055] At least one inner slewing ring is required to achieve the ability of rotation. The inner slewing ring must fit the bearing races of the outer slewing ring. Both the axial bearing race and the radial bearing race. If the tolerances or the chosen types of bearings requires it, the inner slewing ring may comprise of several layers, which in turn are added to the assembly. An effective solution would be flat plane surfaces where a first a second inner slewing ring would be able to slide against each other to allow radial bearing rows to be installed. The inner slewing rings would later be combined by means of fastening if needed.

[0056] To achieve a low friction contact between the outer and inner rings, any suitable type of bearing can be used, as long as the radial bearing locks the slewing ring together as a combined product, while the radial bearing further facilitates continuous rotation even when the slewing ring is exposed to moment thrust.

[0057] The most common bearing types are: Plain bearings, ball bearings, roller bearings, flexure bearings, tilting pad bearings, fluid bearings and magnetic bearings. The most cost-efficient embodiments of the present invention are rolling element bearings or plain bearings.

[0058] Rolling elements are most commonly made from hardened steel alloys, where spherical balls or rollers of different shapes are fixed with equal distance in cages and rolling along bearing races provided to the bearing rings.

[0059] The most common rolling element bearing is the ball bearing, which most often is arranged as: Radial deep groove ball bearing, radial angular contact ball bearing, radial self-aligning ball bearing, axial thrust ball bearing or axial angular contact ball bearing. Bearing rollers vary in shape to fit deferent needs. Spherical rollers are shape to fit the assembly process and even distribution of thrust when in use. Tapered rollers are conical in shape to even the rotational speed of the roller surface in relation to the bearing race.

[0060] The choice of rolling element may benefit the assembly process, like allowing a planar bearing race to slide against a row of tapered rollers.

[0061] Slewing rings often have many rolling elements compared to regular bearings, as well as a high proportional difference between the size of the rolling elements and the diameter of the slewing ring. Normally, the rotational speed of a slewing ring is slow compared to regular bearings.

[0062] Plain bearings comprise of surfaces sliding against each other. These kinds of bearings are often made from materials suited for sliding, or by using different materials which against each other achieves low friction contact. Bearings of selflubricating polymers, which are polymers comprising a percentage of oils, are a made by injection molding or milling, making it very cheap to manufacture, even with special features. Plain bearings may make use of barb elements for keeping a bearing locked together. The surfaces of the barb function can be of plain bearing type.

[0063] If a radial bearing row comprises a roller bearing, the edge of the races and the ends of the roller may have surfaces of plain bearing materials. This will give the roller bearing the ability to slide while exposed to moment thrust.

[0064] Fluid bearings uses plain bearing rows having a liquid fluid in between making the contact close to none-existing.

[0065] Regardless of the choice of bearing types, additional technologies may be added to the present invention. The field of robotics and automation systems often require more than a simple ability of rotation. Encoders are devices used for monitoring speed and direction of a rotation.

[0066] Encoders comprise of a code ring and a sensor to read the code. Code rings are provided with a pattern or similar readable details, which the sensor can detect and transmit for the determination of the circular position and the rotational speed of the code ring. Encoders are classified as either mechanical, optical, magnetic or electromagnetic induction. Further, the output of the sensor is either absolute or incremental. An absolute signal is preferred to determine position, which is crucial in robotics.

[0067] Directional control of a slewing ring is mostly controlled by geared transmissions. These transmissions can be of any suitable type. However, spur and worm gears are the most common. The gears are almost always run by servo or stepper motors, which are precise and easy to control as robots rarely have constant running motors. A transmission gear motor can be mounted as part of both the inner and outer slewing ring, requiring that the gear ring is part of the opposite slewing ring. The transmission could comprise of a gear belt.

[0068] An alternative to a powered transmission could be the use of a motor ring. The motor ring runs by the same physics as ordinary motors, except for the hollow core. The type of motor will certainly be decided by the purpose of the slewing ring. Both AC and DC motors can be adapted to fit within a sleeving ring. AC / DC servo and DC stepper motors are the most precise and easiest to control with micro rotations and accuracy. Motor controllers are required for use of both servos and steppers.

[0069] A servo motor comprises any type of motor in combination with an encoder to monitor position. Motor type may vary with demands to precision and torque.

[0070] Stepper motors are DC brushless motors, which makes use of permanent magnets in the rotor, and electromagnets as part of the stator. A common design for stepper motor rings are a ring arrangement of stator coils pointing inwards towards a rotor ring comprising permanent magnets. Both stator coils and rotor comprising stepper pole teeth. If a slewing ring of the present invention is needed to just run fast and with even pace a simple DC motor design would be efficient.

[0071] Any embodiment of the present invention comprising an electric motor may be arranged to function as an electric generator.

[0072] Alternatives to electric motors are pneumatic motors, hydraulic motor, combustion engines and steam engines.

[0073] Slip rings are widely used in robotics for transfer of current and signals. They comprise of conductive rings having conductive contacts sliding on the surface. Hereby being able to transfer electric power and electric signal between two bodies continuously rotating in different directions. Slip rings are chosen by design and strength of current.

[0074] An alternative transmission of power is wireless power transfer technologies. Wireless transfer of current is done though electromagnetic flux and are categorized as near field or far field. Any suitable technology of wireless power transfer can be integrated in the present invention, however it is obvious that near field technologies would be the best choice. Such a system comprises an electromagnetic transmitter and receiver device extracts power from the generated magnetic field. The transmitter comprises an antenna and an oscillator connected to a power source. The current is converted to an oscillating electromagnetic field by an antenna comprising wire coils or an electric field emitted by metal plate electrodes. The receiver comprises a similar antenna type, which converts the oscillating fields back to an electric current. The antennas may be of different proportions.

[0075] Power loss and electrostatic noise is generated, but there are no wear on conductive contacts.

[0076] The three most suitable wireless power transfer technologies would be inductive coupling, resonant inductive coupling and capacitive coupling. Depending on the system, a need for data transfer between the outer and inner slewing ring might be needed. Such a data transfer can be conducted by slip rings or by a wireless solution. Slip rings are reliable and not easily a subject to spying or hacking.

[0077] The primary type of wireless data transmission in electronics is radio frequency, which is the basis of technologies like blue tooth, Wi-Fi and cellular communications. Any suitable type of wireless data transmission could be integrated in a slewing ring. The embodiment must comprise of the needed components for the required abilities, which depends on the needs for one- or two-way communication and the power supply needed on both the outer and inner slewing ring.

[0078] It is possible for a wireless power transfer system to also transfer data. A system of both power transfer and two-way data transfer is known as Wireless Powered Communication.

[0079] An embodiment could comprise of a main power transfer through slip rings, which has the lowest power loss, and a wireless connection for data transmission.

[0080] Depending on the requirements of the embodiment, micro controller units can be integrated as part of both the inner and outer slewing ring. Micro controllers are integrated in many products for monitoring and control. Micro controller systems can comprise of for instance motors, antennas, light emitting components, speakers, actuators, switches, gyroscope, ultrasound sensor, temperature sensor, infra-red sensor and many other types of sensors.

[0081] If needed, batteries can be integrated on both of the inner and outer slewing ring. Depending on the use, charging pads may be mounted for battery recharge.

[0082] Each outer or inner slewing ring can be provided with flanges to achieve structural strength or to create means of fastening for mounting purposes. Regardless of the embodiment, any slewing ring can comprise of a housing ability, where additional parts of the embodiment are installed and protected as a combined unit or part.

[0083] Any embodiment may be provided with holes or recesses for any purpose, such may be lubrication of bearing rows or to fit gears or sensors of any kind.

[0084] If it is required of an embodiment, it can be provided with suspension. Such suspension can be arranged as part of the inner or outer slewing ring and comprise of flexible material, spring arrangements, hydraulic suspension or pneumatic suspension or any other kind.

[0085] Bearings in general are forged or milled. The outer slewing ring of the present invention relies on a hollow shell shape, which would require further processing than just molding or single plane forging. A molded part could easily have additional milling added to create a deep radial bearing race, deep enough to handle axial moment. Undercut milling or undercut machining would be the preferred technique, preferable with specialized tools.

[0086] Inner slewing rings are easier to mold, also without post processing. Milling of the inner slewing rings is also easy.

[0087] Both the inner and outer slewing ring may be manufactured from any suitable material. For slewing rings which need less strength, it would be cheap to manufacture in polymers. Some polymers would even contribute with benefits such as corrosion resistance, self-lubrication, cost-savings and constant friction coefficient throughout lifetime.

[0088] Carbon fiber or ceramic materials have high strength and are often chosen for bearing races in combination with steel balls.

[0089] An alternative metal manufacturing could be high-pressure pressing and tooled rolling of sheet metal parts. Such manufacturing processes would be able to create strong metal at a low unit cost. Both inner and outer slewing ring could be manufactured in such a fashion.

[0090] The plasticity of a material may help to assemble an embodiment if tight fits are an issue, or to assist in preloading a slewing ring bearing.

[0091] Both the inner and outer slewing rings can each comprise of deferent components. An example of such composites could be thin bearing races made of a strong material and molded into a larger solid body of polymer or another suitable material. Further composite solutions could be bearing races covered with a foil or coatings of any suitable types. For the avoidance of fasteners, the outer slewing ring must comprise of a single combined body at the time of assembly.

[0092] The absence of fasteners in the assembly process does not deny either slewing ring to have fasteners for mounting purposes.

[0093] Each of the outer and inner slewing ring can be part of a larger body, in this way it is easier to incorporate the present invention into a system. The outer slewing ring can simply be manufactured as part of a chassis, without the need of mounting the slewing ring to the chassis as an assembly step.

[0094] Any parts of the present invention may be manufactured by additive manufacturing. Hereby achieving assembly of elements which otherwise would not be able to be assembled. Such manufacturing processes may include materials as metals, metal alloys, ceramics, polymers, carbon composites and composite in general.

[0095] In general, the most common bearing types are: Plain bearings, ball bearings, roller bearings, flexure bearings, tilting pad bearings, fluid bearings and magnetic bearings.

[0096] The most cost-efficient bearings are rolling element bearings or plain bearings. Rolling elements are most commonly made from hardened steel alloys, where spherical balls or rollers are fixed with equal distance in cages and rolling within bearing raceways.

[0097] The most common rolling element bearing is the ball bearing, which most often is arranged as: Deep groove ball bearing or angular contact ball bearing.

[0098] Bearing rollers vary in shape to fit different needs. Needle rollers are cheap cylindrical rollers, which are good at evening the distribution of thrust. Tapered rollers are conical in shape to even the rotational speed of the roller surface in relation to the bearing raceway. Spherical rollers or barrel rollers are shaped to fit the assembly process and even the distribution of thrust when in use.

[0099] Plain bearings or sliding contact bearings are bearings, where low-friction motion is achieved by plain surfaces sliding against each other due to properties of selflubricating materials, general lubrication or due to difference in material properties thus achieving sliding abilities when exposed to thrust.

[0100] An embodiment may be provided with either fluid bearings, magnetic bearings or tilting pad bearings, however these bearing types are intended for extremely high speeds, and a swirling bearing for caster wheels rarely spins fast. The wheel itself may have high speed, but the change in direction is limited.

[0101] The strongest type of bearing, as the applied weight load is direct vertical thrust load, would be an axial bearing.

[0102] The bearing is exposed to some amount of radial thrust, however axial moment forces are far greater than the radial forces. This supports the requirement for the second outer bearing race to be provided with a bearing raceway, thus ensuring low-friction rotation in scenarios of directional change or sudden change in thrust of load, such as in active driving situations.

[0103] An axial bearing may be of any suitable type, preferably of rolling elements or sliding contact. A ball bearing may be a deep groove ball bearing or an angular contact axial bearing, both types capable of receiving radial forces. Other preferable axial bearing types may be roller bearings, such as tapered rollers or barrel rollers.

[0104] Needle rollers are cheap, however the forces applied to a multidirectional caster wheel may be dynamic and consist of a variety of axial and radial forces. Needle rollers might need additional radial support. Such needs may be solved by additional bearing raceways.

[0105] A sliding contact bearing or plain bearing may be adapted with a curvature to receive radial forces.

[0106] The bearing type of the first and the second outer race may be of the same or of a different type, like an embodiment comprising a first outer race provided with a ball bearing raceway and a second outer race provided with a sliding contact bearing raceway.

[0107] The bearing race or raceways of the first and second outer race may be a bearing common to both races, such as if each race comprises one fourth of a four point contact bearing.

[0108] An angular axial raceway of the second outer bearing race may be correlating an angular axial bearing raceway of the first outer bearing race, thus completing a combined radial bearing raceway. Such an assembly will allow a rolling element radial bearing to be loaded with maximum capacity of rolling elements.

[0109] In a preferred embodiment the raceway of the first outer race faces the drive surface, thus the second outer race is installed form the direction intended to face the drive surface.

[0110] The inner bearing race comprises bearing raceways equal to and correlating any bearing raceway of the outer bearing races. Thus, any thrust applied to the outer races will be transferred to the inner race. The inner race may be provided with additional inner races if needed.

[0111] Bearing cages are crucial parts of bearings. Cages keep rolling elements fixed with equal spacing and cages ensure that a bearing will stay in its working arrangement and not fall apart.

[0112] Cages may be made from various materials like metal alloys and polymers. The shapes, sizes and rolling element capacity is often determined by the assembly process of the bearing.

[0113] In a preferred embodiment, the bearing comprises at least one cage adapted to separate the rolling elements.

[0114] Alternatives to cages may be individual spacers. Such spacers are common to four point contact bearings.

[0115] To protect a bearing from its environment, bearing seals are used to keep contamination out, and further to keep lubrication within.

[0116] Bearing seals are often made from flexible materials and often in combination with hollow discs of a harder material. Variations of cages are made with in-build seals as a combined part.

[0117] Bearing shields are often made from metal and are designed to withstand impacts and protect the bearing mechanisms. Shields are arranged between the races and cover the gaps, where a cage or seal is not efficient.

[0118] In highly contaminated environments labyrinth seals are often used to protect axial bearings. Labyrinth seals are non-contact mechanical shields which though a narrow corridor with shifting path of correlating tongue and groove arranged on each bearing race, makes it difficult for dust, dirt and debris to enter an axial bearing. Labyrinths are often combined with seals of flexible materials. Different bearing races may be made from different materials. One race may be made from a material chosen for its high hardness and wear resistance, while another would be chosen for its excellent low-frictional properties to reduce energy loss during rotation.

[0119] Steel based alloys often used in bearing manufacturing are high carbon chromium bearing steel, carburizing steel and stainless steel.

[0120] Titanium alloys are used for bearings requiring high strength and high corrosion resistance.

[0121] Any bearing race may be made from ceramic materials like silicon nitride, alumina oxide, zirconia oxide or silicon carbide.

[0122] In a preferred embodiment, at least one bearing race is made from self-lubricating material.

[0123] Other metal alloys used for bearings would among others be aluminum, copper, indium, tin, lead, silver, gold, brass, babbitt or sintered bronze and iron, which are suitable due to their self-lubricating properties.

[0124] Any inner or outer bearing race may comprise metal salts, such as sulfides, selenides, chlorides, iodides, oxides or hydroxides, which are suitable due to their self-lubricating properties.

[0125] Any bearing race may be made from or comprise of glasses such as boron oxide, silicates or phosphates, which are beneficial for the self-lubricating properties.

[0126] In a preferred embodiment any inner or outer race may be manufactured from polymers.

[0127] At least one bearing race may be made from plastic materials like polyether ether ketone (PEEK), which is used for bearings that need to be lightweight and resistant to corrosion. Any bearing race may be made from polytetrafluoroethylene (PTFE) or linear polyethylene (PE), which are suitable due to their self-lubricating properties.

[0128] A preferred embodiment of the invention may have any inner or outer races or raceways made from pressed sheet metal.

[0129] Yet another preferred embodiment may have races or raceways made from one or more materials molded into any suitable polymer or metal alloy. Hereby combining into a common composite race.

[0130] In a preferred embodiment, the bearing comprises a lubricant.

[0131] The bearing may be lubricated with petroleum-based oils, which are advantageous for their high lubricity and cooling capabilities.

[0132] The bearing may be lubricated with synthetic oils. These lubricants are advantageous for their high-temperature stability and long service life.

[0133] The bearing may be lubricated with greases, which are advantageous for their ability to stay in place and provide long-term lubrication.

[0134] The bearing may be lubricated with dry lubricants like graphite or boron nitride.

[0135] These lubricants are beneficial for reducing friction in harsh conditions where grease and oil will not work, such as radioactive or vacuum environments.

[0136] The bearing may be lubricated with solid film lubricants, which are advantageous in conditions with very high or very low temperatures.

[0137] The first outer race may be part of a larger body or arranged with any type of fasteners, brackets or similar arrangements.

[0138] Any bearing race may comprise of independent bearing raceways, thus allowing for raceways to be made from different materials than the races themselves. This is cost-effective if a race is made from injection molded polymer and the raceway is made from metal.

[0139] The wheel is adapted for rotation around a central axle. The axle is connected to the inner race by a wheel fork. The central axle itself may be adapted for rotation.

[0140] The wheel fork may be an integrated part of the inner race or connected to the inner race in any suitable way.

[0141] The wheel fork or the inner race may be the base of additional added functions, such as sensors.

[0142] Caster wheel tires are made from materials chosen for their properties to drive under certain conditions and in curtain environments. The majority of caster wheel tires are made from polymers; however steel or aluminum alloys are used when exceptional strength or temperature resistance are required.

[0143] In a preferred embodiment a caster wheel tire may be made from polyurethane- elastomer, which is beneficial due to low rolling friction and high toughness towards rifts and cuts.

[0144] In another preferred embodiment at least one caster wheel tire is made from solid rubbers like thermoplastic rubber elastomer or silicone-elastomer, which are advantageous for their strength and low rolling resistance.

[0145] In an embodiment of the invention at least one wheel tire may be arranged with pneumatic rubber tires, which are light weight and gentle to ground surfaces.

[0146] An embodiment intended for cleanroom environments may be made from thermoplastic polyurethane.

[0147] In a preferred embodiment at least one wheel tire is made from polypropylene or polyamide, which are beneficial due to their chemical resistance. Another advantage of polypropylene and polyamide is the option of manufacturing the wheel tire and rim as a single injection molded part.

[0148] Combined rims and tires intended for high heat environments may be made from fenolplastic, which is heat resistant but is in lag of driving performance on uneven surfaces.

[0149] Any wheel system may be arranged with a brake device, which will block one or more wheels when activated. Such breaks are common on caster wheels and advantageous when a vehicle is required to be fixed from running.

[0150] In a preferred embodiment a brake device may block at least one wheel tire.

[0151] In another preferred embodiment a brake device may block at least one wheel rim.

[0152] In yet another preferred embodiment at least one outer race or wheel rim is arranged with a brake disc.

[0153] An embodiment may be adapted with a brake which blocks the swirling bearing from changing the direction of the caster wheel.

[0154] An embodiment may be provided with a levering, which comprises a leg part, which may be activated to gain contact to the drive surface. Such levering may even lift the caster from the drive surface.

[0155] The caster wheel offset is the horizontal distance between the vertical rotational axis of the caster bearing and the horizontal rotational axis of the wheel. This allows for the caster to change direction together with the vehicle on which it is attached and run along in a new direction.

[0156] The offset influences the diameter of a swirling bearing of a low-profile caster wheel.

[0157] An offset which is too short will cause the caster to flutter and repeatedly swing from side to side. The flutter may be reduced by the use of multiple wheels, as the swinging will be stabilized, thus a shorter offset and hereby a smaller enclosing bearing may provide good driving abilities.

[0158] In the field of robotics and automated systems more advanced technologies are often required to control motion in various ways.

[0159] Encoders are devices used for monitoring speed and direction of rotation. Encoders comprise of a code ring and a sensor to read the code. Code rings are provided with a pattern or similar readable details, which the sensor can detect and transmit for the determination of the circular position and the rotational speed of the code ring. Encoders are classified as either mechanical, optical, magnetic or electromagnetic induction. Further, the output of the sensor is either absolute or incremental. An absolute signal is preferred to determine position, which is crucial in robotics.

[0160] Another embodiment may be arranged with vision-based monitoring of rotational position.

[0161] Directionally controlled applications like mobile robots, would benefit from an embodiment being arranged with a row of gear teeth concentric to the bearing raceways. Such gear transmission may be of any suitable type like a spur gear, helical gear, bevel gear, worm gear or magnetic gear. Hereby enabling directional control of the wheel. A gear may be powered by any type of motor. Electric servo or stepper motors a preferable.

[0162] A gear ring be mounted to the inner race or the inner race may be adapted with a gear as at part of the race.

[0163] In another preferred embodiment a gear may be operated by a gear belt.

[0164] An alternative powered transmission could be the use of a motor ring. A motor ring runs by the same physics as ordinary motors, except for the hollow core. Both AC and DC motors can be adapted to fit within a swirling bearing. AC / DC servo and DC stepper motors are the most precise and easiest to control with micro rotations and accuracy. Motor controllers are required for use of both servos and steppers. A servo motor comprises any type of motor in combination with an encoder to monitor position. Motor type may vary with demands to precision and torque.

[0165] In the field of robotics the invention is further advantageous for powered omnidirectional drive. In such embodiments the swirling bearing may be arranged with means for transfer of electric power and signal.

[0166] A preferred embodiment of a caster wheel system may have the swirling bearing arranged with a least one conductive ring for wireless transmission of power or signal. Such conductive rings and correlating conductive contacts is advantageous for powering drive wheels, various sensors, gear motors, brake systems and PCBs, such as microcontrollers or CPUs.

[0167] Another preferred embodiment of a caster wheel system may have the swirling bearing arranged with an induction ring for wireless transmission of power and signal. An induction system comprising two inductive transceivers is advantageous due to a two-way communication.

[0168] The primary type of wireless data transmission in electronics is radio frequency, which is the basis of technologies like blue tooth, Wi-Fi and cellular communications.

[0169] The three most suitable wireless power transfer technologies would be inductive coupling, resonant inductive coupling and capacitive coupling.

[0170] It is possible for a wireless power transfer system to also transfer data. A system of both power transfer and two-way data transfer is known as Wireless Powered Communication.

[0171] An embodiment could comprise of a main power transfer through slip rings, which has the lowest power loss, and a wireless connection for data transmission.

[0172] A preferred embodiment of a caster wheel system may comprise a microcontroller or PCB such as a CPU or motor driver. Any embodiment may comprise of a hollow central axle, which is advantageous due to the ability to have wires and cables passing though the wheel.

[0173] When power and control is transferred to the inner race, means of directional control may be operated from within the swirling bearing. Such arrangement may comprise of at least one smaller gear arranged for rotation as part of the inner race and being in correlation with a gear ring provided to an outer bearing race. Such smaller gear may be powered by any type for suitable motor, like a servo- or stepper-motor. The servomotor is particularly advantageous as it comprises an internal encoder.

[0174] The wheel may be powered by any type of motor. Such motor can be of any AC or DC type, however servos and steppers are the best to control. Hub motors, which are motors integrated in the wheel with either direct drive or planetary gears, are a reliable and compact choice, the stator is part of the inside of the wheel, and the rotor on the outside. Most motors for such a purpose would need a motor controller as part of the circuit. A gear may be provided between the wheel and a chosen motor. Multiple wheels can each be provided with motors.

[0175] Wheels with or without motor may benefit from having an encoder unit as part of the wheel to sense the rotational speed of the wheel. This is crucial to many robotic systems in relation to monitoring its own movement. Such encoders are normally part of the wheel hub mounted on the wheel and the axle.

[0176] A preferred embodiment of a caster wheel system may comprise one or more sensors.

[0177] For the purpose of monitoring position an Inertial Measurement Unit (IMU) which comprises a gyroscope, will measure velocity, orientation, gravitational forces, thus aiding in navigation and control. A position sensor will further aid in determining the precise position in an environment.

[0178] In navigational and orientational aspects a proximity sensor will detect obstacles in path of the wheels; an optical sensor may be used for line tracking and edge detection; an ultrasonic sensor may preform obstacle detection in path of wheels; a laser sensor such as a LiDAR may preform precise distance measurement and obstacle detection; and a magnetic sensor or Hall Effect sensor may detect magnetic fields useful for navigation and positioning.

[0179] A caster wheel system will benefit from a load sensor, which may measure load on wheels and aiding in balancing and optimizing movement.

[0180] To monitor an embodiment of a caster wheel itself a temperature sensor may detect overheating of a motor and other components; a vibration sensor may aid in detecting abnormal vibrations, which might be indicative of mechanical issues; a strain gauge may be measuring deformation or displacement of parts of the device, thus aiding to ensure structural integrity.

[0181] An embodiment of a caster wheel system may benefit from monitoring the environment by an acoustic sensor for change in ambient noise; a pressure sensor for changes in ambient air pressure; and temperature sensor for changes in ambient thermal conditions.

[0182] It is to be understood that a caster wheel system may comprise of any combination of sensors, depending on a specific use of the caster.

[0183] A preferred embodiment of a caster wheel system may comprise one or more batteries.

[0184] Yet another preferred embodiment of a caster wheel system may comprise one or more lights, which are advantageous for vision-based navigation and for hazard indication.

[0185] An embodiment of the invention may be arranged with any type of suspension.

[0186] Suspension systems often comprise of pneumatic or hydraulic pressurized systems, metal springs or elastic polymers. In a preferred embodiment a suspension system is provided between the wheel and the swirling bearing.

[0187] In another embodiment a suspension system is provided between the swirling bearing.

[0188] It is to be understood that additional added technology may be connected to an embodiment by any suitable technique.

[0189] It should be emphasized that the term "comprises / comprising / comprised of' when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0190] Brief description of the drawings

[0191] In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

[0192] Fig. 1A, in an exploded perspective view, shows a slewing ring bearing, according to embodiments of the invention, and which may be assembled according to an embodiment of a method according to another aspect of the invention;

[0193] Fig. 1B, in a sectional side view, show parts of the slewing ring bearing of Fig. 1A, in a partly assembled state;

[0194] Fig. 1C, in a sectional side view, shows the parts of the slewing ring bearing of Fig. 1A during assembly, and where an inner slewing ring of the slewing ring bearing has been laterally displaced relative to an outer slewing ring of the slewing ring bearing; Fig. 1 D, in a partially sectional side view, shows the parts of a slewing ring bearing in a state during insertion of radial bearing balls, and where the inner slewing ring of the slewing ring bearing has been laterally displaced relative to an outer slewing ring of the slewing ring bearing as in Fig. 1C;

[0195] Fig. 1E, in a partially sectional side view, shows the parts of the slewing ring bearing of Fig. 1 D, where the inner slewing ring of the slewing ring bearing has been displaced to a position where it is concentrically arranged relative to the outer slewing ring of the slewing ring bearing;

[0196] Fig. 1 F, in a partially sectional side view, shows the parts of the slewing ring bearing of Fig. 1 E in an assembly stage during arrangement of a bearing cage;

[0197] Fig. 1G, in a perspective view, shows the slewing ring bearing of Figs. 1A-1 F in an assembled state, and with section removed to view the internal arrangement of the component parts;

[0198] Fig. 2A, in a perspective view, illustrates a step in an assembly method of an embodiment of a slewing ring bearing according to an embodiment of the present invention;

[0199] Fig. 2B, in a partly sectional perspective view, illustrates the step in the assembly method illustrated in Fig. 2A, from a different angle;

[0200] Fig. 3, in a perspective view, shows a section through a slewing ring bearing according to an embodiment of the present invention, where the axial bearing comprises rollers, and further illustrates a step in an assembly method thereof;

[0201] Fig. 4, in a perspective view, shows a slewing ring bearing according to another embodiment of the present invention, with a cut-out to show the interior, and where the inner ring of the slewing ring bearing comprises two components, and further illustrates a step in an assembly method thereof; Fig. 5, in a perspective view, illustrates a section through an embodiment of a slewing ring bearing according to an embodiment, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row and where an inner slewing ring comprises a plain axial bearing row.

[0202] Fig. 6, in a perspective view, illustrates a section through a slewing ring bearing according to another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row and an outer slewing ring with a plain axial bearing row.

[0203] Fig. 7, in a perspective view, illustrates a section through a slewing ring bearing according to another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row and an axial angular contact bearing row.

[0204] Fig. 8, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row, and an axial sliding bearing.

[0205] Fig. 9, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row, and an axial roller bearing row;

[0206] Fig. 10, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row, and an axial tapered roller bearing row;

[0207] Fig. 11 , in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row, and an axial bearing comprising a row of rollers having a convex barrel shape, and further illustrating a step in the method of assembling the slewing ring bearing;

[0208] Fig. 12, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a radial angular contact bearing row, and an axial bearing comprising a row of rollers having a concave barrel shape;

[0209] Fig. 13, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising an axial radial angular contact bearing row, and a radial angular contact bearing row with a recess volume;

[0210] Fig. 14, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising an encoder ring, a gear ring and conductive slip rings, and

[0211] Fig. 15, in a perspective view, illustrates a section through a slewing ring bearing according to yet another embodiment of the invention, which may be assembled by the method according to the invention, the slewing ring bearing comprising a worm gear system for rotating the outer slewing ring relative to the inner slewing ring. Detailed description of the embodiments

[0212] The present invention refers to a method of assembling a slewing ring bearing 42, such a slewing ring bearing as shown in in Fig. 1G. In Fig. 1G, the slewing ring bearing 42 is shown with a section cut-out to show the interior of the slewing ring bearing 42.

[0213] The slewing ring bearing 42 at least comprises an outer slewing ring 1 and an inner slewing ring 2, where an axial bearing 200 and a radial bearing 300, both of which are arranged between the inner outer slewing ring 1 and the inner slewing ring 2.

[0214] The axial bearing 200 may be of many different types as described in further detail and exemplified below. The axial bearing 200 shown in Fig. 1G is of a type with bearing balls 3 arranged in a bearing cage (also sometimes referred to simply as a cage), axial bearing cage 5. Below, such axial bearings 200 and other types of axial bearings 200 will be described in further detail.

[0215] The radial bearing 300 is of a type comprising bearing elements in the form of bearing balls 4. These could also be referred to as radial bearing balls 4. The radial bearing 300 shown in Fig. 1 is of a type with bearing ball 4 arranged in a bearing cage, radial bearing cage 6. Below, such radial bearings 300 will be described in further detail.

[0216] The inner slewing ring 2 is configured for fitting within the outer slewing ring 1 . It can also be said that the outer slewing ring and the inner slewing are both configured such that the inner slewing ring 2 is configured for fitting within the outer slewing ring 1.

[0217] When the axial bearing 200 and the radial bearing 300 is provided, the inner slewing ring 2 and the outer slewing ring 1 are connected to each other, such that rotation there between is allowed.

[0218] The axial bearing 200 is provided between mutually facing surfaces of the outer slewing ring 1 and the inner slewing ring 1. These mutually facing surfaces extend generally perpendicular to the axial direction of the slewing ring bearing 42, or at least at an angle to the axial direction.

[0219] The radial bearing 300 is formed between mutually facing lateral surfaces of the outer slewing ring 1 and the inner slewing ring 2. By lateral surfaces are meant surfaces extending in the axial direction of the slewing ring bearing 42, i.e. in the axial direction of the outer slewing ring 1 and the inner slewing ring 2. It will be appreciated that these surfaces are cylindrical surfaces. These cylindrical surfaces of the outer slewing ring 1 and the inner slewing ring 2 are concentric when the slewing ring bearing 42 is in an assembled state.

[0220] It will further be appreciated that the outer slewing ring 1 and the inner slewing ring 2 are concentric when the slewing ring bearing 42 is in an assembled state, for example as shown in Fig. 1G.

[0221] The outer slewing ring 1 is ring-shaped. The outer slewing ring 1 comprises a first wall part T and a second wall part 1”. The first wall part T is ring-shaped and defines a plane, P. The second wall part 1” is also ring shaped. The second wall part 1” comprises a cylindrical portion, which is formed perpendicular to the plane P defined by the first wall part T.

[0222] The first wall part T may be generally plate shaped. The first wall part T preferably has a larger extend in the radial direction (in the plane, P), than in the axial direction of the outer slewing ring 1.

[0223] The second wall part 1”, as mentioned, has a cylindrical shape. The second wall part 1” preferably has a larger extend in the axial direction than in the radial direction (in the plane, P) of the outer slewing ring 1.

[0224] In preferred embodiments, and as shown the first wall part T and the second wall part 1” of the outer slewing ring 1 is formed as a singular piece, i.e. as a single integrated unit. The inner slewing ring 2 is ring shaped. The inner slewing ring 2 is formed such that it has one surface, a first surface 2’, which is an end surface of the inner slewing ring 2 and one radially outer surface, second surface 2” which is cylindrical and extends in the axial direction of the inner slewing ring 2.

[0225] The inner slewing ring 2 may also be formed in one singular piece, a, i.e. as a single integrated unit. This is the case in the embodiment shown in Figs. 1A-G. However, the inner slewing ring 2 may in other embodiments, for example as shown in Fig. 4 comprises two parts.

[0226] When the inner slewing ring 2 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42, the first surface 2’ of the inner slewing ring 2 faces the first wall part T of the outer slewing ring 1. In the embodiment shown in Figs. 1A-G, the first surface 2’ of the inner slewing ring 2 can be said to define a plane P2, which, when the inner slewing ring 2 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42 is parallel to the plane P defined by the first wall of the outer slewing ring 1.

[0227] Further, when the inner slewing ring 2 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42, the second surface 2” of the inner slewing ring 2 faces the second wall part 1” of the outer slewing ring 1. The cylindrical second surface 2” of the inner slewing ring 2 is concentric to the cylindrical second wall part 1 ” of the outer slewing ring 1.

[0228] An outermost diameter of the inner slewing ring 2 is larger than an inner diameter of the outer slewing ring 2. Thereby the first wall 1” of the outer slewing ring and the first surface 2’ of the inner slewing ring will abut on each other, for example via any axial bearing elements 3, 12, 14, to prevent movement in the axial direction towards each other.

[0229] As shown in Figs. 1A-G, the axial bearing 200 may - as also mentioned above - comprise bearing elements in the form of (axial) bearing balls 3. The axial bearing 200 shown in Figs. 1A-G is of a type with bearing balls 3 arranged in a cage, axial bearing cage 5. However, in other embodiments, the axial bearing 200 may be of other types.

[0230] For example the axial bearing 200 may comprise bearing elements in the shape of rollers 12, 14, 150, 151. Such rollers may be arranged in bearing cages 5 as well.

[0231] Examples of slewing ring bearings 42 having cylindrical rollers 12 in the axial bearing 200 is shown in Figs. 3 and 9.

[0232] In some embodiments the bearing elements may be conical rollers 14. An example, where the axial bearing 200 comprises conically shaped rollers 14 is shown in Fig. 10. In such embodiments, it will be appreciated that the first surface 2” of the inner slewing ring 2 and / or the mutually facing surface of the first wall T of the outer slewing ring 1 need not be planar, but may be provided by conical surfaces.

[0233] An example, where the axial bearing 200 comprises convex rollers 150 having a convex outer surface is shown in Fig. 11. An example, where the axial bearing 200 comprises concave rollers 151 having a concave outer surface is shown in Fig. 12.

[0234] In yet other embodiments, the axial bearing may be provided by sliding bearings or other types of bearings described herein.

[0235] Turning now to Figs. 1 B-F, the method according to an embodiment of the invention will be described. The method comprises a number of steps.

[0236] In a first step the inner slewing ring 2 is arranged in the outer slewing ring 1, while providing an axial bearing 200 there between.

[0237] When, as shown in Figs. 1A-G, the axial bearing 200 comprises a row of bearing balls / axial bearing balls 3 formed in a bearing cage 5 / axial bearing cage 5, the bearing cage 5 with the bearing balls 3 is simply arranged in abutment with the first wall T of the outer slewing ring 1 or with the first surface 2” of the inner slewing ring 2. Then the opposite of the outer slewing ring 1 or the inner slewing ring 2 is arranged in abutment with the ball bearings 3 in the bearing cage 5. The same approach is possible with rollers 12, 14, 150, 151, of e.g. the types referred to above, when these rollers are provided in an axial bearing cage 5.

[0238] In this case, whether the axial bearing cage 5 comprises bearing balls 3 or rollers 12, 14, 150, 151, both of the first surface 2’ of the inner slewing ring 2 and the first wall T of the outer slewing ring 1 may be provided with suitable matching bearing races, as exemplified below.

[0239] Alternatively, to the axial bearing balls 3 or axial bearing rollers 12, 14, 150, 151 being arranged in an axial bearing cage 5 before arranging against the first surface 2’ of the inner slewing ring 2 or the first wall 1 ’ of the outer slewing ring 1 , the axial bearing balls 3 or axial bearing rollers 12, 14, 150, 151 may be arranged on a bearing race of the first surface 2’ of the inner slewing ring 2 or the first wall T of the outer slewing ring 1 , whereafter the bearing elements 3, 12, 14, 150, 151 are distributed equidistantly along the bearing race. Then, a bearing cage / axial bearing cage 5 may be snapped to the bearing elements to secure their position relative to each other.

[0240] In the embodiment shown in Figs 1A-G, the axial bearing 200 is provided with an axial angular contact bearing race 11 on the first wall T of the outer slewing ring 1 and another axial angular contact bearing race 11 arranged on the first surface 2’ of the inner ring 2.

[0241] An axial angular contact bearing race 11 is a rounded surface formed between two flat planer levels of the first surface 2’ of the inner ring 2. In some cases, axial angular contact bearing races 11 may comprise a depression.

[0242] In this case of the embodiment shown in Figs. 1A-G, the method of assembly comprises a step (not shown) of installing the axial bearing 200 comprising the axial balls 3 provided in a bearing cage 5, between the axial bearing race 7 (in the form of an axial angular contact bearing race 11) on the outer slewing ring 1 and the axial bearing race 7 (in the form of an axial angular contact bearing race 11) on the inner slewing ring part 2. The result of this step or steps is shown in Fig. 1 B. The axial angular contact bearing races 11 of the axial bearing 200 secures that inner slewing ring 2 is concentrically arranged relative to the outer slewing ring 1 , when the inner and or outer slewing rings are not manipulated. Thus, in the situation shown in Fig. 1B, where the inner slewing ring 2 has been arranged in the outer slewing ring 1, and the axial bearing 200 between them is established, a gap, concentric gap 137 is provided between outer slewing ring 1 and the inner slewing ring 2. The concentric gap 137 is ring-shaped and has a uniform width along its circumference. The gap 137 is thus provided between the outer slewing ring 1 and the inner slewing ring 2 when these are assembled. The width of the concentric gap 137 is smaller than a diameter of a radial bearing ball 4.

[0243] In a subsequent step, and as shown in Fig. 1 C, the inner slewing ring 2 is displaced in a radial direction relative to the outer slewing ring 1. The radial direction may also be referred to as a sideways or lateral direction, and therefore, the displacement of the inner slewing ring 2 relative to the outer slewing ring 1 in the radial direction may also be referred to as lateral displacement or sideways direction.

[0244] The displacement of the inner slewing ring 2 relative to the outer slewing ring 1 in the radial direction creates an intermediary larger width gap 138 lateral to one side of the inner slewing ring 2 and the outer slewing ring 1 , while the concentric gap 137 opposite to the intermediary larger width gap 138 is reduced to an intermediary reduced width gap 139. The intermediary larger width gap 138 is may also be referred to as a loading gap 140 when it reaches it’s maximum size.

[0245] In Fig. 1C the loading gap 140 is shown to the left in the figure, and the intermediary reduced width gap 139 is shown to the right.

[0246] It will be appreciated that in the embodiment of the slewing ring bearing 42 shown in Figs. 1A-G, the displacement of the inner slewing ring 2 relative to the outer slewing ring 1 in the radial direction will cause the axial bearing balls 3 to abut on a portion of the axial angular contact bearing race 11 of the outer slewing ring 1. This will lift up a portion of the inner slewing ring away from the outer slewing ring 1 , thereby tilting the inner slewing ring 2 relative to outer slewing ring 1. This tilting may also be appreciated from Fig. 1C. The creation of the loading gap 140 between the outer slewing ringl and the inner slewing ring 2 allows insertion of radial bearing balls 4 into the radial bearing 300. This is illustrated in Fig. 1D. A suitable number of radial bearing balls is inserted into the radial bearing 300.

[0247] In the embodiment of the slewing ring bearing 42 shown in Figs. 1A-G, the radial bearing 300 is provided by a radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1 , and a corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2.

[0248] The radial bearing balls 4 are as shown in Fig. 1D in between the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1, and the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2.

[0249] When a desired number of radial bearing balls 4 have been inserted between the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1, and the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2, the inner slewing ring 2 is displaced relative to the outer slewing ring 1 in the radial direction and towards the position, where the outer slewing ring 1 and the inner slewing ring 2 are concentrically arranged relative to each other. This will recreate the ring-shaped concentric gap 137 having uniform width along its circumference. This position is shown in Fig. 1 E.

[0250] It will be appreciated that in this situation, all of the radial bearing balls 4 are located immediately adjacent to each other.

[0251] Then, in a not shown subsequent step, the radial bearing balls 4 are distributed along the circumference of the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1, and along the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2. The radial bearing balls 4 are distributed in such a manner that there is a regular equidistant spacing between them. Fig. 1 F shows the situation, where the radial bearing balls have been equidistantly distributed.

[0252] In a final step the, and as illustrated in Fig. 1F, a radial bearing cage 6 may be inserted between into the space between the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1, and the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2, in order to fix the radial bearing balls 4 in their equidistant position relative to each other.

[0253] Fig. 1 F indicates the radial bearing cage 6 in two positions. In the top part of the figure, the radial bearing race 6 is indicated in the disassembled situation, and the arrow indicates the direction of movement into the position where the radial bearing cage 6 is inserted into the space between the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1, and the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2, where tongues 6’ between the radial bearing balls 4 are keeping the radial bearing balls 4 apart.

[0254] The radial bearing cage 6 is preferably a so-called crown-cage. It takes the form of a ring-shaped element with axially extending tongues 6’. The tongues 6’ are equidistantly arranged on the radial bearing cage 6. Between the tongues 6’, bearing ball receiving apertures 6” are formed. Each of the bearing ball receiving apertures 6” is configured to hold one radial bearing ball 4.

[0255] The radial bearing cage 6 may be formed in such a way and such a material that the tongues are resilient such that the bearing balls 4 may snap into a bearing ball receiving apertures 6”.

[0256] It will be appreciated that the step of distributing the radial bearing balls 4 in the space between the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1 , and of the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2, may be carried out by and / or when inserting the radial bearing cage 6 into the space between the radial angular contact bearing race 9 formed on the second wall 1” of the outer slewing ring 1, and of the corresponding radial angular contact bearing race 9 formed on the second surface 2” of the inner slewing ring 2.

[0257] When the radial bearing cage 6 is correctly inserted, the radial bearing 300 is provided. Further, when the radial bearing cage 6 is correctly inserted, the bearing balls 4 are locked in the radial bearing 300, and further, the outer slewing ring and the inner slewing ring are prevented from moving apart. Thereby the slewing ring bearing 42 is locked in its assembled state.

[0258] As a last step, axial and / and or radial bearing seals (not shown) may be installed.

[0259] In the general case, in order to insure the highest possible number of radial bearing balls 4 capable of being loaded in the radial bearing 300, the path of the inner slewing ring 2 during displacement is very important.

[0260] If the inner slewing ring 2, in the side (loading gap 140), where the radial bearing balls 4 are to be loaded, is forced outwards, due to the geometries, such like a groove-type ball bearing race, then a high number of bearing balls risk jamming the inner slewing ring 2 from being repositioned to be concentric with the outer slewing ring 1.

[0261] It is important that in the side, i.e. in the loading gap 140, where the radial bearing balls 4 are loaded, the inner slewing ring 2 remains at level with - or preferably is capable of retracting from the radial bearing row, thereby ensuring that the slewing ring bearing 42 is capable of being assembled with a high number of radial bearing balls 4.

[0262] For this purpose, in one preferred embodiment, the axial bearing 200 may be formed with at least one axial angular contact bearing race 11 either the outer slewing ring 1 or the inner slewing ring 2. As shown in e.g. Fig. 1B in the Fig. 1A-G embodiment, the axial bearing 200 comprises an axial angular contact bearing race 11 on both the outer slewing ring 1 and the inner slewing ring 2. Further, the axial angular contact bearing race 11 is provided with an enlarged arched contact surface with a radius larger than the radial bearing balls 3, such that a recess volume 152 is provided between the axial bearing balls 3 and the inner surface 1 of the first wall 1 ’ of the outer slewing ring 1. Thereby, the radial displacement of the second slewing ring relative to the first slewing ring 1 in order to provide a loading gap 140 for the radial bearing balls 4, is increased, allowing and the path of the inner slewing ring 2 relative to the outer slewing ring 1 during the radial displacement and relocation is better controlled, whereby an increased number of radial bearing balls 4 may be inserted.

[0263] As described, in the Fig. 1A-G embodiment a recess volume 152 is provided in the axial angular contact bearing race 11 provided in between the axial bearing balls 3 and the inner surface T” of the first wall T of the outer slewing ring 1. However, in other embodiments, and as shown in Fig. 13, a recess volume 152 may instead be provide in the inner slewing ring 2.

[0264] In the embodiment shown in Fig. 13 an axial bearing 200 comprising axial bearing balls 3, an axial angular contact bearing race 11 provided in the inner slewing ring 2, and another axial angular contact bearing race 11 provided in the outer slewing ring. A recess volume 152 is provided between the axial bearing balls 3, and the second surface 2” of the inner slewing ring 2 Thereby, a similar effect as in the Fig. 1A-G embodiment is obtained.

[0265] Fig. 3, in a perspective view, illustrates of an assembly method of a slewing ring bearing 42 according to an embodiment of the invention. The slewing ring bearing 42 comprises an axial bearing 200 and a radial bearing 300.

[0266] The radial bearing 300 is of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the inner slewing ring 2.

[0267] The axial bearing 200 comprises a plurality of rollers 12 arranged in a bearing cage 5, an axial roller bearing race 13 of the groove type arranged on the outer slewing ring 1 , and an plain axial bearing race 10 provided on the inner slewing ring 2. The inner slewing ring 2 may as shown in Fig. 3 be brought to slide sideways / laterally / in the radial direction, against the axial bearing rollers 12 during assembly in order to provide a loading gap 140 between the inner slewing ring 2 and the outer slewing ring 1 , which allows for insertion of radial bearing balls 4. The sliding enlarges the gap between the outer and inner slewing rings 1 , 2 in one side of the outer and inner slewing rings 1 , 2, i.e. a loading gap 140. Then, the radial bearing balls 4 may be added to the open radial angular contact bearing races 9 on the outer slewing ring 1. Fig. 3 shows the assembly process at the state, where the radial bearing balls 4 have been added. When this is done, the inner slewing ring 2 is moved radially to the concentric position relative to the outer slewing ring 1 (not shown in Fig.3), and the radial bearing balls 4 are distributed with a regular spacing between them in the radial bearing 300 (not shown in Fig.3). Finally, a radial bearing cage (not shown) is installed to fix the radial bearing balls 4 (not shown in Fig.3).

[0268] Fig. 4, in a perspective view, illustrates a step of an assembly method for an embodiment of the present invention. The slewing ring bearing 42 comprises an axial bearing 200 and a radial bearing 300. Further, the slewing ring bearing 42 comprises an outer slewing ring 1 and an inner slewing ring 2. The inner slewing ring 2 comprises two inner slewing ring parts, a first inner slewing ring part 19, and a second inner slewing ring part 20. The axial bearing 200 is provided between the first inner slewing ring part 19 and the first wall T of the outer slewing ring 1. The radial bearing 300 is provided between the second inner slewing ring part 20 and the second wall 1” of the outer slewing ring 1.

[0269] The radial bearing 300 is of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the inner slewing ring 2.

[0270] The axial bearing 200 is of the type having axial bearing balls 3 arranged between axial bearing races 7 of the groove type on both of the inner slewing ring 2 and the outer slewing ring. In the resulting slewing ring bearing 42, the axial bearing balls 3 are arranged in an axial bearing cage 5, and the radial bearing balls 4 are arranged in a radial bearing cage 6.

[0271] In this case the assembly method comprises a step (not shown) of installing the axial bearing 200 comprising the axial balls 3 provided in a bearing cage 5, between the axial bearing race 7 on the outer slewing ring 1 and the axial bearing race 7 on the first inner slewing ring part 19. A bearing cage 5 with axial bearing balls 3 may be arranged on the axial bearing race 7 on the outer slewing ring 1, whereafter the first inner slewing ring part 19, which is provided with the corresponding axial bearing race 7 (here of the groove-type), is placed upon the axial bearing row 3, 5.

[0272] The first inner slewing ring part 19, and the second inner slewing ring part 20 comprises cooperating plain surfaces.

[0273] The plain surface of the second inner slewing ring part 20 is arranged on the plain surface of the first inner slewing ring part 19.

[0274] The second inner slewing ring part 20 is slid in a radial direction relative to the outer slewing ring 1 and the first inner slewing ring part 19, thereby enlarging the gap between the outer and second inner slewing rings 1, 2 at one side to provide a loading gap 140. The radial bearing balls 4 are then added into the loading gap 140 of the radial angular contact bearing race 9 of the radial bearing 300. The resulting situation, where the radial bearing balls 4 are arranged in the radial angular contact bearing race 9 is shown in Fig. 4.

[0275] Then the second inner slewing ring part 20 is moved to a central - concentric - position relative to the first inner slewing ring part 19 and the outer slewing ring 1. This step is not shown in Fig. 4.

[0276] Then the radial bearing balls 4 provided in the radial bearing 300 are separated equidistantly. This step is not shown in Fig. 4. Finally, a radial bearing cage (not shown) is installed to fix the radial bearing balls 4 of the radial bearing 300 equidistantly apart.

[0277] The first inner slewing ring part 19 and the second inner slewing ring part 20 may have cooperating connecters 17, 17’, 17” such that the first inner slewing ring part 19 and the second inner slewing ring part 20 may be connected fixedly to each other. Such connectors may be bores 17‘ in the first inner slewing ring part 19 and matching bores 17” in the second inner slewing ring part 20, allowing the first inner slewing ring part 19 and the second inner slewing ring part 20 to be connected to each other via suitable means such as a bolt or split, or other connectors known in the art.

[0278] Fig. 5, in a perspective view, illustrates an embodiment of the present invention having a radial bearing 300 comprising radial bearing balls 4 and a radial angular contact bearing race 9. The axial bearing 200 comprises on the outer slewing ring 1 , an axial bearing race 7 of the groove type and on the inner slewing ring (2) an axial bearing race of the plain bearing race 10 type. By having a plain bearing race 10 for one of the axial races it is easier to assemble the embodiment by allowing the inner slewing ring 2 to slide laterally against the axial bearing balls 3. The axial bearing balls 3 are arranged in an axial bearing cage 5. The radial bearing balls 4 are arranged in a radial bearing cage 6.

[0279] Fig. 6, in a perspective view, illustrates an embodiment of the present invention, where the slewing ring bearing 42 has a radial bearing 300 comprising radial bearing balls 4 and radial angular contact bearing races 9 on both the inner slewing ring 2 and the outer slewing ring 1. The axial bearing 200 comprises axial bearing balls 3 and an axial bearing race 7 on the inner slewing ring (2) of the groove type, and the axial bearing race on the outer slewing ring 1 is a of the plain bearing race 10 type. The plain bearing race 10 of the axial race of the outer slewing ring 1 allows for an easier assembly of the embodiment by allowing the inner slewing ring 2 to hold the axial bearing balls 3 while these balls slide against the plain bearing row 10 of the outer slewing ring 1. The axial bearing balls 3 are arranged in an axial bearing cage 5. The radial bearing balls 4 are arranged in a radial bearing cage 6. Fig. 7, in a perspective view, illustrates an embodiment of the present invention where the radial bearing 300 comprise radial bearing balls 4 and radial angular contact bearings 9. The axial bearing comprises axial bearing balls 3 fixed in a bearing cage 5 and angular contact bearings 11. The axial angular contact bearing improves the assembly of embodiments with a reduced diameter, since the axial angular contact bearing race 11 of the inner slewing ring 2 is in less conflict with the axial bearing race of a groove bearing row 7. Further, this design remains strong in a scenario of an axial angular contact bearing 11 assisting to handle radial forces.

[0280] Fig. 8 shows an embodiment of the slewing ring bearing 42, which may be assembled in a manner similar to what is described above for the Fig. 1A-G embodiment. However, instead of the axial bearing 200 being provided by a rolling element-type bearing as in the Fig. 1A-G embodiment, the axial bearing in the Fig. 8 embodiment is provided by cooperating plane axial bearing races 142, one plane axial bearing race 142 on each of the outer slewing ring 1 and the inner slewing ring 2. The cooperating plane axial bearing races 142 allows sliding rotation between the outer slewing ring 1 and the inner slewing ring 2 , when the slewing ring bearing is fully assembled and in use. The cooperating plane axial bearing races 142 further allows sliding between the outer slewing ring 1 and the inner slewing ring 2 during assembly to radially displace the inner slewing ring 2 relative to the outer slewing ring 1 , in order to create a loading gap 140 e(not shown in Fig. 8).

[0281] As mentioned above, Fig. 9, in a perspective view, illustrates an embodiment of a slewing ring bearing 42 which may be assembled by the method according to the present invention comprising. In this case, the axial bearing 200 of the slewing ring bearing 42 an axial roller bearing, comprising axial rollers 12 and arranged in an axial bearing cage 5 between axial bearing races 10, 13 on the inner slewing ring 2 and the outer slewing ring 1, respectively.

[0282] As mentioned, the axial rollers 12 are fixed in a bearing cage 5, and further circularly aligned by an axial roller bearing race 13 of the groove type provided upon an outer slewing ring 1. An inner slewing ring 2 is provided with a plain axial bearing race 10 to enable a sliding ability of the inner slewing ring 2 during assembly. Fig. 10, in a perspective view, illustrates an embodiment of the present invention comprising an axial bearing 200 having tapered bearing rollers 14. The tapered rollers 14 are fixed in a bearing cage 5, and further circularly aligned by an axial tapered roller bearing race 15 of the groove type, provided on an inner slewing ring 2. An outer slewing ring 1 is provided with a plain axial bearing race 10 to enable a sliding function of the inner slewing ring 2 relative to the outer slewing ring 1 on the axial bearing 200 during assembly. The figure further shows the outer slewing ring (1) being closed off by not having a hole through the center.

[0283] Fig. 11, in a perspective view, illustrates a section through a slewing ring bearing 42 according to yet another embodiment of the invention. In Fig 11 the slewing ring bearing 42 is shown with a section cut away to show the interior of the slewing ring bearing 42. Also in this embodiment of the slewing ring bearing 42, it may be assembled by the method according to the invention. The radial bearing 300 of the slewing ring bearing 42 comprises radial angular contact bearing races 9 with radial bearing balls 4, which is shown in the situation during insertion through a loading gap 140 as mentioned in relation to previously described embodiments above. The axial bearing 200 in this embodiment comprises a row of rollers 150 having a convex barrel shape.

[0284] Fig. 12, in a perspective view, illustrates a slewing ring bearing 42 according to yet another embodiment of the invention. In Fig 12 the slewing ring bearing 42 is shown with a section cut away to show the interior of the slewing ring bearing 42. Also in this embodiment of the slewing ring bearing 42, it may be assembled by the method according to the invention. The radial bearing 300 of the slewing ring bearing 42 comprises radial angular contact bearing races 9 with radial bearing balls 3. In this embodiment, the axial bearing 200 comprises a row of rollers 151 having a concave barrel shape.

[0285] In Fig. 12 the slewing ring bearing 42 is shown in a fully assembled state. The figure shows that the axial bearing 200 has been sealed by an axial bearing seal 25. Further, the figure shows that the radial bearing 300 has been sealed by a radial bearing seal 26. It will be appreciated that in any of the other embodiments described herein, the axial bearing 200 of the slewing ring bearings 42 may comprise an axial bearing seal 25 in the same manner as shown in Fig. 12.

[0286] It will further be appreciated that in any of the other embodiments described herein, the radial bearing 300 of the slewing ring bearings 42 may comprise a radial bearing seal 26 in the same manner as shown in Fig. 12.

[0287] As mentioned above, Fig. 14, in a perspective view, illustrates an embodiment of a slewing ring bearing 42, which may be assembled by the method according to the invention and as described above. The slewing ring bearing 42 comprises a gear ring 27, an encoder ring 28 and conductive slip rings 30. The axial bearing 200 in this case comprises axial baring balls 3, and a groove-type bearing race 7 on the inner slewing ring 2 and an angular axial bearing race 11 on the outer slewing ring 1. Further, it will be appreciated from Fig. 14 that the angular axial bearing race 11 on the outer slewing ring 1 is provided with recess volume 152 as described above, improving the lateral displacement of the inner slewing ring 2 relative to the outer slewing ring 1 during assembly of the slewing ring bearing 42 in the manner described above.

[0288] Further, in the Fig. 14 embodiment, the radial (4,6,8) bearing 300 is of the ball bearing type, comprising radial bearing balls 4. Here, the radial bearing 300 comprises groove type bearing races 8 on both the inner and outer slewing rings 2, 1.

[0289] Between the bearing rows 3, 4, 5, 6, 7, 8, 11 and next to the radial bearing 300, 4,6,8, the inner slewing ring 2 is provided with an encoder ring 28 in the radial direction. Next to the encoder ring 28, the inner slewing ring 2 is provided with a gear ring 27 in the radial direction. Between the gear ring 27 and the axial bearing 200, 3, 5, 7, the inner slewing ring 2 is in the axial direction provided with a set of conductive slip rings 30 for the purpose of conducting electric current to the inner slewing ring 2 from the outer slewing ring 1 through conductive contacts 31. For interaction by gear transmission (not shown), encoder reader (not shown) and conductive contacts 31 to the components 27, 28, 30 of the inner slewing ring 2, the outer slewing ring 1 is provided with an opening 29.

[0290] Fig. 15 illustrates a perspective view of a slewing worm gear system, or simply worm gear system 72. A housing unit 71 is provided with a slewing ring bearing 42, which may be assembled by the method according to the invention. The housing unit 71 comprises a gear ring 27. Further the housing unit 71 supports a worm 73, and a gear motor 48, for example in the form of a stepper motor. The worm 73 is controlled by the gear motor 48.

[0291] It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description.

[0292] List of parts

[0293] 1 outer slewing ring

[0294] 1 ’ first wall part of outer slewing ring

[0295] 1” second wall part of outer slewing ring

[0296] 2 inner slewing ring

[0297] 2’ first surface of inner slewing ring, which is an end surface of the inner slewing ring

[0298] 2” second surface of inner slewing ring, radially outer surface

[0299] 3 axial bearing element in the form of an axial bearing ball

[0300] 4 radial bearing element in the form of a radial bearing ball

[0301] 5 axial bearing cage

[0302] 6 radial bearing cage

[0303] 7 axial bearing race

[0304] 8 radial bearing race

[0305] 9 radial angular contact bearing race

[0306] 10 plain axial bearing race

[0307] 11 axial angular contact bearing race

[0308] 12 axial bearing element in the form of an axial bearing roller

[0309] 13 axial roller bearing race

[0310] 14 axial bearing element in the form of an axial tapered bearing roller

[0311] 15 axial tapered roller bearing race

[0312] 17 means of fastening

[0313] 18 radial bearing element in the form of a radial bearing roller

[0314] 19 first inner slewing ring part / first part of inner slewing ring

[0315] 20 second inner slewing ring part / second part of inner slewing ring

[0316] 21 third inner slewing ring part / third part of inner slewing ring, or intermediary inner slewing ring part

[0317] 22 Radial roller bearing race

[0318] 23 Radial tapered bearing roller

[0319] 24 Radial tapered roller bearing race

[0320] 25 axial bearing seal

[0321] 26 radial bearing seal

[0322] 27 Gear ring 28 Encoder ring

[0323] 29 Opening in outer slewing ring

[0324] 30 Conductive slip ring

[0325] 31 Conductive contact

[0326] 32 Access for lubrication

[0327] 33 Rotor ring with permanent magnet

[0328] 34 Stator coil unit

[0329] 35 Combined inner and outer slewing ring

[0330] 36 Load bracket for inner slewing ring

[0331] 37 Axial needle roller

[0332] 38 Constructional flange

[0333] 39 Caster wheel system

[0334] 40 Wheel

[0335] 41 Wheel fork

[0336] 42 Slewing ring bearing

[0337] 43 Wheel hub

[0338] 44 Hollow wheel hub embodiment of the present invention

[0339] 45 Combined inner slewing ring and wheel fork

[0340] 46 Wheel motor

[0341] 47 Transmission gear

[0342] 48 Gear motor

[0343] 71 Housing unit

[0344] 72 Slewing worm gear system

[0345] 73 Worm

[0346] 137 concentric gap, provided between the outer slewing ring and the inner slewing ring when the two are concentrically arranged, the concentric gap is ringshaped and has a uniform width along its circumference

[0347] 138 intermediary larger width gap, lateral to one side of the inner slewing ring and the outer slewing ring, same as loading gap

[0348] 139 reduced width gap, formed opposite to the intermediary larger width gap when inner slewing ring is radially displaced

[0349] 140 loading gap

[0350] 142 Plain axial bearing race

[0351] 150 Convex roller Concave roller Recess volume axial bearing radial bearing

Claims

Claims1. A method of assembling a slewing ring bearing (42), the slewing ring bearing (42) comprising- an outer slewing ring (1),- an inner slewing ring (2) configured for fitting within the outer slewing ring (1),- an axial bearing (200) provided between mutually facing surfaces of the outer slewing ring (1) and the inner slewing ring (2), which surfaces face in an axial direction of the slewing ring bearing (42);- a radial bearing (300) formed between mutually facing lateral surfaces of the outer slewing ring (1) and the inner slewing ring (2), and- bearing balls (4) provided between in the mutually facing lateral surfaces of the radial bearing (300), wherein the outer slewing ring (1) comprises a first wall part (T) and a second wall part (1”), wherein the first wall part (1’) is ring-shaped, and comprises a surface which faces in the axial direction of the slewing ring bearing (42), wherein the second wall (1”) part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing (42), wherein the first wall part T and a second wall part 1” of the outer slewing ring 1 are formed as a single integrated unit formed in one piece, wherein an outmost diameter of the inner slewing ring (2) is larger than an inner diameter of the outer slewing ring (1), wherein the method comprises the steps of:- arranging the inner slewing ring (2) in the outer slewing ring (1), while providing an axial bearing (200) there between,- displacing the inner slewing ring (2) in a radial direction relative to the outer slewing ring (2), thereby providing an temporarily a loading gap (140) between the inner slewing ring (2) and the outer slewing ring (1), which loading gap (140) is dimensioned to receive a radial bearing ball (4),- entering a plurality of radial bearing balls (4) through the loading gap (140) into the radial bearing (300),- sliding the inner slewing ring (2) in a radial direction and relative to the outer slewing ring (2) to a concentric position of the outer slewing ring (1) and the inner slewing ring (2),- distributing the radial bearing balls (4) equidistantly in the radial bearing (300), and- inserting one or more radial bearing ball distributers for securing an even distribution of the plurality of bearing balls (4) in the radial bearing (300).

2. The method according to claim 1, wherein the method comprises adding an axial bearing seal to the axial bearing (200) and / or adding a radial bearing seal to the radial bearing (300).

3. The method according to claim 1 or 2, wherein the axial bearing (200) comprises an axial angular contact bearing race (11) provided in one of the outer slewing ring (1) or the inner slewing ring (2), wherein a recess volume (152) communicating with the axial angular contact bearing race (11) is provided in the one of the outer slewing ring (1) or the inner slewing ring (2) on which the axial angular contact bearing race (11) is provided, and wherein the method comprises the step axially displacing the other one of the outer slewing ring (1) or the inner slewing ring (2) on which the axial angular contact bearing race (11) is provided, and tilting a portion of the radial bearing balls (3) to enter the recess volume (152).

4. The method according to any one of the claims 1-3, wherein the step of inserting one or more radial bearing ball distributers for securing an even distribution of the plurality of bearing balls (4) in the radial bearing (300) comprises inserting a radial ball bearing cage (6).

5. The method according to claim 4, wherein the radial ball bearing cage (6) is a crown bearing cage.

6. A slewing ring bearing (42) comprising- an outer slewing ring (1),- an inner slewing ring (2) configured for fitting within the outer slewing ring (D,- an axial bearing (200) provided between mutually facing surfaces of the outer slewing ring (1) and the inner slewing ring (2), which surfaces face in an axial direction of the slewing ring bearing (42);- a radial bearing (300) formed between mutually facing lateral surfaces of the outer slewing ring (1) and the inner slewing ring (2), and- radial bearing balls (4) provided between in the mutually facing lateral surfaces of the radial bearing (300), wherein the outer slewing ring (1) comprises a first wall part (T) and a second wall part (1”), wherein the first wall part (T) is ring-shaped, and comprises a surface which faces in the axial direction of the slewing ring bearing (42), wherein the second wall (1”) part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing (42), wherein the first wall part T and a second wall part 1” of the outer slewing ring 1 are formed as a single integrated unit formed in one piece, wherein an outmost diameter of the inner slewing ring (2) is larger than an inner diameter of the outer slewing ring (1) and wherein the inner slewing ring (2) is configured for fitting within the outer slewing ring (1) such that the inner slewing ring (2) is movable in a radial direction relative to the outer slewing ring, when no radial radial bearing balls (4) are provided between in the mutually facing lateral surfaces of the radial bearing (300).

7. The slewing ring bearing (42) according to claim 6, wherein the axial bearing (200) comprises an axial angular contact bearing race (11) provided in one of the outer slewing ring (1) or the inner slewing ring (2), wherein a recess volume (152) communicating with the axial angular contact bearing race (11) is provided in the one of the outer slewing ring (1) or the inner slewing ring (2) on which the axial angular contact bearing race (11) is provided.

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