WORK VEHICLE WITH ELECTRIC TRANSAXLE AND TRANSMISSION SHAFT

Abstract

A work vehicle comprises a chassis held above the ground by wheels or tracks engaging the ground, and two transaxles supported by the chassis. The first transaxle has first wheel end units rotatable about a first wheel axis via a first transaxle gear set to rotate a first set of wheels or tracks engaging the ground. The second transaxle has second wheel end units rotatable about a second wheel axis via a second transaxle gear set to rotate a second set of wheels or tracks engaging the ground. The second transaxle includes an electric machine with a shaft rotating about a machine axis, a gearbox rotated by the shaft of the electric machine and designed to produce several gear ratios at a range gear, and a drive gear rotatable about the second wheel axis via the gearbox's range gear.A transmission shaft has a first end coupled to an input assembly engaging with the first transaxle gear set, and a second end coupled to an output gear engaging with the drive gear, in order to transmit power from the second transaxle to the first transaxle via the transmission shaft.

Description

CROSS REFERENCE TO RELATED APPLICATION(S)Not true.EXPLANATION OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot true.FIELD OF DISCLOSUREThis disclosure relates generally to work vehicles and, more particularly, to transaxles for work vehicles.BACKGROUND OF THE DISCLOSUREWorking vehicles, as used in agriculture, construction, forest and mining, generally require drives with high torque in order to provide high tensile forces for driving off road and for driving heavy working tools. Large fuel combustion engines (e.g., diesel engines) are the conventional power plants for such heavy work vehicles. Modern technologies have integrated electric powertrains into work vehicles. Problems have been encountered with regard to the efficient transmission of sufficient force to all wheels or tracks of large-scale vehicles.SUMMARY OF THE DISCLOSUREThe present disclosure provides a work vehicle having an electric transaxle that transmits power to another vehicle transaxle.A work vehicle has, in particular, a running gear which is held over the ground by wheels or chains engaging into the ground. A first transaxle carried by the chassis has first wheel end units rotatable about a first wheel axis via a first transaxle to rotate a first set of ground engaging wheels or chains. A second transaxle carried by the chassis has second wheel end units rotatable about a second wheel axis via a second transaxle to rotate a second set of ground engaging wheels or chains. The second transaxle includes an electric machine having a shaft that rotates about an engine axis, a transmission rotated by the shaft of the electric machine and configured to cause multiple gear ratios on a range gear, and a drive gear rotatable about the second wheel axis via the range gear of the transmission. A transfer shaft has a first end coupled to an input assembly engaging the first transaxle and a second end coupled to a driven gear engaging the drive gear to transfer power from the second transaxle to the first transaxle via the transfer shaft.In certain embodiments of the work vehicle, the first transaxle is purely mechanical without a dedicated electric machine and transmission. The work vehicle does not have a transmission assembly other than the transmission of the second transaxle. The electric machine may also be positioned vertically above the drive gear, with the machine axis offset and parallel to the wheel axis, and the output gear rotating about an output axis perpendicular to the wheel axis.In this and other embodiments, the transmission of the second transaxle includes a first gear set disposed on a first side of an engine axis about which the shaft of the electric machine rotates and a second gear set disposed on a second side of the engine axis about which the shaft of the electric machine rotates. The first gear set is a multi-speed gear set having a first clutch for providing different gear ratios, and the second gear set is a multi-speed gear set having a second clutch for providing different gear ratios. The first gear set may be identical to the second gear set, wherein the first gear set connects to the electric machine shaft via a first gear train and the second gear set connects to the electric machine shaft via a second gear train different from the first gear train. In other embodiments, the first and second gear sets may be different, for example, the first gear set is a multi-speed gear set and the second gear set is an input gear set or a multi-speed gear set with a different gear ratio.The second wheel end units in these and other embodiments comprise two wheel end units each having an elongated hub disposed in the transaxle case for rotation about the second wheel axis. The second wheel end unit includes a planetary gear set that transmits power from the drive gear to the elongated hubs of the wheel end units. A differential assembly may be disposed in the second transaxle case and configured to transmit power from the drive gear to the elongate hubs of the wheel end units for rotation about the second wheel axle at a common speed or at different speeds. The second wheel end units each include a planetary gear set in which a sun gear is rotated by a sun shaft coupled to the drive gear and to the differential assembly, and having a carrier coupled to rotate with a corresponding one of the elongated hubs of the second wheel end units. The planetary gearwheel sets have a power flow configuration of the drive input, sun wheel / output, planetary carrier. Additionally, a locking differential clutch pack may be configured to prevent rotation of the sun gear in one of the planetary gear sets to lock the differential for fixed axis, co-rotational rotation of the wheels or chains.The details of one or more embodiments are set forth in the appended drawings and in the description below. Other features and advantages will be apparent from the description, drawings and claims.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic side view of an example work vehicle in the form of an agricultural tractor having one or more transaxles in accordance with the present disclosure; FIG. 2 is an isometric view of an example electrical transaxle used therefor; FIG. 3 is a corresponding isometric view with the axle housing removed; FIG. 4 is a corresponding rear view; FIG. 5 is a corresponding top view; FIG. 6 is a corresponding front view; FIG. 7 is a corresponding sectional view taken along line 7- 7 of FIG. 4 ; FIG. 8 is a corresponding sectional view taken along line 8- 8 of FIG. 6 ; FIG. 9 is a corresponding sectional view taken along line 9-9 of FIG. 4; FIG. 10 is a corresponding sectional view taken along line 10- 10 of FIG. 4 ; FIGS. 11A-11D are dash charts illustrating gears and power flow of a first example transmission of the example electric transaxle of FIG. 2 ; FIGS. 12A-12C are dash charts illustrating gears and power flow of a second example transmission of the example electric transaxle of FIG. 2 ; FIG. 13 is a schematic illustration of a work vehicle including the example electric transaxle of FIG. 2 as a rear transaxle and transmitting power to a powerless, purely mechanical, front transaxle via a transmission shaft; FIG. 14 is a schematic illustration of a work vehicle including the example electrical transaxle of FIG. 2 as a front transaxle and a rear transaxle without mechanical restraint; and FIG. 15 is a graph showing an example switching pairing sequence according to the control logic of the present disclosure.Like reference numerals in the various drawings indicate like elements.DETAILED DESCRIPTIONThe following discussion describes, in one or more embodiments, an electric transaxle and a work vehicle having one or more electric transaxles as illustrated in the accompanying figures of the drawings briefly described above. Various changes may be made to the exemplary embodiments by those skilled in the art. The disclosed electric transaxles are applicable to various large-scale vehicles, such as those used in agriculture, construction, forest, mining, and other types of working environments.SUMMARYLarge-scale vehicles such as those used in agriculture, construction, forest and mining industries have a high demand for power for off-road traction as well as for powering implements required for performing heavy works. Heretofore, internal combustion engines, such as diesel engines, have been the prime mover of such work vehicles. Modern work vehicles are electrified to reduce emissions. To do so, the vehicle platforms typically have to be completely re-constructed in order to optimize the arrangement of the vehicle subsystems on the chassis, which can be complex and costly.To solve these problems, an aspect of the disclosure is an electrical transaxle including an electric machine having a shaft rotating about a machine axis. The electric transaxle also includes a transmission that is rotated by the electric machine shaft and is configured to provide multiple gear ratios on an output or range gear. The electric transaxle also includes a drive gear that is rotatable about a wheel axis via the range gear of the transmission. The drive gear includes a plurality of tooth mesh locations, including a first tooth mesh location on an outer circle of the drive gear and a second tooth mesh location on an annular face of the drive gear. The range gear of the transmission may mesh with the drive gear at the first tooth meshing location. An output shaft has an inner end that supports an output gear in the transaxle case to engage the input gear at the second tooth engagement location, and has an outer end that extends outside the transaxle case.Another aspect of this disclosure is a work vehicle having two transaxles, at least one of which is an electric transaxle. The work vehicle may include, for example, a first electrical transaxle that is mechanical and a second electrical transaxle, as mentioned above and as will be discussed in more detail below. The first and second electrical transaxles may be supported by a common chassis and have wheel end units for rotating the ground engaging associated wheels or chains.In various embodiments, the work vehicle may include no transmission other than gear sets included in the electric transaxle. The electric transaxle may be made compact, with the electric machine being offset and arranged parallel to the wheel axis vertically above the drive gear and the machine axis about which the shaft of the electric machine rotates. Furthermore, the output shaft can rotate about an output axis which is perpendicular to the wheel axis.In this and other embodiments, the transmission of the electric transaxle may include a first gear set disposed on a first side of the machine axis about which the shaft of the electric machine rotates and a second gear set disposed on a second side of the machine axis. The gear sets may be different or identical. The first and second gear sets may be identical cartridge-like components, for example, each providing a multiple speed gear set with a clutch to effect different gear ratios. The first gear set may connect to the electric machine shaft via a first gear or gear train, and the second gear set may connect to the electric transmission shaft via a second gear or gear train different from the first gear or gear train. The two gear sets may thus be two identical two-speed gear sets that, when coupled to the electric machine via the two different gears or gear trains, cooperate to provide a four-speed transmission. In other examples, the two gear sets may be different, such as comprising a multi-speed gear set and a single-speed gear set, or comprising two multi-speed gear sets having different configurations, gear ratios, or different number of speed stages. The electrical transaxle may also include more than two gear sets.Another aspect of the disclosure is a work vehicle having two or more electric transaxles in which the two electric transaxles are mechanically decoupled. A work vehicle having two electric transaxles may include, for example, one or more sensors for sensing speed, heading, orientation, load, and other characteristics of the work vehicle, and a controller configured to process control logic and having memory and processing architecture. The controller may be configured to process control logic to receive the sensor or operator input of the various measured or other characteristics of the work vehicle. The controller processes the control logic to determine a shift pairing sequence for shifting the first transmission of the first electrical transaxle and a second transmission of the second electrical transaxle based on the received input signal. The shift pairing sequence may define a shift time t S1 for shifting the first transmission and a shift time t S2 for shifting the second transmission, wherein the shift time t S1 may be identical to or different from the shift time t S2. The controller will execute the control logic to generate a first shift command to shift the first transmission at shift time t S1 while the second electrical transaxle is propelling the work vehicle, and generate a second shift command to shift the second transmission at shift time t S2 while the first electrical transaxle is propelling the work vehicle.In various embodiments, the controller determines the switching pairing sequence such that the switching time t S1 is prior to the switching time t S2 when the load on the first electrical transaxle is less than the load on the second electrical transaxle or when the first electrical transaxle is vertically above the second electrical transaxle. The control device can determine this switching pairing sequence such that it has a switching time difference Δt S between switching time t S1 and switching time t S2. The shift time difference Δt S may be larger when the work vehicle is on a planar ground than when it is on inclined (i.e., inclined) terrain. The shift time difference Δt S may be greater when the work vehicle is below a limit load capacity, allowing a given shift sequence a longer dwell time to effect a smoother or seamless shift.In some embodiments, the first electrical transaxle is located forward of the chassis of the work vehicle and the second electrical transaxle is located rearward of the chassis, and the work vehicle accelerates in a forward traveling direction. When the ground engaging wheels or chains of the work vehicle meet an inclinedly ascending terrain, the control device can determine the shift pairing sequence such that the shift time t S1 is before the shift time t S2. When the ground engaging wheels or chains of the work vehicle meet a sloping terrain, the controller may determine the shift pairing sequence such that the shift time t S1 is after the shift time t S2. When the ground engaging wheels or chains of the work vehicle hit flat terrain, the controller may determine the shift timing t S1 and the shift timing t S2 based on the load of the work vehicle. For example, if the load on the first electrical transaxle is greater than the load on the second electrical transaxle, the controller may determine the shift pairing sequence such that the shift time t S1 is earlier than the shift time t S2. Conversely, if the load at the first electrical transaxle is less than the load at the second electrical transaxle, the controller may determine the shift pairing sequence such that the shift timing t S1 is after the shift timing t S2.The first and second transmissions of the electric transaxles may each be multi-speed transmissions including first, second and third speed stages, respectively, or even higher speed stages. The controller may process the control logic (e.g., stored or transmitted aboard the work vehicle) to execute the paired shift sequences in various ways. For example, the controller may receive inputs (e.g., sensor input signals) that result in the first electrical transaxle being vertically above the second electrical transaxle when the first and second transmissions shift from the first speed stages to the second speed stages, and the first electrical transaxle being vertically below the second electrical transaxle when the first and second transmissions shift from the second speed stages to the third speed stages. The controller may determine the shift pairing sequences for shifting the first and second transmissions from the first speed stages to the second speed stages such that the shift time t S1 is prior to the shift time t S2. The controller may determine the shift pairing sequences for shifting the first and second transmissions from the second speed stages to the third speed stages such that the shift time t S1 is after the shift time t S2.It should be appreciated that sensor data of the various characteristics of the work vehicle may be provided from onboard, offboard, or a combination of onboard and offboard sensors. In addition, when determining the shift pairing sequences for shifting the transmissions of the electric transaxles, the control unit may take into account further work vehicle-relevant parameters and factors (for example, operating state of the work vehicle) in addition to speed, driving direction, orientation and load of the work vehicle. The sensor data and various parameters used in determining the switching pairing sequences can also detect attributes of an attachment of the work vehicle. For example, the controller may receive sensor input signals related to tractive forces acting on the work vehicle from a work implement being towed or pushed by the work vehicle. The traction forces may be detected by one or more sensors disposed on the work vehicle or on the work implement or remote from both.EXAMPLE WORK VEHICLES WITH (AN) ELECTRIC TRANSAXLE(S)As shown in FIG. 1, a work vehicle 20 may be implemented as an agricultural tractor or other heavy duty work vehicle as used in agriculture, construction, forest, and mining. The work vehicle 20 includes a landing gear 22 that supports a plurality of ground engaging elements 24, such as wheels or tracks, that maintain the landing gear 22 above the ground. Supported on the chassis 22 are a main housing 26 and an operator cabin 30 to be occupied by an operator of the work vehicle 20.The operator cabin 30 may include one or more display devices 32 and one of various operator interfaces 34 connected to a control system 36. In addition to the display devices 32, the operator interface devices 34 may include various video and audio devices for providing video and audio information, haptic devices that provide haptic feedback, levers, joysticks, steering wheels, pedals, buttons, etc. The operator interface devices 34 may also be a set of input items displayed on the display devices 32, such as links, icons, or other user actuatable mechanisms. Additionally or alternatively, a portion of the operator interfaces 34 may also be integrated with the display devices 32 such that the operator interfaces 34 include physical input elements (e.g., buttons, switches, dials, etc.) on or near the display devices 32, a touch screen module integrated with the display devices 32, or a cursor input device (e.g., joystick, trackball, or mouse) for positioning a cursor for selection of the GUI elements generated on the display devices 32. The display devices 32 may be any imaging device configured for operation within the operator cabin 30 that includes one or more dedicated display consoles and various heads-up display projectors.The display devices 32 and operator interfaces 34 are operatively connected to the control system 36, with various data connections between these components being represented by a number of signal lines representing wired and / or wireless data connections. The control system 36 includes one or more controllers 38 or other control architecture that may take any suitable form for performing the functions described herein, and is provided as a general, non-limiting, designation of the processing architecture or system of the work vehicle 20 or other computing device or group of devices. Controller 38 may include, for example, or correspond to, any convenient number of processors, controllers, computer readable memories, power supplies, storage devices, interface cards, and other standardized components, and may also include or cooperate with any suitable number of firmware and software programs or computer readable instructions configured to perform the various process tasks, computations, and control / display functions described herein, all of which are represented by processor 40. Such computer readable instructions may be stored in a non-transitory sector of local on-board memory 42 accessible by controller 38. Although shown as a single block, the memory 42 may include any number and type of storage media suitable for storing computer readable code or instructions, as well as other data used to aid in the operation of the work vehicle 20. The memory 42 may be integrated into the controller architecture, e.g., as a system-in-package system, a system-on-chip, or other type of microelectronic package or module, in various embodiments.The work vehicle 20 may include various onboard sensors and actuators (actuators), collectively referred to herein by reference numerals 44 and 46, respectively, and a network interface 48. The work vehicle 20 may include, for example, a travel speed sensor that detects the travel speed of the work vehicle 20 in a field, for example, by detecting the rotational speed of the ground engaging elements 24, a driveshaft, the axle, or other components. The measurement of the vehicle speed may also be via a positioning system, such as a global positioning system (GPS), dead reckoning system, LORAN system, or a wide variety of different other systems or sensors that provide an indication of vehicle speed or direction of travel. The on-board sensors 44 may include various different types of sensor architectures to provide the controller 38 with input signals regarding the operating parameters of the work vehicle 20, data regarding the environment of the work vehicle 20, and other information helpful to operate the work vehicle 20. The on-board sensors 44 may include some form of receiver, chipset, or the like for positioning using a satellite navigation system including, but not limited to, GPS, Galileo, Global Navigation Satellite System (GNSS or GLONASS), Compass IGS01, and combinations of the satellites included therein. The onboard sensors 44 may also include various linear and angular position sensors, inertial sensors (e.g., microelectromechanical inertial measurement units "MEMS IMU") devices, strain sensors, pressure sensors, engine speed sensors, temperature sensors, humidity sensors, wear sensors, vibration sensors, image sensors or cameras, and / or sensors for measuring radio frequency (RF) signals.Various of the aforementioned (or other) sensors may individually or in combinations sense the travel speed, the direction of travel, and the spatial orientation (e.g., pitch, roll, and yaw) of the work vehicle 20. Moreover, various of the foregoing (or other) sensors, alone or in combination, may measure the load characteristics (e.g., mass, center of mass, height, etc.) of the work vehicle 20, including the loads of work tools attached to the work vehicle 20 or carried on board (e.g., loaders, backhoes, etc.) and work tools towed behind or in front of the work vehicle 20 (e.g., soil tilling tools, baler, plough, etc.).Likewise, the actuators 46 onboard the work vehicle 20 may take various forms for performing operation assisting functions. For example, the actuators 46 may provide the traction force to the ground engaging elements 24, operate pneumatic and hydraulic onboard systems, and impart linear or rotational motion to the implements attached to the work vehicle 20. The actuators 46 may take any of various forms, including various motors, pumps, linear actuators (e.g., cylinders), solenoid and other valves, clutches, brakes, and any other mechanism that can transfer force from one component to another. The actuators 46 may have mechanical, electrical, and / or hydraulic aspects and may thus be coupled to and draw power from the electric drive system 28.It should be appreciated that the aforementioned onboard sensors 44 and onboard actuators 46 may include any number of sensors and actuators configured to detect parameters of various implements propelled by the work vehicle 20. These implements may include towed implements (e.g., various soil implements, balers, sprayers, winders, backhoes, etc.) mounted to the rear of the work vehicle 20, as well as implements (e.g., various loaders, ploughs, brushes, etc.) mounted to the front of the work vehicle 20. These implements may take various forms of power (e.g., electrical and hydraulic) to be part of the electrical power system 28, or may have separate autonomous drive systems or may be otherwise driveless.The network interface 48 may be any device or module providing access to a network, such as a wireless (e.g., WiFi or cellular) transceiver or data link, including an antenna. The network interface 48 may also be a satellite receiver and may receive data via a satellite link and may allow communication with nearby cell towers or terrestrial nodes, such as wireless RF nodes in a controller area network ("CAN") established over an agricultural area (e.g., a field or group of fields) within which the work vehicle 20 operates. Suitable network interfaces 48 include telematics receivers and transmitters offered by Deere & Company, located in Moline, Illinois, under the trade name "JDLink™.". Regardless of these examples, the particular form assumed by the network interface 48 may vary as long as this network interface 48 provides permanent or intermittent wireless connectivity to the network.The electrical power system 28 may include one or more battery packs 50 that may include battery cells as well as associated circuitry for supplying power to and from battery cells of various technologies (e.g., lead acid, lithium, lithium ions, lithium sulfur, lithium ion phosphate, lithium cobalt, nickel metal hydride, nickel cadmium, ultracapacitors, etc.). The battery packs 50 may include temperature sensors and channels for passing coolant through the battery packs 50. The electrical power system 28 may include a battery management system ("BMS") 52, which may manage charging, detect low charge levels, and predict the remaining run-time, for example. The BMS 52 may also provide information about the current, voltage, and temperature of the battery packs 50. The BMS 52 may also utilize chargers mounted or installed on / in the battery packs 50 to charge the battery packs 50 to optimum charge levels and temperatures. The BMS 52 may include or utilize a universal input / output interface ("GPIO" interface) for communication with the battery pack 50. The electrical power system 28 may include one or more inverters 54 for converting direct current ("DC") to alternating current ("AC"). Inverters 54 may take any suitable form, such as insulated gate bipolar transistors ("IGBT") and silicon carbide ("SiC") inverters. The inverters 54 may receive DC power from the battery packs 50 via the GPIO interface and the DC bus for receiving DC power from the battery packs 50. The inverters 54 may also receive power from other sources (e.g., from an on-board generator or regenerative braking) that may be converted to DC power by the inverter 54 and provided to the battery packs 50 via the GPIO interface and the CD bus.As also seen in FIG. 2, the work vehicle 20 may include an electrical transaxle 100 powered by the electrical power system 28 under the control of the controller 38 of the control system 36 to provide traction control of the ground engaging elements 24 during the working and driving operation of the work vehicle 20. In the depicted example, the electric transaxle 100 includes a central driven transmission 102 in a transaxle case and wheel end units 106 mounted on the transmission 102 on opposite sides. The transaxle case 104 may include a single case or different sub-cases for different components of the transmission 102, and may be monolithic or formed of multiple separate case parts.As also seen in FIG. 8, in the depicted example, the wheel end units 106 are substantially identical (e.g., similar symmetrical right and left versions) and are configured for attachment to one of the ground engaging elements 24, such as by securing bolts via matching bolt hole patterns on rotatable hubs 108 of the wheel end units 106 and the corresponding hubs of the ground engaging elements 24. the hubs 108 are elongated elements that pass through the outer housings 110 of the wheel end units 106 and are rotatably supported via one or more bearings 112 at each laterally inner and outer end so as to rotate about a wheel axis A w about which the ground engaging elements 24 rotate during travel of the work vehicle 20. The laterally inner ends of the elongated hubs 108 couple to the wheel gear trains 114. As also shown in FIG. 10, each wheel countershaft 114 can be designed as a planetary gear set. However, other types of reduction drives may be used. In the depicted embodiment, the laterally inner end of each elongated hub 108 is splined or toothed for engagement with the grooves or teeth of a planet carrier 116. Carrier 116 includes gears that rotatably support (e.g., two, three, or more) planet gears 118 disposed in the annulus between a ring gear 120 formed in or fixed relative to the housing of wheel end unit 106 and a sun gear 122 to mesh with both ring gear 120 and sun gear 122. The sun gear 122 is rigidly connected to a shaft 124 for w co-rotation as a whole about the wheel axis A. Recesses in the laterally outer ends of the shafts 124 receive the heads of screws 126 threaded into the inner ends of the elongated hubs 108 to secure retaining plates 128 in abutment with the beams 116 and thereby retain the elongated hubs 108 on the beams 116 for co-rotation therewith. The illustrated gear reduction gears 114 provide planetary gear arrangements with a power flow of the sun gear-output planetary carrier type that provide a low reduction ratio between the power input to the wheel end units 106 and the power output of the wheel end units 106 to the ground engaging elements 24.As further seen with reference to FIG. 9, the lateral inner end of the shaft 124 of each wheel gear train 114 projects into a differential assembly 130 that rotates about the wheel axis A w relative to the wheel end housings 110 and the transaxle housing 104. In the example shown, the differential assembly 130 includes a differential case 132 that rotates on bearings 134 relative to mounting rings 136 coupled to the wheel end cases 110. The differential housing 132 defines an internal cavity in which differential gears 138 and differential gears 140 are disposed. In the illustrated example, there are four differential drives 138 that support four differential gears 140. The differential gears 138 intersect each other at right angles and are arranged orthogonally to the wheel axis A w with their ends seated in recesses in the interior of the differential case 132. The balance gears 140 mesh with two side gears 142, 144 positioned on opposite sides of the differential assembly 10 and rigidly secured (e.g., press fit or splined) to the laterally inner ends of the shafts 124. The differential gears 140 and the side gears 142, 144 are formed as bevel gears such that their rotational axes are rectangular. As can be seen, the differential assembly 130 allows the side gears 142, 144 to rotate at different speeds, thereby allowing the elongated hubs 108 of the wheel end units 106 to drive the ground engaging elements 24 at different speeds. The overall arrangement of the gears and other torque-transmitting components of the wheel end units 106 and the differential assembly 130 that transmit power to the ground engaging mechanisms 24 may be considered to form one, or a part of, the transaxle assembly.In the depicted embodiment, the differential assembly 130 may be locked via a brake 146. The brake 146 may be electro-hydraulically activated via the operator interface 34 via the control system 36 by moving a piston 148 and engaging the brake 146. The brake 146 includes a pack 150 of alternating interleaved plates and friction plates that are alternately splined to the differential housing 132 and an annular hub 152 of the side gear 142. Application of the brake 146 causes the side gear 142 to move with the differential case 132, and thereby causes the differential gears 138 and balance gears 140 to rotate the side gear 144 with the side gear 142 and the differential case 132. This effectively "locks" the differential assembly 130 so that both of the shafts 124 and the elongated hubs 108 rotate together. As a result, the left and right ground engagement elements 24 are in turn blocked, so that they rotate together in the manner of a rigid axle at the same speed.As shown in FIGS. 8 and 9, and in FIGS. 3-7, power from the transmission 102 of the electric transaxle 100 is transmitted to the differential assembly 130 and thereby to the wheel end units 106 via a drive gear 160. The drive gear 160 is rigidly connected to the differential case 132 so as to rotate therewith about the wheel axis A w. The drive gear 160 is configured with an annular sloped surface 162 defining teeth of any suitable configuration, which in the depicted example are spherical bevel teeth. The drive gear 160 is also configured with a circumferential or peripheral rim 164 that also defines teeth such as spherical bevel teeth. The teeth of the annular ramp 162 and the circumferential edge 164 of the drive gear 160 define two (or more) separate and unique engagement locations or areas for power transmission from the transmission 102 for two separate and unique directions of power flow and purposes. The drive gear 160 may thus serve to transmit traction force to the ground engaging elements 24 and transmit output force to a second energy consumer, such as an on-board non-drive axle, transaxle, or other equipment, or to an off-board implement or the like, as described below.As shown in FIGS. 3, 4, and 7, the drive gear 160 may be coupled to an output shaft 170 via teeth of an output shaft gear 172 that mesh with the teeth of the annular sloped surface 162 of the drive gear 160 at the engagement location ML 1 such that rotation of the drive gear 160 about the wheel axis A w is translated into rotation of the output shaft 170 about an output axis A O The output axis A O extends at an angle (e.g., 90 degrees) to the wheel axis A W and the wheel axis A W( may, for example, vertically above or below), intersect or be offset from it. The cone angles of the drive gear 160 and the output shaft gear 172 may be identical or different. Various exemplary implementations of the work vehicle 20 and the output shaft 170 will be described below with reference to FIGS. 13 and 14. As shown in FIGS. 4, 5, and 7, the drive gear 160 is coupled to the transmission 102 via gear teeth that mesh with the teeth of the circumferential edge 164 of the drive gear 160 at the mesh location ML 2 to cause the drive gear 160 to rotate about the wheel axis A W.In the depicted example, the transaxle 100 includes an electric machine 180 and two gear sets 182A, 182B. In this example, the gear sets 182A, 182B are identical, thus ensuring a reduction in the component variance of the array. In this example, the gear sets 182 are self-contained cartridge-like gear sets that facilitate assembly and reduce manufacturing complexity. Here, the gear sets 182A, 182B each provide two different speed stages that, in combination, result in the four speed stages of the transmission 102. It should be appreciated that the example implementation is only one possible example. In other implementations, the transmission may include more (e.g., three or more) or fewer (e.g., one) gear sets that may be differently configured and stepped such that the transmission has a different number of speed stages with one or more different gear ratios. While a single electric machine is used in the exemplary embodiments illustrated and described here, the transmission can additionally have a plurality of electric machines. Further, the electric machine 180 may be embodied as any suitable electric machine to convert electrical power into torque and rotational motion. The electric machine 180 can therefore be realized as a single electric motor or in combination with one or more gearwheels as a package.In the depicted example, the electric machine 180 includes a motor shaft 183 that drives a motor shaft gear 184 to rotate about a machine axis A M that is offset and substantially (e.g., within 2 degrees) parallel to the wheel axis A W to drive the gear sets 182A, 182B. As shown in FIG. 7, the electric machine 180 may be disposed vertically above the drive gear 160 and laterally oriented, with the gear sets 182A, 182 positioned on (longitudinally) opposite longitudinal sides of the electric machine 180 such that the machine axis A M and the wheel axis A W, about which the drive gear 160 rotates, may define a plane P where the gear sets 182A, 182B are disposed on opposite sides of the plane P.As noted above, the transmission 102 includes a gear train for transmitting rotation from the electric machine 180 at one or more different gear ratios. The gear sets of the transmission 102 may generally be either configured to have respective separate gear ratios, or, if identical, as in the case of gear sets 182A, 182B of the illustrated example, to be coupled to the electric machine 180 via one or more gears or gear trains providing different gear ratios. In either of the two methods mentioned, the transmissions 102 define a combined set of gear ratios that can be independently selected by an operator or a control algorithm.Referring now to FIGS. 6, 7, 10 and 11A- 11D, a more detailed description of the flow of power from the electric machine 180 to the drive gear 160 for an example gear train follows in conjunction with gear sets 182A, 182B providing four operating speed levels. A discussion of a second exemplary transmission 102' will then follow in conjunction with a single gear set cartridge 300 that provides three operating speed levels, as shown in FIGS. 12A-12C.In the example shown, gear sets 182A, 182B are each coupled to electric machine 180 for transmission of power via a respective gear or gear train. Specifically, the electric machine 180 is coupled to the gear set 182A via a gear 190 and to the gear set 182B via a gear train including the gears 192, 194, 196. Each of these gears 190-196 has a different diameter and number of teeth, and the gear 190 provides a different gear ratio from the gear train 192-196. The gear ratios achieved by the combination of gear set 182A and gear 190 may be interleaved with the gear ratios achieved by the combination of gear set 182B and gear train 192-196. Using the identically configured two-stage gear sets 182A, 182B, the transmission 102 may provide four different gears taken together in this manner. Generally, NxM different gear ratios can be achieved for M gear sets having N available gear ratios by using gears or gear trains having different gear ratios. While various arrangements are contemplated, gear train 192-196 is designed so that gears 192 and 194 rigidly secured to a common shaft 200 rotate together, gear 192 meshing with motor shaft gear 184 and, upon meshing with gear 196, causing rotation of gear 196 which, in turn, drives gear set 182B in rotation.In gear set 182A, gear 190 is rigidly secured to a common shaft 202A for co-rotation with gears G 1A, G 2A respectively. Gear G 1A meshes with gear G 3A, and gear G 2A meshes with gear G 4A. Gear G 3A and gear G 4A are rotatably connected to a common shaft 204A so as to rotate independently. An annular shaft sleeve 206A is coaxial with and rotates about the shaft 204A and rigidly fixed to it is a co-rotating output gear G OA, which may be considered a "range" gear. A clutch C 1A is operatively disposed between the shaft sleeve 206A and the gear G 3A and a clutch C 2A is operatively disposed between the shaft sleeve 206A and the gear G 4A. Selective alternate engagement of clutch C 1A and clutch C 2A via controller 38 of control system 36 provides different operating speed levels of gear set 182A. The output gear G OA meshes with the circumferential outer rim 164 of the input gear 160 at the engagement location ML 2A, to transfer power from the gear set 182A to the input gear 160 and through to the differential assembly 130 to provide traction power to the ground engaging elements 24 of the work vehicle 20 in one or the other gear stage.Likewise, in gear set 182B, gear 196 is rigidly secured to a common shaft 202B for co-rotation with gears G 1B, G 2B respectively. Gear G 1B meshes with gear G 3B, and gear G 2B meshes with gear G 4B. Gear G 3B and gear G 4B are rotatably connected to a common shaft 204B so as to rotate independently. An annular shaft sleeve 206B is coaxial with and rotates about the shaft 204B and rigidly secured to it is a co-rotating output gear G OB which may be considered a "range" gear. A clutch C 1B is operatively disposed between the shaft sleeve 206B and the gear G 3B and a clutch C 2B is operatively disposed between the shaft sleeve 206B and the gear G 4B. Selective alternate engagement of clutch C 1B and clutch C 2B via controller 38 of control system 36 provides different operating speed levels of gear set 182B. The output gear G OB meshes with the outer circumferential edge 164 of the input gear 160 at the engagement location ML 2B, to transfer power from the gear set 182B to the input gear 160 and through to the differential assembly 130 to provide traction power to the ground engaging elements 24 of the work vehicle 20 in one or the other gear stage.With this understanding of the gear sets 182A, 182B and the following clutch table, the power flows for each of the four operating speed stages of the example transmission 102 will now be described in detail. FIGS. 11A-11D illustrate the four operating speed stages of the transmission 102 where the power flow paths passing through the gear sets 182A, 182B are shown at rich pressure.1x x x x x x x2x x x x x x x3x x x x x x x4x x x x x x xMore specifically, in the first speed stage or first gear, as shown in FIG. 11A, power from the electric machine 180 is transmitted from the motor shaft gear 184 to the gear 192 and via the shaft 200 to the gear 194 meshing with the gear 196. From gear train 192-196, power flows via shaft 202B to gear G 2B, which meshes with gear G 4B. With clutch C 2B( engaged while all other clutches are disengaged), power is directed from gear G 4B to shaft sleeve 206B, and to output gear G OB which then meshes with drive gear 160. In the second speed stage shown in FIG. 11B, power from the electric machine 180 is directed through the gear train 192- 196 as described with reference to FIG. 11A and then flows via the shaft 202B to the gear G 1B, which meshes with the gear G 3B. With clutch C 1B( engaged while all other clutches are disengaged), power is directed from gear G 3B to shaft sleeve 206B, and to output gear G OB which then meshes with drive gear 160. In the third speed stage or third speed as shown in FIG. 11C, power from the electric machine 180 is transmitted through the gear 190 and then flows via the shaft 202A to the gear G 2A, which meshes with the gear G 4A. With clutch C 2A( engaged while all other clutches are disengaged), power is directed from gear G 4A to shaft sleeve 206A and output gear G OA which then meshes with drive gear 160. In the fourth speed stage shown in FIG. 11D, power is transmitted from the electric machine 180 to the gear G 3A meshing with gear G 1A via the gear 190 and the shaft 202A. With clutch C 1A( engaged while all other clutches are disengaged), power is directed from gear G 1A to shaft sleeve 206A and output gear G OA which then meshes with drive gear 160.The description of the second exemplary transmission 102' will now be described in connection with a single gear set cartridge 300 providing three operating speed levels as illustrated in FIGS. 12A-12C. Here, similar to that described above with respect to power transmission to gear set 182B, electric machine 180' drives motor shaft gear 184' on motor shaft 183' for meshing with gear train 192'-196' (with gears 192' and 194' on common shaft 200'). Gear 196' is rigidly secured to a common shaft 202' for co-rotation with gears G 1', G 2' respectively. Gear G 1' meshes with gear G 3', and gear G 2' meshes with gear G 4'. Gear G 3' and gear G 4' are rotatably connected to a common shaft 204' so as to rotate independently. An annular shaft sleeve 206' is coaxial with and rotates about shaft 204' and a co-rotating output gear G O' is rigidly secured thereto. A gear G 5 is rigidly secured to another shaft 302 which also rotatably supports a gear G 6 to the gear G 5. Clutch C 1' is operatively disposed between shaft sleeve 206' and gear G 3' clutch C 2' is operatively disposed between shaft sleeve 206' and gear G 4' and clutch Cs is operatively disposed between gear G 5 and gear G 6. Selective alternate engagement of clutch C 1', clutch C 2' and clutch C 3 via controller 38 of control system 36 provides different operating speed levels of gear set 300. The output gear G O' meshes with the outer circumferential edge 164 of the input gear 160 to transfer power from the gear set 300 to the input gear 160 and through to the differential assembly 130 to provide traction power to the ground engaging elements 24 of the work vehicle 20 in one of three speed stages.With this understanding of the gear set 300 and the following clutch table, the power flows for each of the three operating speed stages of the exemplary transmission 102' will now be described in detail. FIGS. 12A-12C illustrate the three operating speed stages of the transmission 102' where the power flow paths passing through the gear set 300 are shown in rich pressure.1x x x x x x x2x x x x x x x3x x x x x x xMore specifically, in the first speed stage shown in Figure 12A, power from the electric machine 180 is transmitted from the motor shaft gear 184' to the gear 192' and via the shaft 200' to the gear 194' meshing with gear 196'. From the gear train 192'-196', the force flows via the shaft 202' to the gear G 2', which meshes with the gear G 4'. With clutch C engaged 2'( while all other clutches are disengaged), the force is directed from gear G 4' to shaft sleeve 206', and to output gear G O' which then meshes with drive gear 160. In the second speed stage shown in FIG. 12B, power from the electric machine 180 is directed through the gear train 192'-196' as described with reference to FIG. 12A and then flows via the shaft 202' to the gear G 1', which meshes with the gear G 3'. With clutch C engaged 1'( while all other clutches are disengaged), the force is directed from gear G 3' to shaft sleeve 206', and to output gear G O' which then meshes with drive gear 160. In the third speed stage shown in FIG. 12C, power from the electric machine 180 is directed through the gear train 192'-196' as described with reference to FIG. 12A and then flows via the shaft 202' to the gear G 1', which meshes with the gear G 3' which in turn meshes with the gear G 5. With clutch C 3( engaged while all other clutches are disengaged), power is directed to gear G 6 and further to output gear G OA which then meshes with drive gear 160.The electric transaxle disclosed herein, as embodied in the electric transaxle 100 described above, may be incorporated into the powertrain of a work vehicle in various implementations. In certain powertrains, the electric transaxle may be the only assembly for providing traction force to the work vehicle or a powered work implement coupled to the work vehicle. The electric transaxle may then be the only transaxle in the powertrain, or the powertrain may include multiple transaxles where the other transaxles are non-motive (e.g., without an electric machine, thereby being may be referred to as purely mechanical transaxles), but may include various step and reduction transmissions and differential assemblies. In the context of multiple transaxles, the electrical transaxle may provide force to the powerless or purely mechanical transaxle(s) such that the electrical transaxle is mechanically connected or directly coupled to the powerless or purely mechanical transaxle for the transmission of rotational force. In other powertrains, the electrical transaxle may be one of a plurality of electrical transaxles of the same or different configuration, in which case the electrical transaxles may be decoupled with respect to the mechanical power flow, but instead may be electrically operatively coupled for coordinated operation in providing traction force to the ground engaging elements of the work vehicle. FIGS. 13 and 14 show (schematically illustrated) examples of a single electric transaxle and a two electric transaxle employing the example electric transaxle 100, respectively. It should be appreciated that other configurations of the electric transaxle(s) and the powertrain are included.Referring now to FIG. 13, a work vehicle 20A includes a powertrain 400A that includes the electric transaxle 100 aligned about a wheel axis A WB in combined use with another transaxle 402 aligned about a wheel axis A WA. Here, the transaxle 402 is non-driven or purely mechanical, and is driven exclusively by a rotational force transmitted from the electric transaxle 100. The transaxle 402 may be configured as any conventional known transaxle such as conventional driving by an internal combustion engine through a drive shaft. The transaxle 402 may include, for example, one or more axle casings including a transaxle gear set and differential assembly 404 and wheel end units 406 (having elongated rotating hubs and gear trains as shown with respect to the electric transaxle 100) for transferring power from the assembly 404 to ground engaging elements mounted at the respective end of the transaxle 402.The transaxle 402 may be mechanically coupled to the output shaft 170 of the electric transaxle 100 in various ways for receiving rotational force. For example, the transaxle 402 may include an input assembly 408 (e.g., including an input shaft and a gear or gear train) that is mechanically coupled to the assembly 404. The input arrangement 408 is in turn mechanically coupled to the output shaft 170 of the electrical transaxle 100 via a transmission shaft 410 which may be a monolithic shaft or an arrangement of a plurality of shaft sections. The transfer shaft 410 may be provided with any suitable coupling structures (e.g., yokes, gears, grooves, and so forth) and coupled to the output shaft 170 and the input assembly 408.The electric transaxle 100 may provide a 1:1 rotational power transmission from the output shaft 170 to the input assembly 408 via the transmission shaft 410. The electric transaxle 100 may provide power transmission with other gear ratios through one or more reducer gear assemblies integrated with the powertrain 400A (e.g., directly within the electric transaxle 100, at the input assembly 408, or elsewhere on board the work vehicle 20A outside of the electric transaxle 100 and the transaxle 402). The rotational force transmitted from the electrical transaxle 100 to the transaxle 402 via the transmission shaft 410 may be a continuous rotational force or may be a selective intermittent force by use of a clutch assembly 412 operatively couplable to the control system 36.The control system 36 may be used to control the clutch assembly 412 manually (e.g., by operator input via the operator interface 34 or display device 32) or automatically (e.g., via control commands derived from, or otherwise corresponding to, circuitry stored in the memory 42 and processed by the processor 40 of the controller 38). The clutch assembly 412 can be operated (manually or automatically) to effect various transaxle-engaging drive modes. In a first type of drive, the clutch arrangement 412 can be actuated, for example, in such a way that it disengages and operatively decouples the output shaft 170 from the input arrangement 408. In this mode of drive, the transaxle 402 is operated passively because it does not receive rotational force from the electric transaxle 100. In this case, the associated ground engaging elements passively rotate by frictional contact with the ground during travel of the work vehicle 20A. This type of drive can thus be considered in certain implementations as a two-wheel drive. In a second mode of drive, the clutch assembly 412 may be controlled to engage and operatively couple the output shaft 170 to the input assembly 408 to provide rotational force via the transmission shaft 410. In this driving manner, the transaxle 402 is actively driven by the electric transaxle 100 to supply rotational force for driving the work vehicle 20A to the transaxle 402, thereby rotating the associated ground engaging elements with traction force. This type of drive can thus be considered in certain embodiments as a four-wheel drive or all-wheel drive. In a third type of drive, the clutch assembly 412 may be controlled to selectively partially engage (or disengage) to partially disengage or reduce the engagement of the output shaft 170 with the input assembly 408 to allow for controlled slip that may be used to vary the speed of the input assembly 408 relative to the output shaft 170 and thus allow for a speed difference between the ground engaging elements connected to the electric transaxle 100 as compared to the transaxle 402. This may serve to provide a transient speed or torque variance between front and rear wheels, which may be advantageous in certain operating situations of the work vehicle 20A (e.g., to improve traction when the work vehicle 20A encounters changing or irregular off-road terrain).Referring now to FIG. 14, the work vehicle 20B may include a powertrain 400B having two electric transaxles, such as two identical electric transaxles 100A, 100B aligned about respective wheel axles A WA and A WB as described above. As noted above, in such powertrain realization forms, the electric transaxles may be mechanically decoupled, i.e., may not have a connecting transmission shaft for torque transmission between the electric transaxles, but may be operatively coupled to the controller 38 for coordinated operation by the control system 36. As in other examples, the control system 36 may provide operator input via operator interface 34 or display device 32, or may automatically control the electrical transaxles 100 according to circuitry stored in memory 42 and processed by the processor 40 of the controller 38. As described above, the control system 36 is also received input signals from the vehicle sensors 44 to inform the control system 36 of various parameters or characteristic characteristics (e.g., speed, heading, orientation, load, etc.) of the work vehicle 20B, including any on-board or mounted implements. Various aspects of a work vehicle powertrain, such as powertrain 400B, having multiple electric transaxles 100 will now be discussed with reference to FIG. 15.FIG. 15 shows a shift diagram of exemplary shift logic for the multi-stage driven transmissions 102A, 102B of the respective electric transaxles 100A, 100B, where the four speed stages (y-axis) are depicted as a function of time (x-axis). Shift graph 500A (shown in phantom) refers to transmission 102A of electric transaxle 100A, and shift graph 500B (shown in solid line) refers to transmission 102B of electric transaxle 100B. In the illustrated example, the electric transaxle 100A is located at the front end of the work vehicle 20B, and the electric transaxle 100B is located at the rear end of the work vehicle 20B, with acceleration in the forward travel direction T. As will be explained below, a reverse arrangement of the electric transaxles 100A, 100B and / or a reverse of the travel direction of the work vehicle 20B may significantly change the shift graph (e.g., reverse or reverse the shift pairing sequences).As may be seen in FIG. 15, the shift timings (t s), at which shift events of the transmissions 102A, 102B of the electric transaxles 100A, 100B occur, may differ from one another, although it should be noted that one or more shift points for the different speed stages may also be accomplished simultaneously (e.g., at the same time). For selection of the shift pairing sequence (e.g., relative shift time difference), various parameters may be used by the operator or by the shift logic, which may include some or all of the speed, heading, orientation, and load characteristics of the work vehicle 20B. All of these (and other) parameters may be detected via the vehicle sensors 44 and provided as input signals to the controller 38. The speed and direction of travel of the work vehicle can be determined, for example, using an onboard GPS system. Load characteristics may be determined by detecting the displacement of suspension components or the pressure of hydraulic components of the work vehicle 20B, and strain sensors may detect the tensile forces acting on the work vehicle 20B from a towed work implement. The work vehicle orientation (e.g., pitch and roll) may be detected using onboard MEMS IMU devices embedded in the control system hardware or other locations in the work vehicle 20B.As noted, the controller 38 may be configured to process control logic to receive input signals from the sensors 44 regarding speed, heading, and load characteristics of the work vehicle 20B. The controller 38 processes the control logic to determine a shift pairing sequence for shifting the first transmission 102A of the electric transaxle 100A and the second transmission 102B of the electric transaxle 100B based on the received input signals. In the illustrated example, a shift pairing sequence may be established for each speed stage of the transmissions 102A, 102B, may define a shift time t S1 for shifting the transmission 102A, and a shift time t S2 for shifting the transmission 102B from a given speed stage (e.g., from speed stage 1 to speed stage 2). As noted, the switching time t S1 may be the same as or different from the switching time t S2. The controller 38 will execute the control logic to generate a first shift command to shift the transmission 102A S1 at the shift time t while the electric transaxle 100B is driving the work vehicle 20B and generate a second shift command to shift the transmission 102B S2 at the shift time t while the electric transaxle 100A is driving the work vehicle 20B.The controller 38 may generally determine a given shift pairing sequence such that the shift time (e.g., t S1) of one transmission (e.g., transmission 102A) is prior to the shift time (e.g., t S2) of the other transmission (e.g., transmission 102B) when the load on the one electrical transaxle (e.g., electrical transaxle 100A) is less than the load on the other electrical transaxle (e.g., electrical transaxle 100B) or when the one electrical transaxle (e.g., electrical transaxle 100A) is vertically above the other transaxle (e.g., electrical transaxle 100B). When the ground engaging elements of the work vehicle 20B meet sloped terrain, the controller 38 may determine the shift pairing sequence such that the shift time (e.g., t S1) is after the shift time (e.g., t S2). When the ground engaging elements of the work vehicle 20B meet flat terrain, the controller 38 may determine the shift timing t S1 and the shift timing t S2 based on load characteristic characteristics of the work vehicle other than the orientation. For example, in the work vehicle 20B, when the one electric transaxle is more heavily loaded than the other, the controller 38 may determine the shift pairing sequence such that the shift timing of the more lightly loaded electric transaxle is earlier than the shift timing of the more heavily loaded electric transaxle. In some cases, the controller 38 may resolve the shift pairing sequence to include a shift time difference Δts between shift times (e.g., t S2- t s1) which may be either a positive or negative absolute value. The shift time difference Δt S may be larger when the work vehicle 20B is on a planar ground than when it is on inclined terrain. The shift time difference Δt S may also be greater when the work vehicle 20B is below a prescribed limit load capacity, allowing a given shift sequence a longer dwell time to effect a smoother or seamless shift in a given speed stage.In a scenario depicted by t S1 and t S2 in FIG. 15, the work vehicle 20B may ramp up an incline (e.g., an incline greater than 5 degrees). The higher (i.e., vertically higher) electrical transaxle 100A is switched first at switching time t S1 and the lower electrical transaxle 100B is switched second at time t S2. The shift time difference Δt S2-S1 for the execution of the shift event may be relatively small compared to a case where the work vehicle 20B is on a planar ground (e.g., between + / - 5 degrees), thereby providing the traction force to the work vehicle 20B more quickly. The difference in shift timings may decrease as the angle of inclination increases, such that the shift is no longer as smooth, but the delivery of a more continuous force to the ground engaging elements is promoted.In a scenario illustrated by t S3 and t S4 in FIG. 15, the work vehicle 20B may be going down a grade (e.g., a grade greater than 5 degrees). The higher electric transaxle 100B is first switched at the switching time t S3 and the lower electric transaxle 100A is second switched at the time t S4. As compared with shift times when the work vehicle 20B is on level terrain (for example, slope less than 5 degrees), the shift time difference Δt S4-S3 may be small. The difference in switching instants may decrease with increasing gradient.In a third scenario, represented by t S5 and t S6 in FIG. 15, the work vehicle 20B is on level terrain (e.g., grade or grade below 5 degrees), with the electrical transaxle 100B being more heavily loaded than the electrical transaxle 100A. In this example, the electrical transaxle 100B is first switched at the switching time t S5 and the electrical transaxle 100A is second switched at the time t S6. Here, the shift time difference Δt S6-S5 may depend on other parameters or characteristic characteristics of the work vehicle such as traveling speed or acceleration of the work vehicle 20B, so that the shift time difference Δt S6-S5 may decrease with (for example, proportional to) the acceleration of the work vehicle 20B and may increase with (for example, proportional to) the traveling speed of the work vehicle 20B.The switching pairings can thus be executed by the control unit 38 in accordance with a stored switching logic, following various rules, logics or algorithms. These can comprise, for example, such rules or logic as: the more heavily loaded electric transaxle is switched first; the vertically higher electric transaxle is switched first; the greater the slope or the slope, the less the variance of the switching instants, the greater the travel speeds of the work vehicle, the greater the variance of the switching instants for promoting smooth operation; the higher the acceleration, the less the variance of the switching instants; and the switching time variance can be increased with decreasing load, as by increasing the switching time variance when the load falls below a threshold value. Other rules, logics, and algorithms may also be incorporated into the circuitry stored onboard or sent to the work vehicle.The terminology used herein is for the purpose of describing particular embodiments only and is not to be interpreted as limiting the disclosure. As used herein, the singular forms "a", "an" and "the / s" are intended to include the plurality as well, unless clearly stated otherwise in the context. Further, it is understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, acts, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, acts, elements, components, and / or groups thereof.As used herein, enumerations with items separated by keywords (e.g., "and"), and also preceded by the phrase "one or more of" or "at least one of", unless otherwise limited or modified, indicate configurations or arrangements that potentially include individual items of the enumeration, or any combination thereof. For example, "at least one of A, B, and C" or "one or more of A, B, and C" respectively indicate the possibilities of only A, only B, only C, or any combination of two or more of A, B, and C (for example, A and B; B and C; A and C; or A, B, and C).The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limiting of the disclosure in the form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. Embodiments expressly set forth herein were chosen and described in order to best explain the principles of the disclosure and its practical application, and to enable others of ordinary skill in the art to understand the disclosure and recognize many alternatives, modifications, and variations of the example or examples described. Accordingly, various embodiments and implementations other than those explicitly described are within the scope of the following claims.

Claims

A work vehicle (20) having a chassis (22) supported above the ground by ground engaging wheels or chains (24), the work vehicle (20) comprising: a first transaxle (402) supported by the chassis (22) and having first wheel end units (406) rotatable about a first wheel axis via a first transaxle gear set (404) to rotate a first set of ground engaging wheels or chains (24); a second transaxle (100) supported by the chassis (22) and having second wheel end units (106) rotatable about a second wheel axis via a second transaxle (182) to rotate a second set of ground engaging wheels or chains (24), the second transaxle (100) comprising: an electric machine (180) having a shaft (183) rotating about a machine axis; a transmission (102) rotated by the electric machine shaft (183) and configured to effect multiple gear ratios on a range sprocket; and a drive sprocket (160) rotatable about the second wheel axis via the range sprocket of the transmission (102); and a transmission shaft (410) having a first end coupled to an input assembly (408) engaging the first transaxle gear set (404), and a second end coupled to a driven gear (172) engaging the drive gear (160) to transmit power from the second transaxle (100) to the first transaxle (402) via the transmission shaft (410).The work vehicle (20) of claim 1, wherein the first transaxle (402) is purely mechanical without a dedicated electric machine and without a dedicated transmission; and wherein the work vehicle (20) does not have a transmission arrangement other than the transmission (102) of the second transaxle (100).The work vehicle (20) of claim 1 or 2, wherein the electric machine (180) is positioned vertically above the drive gear (160); wherein the machine axis is offset and parallel to the wheel axis; and wherein the output gear (172) rotates about an output axis that is perpendicular to the wheel axis.The work vehicle (20) of any preceding claim, wherein the transmission (102) of the second transaxle (100) comprises a first gear set (182) disposed on a first side of an engine axis about which the electric machine shaft (183) rotates and a second gear set (182) disposed on a second side of the engine axis about which the electric machine shaft (183) rotates.The work vehicle (20) of claim 4, wherein the first gear set (182) is a multi-speed gear set having a first clutch for causing different gear ratios; and wherein the second gear set (182) is a multi-speed gear set having a second clutch for causing different gear ratios.The work vehicle (20) according to claim 4 or 5, wherein the first gear set (182) is identical to the second gear set (182); and wherein the first gear set (182) connects to the electric machine shaft (183) via a first gear train and the second gear set (182) connects to the electric machine shaft (183) via a second gear train different from the first gear train.The work vehicle (20) of claim 4, wherein the first gear set (182) is a multi-speed gear set and the second gear set (182) is a single-speed gear set or a multi-speed gear set.The work vehicle (20) of any preceding claim, wherein the second wheel end units (106) comprise two wheel end units, each having an elongated hub (108) disposed in a transaxle housing (104) for rotation about the second wheel axis; wherein the second wheel end units (106) comprise a planetary gear set (114) that transmits a force from the drive gear (160) to the elongated hubs of the wheel end units (106).The work vehicle (20) of claim 8, further comprising a differential assembly (130) disposed within the second transaxle housing (104) and configured to transmit power from the drive gear (160) to the elongated hubs (108) of the wheel end units (106) for rotation about the second wheel axle at a common speed or at different speeds.The work vehicle (20) of claim 9, wherein each planetary gear set (114) comprises a sun gear (122) rotated by a sun shaft (124) coupled to the drive gear (160) and the differential assembly (130); wherein each planetary gear set (114) comprises a carrier (116) coupled to rotate with a corresponding one of the elongated hubs (108) of the second wheel end units (106); and wherein the planetary gear sets (114) have sun gear-driven planetary carrier power flow configurations.The work vehicle (20) of claim 10, further comprising a differential lock (146) configured to selectively prevent rotation of the sun gear (122).

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