Tandem wheel assembly with pivot damping system

Abstract

A tandem wheel assembly for a work vehicle includes a tandem wheel housing having a central opening extending along a pivot axis and a wheel end opening extending along an associated wheel end axis. The tandem wheel housing is pivotally mounted to a chassis of the work vehicle about the pivot axis. A central sprocket is rotatably disposed within the tandem wheel housing. Wheel end assemblies are disposed at the wheel end openings and each include a wheel end sprocket, a wheel end gear train, and a wheel end hub. A pair of reaction rods are pivotally coupled at first ends to the chassis and at second ends to components of respective wheel end assemblies. A pivot damping system is positioned at least partially axially between the tandem wheel housing and the components of at least one of the chassis or the wheel end assemblies. The pivot damping system is configured to dampen pivoting of the tandem wheel housing relative to the chassis.

Description

Technical Field

[0001] This disclosure relates to work vehicles, and more specifically, to tandem wheel assemblies for work vehicles. Background Technology

[0002] For example, work vehicles used in forestry, construction, agriculture, mining, and other industries can utilize tandem wheel assemblies (also known as bogie axles) to support significant loads across four or more ground-engaged wheels or tracked wheels using a single axle. This single axle allows the wheels to pivot together to maintain ground contact over changing terrain without significantly displaced other areas of the work vehicle, including the operator's cabin and work tools (e.g., cranes). Such tandem wheel assemblies can also be driven (e.g., from the work vehicle's powertrain via a transmission, or they can be self-powered). One type of work vehicle that frequently utilizes tandem wheel assemblies is the haulage machine used in tree harvesting operations. Applications may require the haulage machine to deliver high torque and potentially low-speed power to the ground-engaged wheels, accomplished through high-ratio gear reduction. Different applications may be suited to different haulage machines or other machine platforms with different load-bearing capacities. Summary of the Invention

[0003] This disclosure provides a work vehicle train wheel assembly with a pivot damping system.

[0004] In one aspect, this disclosure provides a tandem wheel assembly for a work vehicle having a chassis and wheels. The tandem wheel assembly includes: a tandem wheel housing defining a central opening extending along a pivot axis and wheel end openings extending along an associated wheel end axis, the tandem wheel housing being pivotally mounted to the chassis about the pivot axis. A central sprocket is disposed within the tandem wheel housing and is rotatable relative to the tandem wheel housing. Wheel end assemblies are disposed at each of the wheel end openings and each has a wheel end sprocket, a wheel end gear train, and a wheel end hub. Each wheel end sprocket is supported within the tandem wheel housing for rotation via at least one chain coupled to the central sprocket. Each wheel end gear train is coupled to rotate via the associated wheel end sprocket and is configured to achieve a gear ratio change and to rotate the associated wheel end hub about the associated wheel end axis. A pair of reaction rods are each pivotally coupled at a first end to the chassis and at opposite second ends to a component of the respective wheel end assembly. A pivoting damping system is positioned at least partially axially between at least one of the components of the train wheel housing and the chassis or wheel end assembly. The pivoting damping system is configured to inhibit the pivoting of the train wheel housing relative to the chassis.

[0005] In another aspect, this disclosure provides a tandem wheel assembly comprising: a tandem wheel housing defining a central opening extending along a pivot axis and wheel end openings extending along an associated wheel end axis, the tandem wheel housing being pivotally mounted to a chassis about the pivot axis. A central sprocket is disposed within the tandem wheel housing and is rotatable relative to the tandem wheel housing. Wheel end assemblies are disposed at each of the wheel end openings and each has a wheel end sprocket, a wheel end gear train, and a wheel end hub. Each wheel end sprocket is supported within the tandem wheel housing for rotation via at least one chain coupled to the central sprocket. Each wheel end gear train is coupled to rotate via the associated wheel end sprocket and is configured to achieve a gear ratio change and to rotate the associated wheel end hub about the associated wheel end axis. A pair of reaction rods are each pivotally coupled to the chassis at a first end and pivotally coupled to a component of the respective wheel end assembly at an opposite second end. A pivoting damping system is configured to suppress the pivoting of the train wheel housing relative to the chassis. The pivoting damping system includes a clutch assembly axially positioned between the train wheel housing and a component of the chassis or at least one wheel end assembly. The clutch assembly includes: a plurality of discs, some rotatably fixed to the train wheel housing and some rotatably fixed to the chassis; and an actuator that actuates the discs to engage or disengage.

[0006] In another aspect, this disclosure provides a tandem train wheel assembly comprising: a tandem train wheel housing defining a central opening extending along a pivot axis and wheel end openings extending along an associated wheel end axis. A pivot cage is disposed within the central opening to allow the tandem train wheel housing to pivot about the pivot axis. The pivot cage is fixedly mounted to the chassis. A central sprocket is disposed within the pivot cage and is rotatable relative to the tandem train wheel housing. Wheel end assemblies are disposed at each of the wheel end openings and each has a wheel end sprocket, a wheel end gear train including a planetary gear set with a ring gear, and a wheel end hub. Each wheel end sprocket is supported within the tandem train wheel housing for rotation via at least one chain coupled to the central sprocket. Each wheel end gear train is coupled to rotate via the associated wheel end sprocket and is configured to achieve a gear ratio change and to rotate the associated wheel end hub about the associated wheel end axis. A pair of reaction rods are each pivotally connected to the pivot cage at a first end spaced apart from the pivot axis, and pivotally connected to the ring gear of the respective wheel end assembly at an opposite second end. A pivot damping system is configured to suppress the pivoting of the train wheel housing relative to the chassis. The pivot damping system includes a clutch assembly at least partially axially positioned between the train wheel housing and the ring gear of the respective wheel end assembly. The clutch assembly has: a plurality of discs; some of the discs rotatably fixed to the train wheel housing, and some of the discs fixed to the ring gear of the respective wheel end assembly; and an actuator positioned within the train wheel housing, the actuator causing the discs to engage or disengage.

[0007] Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description, drawings, and claims. Attached Figure Description

[0008] Figure 1 This is a simplified perspective view of an exemplary working vehicle in the form of a tree harvester and concentrator, in which a tandem train wheel assembly with a pivoting damping system according to the present disclosure can be used;

[0009] Figure 2 This is an isometric view of an exemplary train wheel assembly for an exemplary container transport machine;

[0010] Figure 3 Is it through Figure 2 Top cross-sectional view of an exemplary tandem train wheel assembly in plane 3-3;

[0011] Figure 4 This is an exploded isometric view of an exemplary tandem train wheel assembly according to an embodiment;

[0012] Figure 5 This is a side elevation view of the tandem wheel housing of an exemplary tandem wheel assembly;

[0013] Figure 6 This is an isometric view of an exemplary tandem train wheel assembly's pivot cage.

[0014] Figure 7 This is a top plan view of the pivot cage;

[0015] Figure 8 This is a bottom plan view of the pivot cage;

[0016] Figure 9 This is an isometric view of the reaction rod support of an exemplary tandem train wheel assembly;

[0017] Figure 10 This is a partial top elevation view of the tandem train wheel assembly, showing the tandem train wheel housing cut open.

[0018] Figure 11 This is a partial top elevation view of an exemplary tandem train wheel assembly in which the tandem train wheel housing is shown cut open and the clutch assembly is schematically shown in cross-section.

[0019] Figure 12 It shows Figure 2 A cross-sectional view of an exemplary tandem train wheel assembly according to an embodiment, in region 12-12;

[0020] Figure 13 yes Figure 12 Enlarged view of area 13-13;

[0021] Figure 14 Similar to Figure 13 The area shown, but according to another embodiment;

[0022] Figure 15 It is shown Figure 2 A cross-sectional view of an exemplary tandem train wheel assembly in region 15-15;

[0023] Figure 16 This is an isometric exploded view of the disc of the clutch assembly of an exemplary tandem train wheel assembly.

[0024] Figure 17 It is a partial isometric view shown in the cross-section of the disk; and

[0025] Figure 18 This is a schematic diagram of the sample control and hydraulic system.

[0026] In the various figures, similar reference numerals indicate similar elements. Detailed Implementation

[0027] One or more exemplary embodiments of the disclosed tandem train wheel assembly are described below, as illustrated in the accompanying drawings of the diagrams briefly described above. Various modifications to the exemplary embodiments will be anticipated by those skilled in the art.

[0028] As used herein, unless otherwise limited or modified, a list having elements separated by conjunction terms (e.g., “and”) and preceded by the phrase “one or more of…” or “at least one of…” indicates a configuration or arrangement that potentially includes individual elements of the list or any combination thereof. For example, “at least one of A, B, and C” or “one or more of A, B, and C” indicates the possibility of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C).

[0029] Furthermore, in describing this disclosure in detail, directional and orientational terms such as “longitudinal,” “internal,” “external,” “radial,” “axial,” “circumferential,” “lateral,” and “transverse” may be used. Such terms are defined at least partially relative to wheel axles, pivot axes, and / or the work vehicle. As used herein, the term “longitudinal” indicates orientation along the length of the equipment; the term “lateral” indicates orientation along the width of the equipment and orthogonal to the longitudinal orientation; and the term “transverse” indicates orientation along the height of the equipment and orthogonal to both the longitudinal and transverse orientations. These orientations may be relative to the work vehicle to which the component may be attached or the direction of travel of the work vehicle. In other examples, according to this disclosure, the components referred to by those terms may be reversed.

[0030] Overview

[0031] Work vehicles (e.g., tree harvesting and collection machines) typically include components such as a chassis, powertrain (e.g., engine and drivetrain), suspension, and work tools (e.g., cranes) for performing tasks in various terrains and conditions. Work vehicles often perform tasks requiring consistent work tool positioning (e.g., cranes grabbing and moving felled trees). The wheel axle area can bear significant static weight loads from onboard components (e.g., engine, transmission, axles, work tools, etc.) and encounters significant operational loads (e.g., via attached work tools and shocks / loads through the wheels and suspension). Therefore, work vehicles must adapt to varying terrain, static loads, and operational loads caused by the work task while maintaining the desired tool positioning. Tandem wheel assemblies can accommodate such load or gradient changes by mounting the wheel assemblies (typically the rear wheel assemblies) together to pivot relative to the work vehicle, thus providing ground contact to the wheels without significantly hindering work tool placement.

[0032] In the case of tree harvesting haulage machines, the operating tool is typically a crane that lifts the felled trees onto the haulage machine's load space during operation. The haulage machine, carrying large quantities of felled trees, must travel at sufficient speed to be efficient while preventing unwanted bounce and swaying; for example, the haulage machine can operate at speeds ranging from slow speeds (e.g., 1 to 10 mph) to higher speeds (e.g., 40 mph or higher during transport and other operational states). During use, the haulage machine experiences the load forces from the weight of the felled trees and from impacts from ground obstacles encountered during travel. The corresponding operational load is transmitted to the chassis and drivetrain, and through the chassis and drivetrain to the wheels, which transfer the load to the ground surface. Thus, the drivetrain and wheels contribute to the haulage machine's performance by maintaining ground contact for consistent traction.

[0033] This disclosure provides a tandem wheel assembly with pivot damping configured to provide improved ride stability and traction during operation of a work vehicle. As the work vehicle moves in the forward direction, the tandem wheel assembly follows the connection between the crane and the rear frame, supporting a significant portion of the weight on the rear frame. During acceleration and deceleration of the work vehicle, or when the work vehicle traverses an uphill / downhill slope or encounters an obstacle, torque is applied to the tandem wheel assembly, and the tandem wheel assembly can pivot clockwise relative to the chassis of the work vehicle. A reaction assembly of the tandem wheel assembly, which can form a walkway configuration, counteracts the force causing the tandem wheel assembly to pivot in the opposite clockwise direction by applying a downforce that causes the tandem wheel assembly to pivot both wheels back into contact with the ground. The reaction assembly acts to drive either the front or rear wheel back into contact with the ground.

[0034] The tandem wheel assembly and the work vehicle in which it is incorporated include a pivoting damping system designed to further improve wheel-to-ground traction engagement and overall vehicle ride stability. The pivoting damping system operates to impart pivoting deceleration forces (and in some cases, braking or locking forces) to the tandem wheel assembly, and thereby to the front or rear wheels of the tandem wheel assembly, to better distribute downforce applied by the reaction assembly. The pivoting damping system can be used to suppress, mitigate, or prevent the tandem wheel assembly from pivoting due to events such as changes in acceleration, riding on an obstacle, or riding uphill / downhill, thereby affecting the amount (if any) the tandem wheel assembly initially pivots in response to such events. If pivoting of the tandem wheel assembly is permitted, the pivoting damping system can also be used to suppress or mitigate counter-pivot actions, such as counter-pivot actions imposed by downforce from the reaction assembly, thus tending to return the tandem wheel assembly to its previous wheel-to-ground engagement orientation. Typically, it might be desirable for the wheels to quickly return to ground contact; however, a pivoting damping system allows the application of a preset or selectable damping force opposite to the downforce to achieve the desired balance between traction and ride stability of the work vehicle. Therefore, in the case of a pivoting damping system, the tandem wheel assembly can respond sufficiently to maintain or quickly return all wheels to ground contact, providing good traction control of the work vehicle while avoiding excessively sudden reaction downforce (i.e., buffered reaction downforce), further improving wheel traction engagement and enhancing the ride quality for the vehicle operator.

[0035] In some embodiments, the pivoting damping system includes a clutch assembly having multiple discs, such as staggered backing plates and friction discs, that cooperate to inhibit or lock relative pivoting of the tandem wheel assemblies. For example, a single central clutch assembly may be present about a pivot axis affecting the pivoting of each tandem wheel assembly. Alternatively or additionally, clutch assemblies may be present at one or both wheel ends, for example about the axis of rotation of each front and rear wheel of the tandem wheel assembly. In each case, each clutch assembly is configured to impart damping forces to the tandem wheel assembly (e.g., by applying forces directly or indirectly to the tandem wheel housing or reaction assembly of the tandem wheel assembly).

[0036] Pivot damping systems can be implemented actively or passively. Active implementations of pivot damping systems allow for enhanced control options and selective application of pivot damping. An active pivot damping system can be achieved by applying selective force to the clutch assembly using an actuator. For example, a hydraulic piston (e.g., with an apply or return spring in a spring-applied hydraulic release or inverted configuration) can be actively controlled to engage or disengage from the clutch assembly disc. Therefore, an active pivot damping system allows for the ability to select when and to what extent damping force is applied, and also allows for additional control settings to allow the tandem wheel assembly to pivot freely (i.e., zero damping) or be locked against pivoting (i.e., fully damped). Using electronic control, the hydraulic piston can be selectively operated by an operator or under a control algorithm that sets and applies damping force based on certain vehicle operations or sensor inputs. As an example, a pivoting damping system can be configured to lock the tandem wheel assembly to prevent pivoting when the work vehicle is traveling on a road, or it can be configured to apply a preselected or gradually increasing damping force in response to an input from a sensor associated with the tandem wheel assembly of the work vehicle. Passive implementations can provide the aforementioned improvements in traction and ride quality, as well as less mechanically and electronically complex applications, in a continuous manner. As an example, a passive pivoting damping system can be implemented by applying a continuous or variable biasing force to a clutch assembly. In some embodiments, this is implemented by means of a spring (e.g., a disc spring) positioned to apply a continuous biasing force to the disc of the clutch assembly, thereby applying a constant force against pivoting of the tandem wheel assembly in either clock direction (i.e., the initial and return pivoting clock directions). Thus, the biasing force is always present while allowing the tandem wheel assembly to pivot in either clock direction.

[0037] The following describes one or more exemplary embodiments of the disclosed tandem wheel housing with a pivoting damping system. While the discussion herein may sometimes focus on exemplary applications of the tandem wheel assembly in tree harvesting and transport vehicles, the disclosed tandem wheel assembly can also be applied to bogie axles or tandem axles in other types of work vehicles, including self-propelled or towed work vehicles and various other agricultural machinery (e.g., articulated tractors, general-purpose tractors, motorized graders, front-end loaders, harvesters, and the like), various construction and forestry machinery (e.g., timber harvesters, etc.), and transport vehicles (e.g., semi-trailers).

[0038] Exemplary embodiments of the train wheel assembly

[0039] refer to Figure 1In some embodiments, the disclosed work vehicle 10 may be a tree harvesting and transport machine, although, as noted, the tandem wheel assembly 12 described herein can be applied to a variety of machines, such as motorized graders, timber harvesters, other construction vehicles, agricultural vehicles including articulated frame tractors, other forestry vehicles, and transport vehicles (e.g., semi-trailers). As shown, the work vehicle 10 may be considered to comprise a chassis 14 consisting of a rear frame 16 having a load space 18 formed for transporting felled trees and a front frame 20 having an operator's cab 22. The rear frame 16 and the front frame 20 may be connected by an articulated joint. A crane 24, intended for maneuvering felled trees into the load space 18, is mounted behind the rear frame 16 at the rear of the operator's cab 22. At the head of the crane 24, loading hooks 26 are provided with known gripping members that rotate toward or away from each other by actuators disposed therein, wherein the loading hooks 26 may be used to grip one or more tree trunks for dragging them to a desired location. The loading hook 26 can also be rotated so that the felled trees in the loading hook 26 can be brought to a suitable position, for example, when loaded into or unloaded from the load space 18. The crane 24 is selectively positioned by the drive system 28. The work vehicle 10 can be further considered to include a power transmission system 30, a control system 32, and a hydraulic system 34. The work vehicle 10 includes a tandem wheel assembly 12 on the rear frame 16 for mounting two wheels 36, 38 on the left side of the work vehicle 10 and for mounting two wheels 40, 42 on the right side of the work vehicle 10, and can further have a similar tandem wheel assembly on the front frame 20 for mounting two wheels on the left side of the work vehicle 10 and for mounting two wheels on the right side of the work vehicle 10. Each wheel 36, 38, 40, 42 is mounted on the tandem wheel assembly 12 via a wheel end hub 44. Wheels 36, 38, 40, and 42 comprise a pair of left wheels defined by a first left wheel 36 and a second left wheel 38, and a pair of right wheels defined by a first right wheel 40 and a second right wheel 42 (also collectively referred to as "four tandem wheels 36, 38, 40, and 42"). It should be noted that any left / right wheel pair can be arranged for each left / right side of the work vehicle 10 (e.g., in...). Figure 1 The two wheels are on the side (in the x-direction shown in the diagram).

[0040] Typically, the powertrain 30 includes a propulsion source 46 (e.g., an engine) that supplies power to the work vehicle 10 as direct mechanical power or after being converted into electric power (e.g., via a battery) or hydraulic power. In one example, the engine may be an internal combustion engine, such as a diesel engine, controlled by an engine control module (not shown) of the control system 32. It should be noted that the use of an internal combustion engine is merely an example, as the propulsion source 46 may be a fuel cell, an electric motor, a mixed-gas electric motor, or other power generation device. The transmission 48 transmits power from the propulsion source 46 to one or more of the wheels 36, 38, 40, and 42. Additionally, the powertrain 30 has wheel steering components 50, which include various means (e.g., power steering pumps and lines, steering mechanisms, and the like) that connect manual (e.g., operator steering controls or wheels) and / or automatic (via the control system 32) steering inputs to one or more of the wheels in the group.

[0041] In addition to providing traction power to propel the work vehicle 10, propulsion source 46 can also power various onboard subsystems, including various electrical and hydraulic components of the work vehicle 10, and provide off-board power to other subsystems located away from the work vehicle 10. For example, propulsion source 46 can provide mechanical power, which is converted into an electrical format to operate the electronics of control system 32 and one or more electric actuators of the work vehicle 10. Therefore, powertrain 30 can have a mechanical-to-electric conversion unit 52, one or more batteries 54, and associated electronics, including various alternators, generators, voltage regulators, rectifiers, inverters, and the like. Propulsion source 46 can also provide mechanical power, which is converted into a hydraulic format to power various pumps and compressors that pressurize fluids to drive various actuators of hydraulic system 34 to power the steering and braking of the wheels on the work vehicle 10 and various work tools. The hydraulic system 34 may include other components (e.g., valves, flow lines, pistons / cylinders, seals / gaskets, etc.) so that the control of various devices can be achieved by hydraulic, mechanical or other signals and movements, and is based on hydraulic, mechanical or other signals and movements.

[0042] The control system 32 can be configured as a computing device with associated processor and memory architecture, hardwired computing circuitry (or circuitry), programmable circuitry, hydraulic, electrical, or electrohydraulic controller. The control system 32 can be configured to perform various computational and control functions relating to the work vehicle 10, including various means associated with the drive system 28, powertrain 30, hydraulic system 34, and various additional components of the work vehicle 10. In some embodiments, the control system 32 can be configured to receive input signals of various formats (e.g., as hydraulic signals, voltage signals, current signals, etc.) and output command signals of various formats (e.g., as hydraulic signals, voltage signals, current signals, mechanical movement, etc.).

[0043] As described above, the hydraulic system 34 can be controlled by the control system 32 (automatically, via operator input, or both). The hydraulic system 34 can be powered by the propulsion source 46 and configured in various arrangements to serve multiple hydraulic functions (e.g., powering the drive system 28). Thus, the hydraulic system 34 can have components including a reservoir 56 for storing hydraulic fluid, a pump 58 for supplying pressurized hydraulic fluid from the reservoir 56, various valves (e.g., control valves), and pipelines 60 associated with each function.

[0044] In the illustrated example, when the work vehicle 10 is driven in the forward direction (in... Figure 1 As indicated in the diagram, the tandem wheel assembly 12 follows the connection between the crane 24 and the rear frame 16, and supports the majority of the weight on the rear frame 16. The tandem wheel assembly 12 is pivotable about a pivot axis 62. Specifically, each of the pair of left wheels 36, 38 and the pair of right wheels 40, 42 can pivot independently relative to the work vehicle 10 about the pivot axis 62. During use, if the work vehicle 10 encounters an obstacle or uneven surface, the tandem wheel assembly 12 adapts to this by pivoting relative to the chassis 14 of the work vehicle 10. During operation of the work vehicle 10, particularly during acceleration and deceleration, the reaction assembly 64, forming a walkway configuration, counteracts the forces that cause the tandem wheel assembly 12 to pivot, providing an improved downforce distribution to each of the pair of left wheels 36, 38 and the pair of right wheels 40, 42. The reaction assembly 64 responds to changes in input torque by means of a reaction force or torque to maintain engagement of each of the pair of left wheels 36, 38 and the pair of right wheels 40, 42 with the ground. When the work vehicle 10 traverses an uphill / downhill section or encounters an obstacle in the road, the pivoting damping system 66 suppresses the pivoting of the tandem wheel assembly 12 to further improve the traction engagement of the wheels 36, 38, 40, 42 with the ground and the overall ride stability of the work vehicle 10.

[0045] The tandem train wheel assembly 12 mounts four tandem train wheels 36, 38, 40, and 42 below the rear frame 16. Figure 2 An exemplary tandem wheel assembly 12 may include a differential housing 68, a first mounting arm 70, a second mounting arm 72, first and second pivot cages 74, and first and second tandem wheel housings 76, to which a reaction assembly 64 and a pivot damping system 66 are respectively mounted. The pivot cages 74 are arranged about a pivot axis 62, rigidly fixed relative to the rear frame 16, and each partially serves as a central pivot around which the tandem wheel assembly 12 and the four tandem wheels 36, 38, 40, 42 pivot relative to the work vehicle 10. The pivot cages 74 form part of the chassis 14 and may be integrally formed with the rear frame 16 or may be formed separately and fixedly attached to the rear frame 16. The differential housing 68 is rigidly attached to the first mounting arm 70 and the second mounting arm 72, which are fixed to the chassis 14 of the work vehicle 10 (e.g., via bolts through arm holes in the mounting arms 70, 72). Therefore, the differential housing 68 and the pivot cage 74 are fixed in place relative to each other, and one or both of the first and second train wheel housings 76 pivot independently relative to the differential housing 68 and the corresponding first and second pivot cages 74.

[0046] As described above, the tandem wheel assembly 12 includes components of the power transmission system 30 to transmit prime mover power to each of the four wheels 36, 38, 40, and 42. Figure 3 Differential 80 is mounted in differential housing 68 and connected to drive shaft 82 driven by transmission 48. Differential 80 includes gear transmission components to laterally separate and translate the rotational side of drive shaft 82 toward first and second tandem wheel housings 76. A pinion 84 at the end of drive shaft 82 meshes with a differential ring gear 86 mounted in differential housing 88, which is connected (via side gear 94) to first shaft 90 and second shaft 92. Differential 80 may be a limited-slip differential with a clutch assembly 96 for preventing slippage. Although not shown in detail, differential housing 68 may house additional components of differential 80, including brakes, multiple U-joints, ring gear, multiple pinion shafts, multiple pinions, multiple planetary gears, side gears, clutch plates, bearings, and the like. Any type of differential may be implemented within tandem wheel assembly 12, including open differentials, limited-slip differentials, or the like. The differential housing 68 also mounts multiple portions of the drive shaft 82 and multiple portions of the first shaft 90 and the second shaft 92. As is known in the art, a hydraulically applied brake 98 may be provided and engaged with the shafts 90, 92.

[0047] Also refer to Figures 6 to 8Each pivot cage 74 has an annular body 100 disposed around a pivot axis 62, and the annular body 100 extends between its inner end 102 and its outer end 104. Each pivot cage 74 further has an annular bearing receiving body portion 106 extending between its inner end 108 and its outer end 110. The bearing receiving body portion 106 extends from the inner end 102 of the annular body 100. Each pivot cage 74 further has a chassis connection body portion 112 extending from the inner end 108 of the bearing receiving body portion 106, and connecting to the chassis 14 and the differential housing 68 at its inner end 114. The bearing receiving body portion 106 has a diameter smaller than the diameter of the annular body 100. A cavity 116 extends from the inner end 114 of the chassis connection body portion 112 to the outer end 104 of the annular body 100. An annular flange 118 extends radially outward from the bearing receiving body portion 106 at the inner end 108. Flange 118 may have the same diameter as the annular body 100. At least one opening is provided through the annular body 100 between ends 102, 104 and communicates with cavity 116. As shown, at least one opening is provided by a forward upper opening 120, a rearward upper opening 122, a forward lower opening 124, and a rearward lower opening 126. As shown, each upper opening 120, 122 is generally T-shaped and has a lower portion 120a, 122a that is wider than the upper portions 120b, 122b. The upper portions 120b, 122b are laterally offset from each other, and the lower portions 120a, 122a are aligned with each other in the front-rear direction. As shown, the upper portion 120b of the forward upper opening 120 is outside the upper portion 122b of the rearward upper opening 122; however, the upper portion 120b of the forward upper opening 120 may be inside the upper portion 122b of the rearward upper opening 122. This reduces the size of the pivot cage 74. In the embodiment, the upper portions 120b and 122b are aligned with each other in the front-rear direction. The lower portion 120a is laterally aligned with the forward lower opening 124; the lower portion 122a is laterally aligned with the rearward lower opening 126. The lower openings 124 and 126 are aligned with each other in the front-rear direction. The first and second pivot cages 74 may be formed of cast metal or other suitable structural materials.

[0048] Each train wheel housing 76 ( Figure 2 , Figure 3 and Figure 5The inner wall 128 and outer wall 130 of the train wheel housing 76 are generally hollow portions having an inner wall 128 and an outer wall 130 defining an internal volume 132, which extends from the front wall 134 to the rear wall 136 and extends between the upper wall 138 and the lower wall 140. The longitudinal axis 142 of the train wheel housing 76 is defined between the front wall 134 and the rear wall 136 and is perpendicular to the pivot axis 62. The inner wall 128 defines a central opening 144 around the pivot axis 62, which communicates with the internal volume 132, and the outer wall 130 defines a central opening 146 around the pivot axis 62, which communicates with the internal volume 132 and is aligned with the central opening 144. A cylindrical protrusion 148 extends from the inner wall 128 and defines a central channel 150 around the pivot axis 62, which extends from the opening 144 and communicates with the internal volume 132. The central channel 150 defines an inner diameter smaller than the inner diameter defined by the central openings 144, 146, such that the protrusion 148 forms an outer shoulder. The annular body 100 of the corresponding pivot cage 74 nests or sits within the central openings 144, 146, and is close to the shoulder formed by the outer end of the annular protrusion 152, allowing the train wheel housing 76 to pivot about the pivot cage 74 and relative to the chassis 14. Cylindrical protrusions 152 extend from the outer wall 130 near the front wall 134 and near the rear wall 136. Wheel end openings 154 are provided through the outer wall 130 at the center of each cylindrical protrusion 152 communicating with the internal volume 132. Arched openings 156 are provided through the outer wall 130 and are close to the inner wall formed by each protrusion 152. Openings 156 are spaced apart from and vertically spaced above the wheel end openings 154. Each train wheel housing 76 can be formed from cast metal or other suitable structural materials. Each train wheel housing 76 can be made in modular form; as shown, each train wheel housing 76 has three parts attached together.

[0049] Circular bushing 158 and a pair of circular inner and outer thrust bearings 160, 162 ( Figure 10 and Figure 12 A bushing 158 is disposed between the pivot cage 74 and the train wheel housing 76 to facilitate pivoting of the train wheel housing 76 relative to the pivot cage 74. A bushing 158 is disposed between the inner surface of the annular protrusion 148 and the outer surface of the bearing receiving body portion 106 on the outer side of the flange 118. An inner thrust bearing 160 is disposed between the outer surface of the flange 118 and the inner surface of the bearing receiving body portion 106. An outer thrust bearing 162 is disposed between the inner end 102 of the annular body 100 and the outer end 110 of the bearing receiving body portion 106.

[0050] The components in each train wheel housing 76 can be identical mirror images. Each train wheel housing 76 has a central sprocket 172 mounted to rotate with a corresponding axle 90, 92, a first chain 174 connecting the central sprocket 172 to a front wheel end assembly 176 on a first side of the central sprocket 172, and a second chain 178 connecting the central sprocket 172 to a rear wheel end assembly 180 on a second side of the central sprocket 172. Figure 12 In some embodiments, the center sprocket 172 is a double-ring sprocket that mounts a first chain 174 extending to the front wheel end assembly 176 and a second chain 178 extending to the rear wheel end assembly 180. The center sprocket 172 is laterally positioned outside the bushing 158.

[0051] Each wheel end assembly 176, 180 ( Figure 13 The assembly includes a wheel end sprocket 182 mounted on a shaft 184 for rotation therewith, a wheel end gear train 188 coupled to the shaft 184, a wheel end housing 190, and a wheel end hub 44. The wheel end housing 190 of the front wheel end assembly 176 is fixedly mounted on the outer wall 130 of the tandem wheel housing 76 within the cylindrical protrusion 152, and the wheel end housing 190 of the rear wheel end assembly 180 is fixedly mounted on the outer wall 130 of the tandem wheel housing 76 within the cylindrical protrusion 152. The shaft 184 of each wheel end assembly 176, 180 is rotatably mounted to the inner wall 128, extends through a corresponding wheel end opening 154 in the outer wall 130, and extends laterally outward from the outer wall 130. The shaft 184 of each wheel end assembly 176, 180 extends laterally outward from the outer wall 130 and is coupled to the wheel end gear train 188. The wheel end axis 194 is defined by the shaft 184 and is parallel to the pivot axis 62.

[0052] The wheel end sprocket 182 of the front wheel end assembly 176 is aligned with one of the double rings of the center sprocket 172 and thereby connected by a first chain 174. The first chain 174 passes through the lower portion 120a of the forward upward opening 120 in the pivot cage 74, around the center sprocket 172, through the forward downward opening 124 in the pivot cage 74, and around the wheel end sprocket 182 of the front wheel end assembly 176. The wheel end sprocket 182 of the rear wheel end assembly 180 is aligned with the other of the double rings of the center sprocket 172 and thereby connected by a second chain 178. The second chain 178 passes through the lower portion 122a of the rearward upward opening 122 in the pivot cage 74, around the center sprocket 172, through the rearward downward opening 126 in the pivot cage 74, and around the wheel end sprocket 182 of the rear wheel end assembly 180. Although the first chain 174 is illustrated as mounted inside relative to the second chain 178, these relative positions can be reversed. The wheel end sprockets 182 will have equal dimensions (e.g., equal number of teeth) to drive the corresponding first left wheel 36 and second left wheel 38 (or first right wheel 40 and second right wheel 42) at substantially equal speeds. The first chain 174 and the second chain 178 can be plate chains, roller chains, or other suitable drive chains for heavy construction applications. Chains 174, 178 can be continuous chains with unremoved links or "master" links to improve torque handling capabilities. In some embodiments, openings 120, 124 are continuous, and openings 122, 126 are continuous. In some embodiments, openings 120, 122 are continuous, and openings 124, 126 are continuous. In some embodiments, all openings 120, 124, 122, 126 are continuous.

[0053] The wheel end gear train 188 includes a ring gear 196 and a planetary gear carrier 198 coupled to the ring gear 196. A shaft 200 of the wheel end hub 44 extends through a wheel end opening 202 in the wheel end housing 190 and is coupled to the planetary gear carrier 198. The shaft 200 supports the wheel end hubs 44 of the respective wheels 36, 38, 40, and 42 for rotation about and with the wheel end axis 194. The wheel end gear train 188 is mounted within the wheel end housing 190 and enables gear ratio changes to rotate the associated wheel end hub 44 and its shaft 200 about the associated wheel end axis 194. As described herein, the ring gear 196 is rotatable relative to the wheel end housing 190. Other configurations of the wheel end gear train 188 may be included without departing from the scope of this disclosure.

[0054] Each wheel end housing 190 extends laterally outward from the outer side wall 130 and has a wheel end opening 202 at its end that supports at least a portion of the wheel end hub 44. The wheel end housing 190 may be conical in shape. The shaft 200 of the wheel end hub 44 extends through the wheel end housing 190 and the wheel end opening 202, and the shaft 200 and its wheel end hub 44 are supported in the wheel end housing 190 by a swivel bearing 204. Various additional support components (not shown), such as roller bearings, may be mounted on the wheel end housing 190.

[0055] The wheel end axle 184 of the front wheel end assembly 176 defines a front wheel end axis 194, which is the axis of rotation of the front wheel end hub 44 and wheel 36 (or wheel 42 on the right side of the work vehicle 10), the front wheel end axle 184, and the front wheel end sprocket 182 when driven by the center sprocket 172 via the first chain 174. This front wheel end axis 194 is substantially parallel to the pivot axis 62. The wheel end axle 184 of the rear wheel end assembly 180 defines a rear wheel end axis 194, which is the axis of rotation of the rear wheel end hub 44 and wheel 38 (or wheel 44 on the right side of the work vehicle 10), the rear wheel end axle 184, and the rear wheel end sprocket 182 when driven by the center sprocket 172 via the second chain 178. This rear wheel end axis 194 is substantially parallel to the pivot axis 62. Therefore, when the central sprocket 172 rotates, chains 174 and 178 provide the common rotation of the wheel end sprocket 182 of the wheel end assemblies 176 and 180 as well as the rotation of the wheels 36, 38, 40, and 42.

[0056] Each reaction component 64 ( Figure 4 The device includes: a pivot cage 74; a front reaction rod support 210 attached to the inner end of the ring gear 196 of the wheel end gear train 188 of the front wheel end assembly 176 for rotation therewith; a rear reaction rod support 212 attached to the inner end of the ring gear 196 of the wheel end gear train 188 of the rear wheel end assembly 180 for rotation therewith; a front reaction rod 214 connected between the front reaction rod support 210 and the pivot cage 74; and a rear reaction rod 216 connected between the rear reaction rod support 212 and the pivot cage 74.

[0057] Each reaction rod support member 210, 212 ( Figure 9The ring-shaped body portion 218 has a central aperture 220 passing through it, which is slightly larger than the aperture passing through the ring gear 196. The outer end of the ring-shaped body portion 218 is attached to the inner end of the ring gear 196 for co-rotation with it. An attachment portion 222 extends from the inner end of the body portion 218 and has a recess 224 therein. The recess 224 of the front reaction rod support 210 faces rearward, and the recess 224 of the rear reaction rod support 212 faces forward. Each recess 224 may be generally square in shape. The attachment portions 222 of the reaction rod supports 210, 212 extend through corresponding arcuate receiving openings 226, 228 in the outer wall 130 of the tandem wheel housing 76. Figure 5 An arc-shaped receiving opening is located at the opposite end of the tandem wheel housing 76, near the wheel end opening 154. Receiving openings 226 are vertically spaced above the respective wheel end openings 154. Each receiving opening 226, 228 has a length in the longitudinal direction greater than the length of the attachment portion 222. Receiving openings 226, 228 provide communication between the internal volume of the wheel end housing 190 and the internal volume 132 of the tandem wheel housing 76.

[0058] Each reaction rod 214, 216 ( Figure 4 It is a slender and rigid component. The front reaction rod 214 includes a front end portion 214a, which is seated in a recess 224 of the front reaction rod support 210. Figure 11 The pivot cage 74 is pivotally connected to the attachment portion 222 of the front reaction rod support 210 via a pivot pin 230, which extends through the front end portion 214a and sits in a hole in the wall forming the recess 224 of the reaction rod support 210; and includes a rear end portion 214b, which sits in the forward upper opening 120 of the pivot cage 74 and is pivotally connected to the annular body 100 of the pivot cage 74 via a pivot pin 232, which extends through the rear end portion 214b and sits in a hole in the wall forming the upper portion 120b of the forward upper opening 120. Figure 10The front reaction rod 214 is offset laterally from the chain 174 and, as shown, laterally inward of the chain 174. The front reaction rod 214 can pivot relative to the pivot cage 74 and relative to the front reaction rod support 210. The rear reaction rod 216 includes a rear end portion 216a, which is seated in a recess 224 of the rear reaction rod support 212 and pivotally connected to an attachment portion 222 of the reaction rod support 212 via a pivot pin 234, which extends through the rear end portion 216a and is seated in a hole in the wall forming the recess 224 of the rear reaction rod support 212; and a front end portion 216b, which is seated in a rearwardly upward opening 122 of the pivot cage 74 and pivotally connected to an annular body 100 of the pivot cage 74 via a pivot pin 236, which extends through the front end portion 216b and is seated in a hole in the wall forming the upper portion 122b of the rearwardly upward opening 122. The reaction rod 216 is laterally offset from the chain 178 and, as shown, is located laterally outward from the chain 178. The rear reaction rod 216 is pivotable relative to the pivot cage 74 and relative to the rear reaction rod support 212. The front reaction rod 214 and the rear reaction rod 216 are pivotable relative to each other. The reaction rods 214 and 216 are housed within the internal volume 132 of the tandem wheel housing 76. This provides a significantly more compact design compared to prior art designs that expose the reaction rods. Furthermore, housing the reaction rods 214 and 216 within the internal volume 132 prevents moving parts from being exposed to external elements that could damage the reaction rods 214 and 216.

[0059] The pivoting damping system 66 suppresses pivoting of the tandem wheel assembly 12 to further improve traction engagement of the wheels 36, 38, 40, 42 with the ground and the overall ride stability of the work vehicle 10. The pivoting damping system 66 operates to impart pivoting deceleration forces (and in some cases, braking or locking forces) to the tandem wheel assembly 12, and thereby to the wheels 36, 38, 40, 42, to better distribute the downforce applied by the reaction assembly 64. The pivoting damping system 66 can be used to suppress, mitigate, or prevent pivoting of the tandem wheel assembly 12 due to events such as changes in acceleration, riding on an obstacle, or riding on an uphill / downhill section, thereby affecting the amount (if any) of initial pivoting of the tandem wheel assembly 12 in response to such events. In a first embodiment, the pivoting damping system 66 includes a single central clutch assembly 238 disposed between the tandem wheel housing 76 and the pivot cage 74. In a second embodiment, the pivoting damping system 66 includes a clutch assembly 238 disposed between at least one of the train wheel housing 76 and wheel end assemblies 176, 180. In this second embodiment, each wheel end assembly 176, 180 may have an associated clutch assembly 238 (and a clutch assembly 238 not disposed at the pivot cage 74; similarly, when the clutch assembly 238 is disposed at the pivot cage 74, a clutch assembly 238 is not disposed at at least one wheel end assembly 176, 180). See also Figure 16 and Figure 17 Each clutch assembly 238 includes a plurality of intersecting friction discs 240 and backing discs 242, some of which are rotatably fixed to the train wheel housing 76 and some of which are rotatably fixed to the pivot cage 74 or wheel end assemblies 176, 180 and actuator 244.

[0060] The friction disc 240 is circular, having inner and outer surfaces 246 and 248, and a central opening 250. Friction material 252 is disposed on the inner surface 246, and friction material 254 is disposed on the outer surface 248 (for illustrative purposes, ...). Figure 16The friction materials 252, 254 are shown in exploded view from the friction disc 240. The friction materials 252, 254 may have rough surfaces, raised surfaces, and the like. A plurality of spaced-apart teeth 256 are provided on the inner diameter of each friction disc 240 defined by an opening 250, and the outer surface 258 defined by the outer diameter of each friction disc 240 is smooth. The backing disc 242 is circular, having flat inner and outer surfaces 260, 262 and a central opening 264. A plurality of spaced-apart teeth 266 are provided on the outer surface of each friction disc 240, and the inner surface 268 defined by the opening 264 of each backing disc 242 is smooth. When positioned between components in the tandem wheel assembly 12, the friction disc 240 is located between two adjacent backing discs 242. The teeth 256 of the friction disk 240 extend inward from the inner surface 268 of the backing disk 242, and the teeth 266 of the backing disk 242 extend outward from the outer surface 258 of the friction disk 240.

[0061] In such Figure 4 and Figures 12 to 14In the first embodiment shown, the outer sidewall 130 includes a cover 270 seated above a central opening 146. A clutch assembly 238 is positioned between the cover 270 and the pivot cage 74. The cover 270 has an outer wall 272 fixed to the outer sidewall 130 of the train wheel housing 76 and an inner cylindrical protrusion 274 extending inwardly from the outer wall 320. An axis defined through the center of the protrusion 274 is aligned with the pivot axis 62. The protrusion 274 has a plurality of spaced channels 276 mirroring the shape of teeth 256 on the friction disc 240. The channels 276 extend along an axis parallel to the pivot axis 62. The pivot cage 74 further includes a clutch housing 278 at the outer end 104 of the annular body 100. In this embodiment, the clutch housing 278 includes a retaining plate 280 and a backing plate 282 fixedly engaged together. The retaining plate 280 is annular and has a central opening 284. The backing plate 282 is annular and has a central opening 286. A retaining plate 280 is located at the outer end 104 of the annular body 100, and the backing plate 282 is located at the outer end 288 of the retaining plate 280. The mating retaining plate 280 and backing plate 282 form a recess 290 with an end opening therein, in which discs 240, 242 and actuator 244 are seated. The recess 290 has an inner wall 292 formed by the retaining plate 280, an outer wall 294 formed by the backing plate 282, and an outer wall 296 formed by the retaining plate 280, and the outer wall 296 extends between the inner wall 292 and the outer wall 294 in a direction parallel to the pivot axis 62; the recess 290 opens toward the central opening 284 of the retaining plate 280. The outer wall 296 of the recess 290 has a plurality of spaced channels 298 formed therein, mirroring the shape of the teeth 266 on the backing disc 242. Channel 298 extends along an axis parallel to pivot axis 62. Discs 240, 242 surround the protrusion 274 of the cover, and teeth 256 on the friction disc 240 are seated within the channel 276 in the protrusion 274, and teeth 266 are seated within the channel 298 in the retaining plate 280. Discs 240, 242 extend through the open end of the recess 290. The engagement of teeth 256 in the channel 276 provides sliding movement of the friction disc 240 relative to the protrusion 274 while preventing rotational movement relative to the protrusion 274, and the engagement of teeth 266 in the channel 298 provides sliding movement of the backing disc 242 relative to the retaining plate 280 and the backing plate 282 while preventing rotational movement relative to the retaining plate 280 and the backing plate 282.

[0062] In some embodiments, actuator 244 provides an actively controlled system that allows for active control of the pivoting damping system 66. For example... Figure 12 and Figure 13As shown, actuator 244 is a hydraulic piston engaged with inner backing disc 242 within recess 290. The hydraulic piston is hydraulically connected to hydraulic system 34 via hydraulic line 300, such that the hydraulic piston is controlled by control system 32. When the hydraulic piston is actuated by hydraulic system 34 under the control of control system 32, discs 240, 242 are pushed into engagement with each other. Due to friction materials 252, 254, this slows the pivoting of train wheel housing 76 (via cover 270) relative to pivot cage 74 (via clutch housing 278), and thus inhibits the pivoting of reaction rods 212, 214. The hydraulic piston can always engage with inner backing disc 242 to provide load on discs 240, 242, thereby reducing the stroke that the hydraulic piston must travel to actuate pivot damping system 66 and providing constant damping. In some embodiments, control system 32 responds to input 302 indicating that pivoting of the train wheel housing 76 may have occurred or is occurring, and activates hydraulic system 34 to engage a hydraulic piston against discs 240, 242. Such input 302 may be, but is not limited to, a vision system for detecting obstacles, a rotation sensor indicating that pivoting of the train wheel housing 76 has begun, an engine sensor, a transmission sensor, or any other sensor or system that directly or indirectly provides an indication that the train wheel housing 76 is pivoting around the pivot cage 74. When input 302 indicates that pivoting of the train wheel housing 76 may have stopped or has stopped, control system 32 commands hydraulic system 34 to release hydraulic pressure on the hydraulic piston, causing the hydraulic piston to release or remove pressure from discs 240, 242. The return of the hydraulic piston may be achieved by spring 304, which may be between the hydraulic piston and the inner backing disc 242, or may be inside the hydraulic line piston. In some embodiments, control system 32 responds to operator input 306. Figure 18As schematically shown, the control system 32 can be configured to automatically command the hydraulic system 34 under a control algorithm, depending on input 302 or in response to input 306 from the operator, to activate hydraulic pistons to apply a set pressure or a varying amount of pressure to discs 240, 242 in opposition to the downward pressure of the reaction assembly 64, in order to achieve a desired balance between traction and ride stability of the work vehicle 10. To suppress the pivoting of the tandem wheel housing 76 so that the wheels quickly return to ground contact, a large amount of pressure can be applied to discs 240, 242 via hydraulic pistons. Similarly, to slowly suppress the pivoting of the tandem wheel housing 76, a smaller amount of pressure can be applied to discs 240, 242 via hydraulic pistons. Therefore, with the pivot damping system 66, the tandem wheel assembly 12 can respond sufficiently to maintain or quickly return all wheels 36, 38, 40, 42 to ground contact, providing good traction control for the work vehicle 10 while avoiding excessively sudden reaction pressure, further improving traction engagement of wheels 36, 38, 40, 42 and enhancing the ride quality for the operator of the work vehicle 10. The control system 32 can be configured to command the hydraulic system 34 to activate hydraulic pistons to apply sufficient pressure to discs 240, 242 to lock or substantially lock the tandem wheel housing 76 in place, preventing or substantially preventing relative movement between the tandem wheel housing 76 and the pivot cage 74. Thus, the active pivot damping system 66 allows for both the ability to select when and to what extent damping force is applied, and also allows for additional control settings to allow the tandem wheel assembly 12 to pivot freely (i.e., zero damping) or be locked against pivoting (i.e., fully damped).

[0063] In some embodiments, actuator 244 provides, for example Figure 14 The passive system is shown. The actuator 244 is one or more springs, such as disc springs, that engage with the inner backing disc 242 within the recess 290. In the embodiment, the springs always push the discs 240, 242 into engagement with each other, thereby applying a constant bias force to the discs 240, 242 that resists pivoting of the tandem wheel assembly 12 in either clock direction. The friction materials 252, 254 thus always slow the pivoting of the tandem wheel housing 76 relative to the pivot cage 74, while still allowing the tandem wheel assembly 12 to pivot in either clock direction.

[0064] In such Figure 15In the second embodiment shown, the clutch assembly 238 is not located at the pivot cage 74 except for the cover 270 which closes the central opening 146. In the second embodiment, the clutch assembly 238 is positioned between the tandem wheel housing 76 and at least one of the wheel end assemblies 176, 180. As shown, the clutch assembly 238 is positioned between the inner surface of the cylindrical protrusion 152 of the tandem wheel housing 76 and the outer surface of the ring gear 196. The protrusion 152 has a plurality of spaced channels 276 on its inner surface, the channels 276 being mirror images of the teeth 266 on the backing plate 242, and the channels 276 extending along an axis parallel to the wheel axis 194. The outer side wall 130 serves as the retaining plate 280 of the first embodiment, and the mounting flange 308 of the wheel end housing 190, which attaches the wheel end housing 190 to the outer end of the protrusion 152, serves as the backing plate 282 of the first embodiment. The mating protrusion 152 and wheel end housing 190 form a recess 290 with an end opening therein, in which discs 240, 242 and actuator 244 are seated. The recess 290 has an inner wall 292 formed by an outer wall 130, an outer wall 294 formed by a mounting flange 308, and an outer wall 296 formed by the protrusion 152, the outer wall 296 extending between the inner wall 292 and the outer wall 294 in a direction parallel to the pivot axis 62; the recess 290 opens toward a central opening formed by the protrusion 152. The outer wall 296 of the recess 290 has a plurality of spaced channels 298 mirroring the shape of the teeth 266 on the backing disc 242. The channels 298 extend along an axis parallel to the wheel axis 194. Discs 240 and 242 surround the ring gear 196, and teeth 256 on the friction disc 240 are seated within channels 276 in the ring gear 196, and teeth 266 are seated within channels 298 in the protrusion 152. The engagement of teeth 256 in channels 276 provides sliding movement of the friction disc 240 relative to the ring gear 196 while preventing rotational movement relative to the ring gear 196, and the engagement of teeth 266 in channels 298 provides sliding movement of the backing disc 242 relative to the protrusion 152 while preventing rotational movement relative to the protrusion 152. Similar to the actuator of the first embodiment, actuator 244 can be an actively controlled system that allows active control of the pivoting damping system 66, or it can be a passive system (the passive system in...). Figure 15 As shown in the diagram, but an active system may be provided. Specific details of the system will not be elaborated upon herein. In the second embodiment, rotation of the train wheel housing 76 is suppressed relative to the pivot cage 74 via the connection between the ring gear 196, reaction rod supports 210 and / or 212, reaction rods 214 and / or 216, and the pivot cage 74.

[0065] To propel the work vehicle 10, propulsion source 46 supplies power to transmission 48, which drives differential 80 and shaft 90, which in turn drives center sprocket 172 in each tandem wheel housing 76. Center sprocket 172 drives first chain 174 and second chain 178, which respectively rotate first and second wheel end sprockets 182 and their shafts 200 to ultimately rotate a pair of right wheels 36, 38 mounted on wheel end assemblies 176, 180 (or ultimately rotate a pair of left wheels 36, 38 mounted on wheel end assemblies 176, 180 in the left tandem wheel housing 76). Transmission 48 typically includes one or more gear arrangements and / or clutches (not shown) to modify the speed of input from propulsion source 46 to one or more speeds suitable for the tandem wheel assemblies 12. Rotation of the shaft 200 of the front wheel end assembly 176 causes rotation of the wheel end gear train 188, including rotation of the ring gear 196 and the front reaction rod support 210 relative to the wheel end housing 190. The amount of rotation of the ring gear 196 and the front reaction rod support 210 is limited by the length of the receiving opening 226. Similarly, rotation of the shaft 200 of the rear wheel end assembly 180 causes rotation of the wheel end gear train 188, including rotation of the ring gear 196 and the rear reaction rod support 212 relative to the wheel end housing 190. The amount of rotation of the ring gear 196 and the rear reaction rod support 212 is limited by the length of the receiving opening 228.

[0066] In some scenarios, an increase in power from propulsion source 46 may tend to cause the tandem wheel assembly 12 to pivot about pivot axis 62, thereby lifting the front wheels 36 or 42 off the ground while increasing downward pressure on the rear wheels 38 or 44. To counteract this tendency, reaction rods 214, 216 provide opposing forces, thereby transmitting torque directly to the chassis 14. Furthermore, a sudden decrease in power from propulsion source 46 may reverse the direction of pivoting of reaction assembly 64 about pivot axis 62; however, these forces can be counteracted by reaction rods 214, 216. Therefore, the pivoting of reaction assembly 64 relative to chassis 14 can be limited, and the torque delivered to wheels 36, 38 or 40, 42 can be substantially equal. Pivot damping system 66 suppresses the pivoting of reaction assembly 64, thereby improving ride quality.

[0067] As the work vehicle 10 traverses an obstacle in the road, the front wheels 36 and / or 40 rise, and the tandem wheel housing 76 pivots clockwise relative to the pivot cage 74. After the front wheels 36 and / or 40 have passed the obstacle, the pivot damping system 66 prevents the tandem wheel housing 76 from pivoting counterclockwise relative to the pivot cage 74 by inhibiting its pivoting. As the work vehicle 10 continues to traverse the obstacle, the rear wheels 38 and / or 42 rise, and the tandem wheel housing 76 pivots counterclockwise relative to the pivot cage 74. After the rear wheels 38 and / or 42 have passed the obstacle, the pivot damping system 66 prevents the tandem wheel housing 76 from pivoting clockwise relative to the pivot cage 74 by inhibiting its pivoting. This improves ride quality.

[0068] One or more exemplary tandem wheel assemblies have been described in detail above. Various other configurations are possible within the scope of this disclosure. For example, the double-ring, double-chain drive mechanism in the disclosed tandem wheel housing can be replaced with a single-ring center sprocket and a single chain connecting the center sprocket to the end sprockets of the two wheels.

[0069] Enumeration Examples

[0070] Furthermore, the following examples are provided, and these examples have been numbered for easy reference.

[0071] 1. A tandem wheel assembly for a work vehicle having a chassis and wheels, the tandem wheel assembly comprising: a tandem wheel housing defining a central opening extending along a pivot axis and wheel end openings extending along an associated wheel end axis, the tandem wheel housing being pivotally mounted to the chassis about the pivot axis; a central sprocket disposed within the tandem wheel housing and rotatable relative to the tandem wheel housing; and wheel end assemblies, each wheel end assembly disposed at one of the wheel end openings, each wheel end assembly having a wheel end sprocket, a wheel end gear train, and a wheel end hub, each wheel end sprocket being supported within the tandem wheel housing for connection At least one chain rotates to the central sprocket, each wheel end gear train is coupled to rotate via an associated wheel end sprocket and configured to achieve a gear ratio change and cause the associated wheel end hub to rotate about the associated wheel end axis; a pair of reaction rods, each pivotally coupled at a first end to the chassis and at an opposite second end to a component of the respective wheel end assembly; and a pivoting damping system, the pivoting damping system being at least partially axially positioned between the train wheel housing and at least one of the components of the chassis or wheel end assembly, the pivoting damping system being configured to suppress the pivoting of the train wheel housing relative to the chassis.

[0072] 2. The tandem wheel assembly according to Example 1, wherein the pivoting damping system includes a clutch assembly having a plurality of discs, some of which are rotatably fixed to the tandem wheel housing, and some of which are rotatably fixed to the chassis or the component.

[0073] 3. The tandem wheel assembly according to Example 2 further includes: an actuator that causes the disc to engage or disengage.

[0074] 4. The tandem train wheel assembly according to Example 3, wherein the actuator is a hydraulically driven piston.

[0075] 5. The tandem wheel assembly according to Example 4 further includes: a spring coupled to the disc and configured to engage or disengage the disc.

[0076] 6. The tandem train wheel assembly according to Example 4, wherein the activation of the hydraulically driven piston is controlled by a controller configured to control the hydraulic pressure supplied to the hydraulically driven piston.

[0077] 7. The tandem wheel assembly according to Example 2 further includes: an actuator comprising a spring configured to apply a biasing force to engage the disc.

[0078] 8. The tandem wheel assembly according to Example 2, wherein each wheel end gear train is a planetary gear set having a ring gear; and wherein the ring gear is the component of each wheel end assembly to which the second end of the reaction rod is connected.

[0079] 9. The tandem wheel assembly according to Example 8, wherein the annular gear of each wheel end gear train is positioned within the respective wheel end hub and has an attachment portion extending into the interior of the tandem wheel housing.

[0080] 10. The tandem wheel assembly according to Example 9, wherein the second end of each reaction rod is pivotally connected to the corresponding attachment portion by a pin.

[0081] 11. The tandem train wheel assembly according to Example 2 further includes: a pivot cage arranged around the pivot axis of the tandem train wheel housing, the pivot cage being fixedly mounted to the chassis; and wherein the first end of each reaction rod is pivotally connected to the pivot cage at a position spaced apart from the pivot axis.

[0082] 12. The tandem wheel assembly according to Example 11, wherein the pivot cage extends into the tandem wheel housing, and the reaction rod extends within the tandem wheel housing between the pivot cage and the wheel end assembly.

[0083] 13. The train wheel assembly according to Example 11, wherein the pivoting damping system includes a clutch assembly having a clutch housing fixedly attached to an outer end of the pivoting cage, the clutch housing defining a recess in which the clutch assembly is positioned; and wherein the clutch assembly includes a plurality of discs engaging with the clutch housing.

[0084] 14. The tandem train wheel assembly according to Example 13 further includes: a cover fixedly attached to an outer side wall of the tandem train wheel housing; and wherein the cover has a cylindrical protrusion extending into the clutch housing, and the disc engages with the cylindrical protrusion.

[0085] 15. A tandem wheel assembly for a work vehicle having a chassis and wheels, the tandem wheel assembly comprising: a tandem wheel housing defining a central opening extending along a pivot axis and wheel end openings extending along an associated wheel end axis; a pivot cage disposed within the central opening to allow the tandem wheel housing to pivot about the pivot axis, the pivot cage being fixedly mounted to the chassis; a central sprocket disposed within the pivot cage and rotatable relative to the tandem wheel housing; and wheel end assemblies, each wheel end assembly disposed at one of the wheel end openings, each wheel end assembly having a wheel end sprocket, a wheel end gear train, and a wheel end hub, each wheel end sprocket being supported within the tandem wheel housing for rotation by at least one chain coupled to the central sprocket, each wheel end gear train being coupled in a continuous manner. The system includes: a sprocket for rotation via an associated wheel end, configured to change the gear ratio and rotate the associated wheel end hub about the associated wheel end axis; a pair of reaction rods, each pivotally connected at a first end to the pivot cage and at opposite second ends to a component of the wheel end assembly; and a pivot damping system configured to suppress the pivoting of the train wheel housing relative to the chassis, the pivot damping system including a clutch assembly at least partially axially positioned between the train wheel housing and a component of at least one of the chassis or wheel end assembly, the clutch assembly having: a plurality of discs, some of which are rotatably fixed to the train wheel housing and some of which are rotatably fixed to the chassis; and an actuator that causes the discs to engage or disengage.

[0086] in conclusion

[0087] The examples discussed above lead to various benefits of the disclosed tandem wheel assembly. For instance, a reaction rod is pivotally connected at one end to the annular body of the pivot cage and at the opposite end to a component of the wheel-end gear train to provide force transmission and distribution between the wheels as the work vehicle travels. Furthermore, the pivoting damping system suppresses pivoting of the tandem wheel assembly when the work vehicle traverses uphill / downhill sections or encounters obstacles on the road, further improving wheel-to-ground traction engagement and overall ride stability of the work vehicle. An active or passive pivoting damping system is provided. An active pivoting damping system allows for enhanced control options and selective application of pivot suppression, providing the ability to select when and to what extent damping force is applied, and also provides additional control settings to allow the tandem wheel assembly to pivot freely (i.e., zero damping) or be locked against pivoting (i.e., fully damped). A passive pivoting damping system allows for continuous suppression and less mechanically and electronically complex applications.

[0088] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Unless expressly indicated otherwise, the singular forms “a,” “an,” and “described” as used herein are intended to include the plural meaning. It will be further understood that the terms “comprises” and / or “comprising” as used in this specification specify the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0089] The description herein is given for purposes of illustration and description, and is not intended to be exhaustive or to limit the disclosure to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments expressly referenced herein have been chosen and described in order to best explain the principles of this disclosure and its practical application, and to enable others skilled in the art to understand this disclosure and recognize the many substitutions, modifications, and variations to the described examples(s). Therefore, various embodiments and implementations other than those expressly described are within the scope of the following claims.

Claims

1. A tandem wheel assembly (12) for use in a work vehicle (10) having a chassis (14) and wheels (36, 38, 40, 42), the tandem wheel assembly (12) comprising: A tandem wheel housing (76) defines a central opening (144, 146) extending along a pivot axis (62) and a wheel end opening (154) extending along an associated wheel end axis (194), the tandem wheel housing (76) being pivotally mounted to the chassis (14) about the pivot axis (62). A central sprocket (172) is disposed within the train wheel housing (76) and is rotatable relative to the train wheel housing (76); Wheel end assemblies (176, 180), each wheel end assembly being disposed at one of the wheel end openings (154), each wheel end assembly (176, 180) having a wheel end sprocket (182), a wheel end gear train (188) and a wheel end hub (44), each wheel end sprocket (182) being supported to rotate by at least one chain (174, 178) connected to the central sprocket (172), each wheel end gear train (188) being connected to rotate by the associated wheel end sprocket (182), and each wheel end gear train being configured to achieve a gear ratio change and cause the associated wheel end hub (44) to rotate about the associated wheel end axis (194); A pair of reaction rods (214, 216), each reaction rod being pivotally connected at a first end to the chassis (14) and at the opposite second end to a component of a corresponding wheel end assembly (176, 180); and A pivoting damping system (66) is provided, which is at least partially axially positioned between the train wheel housing (76) and a component of at least one of the chassis (14) or wheel end assemblies (176, 180), and is configured to suppress pivoting of the train wheel housing (76) relative to the chassis (14). The pivoting damping system (66) includes a clutch assembly (238) having multiple discs (240, 242).

2. The tandem train wheel assembly (12) according to claim 1, wherein, Some of the discs are rotatably fixed to the train wheel housing (76), and some of the discs are rotatably fixed to the chassis (14) or the component.

3. The tandem wheel assembly (12) according to claim 2, further comprising an actuator (244) that causes the discs (240, 242) to engage or disengage.

4. The tandem train wheel assembly (12) according to claim 3, wherein, The actuator (244) is a hydraulically driven piston.

5. The tandem wheel assembly (12) according to claim 4, further comprising a spring (304) coupled to the discs (240, 242) and configured to engage or disengage the discs (240, 242).

6. The tandem train wheel assembly (12) according to claim 4, wherein, The activation of the hydraulically driven piston is controlled by a controller (32) configured to control the hydraulic pressure supplied to the hydraulically driven piston.

7. The tandem train wheel assembly (12) according to claim 2, further comprising: An actuator (244) includes a spring configured to apply a biasing force to engage the discs (240, 242).

8. The tandem train wheel assembly (12) according to claim 2, wherein, Each wheel end gear train (188) is a planetary gear set (198) with a ring gear (196); and The ring gear (196) is the component to which the second end of the reaction rod (214, 216) is connected to each wheel end assembly (176, 180).

9. The tandem train wheel assembly (12) according to claim 8, wherein, The ring gear (196) of each wheel end gear train (188) is positioned within the corresponding wheel end hub (44) and has an attachment portion (222) extending into the interior of the train wheel housing (76).

10. The tandem train wheel assembly (12) according to claim 9, wherein, The second end of each reaction rod (214, 216) can be pivotally connected to the corresponding attachment part (222) by means of pins (230, 234).

11. The tandem train wheel assembly (12) according to claim 2, further comprising: A pivot cage (74) is provided around the pivot axis (62) of the train wheel housing (76), and the pivot cage (74) is fixedly mounted to the chassis (14); and The first end of each reaction rod (214, 216) is pivotally connected to the pivot cage (74) at a position spaced apart from the pivot axis (62).

12. The tandem train wheel assembly (12) according to claim 11, wherein, The pivot cage (74) extends into the train wheel housing (76), and the reaction rods (214, 216) extend within the train wheel housing (76) between the pivot cage (74) and the wheel end assemblies (176, 180).

13. The tandem train wheel assembly according to claim 11, wherein, The pivoting damping system (66) includes a clutch assembly (238) having a clutch housing (278) fixedly attached to an outer end (104) of the pivoting cage (74), the clutch housing (278) defining a recess (290) in which the clutch assembly (238) is positioned; and wherein the clutch assembly (238) includes a plurality of discs (240, 242) engaging with the clutch housing (278).

14. The tandem train wheel assembly of claim 13, further comprising: A cover (270) is fixedly attached to the outer wall (130) of the train wheel housing (76); and wherein the cover (270) has a cylindrical protrusion (274) extending into the clutch housing (278), and the disc (240, 242) engages with the cylindrical protrusion (274).

15. A tandem wheel assembly (12) for use in a work vehicle (10) having a chassis (14) and wheels (36, 38, 40, 42), the tandem wheel assembly (12) comprising: A tandem train wheel housing (76) defines a central opening (144, 146) extending along a pivot axis (62) and a wheel end opening (154) extending along an associated wheel end axis (194). A pivot cage is disposed within the central opening to allow the train wheel housings to pivot about the pivot axis, the pivot cage being fixedly mounted to the chassis; A central sprocket (172) is disposed within the pivot cage and is rotatable relative to the train wheel housing (76); Wheel end assemblies (176, 180), each wheel end assembly being disposed at one of the wheel end openings (154), each wheel end assembly (176, 180) having a wheel end sprocket (182), a wheel end gear train (188) and a wheel end hub (44), each wheel end sprocket (182) being supported within the train wheel housing (76) to rotate by at least one chain (174, 178) connected to the central sprocket (172), each wheel end gear train (188) being connected to rotate by the associated wheel end sprocket (182), and each wheel end gear train being configured to achieve a gear ratio change and to rotate the associated wheel end hub (44) about the associated wheel end axis (194); A pair of reaction rods (214, 216), each reaction rod being pivotally connected at a first end to the pivot cage (74) and at the opposite second end to a component of a corresponding wheel end assembly (176, 180); and A pivoting damping system (66) configured to suppress pivoting of the train wheel housing (76) relative to the chassis (14), the pivoting damping system (66) including a clutch assembly (238) at least partially axially positioned between the train wheel housing (76) and a portion of the chassis (14) or at least one of the wheel end assemblies (176, 180), the clutch assembly (238) having: a plurality of discs (240, 242), some of which are rotatably fixed to the train wheel housing (76) and some of which are rotatably fixed to the chassis (14); and an actuator (244) that causes the discs (240, 242) to engage or disengage.

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