Crawler drive system for a crawler work vehicle

Abstract

Crawler work vehicle, comprising: an axle drive shaft (46) defining an axis of rotation (R2); a differential gear housing (48) with at least one planetary gear set (100); a chain drive system (12) at least partially contained within the differential gear housing (48) and comprising: a first gear (122) coupled to the axle drive shaft (46); a second gear (124) coupled to the first gear (122); a bevel gear assembly (126) coupled to the second gear (124); a bevel gear set (130) coupled to the at least one planetary gear set (100); a ring gear (128) coupled to the bevel gear set (130) and to the bevel gear assembly (126); a gear housing (120), wherein the first gear (122) and the second gear (124) are each rotatably supported by the gear housing (120), at least one drive axle shaft (72) coupled to at least one planetary gear set (100); and a drive wheel (58) for driving a chain (56) with continuous ground contact, wherein the at least one drive axle shaft (72) has an axis of rotation (R), wherein the axis of rotation (R) of the drive axle shaft (72) is coaxial with a central axis (C) of the drive wheel (58) and vertically offset from the axis of rotation (R2) of the axle drive shaft (46).

Description

AREA OF REVELATION

[0001] This disclosure relates to work vehicles and, more particularly, to tracked work vehicles having an elevated track drive system. BACKGROUND OF REVELATION

[0002] Various work vehicles, such as tractors, include tracks that provide additional traction to enable tractors to move more easily through rough or muddy fields. These tracks are driven by drive wheels. In typical cases, the drive wheels are driven so that a centerline of each track drive wheel is at the same height as a tractor drive axle shaft. In other cases, such as described in US Pat. No. 5,924,503, to improve performance, a gear set is coupled to the drive wheel outside a differential gear case to raise the height of a drive axle shaft to drive the drive wheels at a higher elevation. This requires an external gear set for each of the drive wheels, increasing the number of parts and the weight of the tracked work vehicle.Furthermore, the multiple gear sets each require maintenance, which can impair the productivity of the tracked work vehicle. For example, US 2004 / 000450 A1 discloses a driveline assembly comprising a transmission, a differential assembly, and first and second final drive assemblies. The driveline assembly includes an input member and two output members. The input member is driven by an engine. Rotation of the input member is transmitted to the output members via the transmission, the differential assembly, and the final drive assemblies to cause rotation of the output members. Other drive systems for work vehicles are described in EP 2 883 735 A1, US 6 374 933 B1, and DE 10 2014 009 461 A1. SUMMARY OF REVELATION

[0003] The disclosure provides a tracked work vehicle having a track drive system within a differential housing that raises a portion of a drive train to an axle coaxial with a centerline of a drive wheel.

[0004] In one aspect, the disclosure provides a tracked work vehicle. The tracked work vehicle includes an axle drive shaft defining a first axis of rotation and a differential gear housing having at least one planetary gear set. A tracked work vehicle includes a track drive system at least partially contained within a differential gear housing. The track drive system includes a first gear coupled to the axle drive shaft and a second gear coupled to the first gear. The track drive system includes a bevel gear assembly coupled to the second gear and a bevel gear set coupled to the at least one planetary gear set. The tracked work vehicle includes at least one drive axle shaft coupled to the at least one planetary gear set and a drive sprocket for driving a continuous ground contact track.The at least one drive axle shaft has a second axis of rotation that is vertically offset from the first axis of rotation and substantially coaxial with a central axis of the drive wheel.

[0005] In another aspect, the disclosure provides a tracked work vehicle. The tracked work vehicle includes an axle drive shaft defining a first axis of rotation and a differential gear housing having at least one planetary gear set. A tracked work vehicle includes a track drive system at least partially contained within a differential gear housing. The track drive system includes a first gear coupled to the axle drive shaft and a second gear coupled to the first gear. The track drive system includes a bevel gear assembly coupled to the second gear and a bevel gear set coupled to the at least one planetary gear set. The track drive system includes a ring gear coupled to a bevel gear set and the bevel gear assembly.The tracked work vehicle includes at least one drive axle shaft coupled to the at least one planetary gear set and a drive gear for driving a track with continuous ground contact. The at least one drive axle shaft has a second axis of rotation vertically offset from the first axis of rotation and substantially coaxial with a center axis of the drive gear.

[0006] In yet another aspect, the disclosure provides a tracked work vehicle. The tracked work vehicle includes an axle drive shaft defining a first axis of rotation and a differential gear housing having at least one planetary gear set. A tracked work vehicle includes a track drive system at least partially contained within a differential gear housing. The track drive system includes a first gear coupled to the axle drive shaft and a second gear coupled to the first gear. The track drive system includes a bevel gear assembly having a shaft and a bevel gear. The shaft is coupled to a second gear. The track drive system includes a bevel gear set coupled to the at least one planetary gear set and a ring gear coupled to the bevel gear set and the bevel gear.The tracked work vehicle includes at least one drive axle shaft coupled to the at least one planetary gear set and a drive gear coupled to at least one drive axle shaft for driving a track with continuous ground contact. The at least one drive axle shaft has a second axis of rotation vertically offset from the first axis of rotation and substantially coaxial with a central axis of the drive gear.

[0007] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, as well as the claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. is a side view of an exemplary tracked work vehicle in the form of a farm tractor incorporating a track drive system according to various embodiments of this disclosure; Fig. is a schematic perspective view of a drive train for the tracked work vehicle of Fig. , with one section of each saddle arrangement omitted for clarity; Fig. is a perspective view of a differential gear housing and a portion of the track drive system of the work vehicle of Fig. , which represents the crawler drive system coupled to the differential gear housing; Fig. is a partial exploded view of Fig. ; Fig. is a cross-sectional view of the differential gear housing and the chain drive system section of Fig. , taken along line 4-4 from Fig. ; Fig. is an exploded view of the crawler drive system of Fig. ; Fig. is a cross-sectional view of the differential gear housing and the chain drive system section of Fig. , taken along line 6-6 from Fig. ; and Fig. is a perspective view of the crawler drive system of Fig. .

[0008] The same reference symbols in the different drawings indicate the same elements. DETAILED DESCRIPTION

[0009] The following describes one or more exemplary embodiments of the disclosed track drive system, as shown in the accompanying figures of the drawings briefly described above. Various modifications of the exemplary embodiments may be contemplated by those skilled in the art.

[0010] As used herein, lists with items separated by conjunctive expressions (e.g., "and") and also preceded by the phrase "one or more of" or "at least one of" denote configurations or agreements that may include individual items of the list or a combination thereof. For example, "at least one of A, B, and C" or "one or more of A, B, and C" indicates the possibilities 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).

[0011] As used herein, the term "axial" refers to a direction that extends generally parallel to an axis of rotation, an axis of symmetry, or a central axis of a component or components. For example, in a cylinder or disk having a central axis and opposing generally circular ends or faces, the "axial" direction may refer to the direction that extends generally parallel to the central axis between the opposing ends or faces. In certain cases, the term "axial" may be used with respect to components that are not cylindrical (or otherwise radially symmetric). For example, for a rectangular housing containing a rotating shaft, the "axial" direction may be considered to be a direction that extends generally parallel to the axis of rotation of the shaft.Furthermore, the term "radial," as used herein, may refer to a direction or relationship of components with respect to a line extending outward from a common central axis, axis, or similar reference, for example, in a plane of a cylinder or disk that is perpendicular to the central axis or axis. In certain cases, components may be considered to be "radially" oriented even though one or both components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms "axial" and "radial" (and any derivatives thereof) may encompass directional relationships that are otherwise aligned, that is, not exactly aligned, with the true axial and radial dimensions, provided the relationship is predominantly in the respective nominal axiality or radial direction.

[0012] The following describes one or more exemplary implementations of the disclosed system for a track drive system for a tracked work vehicle, as shown in the accompanying figures of the drawings briefly described above. In general, the disclosed systems (and work vehicles in which they are employed) provide for raising a drive axle shaft associated with a respective drive wheel to a height above a height associated with a transmission output shaft or final drive shaft of the tracked work vehicle in a differential gear housing connected to the tracked work vehicle. This allows the drive wheels to be driven at a higher height while reducing the number of parts and weight associated with the elevation change, thereby improving the cost and productivity of the work vehicle.

[0013] In the example of the present disclosure, the track drive system is entirely contained within the differential gear housing and includes a first spur gear, a second spur gear, a bevel gear assembly, and a bevel gear set. The first spur gear is coupled to the drive axle shaft, such as a rear axle of the tracked work vehicle, and the first spur gear is coupled to the second spur gear. The first spur gear and the second spur gear are each rotatably supported by a gear housing. The second spur gear is coupled to the bevel gear assembly, and a bevel gear of the bevel gear assembly drives a ring gear. The ring gear, in turn, is coupled to a bevel gear set and drives a bevel gear set. The bevel gear set is coupled to a pair of planetary gear sets, which in turn are coupled to the drive axle shafts, which drive a pair of drive gears.

[0014] Because the second spur gear is rotatably stacked or coupled vertically above the first spur gear, the second spur gear cooperates with the bevel gear assembly to raise a height of the drive axle shafts such that the drive axle shafts are coaxial with a center axis of the drive gears but offset from a rotational axis of the axle drive shaft.

[0015] As mentioned above, the system described herein may be used with respect to a variety of work vehicles, including various agricultural or other work vehicles. In certain embodiments, the described system may be used with respect to a tractor. However, it should be understood that the system disclosed herein may be used with various other work vehicles, such as road graders, excavators, etc. With reference to Fig. 1 shows a tracked work vehicle, such as a tractor 10. The tractor 10 includes a plurality of track systems 12 and a power source, such as an engine 20. The engine 20 supplies power to the transmission 22. As described below, the transmission 22 transfers power from the engine 20 to a suitable drive system 24 coupled to one or more of the track systems 12 of the tractor 10 to enable the tractor 10 to move. In one example, the engine 20 is an internal combustion engine, such as a diesel engine, controlled by an engine controller. It should be noted that the use of an internal combustion engine is merely an example, as the power device may be a fuel cell, an electric motor, a hybrid electric motor, etc.

[0016] The tractor 10 also includes one or more pumps 26 that may be driven by the engine 20 of the tractor 10. The flow of the pumps 26 may be directed through various control valves 28 and various lines (e.g., flexible hoses and conduits) to control various components associated with the tractor 10. The flow of the pumps 26 may also drive various other components of the tractor 10. The flow of the pumps 26 may be controlled in various ways (e.g., by controlling the various control valves 28 and / or a controller 30 associated with the tractor 10). As described herein, the flow of the pumps 26 may be directed through one or more of the control valves 28 and various lines to lubricate a portion of the differential gear case 48.

[0017] In general, the controller 30 (or multiple controllers) may be provided for controlling various aspects of the operation of the tractor 10 in general. The controller 30 (or others) may be configured as a computing device with associated processing devices and memory architectures, as a hard-wired computer circuit (or circuits), as a programmable circuit, as a hydraulic, electrical, or electro-hydraulic controller, or otherwise. Thus, the controller 30 may be configured to perform various computer-based and control functions with respect to the tractor 10 (or other machine). In some embodiments, the controller 30 may be configured to receive input signals in various formats (e.g., hydraulic signals, voltage signals, current signals, etc.) and to output command signals in various formats (e.g., hydraulic signals, voltage signals, current signals, mechanical movements, etc.).). In some embodiments, the controller 30 (or a portion thereof) may be configured as an assembly of hydraulic components (e.g., valves, flow lines, pistons and cylinders, etc.) such that control of various devices (e.g., pumps or motors) may be performed and act with hydraulic and mechanical or other signals and movements.

[0018] The controller 30 may be in electronic, hydraulic, mechanical, or other communication with various other systems or devices of the tractor 10 (or other machine, such as an implement coupled to the tractor 10). For example, the controller 30 may be in electronic or hydraulic communication with various actuators, sensors, and other devices inside (or outside) the tractor 10, including various devices associated with the pumps 26, control valves 28, etc. The controller 30 may communicate with other systems or devices (including other controllers, such as a controller associated with an implement) in a variety of known ways, including via a CAN bus (not shown) of the tractor 10, via wireless or hydraulic communication means, or otherwise.

[0019] Various sensors may also be provided to monitor various conditions associated with the tractor 10. In some embodiments, various sensors 34 (e.g., pressure, flow, or other sensors) may be located near the pumps 26 and control valves 28 or elsewhere on the tractor 10. For example, sensors 34 monitor pressure associated with the pumps and generate sensor signals based thereon.

[0020] The tractor 10 also includes a cab 40 that includes a human-machine interface. The controller 30 receives input commands and connects to the operator via the human-machine interface 42.

[0021] As in Fig. As shown, the tractor 10 includes a pair of track systems 12 associated with a first or front axle assembly 44 of the tractor 10 in a forward travel direction D, and a pair of track systems 12 associated with a transmission output shaft or lower drive shaft 49 of the tractor 10 (only a portion of the track systems 12 is shown in Fig. shown for clarity) coupled to a final drive shaft 46 of a second or rear axle assembly 47. It should be understood that although the tractor 10 is illustrated as including multiple track systems 12, the tractor 10 may include any number of track systems 12, such as one or two. The pair of track systems 12 associated with the final drive shaft 46 of the tractor 10 are each coupled to the differential gear housing 48, which receives input torque from the transmission 22 via the final drive shaft 46.

[0022] In this example, with reference to Fig. , each of the track systems 12 includes a chassis assembly 52, a saddle assembly 54, a chain 56, and a drive sprocket 58. The drive sprocket 58 is attached to a drive axle shaft 72 and is supported by an axle housing 60. The drive sprocket 58 is annular and defines an outer periphery 62 and a drive sprocket hub 64. The drive sprocket 58 is generally made of a metal or metal alloy that is cast as a single piece. However, it should be understood that the drive sprocket 58 may be made of multiple pieces that are welded or otherwise secured together. The outer periphery 62 defines a plurality of chain guides 66 ( Fig. ) substantially continuously around a circumference. In this example, the multiple chain guides 66 include a plurality of slots substantially evenly spaced about the circumference of the outer periphery 62 for transmitting torque from the drive gear 58 to the chain 56. Generally, the multiple chain guides 66 each receive one of the plurality of teeth (not shown) of the chain 56 for driving the chain 56 with the drive gear 58.

[0023] The drive wheel hub 64 couples the drive wheel 58 to the axle housing 60. Generally, the drive wheel hub 64 defines one or more bores, each receiving one of one or more mechanical fasteners for coupling the drive wheel 58 to an axle flange 70 associated with the axle housing 60. Referring to Fig. the axle housing 60 is substantially cylindrical and substantially encloses the drive axle shaft 72 ( Fig. ) coupled to the axle flange 70. In one example, the drive axle shaft 72 is formed as a single piece. The axle flange 70 extends from the axle housing 60 to allow rotation of the drive gear 58 relative to the axle housing 60. Referring to Fig. The axle flange 70 is coupled to the drive wheel hub 64 of the drive wheel 58 such that the torque is transmitted from the drive axle shaft 72 to the drive wheel 58 to drive the drive wheel 58. As further described below, the drive axle shaft 72 is coupled to the differential gear housing 48 to receive the input torque. The axle housing 60 also includes a flange 73 that couples the caliper assembly 54 to the axle housing 60. As shown in Fig. As shown, the flange 73 extends around a circumference of the axle housing 60 at an end of the axle housing 60 that is substantially opposite the end of the axle housing 60 that is near or adjacent to the axle flange 70.

[0024] With reference to Fig. In one example, the chassis assembly 52 is movably or pivotably coupled to the saddle assembly 54. The chassis assembly 52 is not coupled to the drive wheel 58. Generally, the chassis assembly 52 includes a plurality of first idler gears 74 and a plurality of pivotable or second idler gears 76, each rotatably mounted relative to a chassis frame 78. In this example, the chassis assembly 52 includes two pairs of the first idler gears 74 and two pairs of the second idler gears 76. Each of the first idler gears 74 and second idler gears 76 cooperate to guide the track 56 along the ground when driven by the drive wheel 58. It should be noted that this arrangement of the idler gears 74, 76 is only exemplary, as any number and arrangement of the idler gears may be used.

[0025] The saddle assembly 54 includes a pair of arms 80 each extending outwardly from an annular base 82. Referring to Fig. The arms 80 each extend outwardly from the base 82 so that they are positioned on opposite sides of the drive wheel 58. The arms 80 each guide the chain 56 as the chain 56 moves around the drive wheel 58. Referring to Fig. The arms 80 may each include a flange 84 that couples the respective arm 80 to the base 82. The flange 84 may be bent to facilitate the arrangement of the arms 80 around the drive wheel 58.

[0026] The base 82 defines a central bore 86 that allows the caliper assembly 54 to be releasably coupled to the axle housing 60. By releasably coupling the caliper assembly 54 to the axle housing 60, the caliper assembly 54 can be easily removed for maintenance or repair. The base 82 defines a plurality of through-bores around a circumference of the bore 86, each receiving one of one or more mechanical fasteners to couple the base 82 to the flange 73 of the axle housing 60.

[0027] With reference to Fig. the chain 56 is continuous and is received around the drive sprocket 58 and the chassis assembly 52. Generally, the chain 56 is tensioned around the drive sprocket 58 and the chassis assembly 52. In this example, the chain 56 is made of a polymeric material, however, the chain 56 may be made of a metal or a metal alloy. An outer surface of the chain 56 includes a plurality of projections or steps (not shown) projecting from the outer surface to engage the terrain over which the tractor 10 travels. An inner surface includes a plurality of teeth (not shown) extending outwardly from the inner surface to engage the drive sprocket 58, the first idler gears 74, and the second idler gears 76 to move or drive the chain 56 around the circumference of the drive sprocket 58 and the chassis assembly 52.

[0028] With reference to Fig. The track systems 12 associated with the final drive shaft 46 are each coupled to the differential gear housing 48. The differential gear housing 48 is coupled to a frame of the tractor 10. The differential gear housing 48 receives input torque from the transmission 22 via the final drive shaft 46. The differential gear housing 48 includes a pair of final drive gear sets or planetary gear sets 100 and a track drive system 102. The planetary gear sets 100 are generally housed within a differential reservoir or housing 104 of the differential gear housing 48, and the track drive system 102 is also housed within the housing 104. The track drive system 102 is lubricated by a lubricating fluid supplied by a lubrication system 200, as further described below.

[0029] With reference to Fig. The planetary gear sets 100 generally receive the input torque from the track drive system 102. The planetary gear sets 100 increase the received torque and transmit the increased torque to the drive axle shaft 72. In this example, each of the planetary gear sets 100 includes three planet gears 106 driven by a sun gear 108 via a ring gear 110. The sun gear 108 is coupled to a sun drive shaft 112. Referring to Fig. a planet carrier 114 carries the planet gears 106 and is coupled to one end of the drive axle shaft 72.

[0030] As in Fig. As shown, a rotational axis R of the drive axle shaft 72 is coaxial with a central axis C of the drive wheel 58 and offset from a rotational axis R2 of the final drive shaft 46. The track drive system 102 receives the input torque from the final drive shaft 46 and increases the input torque to a rotational axis R3 that is generally transverse to and substantially intersects the rotational axis R of the drive axle shaft 72. The track drive system 102 enables the drive axle shafts 72 to be driven at a height E that is greater than or above a height E1 of the final drive shaft 46 of the tractor 10 ( Fig. ). A distance D1 greater than zero is defined between height E and height E1. Thus, the rotational axis R of the drive axle shaft 72 is vertically offset from the rotational axis R2 of the axle drive shaft 46.

[0031] With reference to Fig. The track drive system 102 is shown in more detail. The track drive system 102 includes a gear housing 120, a first spur gear 122, a second spur gear 124, a bevel gear assembly 126, a ring gear 128, and a bevel gear set 130. The gear housing 120 is made of a metal or metal alloy and may be comprised of multiple parts that are cast, machined, stamped, etc., to define the gear housing 120. The gear housing 120 rotatably supports the first spur gear 122, the second spur gear 124, and the bevel gear 160. The gear housing 120 also supports a portion of the final drive shaft 46. The gear housing 120 includes the main housing 132 and a rear wall 134. The main housing 132 has a first side 136 and a second, opposite side 138, with a first chamber 140 and a second chamber 142 defined by the main housing 132 from the first side 136 to the second side 138.The back wall 134 is coupled to the second side 138 via one or more mechanical fasteners to enclose the gear housing 120.

[0032] With reference to Fig. On the first side 136, the first chamber 140 houses the final drive shaft 46, which is rotatably supported by one or more bearings in the first chamber 140. On the second side 138, the first chamber 140 houses the first spur gear 122. The second chamber 142 is vertically spaced from the first chamber 140. On the first side 136, the second chamber 142 houses the bevel gear assembly 126, which is rotatably supported by one or more bearings in the second chamber 142. On the second side 138, the second chamber 142 houses the second spur gear 124, which is rotatably coupled to the first spur gear 122. As described below, the gear housing 120 also cooperates with the lubrication system 200 associated with the track drive system 102.

[0033] With reference to Fig. The first spur gear 122 includes a central bore 144. A spline may be defined on an inner side of the bore 144 for coupling to a spline 46a of the final drive shaft 46 on the first spur gear 122. A nut threadingly engaging a portion of the final drive shaft 46 proximate the spline 46a may be used to further couple the final drive shaft 46 to the first spur gear 122. The first spur gear 122 is coupled to the final drive shaft 46 such that the first spur gear 122 rotates with or is driven by the final drive shaft 46. The first spur gear 122 is made of a metal or metal alloy and is stamped, machined, cast, etc. The first spur gear 122 has a diameter D2 that is different from the diameter D3 of the second spur gear 124. In this example, the diameter D2 is larger than the diameter D3.The first spur gear 122 defines a plurality of tooth sets 148 around a circumference or outer circumference of the first spur gear 122. The plurality of tooth sets 148 mesh with a plurality of tooth sets 150 of the second spur gear 124.

[0034] The second spur gear 124 defines the plurality of gear teeth 150 around a circumference or outer periphery of the second spur gear 124. The plurality of gear teeth 150 mesh with a plurality of gear teeth 148 such that the first spur gear 122 drives the second spur gear 124. The second spur gear 124 defines a central bore 152. A spline may be defined on an inner side of the bore 152 for coupling to a spline tooth 154 of the bevel gear assembly 126. A bolt with washer 156 may be received in the bore 152 to couple the bevel gear assembly 126 to the second spur gear 124. The second spur gear 124 is made of a metal or metal alloy and is stamped, machined, cast, etc. The second spur gear 124 is coupled to the bevel gear assembly 126 to drive the bevel gear assembly 126.

[0035] The bevel gear assembly 126 includes a pinion shaft 158 and a bevel gear 160. The pinion shaft 158 and the bevel gear 160 are each made of a metal or metal alloy and are each stamped, machined, cast, etc. The pinion shaft 158 can be discretely formed from the bevel gear 160 and coupled together via a suitable post-machining step, or it can be formed as a single piece. The pinion shaft 158 includes the spline 154. The pinion shaft 158 is received in the second chamber 142 and rotatably supported in the second chamber 142 in one or more bearings. One end of the pinion shaft 158 opposite the spline 154 is coupled to the bevel gear 160.

[0036] The bevel gear 160 extends generally across the second chamber 142 of the gear housing 120 ( Fig. ). The bevel gear 160 defines a plurality of bevel gear teeth 162 around a circumference or outer periphery of the bevel gear 160. The bevel gear teeth 162 mesh with a plurality of bevel gear teeth 164 defined on the ring gear 128. The bevel gear teeth 162, 164 are generally spiral bevel gear teeth, but the bevel gear teeth 162, 164 may comprise hypoid bevel gear teeth. The bevel gear 160 drives the ring gear 128.

[0037] The ring gear 128 includes a first surface 166 opposite a second surface 168 and a central bore 170. The ring gear 128 is made of a metal or metal alloy and is stamped, machined, cast, etc. The plurality of bevel gear teeth 164 are defined on the first surface 166. The plurality of bevel gear teeth 164 are defined about the first surface 166 such that the plurality of bevel gear teeth 164 surround or define the bore 170. The second surface 168 is substantially planar and coupled to the bevel gear set 130. A portion of the bevel gear set 130 is also received by the bore 170. Rotation of the ring gear 128 drives the bevel gear set 130, which transmits torque to the sun drive shafts 112 of the planetary gear sets 100.

[0038] The bevel gear set 130 includes a second set of three planetary gears 174, a differential side gear 176, and a carrier housing 178. A plurality of teeth may be defined around the second surface 168 of the ring gear 128, which teeth may be observed by a sensor, such as a speed sensor. Referring to Fig. The second set of three planetary gears 174 is coupled to the carrier housing 178. The movement of the carrier housing 178 drives the second set of planetary gears 174. The second set of planetary gears 174 each meshes with the differential side gear 176. The differential side gear 176 is coupled to each of the sun drive shafts 112. The movement of the second planetary gears 174 drives the differential side gear 176, which in turn drives each of the sun drive shafts 112.

[0039] The lubrication system 200 provides oil or other lubricating fluid for the track drive system 102. In this example, the lubrication system 200 receives the oil from one or more pumps 26 associated with the tractor 10 via one or more lines ( Fig. . The lubrication system 200 cooperates with the gear housing 120 to lubricate the first spur gear 122, the second spur gear 124, the bevel gear assembly 126, and the final drive shaft 46. Referring to Fig. The lubrication system 200 includes a clean oil reservoir 202, a spring lubrication tube or first oil line 204, and a spiral cone lubrication tube or second oil line 206.

[0040] The clean oil tank 202 receives the oil from the pumps 26 and / or control valves 28 of the tractor 10 via one or more lines ( Fig. . The clean oil reservoir 202 is continuously filled during operation of the tractor 10, and once the clean oil reservoir 202 is filled with oil, the clean oil escapes from the clean oil reservoir 202 through the first oil line 204. The clean oil reservoir 202 is isolated from the rest of the differential gear housing 48 by one or more sealing elements, such as O-rings 202a, 202b.

[0041] The first oil line 204 is tubular and carries the clean oil from the clean oil reservoir 202 to the gear housing 120. The first oil line 204 includes an inlet 204a in fluid communication with the clean oil reservoir 202 and an outlet 204b. The outlet 204b is disposed substantially above the gear housing 120 in the differential gear housing 48. The clean oil escapes from the first oil line 204 via the outlet 204b and enters the gear housing 120 via a lubrication hole 208 defined in the gear housing 120. The lubrication hole 208 is in fluid communication with the second chamber 142 and is also in fluid communication with the first chamber 140. The clean oil taken into the gear housing 120 via the lubrication hole 208 fills the gear housing 120 with the clean oil until the oil level in the gear housing 120 reaches a predetermined value.The back wall 134 retains the oil in the gear housing 120, and a seal 210 coupled to the first chamber 140 retains the oil in the first chamber 140 to allow the gear housing 120 to fill with oil.

[0042] When the oil in the gear housing 120 reaches the predetermined level, the oil leaves the gear housing 120 at points A and B near the bevel gear assembly 126. The air pressure in the gear housing 120 also exits via a hollow chamber 212 defined within the final drive shaft 46 and the lower drive shaft 49. The air flows through the final drive shaft 46 and the lower drive shaft 49 and returns to the transmission 22 ( Fig. to equalize the air pressure with the atmosphere.

[0043] The second oil line 206 is in fluid communication with the pumps 26 and / or control valves 28 of the tractor 10 via one or more lines for receiving oil or other lubricating fluid. In this example, the second oil line 206 is distinct from the clean oil reservoir 202 and the first oil line 204. The second oil line 206 receives clean oil at an inlet 206a. The second oil line 206 is tubular and directs the clean oil along the first side 136 of the gear housing 120. Downstream of the inlet 206a and along the first side 136 of the gear housing 120 adjacent or proximate the second chamber 142, the second oil line 206 defines an outlet portion 214. The outlet portion 214 is substantially U-shaped to enclose at least a portion of the bevel gear 160.The outlet portion 214 includes a plurality of bores 216 spaced along the second oil passage 206 and aligned to direct oil to a surface 160a of the bevel gear 160, to the bevel gear teeth 162 of the bevel gear 160, and to the bevel gear teeth 164 of the ring gear 128. In other words, the second oil passage 206 defines the plurality of bores 216 through the second oil passage 206 to supply oil to the bevel gear assembly 126. In one example, the outlet portion 214 includes about four holes having a diameter of about 1.5 millimeters (mm) to about 2.0 millimeters (mm).

[0044] With reference to Fig. the track drive system 102 can be mounted for mounting the differential gear housing 48 and coupled to the differential gear housing 48. With reference to Fig. In one example, with the bevel gear 160 coupled to the pinion shaft 158, the pinion shaft 158 is inserted through the second chamber 142 and coupled to the second spur gear 124. The first spur gear 122 is coupled to the first chamber 140, and the back wall 134 is coupled to the gear housing 120 to retain the first spur gear 122, the second spur gear 124, and the oil or lubricating fluid within the gear housing 120. The ring gear 128 is coupled to the assembled bevel gear set 130, and the ring gear 128 is positioned so that the bevel gear teeth 162, 164 mesh.

[0045] With reference to Fig. With the track drive system 102 assembled, the track drive system 102 is disposed within the differential gear housing 48. The final drive shaft 46 is inserted into the differential gear housing 48 and coupled to the first spur gear 122. With the clean oil reservoir 202 defined in the differential gear housing 48, the O-rings 202a, 202b can be coupled to the differential gear housing 48 to seal the clean oil reservoir 202 from the environment. The first oil line 204 can be coupled to the differential gear housing 48 such that the outlet 204b is aligned with the lubrication hole 208 of the gear housing 120. The second oil line 206 can be coupled to the differential gear housing 48 and positioned such that the outlet portion 214 surrounds a portion of the surface 160a of the bevel gear 160.

[0046] With reference to Fig. When the planetary gear sets 100 are assembled, the sun drive shafts 112 are each coupled to the differential side gear 176 of the bevel gear set 130. The drive axle shafts 72 are coupled to a respective one of the planet carriers 114 of the planetary gear sets 100, and the axle housing 60 is coupled to the planetary gear sets 100 about the drive axle shafts 72. With reference to Fig. a respective one of the saddle assemblies 54 is coupled to a respective one of the axle housings 60, and a respective one of the drive wheels 58 is coupled to a respective one of the axle flanges 70. With reference to Fig. a respective one of the chassis assemblies 52 is coupled to a respective one of the saddle assemblies 54 and a respective one of the chains 56 is arranged around a respective one of the drive wheels 58.

[0047] With reference to Fig. When the tractor 10 is in motion, torque is transmitted from the final drive shaft 46 to the track drive system 102. The torque of the final drive shaft 46 drives the first spur gear 122, which in turn drives the second spur gear 124. The second spur gear 124 drives the bevel gear assembly 126, and the bevel gear 160 drives the ring gear 128. The ring gear 128 drives the bevel gear set 130. Referring to Fig. The bevel gear set 130 drives the planetary gear sets 100, which in turn drive the drive axle shafts 72 and thus the drive wheels 58. The rotational axis R of the drive axle shafts 72 is coaxial with the center axis C of the drive wheels 58, which are spaced a distance D1 from the rotational axis R2 of the axle drive shaft 46. Thus, the track drive system 102 enables the drive axle shafts 72 and the drive wheels 58 to be driven at a height E that is greater than the height E1 of the axle drive shaft 46.

[0048] In addition, the pumps 26 and / or control valves 28 supply during operation of the tractor 10, with reference to Fig. , the clean oil reservoir 202 with clean oil. After filling, the clean oil escapes from the clean oil reservoir 202 and flows through the first oil line 204 into the gear housing 120 via the lubrication hole 208. The oil fills the gear housing 120 until the predetermined level is reached and exits through point A and / or point B. The second oil line 206 additionally supplies the surface 160a of the bevel gear 160 with oil via the holes 216.

Claims

[1] Tracked work vehicle, comprising: an axle drive shaft (46) defining an axis of rotation (R2); a differential gear housing (48) with at least one planetary gear set (100); a chain drive system (12) at least partially contained within the differential gear housing (48) and comprising: a first gear (122) coupled to the axle drive shaft (46); a second gear (124) coupled to the first gear (122); a bevel gear assembly (126) coupled to the second gear (124); a bevel gear set (130) coupled to the at least one planetary gear set (100); a ring gear (128) coupled to the bevel gear set (130) and to the bevel gear assembly (126); a gear housing (120), wherein the first gear (122) and the second gear (124) are each rotatably supported by the gear housing (120), at least one drive axle shaft (72) coupled to at least one planetary gear set (100); and a drive wheel (58) for driving a chain (56) with continuous ground contact, wherein the at least one drive axle shaft (72) has an axis of rotation (R), wherein the axis of rotation (R) of the drive axle shaft (72) is coaxial with a central axis (C) of the drive wheel (58) and vertically offset from the axis of rotation (R2) of the axle drive shaft (46). [2] A tracked work vehicle according to claim 1, wherein the bevel gear assembly (126) includes a shaft (158) and a bevel gear (160), and the shaft (158) is coupled to the second gear (124); wherein the bevel gear (160) is coupled to the ring gear (128) and the ring gear (128) is coupled to the bevel gear set (130) to drive the bevel gear set (130) and the at least one planetary gear set (100). [3] A tracked work vehicle according to claim 1 or 2, wherein the bevel gear assembly (126) defines an axis of rotation (R3) and wherein the axis of rotation (R) of the drive axle shaft (72) intersects the axis of rotation (R3) of the bevel gear assembly (126). [4] A tracked work vehicle according to claim 1, wherein the gear housing (120) comprises a first side and a second side, with a first chamber (140) and a second chamber (142) each defined from the first side to the second side, and the first gear (122) and the second gear (124) are coupled to the second side. [5] The crawler work vehicle according to claim 4, wherein the first gear (122) is coupled to the first chamber (140) and the axle drive shaft (46) is received in the first chamber (140) on the first side to couple the axle drive shaft (46) to the first gear (122). [6] A tracked work vehicle according to claim 4 or 5, wherein the second gear (124) is coupled to the second chamber (142) and the bevel gear assembly (126) is received in the second chamber (142) on the first side to couple the bevel gear assembly (126) to the second gear (124). [7] A tracked work vehicle according to any one of the preceding claims, further comprising a lubrication system (200), wherein the track drive system (12) includes the gear housing (120), and the lubrication system (200) includes a first line (204) supplying lubricating fluid to the gear housing (120) and a second line (206) supplying lubricating fluid to the bevel gear assembly (126). [8] A tracked work vehicle according to claim 7, wherein the second conduit (206) includes an outlet portion (214) defining a plurality of holes that supply lubricating fluid to the bevel gear assembly (126). [9] A tracked work vehicle according to any one of the preceding claims, further comprising at least one axle housing (60) coupled to at least one saddle assembly (54) that guides the track (56).

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