DOUBLE DRIVE CRACKER TRACK SYSTEM

Abstract

Crawler track undercarriage (320; 502), comprising: a drive shaft (522) which provides torque to the crawler track undercarriage (320; 502) which is generated by a drive motor (318), wherein the drive shaft (522) is coupled to the drive motor (318) via a gearbox (322); a first drive wheel (304) having a first diameter; a second drive wheel (306) having a second diameter, wherein the first diameter of the first drive wheel (304) is larger than the second diameter of the second drive wheel (306); and a gear assembly (402) which rotatably couples both the first drive wheel (304) and the second drive wheel (306) to the drive shaft (522), characterized in that the crawler track undercarriage (320; 502) further comprises: an intermediate wheel (314) which is rotatably coupled to a chassis frame (316); and a crawler track (310) positioned to at least partially touch the first drive wheel (304), the second drive wheel (306) and the intermediate wheel (314) in order to move around the chassis frame (316) to selectively move a working machine (300) along the ground.

Description

Territory of Revelation

[0001] The present disclosure relates to a crawler track chassis that implements multiple drive wheels to move a crawler track. BACKGROUND

[0002] Many construction machines use crawler tracks to propel themselves across a surface. Often, a drive engine, such as a gas or diesel engine, burns fuel to generate torque, which is transmitted to each track via a drive wheel. The drive wheel engages with a track, rotating around rollers of the track to engage with the ground and move the machine along it. The drive wheel typically engages either by using a toothed drive wheel that meshes with teeth on the track or by friction against an inner surface of the track.

[0003] The drive sprocket is often sized to ensure sufficient contact with the track to prevent slippage. With a toothed drive sprocket, slippage can occur if the belt teeth skip or are otherwise positioned outside the corresponding toothed recess of the drive sprocket. Similarly, with a friction drive sprocket, slippage can occur if the drive sprocket rotates at a different speed than the adjacent belt. In both cases, slippage between the drive sprocket and the track results in inefficient power transmission from the drive motor to the track, leading, among other things, to unpredictable machine control.From the generic DE 102 24 658 A1, a tracked vehicle with smooth drive and deflection wheels is known, which transmit the tractive force to tracks and in particular to rubber tracks by frictional engagement and which are mounted by means of a frame which carries at least one drive motor.

[0004] The object of the invention is to reduce the occurrence of slippage between the drive wheel and the crawler track. SUMMARY

[0005] A tracked chassis according to the invention, comprising a drive shaft that provides torque to the tracked chassis, which is generated by a drive motor, wherein the drive shaft is coupled to the drive motor via a gearbox; a first drive wheel having a first diameter; a second drive wheel having a second diameter, wherein the first diameter of the first drive wheel is larger than the second diameter of the second drive wheel; an intermediate wheel rotatably coupled to a chassis frame; a track chain positioned to at least partially contact the first drive wheel, the second drive wheel and the intermediate wheel in order to move around the chassis frame to selectively move a drive machine along the ground; and a gearbox assembly rotatably coupled both the first drive wheel and the second drive wheel to the drive shaft.

[0006] In one example of this embodiment, one of the first and second drive wheels is a gear drive wheel that engages with the teeth of a crawler track. In another aspect of this example, the other of the first and second drive wheels is a friction drive wheel that transmits torque to the crawler track by frictionally engaging with it.

[0007] In another example of this embodiment, both the first and second drive wheels are gear drive wheels that engage with the teeth of a caterpillar track.

[0008] In another example, both the first and second drive wheels are friction drive wheels that transfer torque to a crawler track by engaging with the crawler track in a frictional manner.

[0009] In another example, the gear assembly comprises a drive shaft gear, a first drive gear, and a second drive gear. The drive shaft gear, the first drive gear, and the second drive gear are rotaryally coupled to each other. In one aspect of this example, the gear assembly includes a first intermediate gear that meshes with both the drive shaft gear and the first drive gear, and a second intermediate gear that meshes with both the drive shaft gear and the second drive gear.

[0010] The first drive gear has the first diameter, and the second drive gear has the second diameter, where the first diameter is larger than the second diameter. In one aspect of this example, the gear assembly rotates the first drive gear with a first drive ratio relative to the rotational speed of the drive shaft, and the gear assembly rotates the second drive gear with a second drive ratio relative to the rotational speed of the drive shaft, where the first drive ratio differs from the second drive ratio.

[0011] One embodiment is a working machine with at least one crawler track undercarriage, wherein the working machine has a drive motor which is rotaryally coupled to the at least one crawler track undercarriage via a gearbox, a drive shaft which provides torque from the gearbox to the crawler track undercarriage, a first drive wheel, a second drive wheel and a gearbox assembly which rotaryly couples both the first drive wheel and the second drive wheel to the drive shaft.

[0012] In one example of this embodiment, the gear assembly further comprises a primary planetary gear set with a primary sun gear, a primary planetary gear set, and a primary ring gear. In one aspect of this example, the drive shaft is rotaryally coupled to the primary planetary gear set. In another aspect of this example, the first drive gear is rotaryally coupled to the primary planetary gear set via the primary ring gear, and the second drive gear is rotaryally coupled to the primary planetary gear set via the primary sun gear.

[0013] In another example, a first drive-gear planetary gear is positioned between the primary planetary gear and the first drive gear. One aspect of this example involves a second drive-gear planetary gear positioned between the primary planetary gear and the second drive gear. Another aspect of this includes at least one reduction assembly located between the primary planetary gear and either the first or second drive-gear planetary gear.

[0014] Another embodiment of this disclosure is a method for transmitting torque to a track of a tracked undercarriage, comprising providing a drive machine rotatably coupled to the tracked undercarriage via a gearbox, a drive shaft providing torque from the gearbox to the tracked undercarriage, a first drive wheel, a second drive wheel and a gearbox assembly rotatably coupled both the first drive wheel and the second drive wheel to the drive shaft with the gearbox assembly.

[0015] An example of this embodiment involves positioning at least one planetary gear between the drive shaft and the first or second drive wheel.

[0016] Another example of this embodiment involves coupling a drive shaft gear to the drive shaft and rotary coupling the first and second drive gears to the drive shaft gear. An aspect of this example involves providing at least one intermediate gear between the drive shaft and at least one of the first and second drive gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above-mentioned aspects of the present disclosure and the manner in which they are obtained become clearer, and the disclosure itself is better understood by reference to the following description of the embodiments of the disclosure in conjunction with the accompanying drawings, wherein: Fig. 1 is an embodiment of a crawler tracked work machine according to the prior art; Fig. 2 is a further embodiment of a crawler tracked work machine according to the prior art; Fig. 3 is an embodiment of a tracked work machine according to the invention; Fig. 4 A schematic view of a crawler track undercarriage of the work machine of Fig. 3 is; and Fig. Figure 5 is a schematic view of a crawler track chassis with a suspension according to the invention.

[0018] In the different views, identical parts are designated by the same reference numbers. DETAILED DESCRIPTION

[0019] For a better understanding of the principles of the present disclosure, reference is now made to the embodiments described herein and illustrated in the drawings.

[0020] In Fig. Figure 1 is a non-exclusive example of a tracked vehicle 100, depicted as a fully tracked agricultural tractor with a tractor frame 102, which includes a drive motor and a transmission for driving one or more tracked undercarriages. The chassis 104 can be coupled to the frame 102. Furthermore, the chassis 104 comprises a main drive wheel 106, driven by the transmission, and an intermediate wheel 108. A positively driven belt chain 110 surrounds part of the main drive wheel 106 and the intermediate wheel 108. Track rollers 112 are rotatably mounted on a track roller frame 114, which is pivotally coupled to the chassis 104.

[0021] In the embodiment of Fig. 1 The main drive wheel 106 engages frictionally with an inner surface of the crawler track 110 to move the crawler track 110 around the chassis 104. In one aspect of this disclosure, the crawler track vehicle 100 is defined by Fig. 1. A friction contact section 116 exists between the main drive wheel 106 and the crawler track 110. The friction contact section 116 can be the section of the main drive wheel that contacts the inner surface of the crawler track 110 as it moves along it. It is understood that the length of the friction contact section 116 increases with the diameter of the main drive wheel 106.

[0022] The 100-tracked vehicle from Fig. 1 can rely on the frictional engagement between the main drive wheel 106 and the track 110 along the friction contact section 116 to move the track 110 around the chassis 104 and thereby move the tracked vehicle 100. If the friction contact section 116 is too small, the main drive wheel 106 can slip relative to the track 110 when the track 110 resists rotation around the chassis (for example, when the tracked vehicle 100 is towing a heavy implement). Accordingly, the use of a single drive wheel 106 engaging frictionally with the track 110 often requires a large-diameter drive wheel 106 to maximize the friction contact section 116 and thereby reduce slippage between the drive wheel 106 and the track 110.

[0023] Referring now to Fig. Figure 2 shows another embodiment of a tracked vehicle 200. Fig. Figure 2 is another non-exclusive example of a tracked vehicle 200, depicted as a fully tracked agricultural tractor, which has a tractor frame 202 that holds a drive motor and a transmission for driving one or more tracked running gears. The chassis 204 can be coupled to the frame 202. Furthermore, the chassis 204 includes a main drive wheel 206, which is driven by the transmission, and a first and a second intermediate wheel 208, 209. A positively driven track 210 surrounds part of the main drive wheel 206 and the running wheels 208, 209. Track rollers 212 are rotatably mounted on a track roller frame 214, which is coupled to the chassis 204.

[0024] In the embodiment of Fig. In Figure 2, the main drive wheel 206 is dimensioned to accommodate teeth 218 defined along an inner surface of the crawler track chassis to move the crawler track 210 around the chassis 204. The toothed drive wheel 206 may have cavities or the like defined radially around it to accommodate the teeth 218 of the crawler track 210, thereby moving the crawler track 210 around the chassis 204 without the crawler track 210 slipping relative to the drive wheel 206. The toothed drive wheel 206 utilizes the teeth 218 in the crawler track 210 to reduce slippage. In this embodiment, the toothed drive wheel 206 may have a smaller diameter than the main drive wheel 106 from the embodiment of Figure 2. Fig. 1, since the toothed drive wheel 206 does not require a significant friction contact section 116 to avoid slippage relative to the crawler chain 210.

[0025] The 200-series tracked vehicle from Fig. 2 can rely on the teeth 218 of the track 210 to transmit the rotation of the toothed drive wheel 206 to move the track 110 around the chassis 204 and thereby move the tracked vehicle 200. The track 210 can be positioned adjacent to the outer section of the main drive wheel 206 along a toothed contact section 216 of the drive wheel 206. The toothed relationship of the drive wheel 206 and the track 210 can allow the toothed contact section 216 to be smaller than the friction contact section 116 of the drive wheel 206. Fig. 1, while the crawler track undercarriage of Fig. 2 under similar conditions as in Fig. 2 can move forward without jumping. In other words, the crawler track undercarriage requires Fig. 2 a larger friction contact section 116 than the toothed contact section 216, since the friction drive interface may be more prone to slippage than the toothed drive interface.

[0026] While the toothed drive wheel 206 can enable a smaller diameter drive wheel to drive the crawler track 210 compared to the friction drive wheel 106, the toothed drive wheel 206 can still slip relative to the crawler track 210 under strong resistance from the track 210. In particular, if the crawler track 210 resists movement around the chassis 204, the teeth of the crawler track 218 can jump out of the intended corresponding cavity of the toothed drive wheel 206 or be positioned otherwise. Accordingly, while the toothed drive wheel 206 may have a smaller diameter than the drive wheel 106, which relies on the friction contact section 116 to move the crawler chain 110, the toothed drive wheel 206 must still be large enough to minimize cases in which the teeth 218 pop out of the corresponding cavities of the toothed drive wheel 206.Accordingly, the use of a toothed drive wheel 206 engaging with the teeth 218 of the crawler chain 210 requires a sufficiently dimensioned toothed contact section 216 to minimize the conditions under which the teeth 218 skip the cavities of the corresponding toothed drive wheel 206.

[0027] In both embodiments of the Fig. 1 and Fig. 2. The individual drive wheel 106, 206 must be adequately dimensioned to prevent slippage or skipping of the crawler track 110, 210 with respect to the drive wheel 106, 206. If the crawler track 110, 210 slips or skips, the operator may lose foreseeable control over the crawler vehicle 100, 200. Accordingly, the embodiments of Fig. 1 and Fig. 2 have a sufficiently large drive wheel 106, 206 to ensure that the occurrence of slippage and skipping is minimized.

[0028] Referring now to Fig. 3 and Fig. Figure 4 shows an embodiment of a working machine 300 according to the invention. The working machine 300 can have a drive motor 318, such as a gas, diesel, or electric motor, which is selectively coupled via a transmission 322 to at least one crawler track undercarriage 320 to enable the working machine 300 to move along a surface. In this embodiment, a transmission assembly 402 rotaryally couples a first drive wheel 304 and a second drive wheel 306 to a drive shaft gear 408 (see Figure 4). Fig. 4) The working machine 300 can have crawler track rollers 312 and an intermediate wheel 314 which is rotatably coupled to a chassis frame 316, similar to the embodiments of Fig. 1 and Fig. 2. A belt or track 310 can be positioned to at least partially touch the drive wheels 304, 306, the rollers 312 and the intermediate wheel 314 in order to move around the chassis frame 316 to selectively move a working machine 300 along the ground.

[0029] While in Fig. While Figure 3 shows a single intermediate wheel 314 and four rollers 312, this disclosure considers the use of any number of wheels 314 and rollers 312. Accordingly, other embodiments considered herein have more than one intermediate wheel and fewer than four rollers 312. Furthermore, some embodiments may have more than four rollers 312.

[0030] The drive shaft gear 408 can be rotaryally coupled to the drive motor 318 via the gearbox 322. Furthermore, the drive shaft gear 308 can supply torque generated by the drive motor 318 to both the first drive wheel 304 and the second drive wheel 306 via the gearbox assembly 402. In this configuration, the torque distributed to both the first and second drive wheels 304 and 306 can be transmitted to the belt or track 310 using any known track engagement method. Regardless of the track engagement method, driving both the first and second drive wheels 304 and 306 can reduce the occurrence of slippage or skipping of the belt 310 compared to similarly sized track assemblies that drive only one drive wheel.

[0031] In a non-exclusive embodiment, the first drive wheel 304 is a toothed drive wheel having cavities similar to the teeth on the crawler track 310, similar to the main drive wheel 206 of Fig. 2. In this embodiment, the second drive wheel 306 can be a friction drive wheel similar to the main drive wheel 106 of Fig. 1. Accordingly, in this embodiment, the first drive wheel 304 can apply the torque generated by the drive motor to the crawler chain 310 via a toothed interface, while the second drive wheel 306 can apply the torque generated by the drive motor to the crawler chain 310 via a friction interface.

[0032] In other embodiments, both the first and second drive wheels 304, 306 can have a toothed interface and engage with corresponding teeth on the crawler track 310. Alternatively, in other embodiments, both the first and second drive wheels 304, 306 can have a friction interface that engages with the crawler track 310 without the use of teeth. Furthermore, in another embodiment of this disclosure, the first drive wheel 304 has a friction interface, while the second drive wheel 306 has a toothed interface with the crawler track 310. Accordingly, this disclosure considers the use of any known drive wheel / crawler track interface in any combination with the first and second drive wheels 304, 306.

[0033] The gear assembly 402 can rotaryly couple the drive shaft gear 408 to a first drive gear 410, which is coupled to the first drive gear 304, and to a second drive gear 412, which is coupled to the second drive gear 306. In this configuration, when torque is supplied to the drive shaft gear 408 by the drive motor 318, the torque is transmitted via the gear assembly 402 to both the first and second drive gears 410 and 412.

[0034] In an example of the embodiment of Fig. 4. The gear assembly 402 can have a first intermediate gear 414 positioned between the drive shaft gear 408 and the first drive gear 410. Similarly, a second intermediate gear 416 can be positioned between the drive shaft gear 408 and the second drive gear 412. In this configuration, the drive shaft gear 408 transmits torque via the respective first and second intermediate gears 414 and 416 to the first and second drive gears 304 and 306.

[0035] In one aspect of this disclosure, the gear assembly 402 is configured to ensure that both the first and second drive wheels 304, 306 rotate at a suitable rate relative to each other to ensure that the belt 310 is reversed around the crawler track 320 at the same speed. In other words, if the outside diameters of the first and second drive wheels 304, 306 are not the same, the gear assembly 402 can have a gear ratio that ensures that the portion of the drive wheels 304, 306 that contacts the crawler track 310 has substantially the same speed at the point of contact with the crawler track 310. In a non-exclusive example, the second drive wheel 306 can have an outside diameter that is smaller than the outside diameter of the first drive wheel 304.In this configuration, the gear assembly 402 would be configured to rotate the second drive wheel 306 at a faster angular velocity than the first drive wheel 304, in order to accommodate the different outside diameters of the drive wheels 304, 306.

[0036] Experts understand that the specific transmission ratios of the gear assembly 402 can be modified to accommodate drive wheels 304, 306 with different outer diameters. In particular, the specific transmission ratios of the gear assembly 402 can be such that the crawler track 310 is guided uniformly by both drive wheels 304, 306. Accordingly, one embodiment may have a first drive wheel with a diameter smaller than that of the second drive wheel 306. In yet another embodiment, the diameters of the first and second drive wheels can be essentially the same. In yet another embodiment, the second drive wheel 306 may have a diameter smaller than that of the first drive wheel 304.Accordingly, this disclosure includes the implementation of a gear assembly 402 to accommodate any combination of drive wheel diameters 304, 306.

[0037] Furthermore, the transmission ratio of the gear assembly 402 can be modified by changing any one or more of the first and second drive gears 410, 412. Accordingly, the size of any of the gears 408, 410, 412, 414, 416 of the gear assembly 402 can be changed to ensure that the crawler track undercarriage 320 functions properly and that the crawler track 310 is moved along it at the same rate through both drive gears 304, 306.

[0038] Referring now to Fig. Figure 5 shows a further embodiment of the present disclosure. Fig. Figure 5 illustrates a schematic view of a gear assembly 500 of another drive configuration for a crawler track undercarriage 502. The drive configuration can include a first and a second drive wheel 504, 506 similar to the embodiment of Fig. 3 and Fig. 4 exhibit. In the embodiment of Fig. A suspension assembly 508 can couple the crawler track undercarriage 502 to a frame section 510 of the crawler vehicle. Both the first and second drive wheels 504, 506 can be driven simultaneously by corresponding first and second cardan shafts 512, 514. The cardan shafts 512, 514 enable the crawler track to move relative to the frame section 510, while the torque generated by the drive motor is transmitted to the drive wheels 504, 506. In a non-exclusive example, each end of the cardan shafts 512, 514 can have a universal joint or the like to allow at least some movement between the crawler track undercarriage 502 and the frame section 510.

[0039] In the embodiment of Fig. The transmission assembly can include a primary planetary gear 516, a first drive wheel planetary gear 518, and a second drive wheel planetary gear 520. Each of the gear sets 516, 518, 520 can ultimately be rotaryally coupled to a drive shaft 522 of the transmission to distribute torque to the corresponding drive wheels 504, 506. The drive wheels 504, 506 can then engage with a crawler track via a toothed, friction-fit, or similar engagement to move the crawler track around the crawler track undercarriage, as described above. Fig. 4 described.

[0040] The primary planetary gear set 516 can include a primary planetary gear set 524 coupled to the drive shaft 522. The primary planetary gear set 516 can also include a primary ring gear 526 rotary-coupled to the first cardan shaft 512. In a non-exclusive example, the first cardan shaft 512 can include a first cardan shaft gear 528 rotary-coupled to the primary ring gear 526 to transmit torsional loads applied through the drive shaft 522 to the cardan shaft 512.

[0041] As discussed above, the first cardan shaft 512 can extend between the crawler track assembly 502 and the frame section 510, allowing the crawler track assembly 502 to move relative to the frame section 510 via the suspension assembly 508 while transmitting torque to the first drive wheel 504. The first cardan shaft 512 can also be coupled to the first drive wheel planetary gear 518. In particular, the first cardan shaft 512 can be rotaryally coupled to a first drive wheel sun gear 530. Finally, the first drive wheel 504 can ultimately be coupled to the first drive wheel planetary gear set 518 via a first drive wheel planetary gear 532. Accordingly, the first drive wheel 504 can have torque, which is transmitted to it from the drive motor via the primary planetary gear 516, the first cardan shaft 512 and the first drive wheel planetary gear 518.

[0042] The second cardan shaft 514 can be coupled to a primary sun gear 534 of the primary planetary gear set 516. In this configuration, when the drive shaft 522 provides torque to the primary planetary gear set 524 of the primary planetary gear set 516, the torque is distributed via the primary ring gear 526 to the first cardan shaft 512 and via the primary sun gear 534 to the second cardan shaft 514. A reduction assembly 536 can be coupled to the second cardan shaft 514 at the end of the crawler track assembly 502. The reduction assembly 536 can be one or more gears coupled together to provide an input to the second drive wheel planetary gear set 520 corresponding to any diameter differences between the first drive wheel 504 and the second drive wheel 506.In other words, the reduction assembly 536 can provide a reduction such that the second drive wheel planetary gear 520 receives an input that drives both the first and second drive wheels 504, 506, providing the same speed at which the drive wheels 504, 506 contact the crawler track.

[0043] The reduction assembly can provide an output to a second drive wheel sun gear 538 of the second drive wheel planetary gear set 520. The second drive wheel sun gear 538 can mesh with a second drive wheel planetary gear set 540. Furthermore, the second drive wheel planetary gear set 540 can be coupled to the second drive wheel 506 to rotate the second drive wheel 506.

[0044] In the embodiment of Fig. In the embodiment 5, the crawler track undercarriage 502 is coupled to the frame section 510 by the suspension assembly 508 to allow the crawler track undercarriage 502 to move relative to the frame section 510. Furthermore, the first and second cardan shafts 512, 514 are positioned to allow the crawler track undercarriage 502 to move relative to the frame section 510, while the primary planetary gear 516 is rotaryally coupled to both the first and second drive wheel planetary gears 518, 520. Accordingly, in one aspect of the embodiment of Fig. 5. Torque is provided by the drive motor to both drive wheels 504, 506 and the crawler chain can move relative to the frame section 510.

[0045] While certain examples of planetary gears and gear configurations are described herein, these are to be understood as only one example, and others are also considered. One aspect of this disclosure is the driving of both the first and second drive wheels 504, 506, while enabling the crawler track undercarriage 502 to move independently of the frame section 510. Accordingly, other gear configurations and the like are also considered herein.

Claims

[1] Crawler track system (320; 502), comprising: a drive shaft (522) which provides torque to the crawler track undercarriage (320; 502) which is generated by a drive motor (318), wherein the drive shaft (522) is coupled to the drive motor (318) via a gearbox (322); a first drive wheel (304) having a first diameter; a second drive wheel (306) having a second diameter, wherein the first diameter of the first drive wheel (304) is larger than the second diameter of the second drive wheel (306); and a gear assembly (402) which rotatably couples both the first drive wheel (304) and the second drive wheel (306) to the drive shaft (522), characterized by , that the crawler track undercarriage (320; 502) further includes: an intermediate wheel (314) which is rotatably coupled to a chassis frame (316); and a crawler track (310) positioned to at least partially touch the first drive wheel (304), the second drive wheel (306) and the intermediate wheel (314) in order to move around the chassis frame (316) to selectively move a working machine (300) along the ground. [2] Crawler track undercarriage (320; 502) according to claim 1, wherein one of the first and second drive wheels (304, 306) is a gear drive wheel that engages with the teeth (318) of a crawler track (310). [3] Crawler track undercarriage (320; 502) according to claim 2, wherein the other of the first and second drive wheels (306) is a friction drive wheel which transmits torque to the crawler chain (310) by frictionally engaging with the crawler chain (310). [4] Crawler track undercarriage (320; 502) according to one of claims 1 to 2, wherein both the first and the second drive wheel (306) are gear drive wheels that engage with the teeth (318) of a crawler track (310). [5] Crawler track undercarriage (320; 502) according to claim 1, wherein both the first and the second drive wheel (306) are friction drive wheels which transmit torque to the crawler track (310) by frictionally engaging with the crawler track (310). [6] Crawler track undercarriage (320; 502) according to one of claims 1 to 5, wherein the transmission assembly (402) further comprises: a drive shaft gear (408); a first drive gear (410); and a second drive gear (412); wherein the drive shaft gear (408), the first drive gear (410) and the second drive gear (412) are rotaryally coupled to each other. [7] Crawler track undercarriage (320; 502) according to claim 6, wherein the transmission assembly (402) further comprises: a first intermediate gear (414) which engages with both the drive shaft gear (408) and the first drive gear (410); and a second intermediate gear (416) which engages with both the drive shaft gear (408) and the second drive gear (412). [8] Crawler track undercarriage (320; 502) according to one of claims 1 to 7, wherein the gear assembly (402) further rotates the first drive wheel (304) with a first drive shaft ratio relative to the rotational speed of the drive shaft (522) and the gear assembly (402) rotates the second drive wheel (306) with a second drive shaft ratio relative to the rotational speed of the drive shaft (522), wherein the first drive shaft ratio differs from the second drive shaft ratio. [9] Crawler track undercarriage (320; 502) according to one of claims 1 to 8, wherein the gear assembly (402) further comprises a primary planetary gear (516) with a primary sun gear (534), a primary planet gear set (524) and a primary ring gear (526). [10] Crawler track undercarriage (320; 502) according to claim 9, wherein the drive shaft (522) is further rotatably coupled to the primary planetary gear set (524). [11] Crawler track undercarriage (320; 502) according to claim 10, wherein the first drive wheel (304) is further rotatably coupled to the primary planetary gear (516) via the primary ring gear (526) and the second drive wheel (306) is rotatably coupled to the primary planetary gear (516) via the primary sun gear (534). [12] Crawler track undercarriage (320; 502) according to one of claims 9 to 11, further comprising a first drive wheel planetary gear (518) positioned between the primary planetary gear (516) and the first drive wheel (304). [13] Crawler track undercarriage (320; 502) according to claim 12, further comprising a second drive wheel planetary gear (520) positioned between the primary planetary gear (516) and the second drive wheel (306).

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