Track assembly with a torque-limiting arm

Abstract

The present disclosure concerns a track assembly of a vehicle comprising a chassis, the track assembly comprising: a frame rotatably mountable to the chassis, track-contacting wheels including a track-engaging wheel rotatably mounted to the frame and a plurality of roller wheels, an endless track disposed around the track-contacting wheels, the track-engaging wheel engaging the endless track to drive the endless track, the roller wheels being disposed to roll on a bottom run of the endless track. The assembly further comprises a suspension assembly connecting a mid-roller to the frame, one of a braking system and a motor selectively couplable to the track-engaging wheel to brake or drive into rotation the track-engaging wheel and a torque-limiting arm comprising a first end portion connected to said one of a braking system and a motor and a second end portion rotatably connectable to the chassis.

Description

TRACK ASSEMBLY WITH A TORQUE-LIMITING ARMPRIOR APPLICATION

[0001] The present application claims priority from U.S. provisional patent application No. 63 / 611 ,805, filed on December 19, 2023, and entitled “TRACK ASSEMBLY WITH A TORQUE-LIMITING ARM”, the disclosure of which being hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The technical field relates to track assemblies for traction of vehicles, and more particularly to track assemblies for towed vehicles comprising a braking system.BACKGROUND

[0003] In some circumstances and / or to comply with local regulations, towed vehicles (such as for instance trailers) need to be equipped with a braking system. For vehicles equipped with one or more track assemblies, especially when the track assemblies comprise a suspension assembly, the braking system might jeopardize a stability of the towed vehicle, due to a transmission of braking loads to components of the track assembly. The actuation of the braking system can also reduce significantly a tension of a track of the track assembly. Similar drawbacks could occur when the vehicle is equipped with a motor, since its actuation might jeopardize the stability of the vehicle.

[0004] In view of the above, there is a need for a track assembly which would be able to limit an impact of the actuation of the braking system or the motor on the stability of the track assembly without reducing an ability of the suspension assembly to optimally distribute loads when traveling, for instance, off-road or over obstacles.BRIEF SUMMARY

[0005] It is therefore an aim of the present invention to at least partially address the above-mentioned issues.

[0006] According to a general aspect, there is provided a track assembly of a vehicle comprising a chassis, the track assembly comprising: a frame rotatably mountable to the chassis; a plurality of track-contacting wheels including: a track-engaging wheel rotatably mounted to the frame; and a plurality of mid-rollers; an endless track disposed around the track-contacting wheels, the track-engaging wheel engaging the endless track to drive the endless track, the mid-rollers being disposed to roll on a bottom run of the endless track; a suspension assembly connecting at least one midroller to the frame; one of a braking system and a motor selectively couplable to the track-engaging wheel to brake or drive into rotation the track-engaging wheel. The track assembly further comprises a torque-limiting arm comprising: a first end portion connected to said one of a braking system and a motor; and a second end portion rotatably connectable to the chassis.

[0007] According to another aspect, the first end portion is connected in the vicinity of an axle of the track-engaging wheel.

[0008] According to another aspect, the first end portion is vertically offset in an upward direction with respect to an axle of the track-engaging wheel.

[0009] According to another aspect, the first end portion is vertically aligned with the axle of the track-engaging wheel.

[0010] According to another aspect, the first end portion is pivotally mounted to said one of a braking system and a motor.

[0011] According to another aspect, said one of a braking system and a motor is pivotally mounted to the axle of the track-engaging wheel.

[0012] According to another aspect, the torque-limiting arm comprises a rod member extending along a longitudinal direction between the first and second end portions.

[0013] According to another aspect, the torque-limiting arm is at least partially made of steel.

[0014] According to another aspect, the track assembly comprises a bogie carrying at least one of the mid rollers and movable relative to the frame, wherein the suspension assembly connects the bogie to the frame.

[0015] According to another aspect, the suspension assembly comprises a suspension link comprising a frame-mounting portion rotatably mounted to the frame about a first rotation axis and a bogie-mounting portion rotatably mounted to the bogie about a second rotation axis, the bogie being mounted to the frame via the suspension link.

[0016] According to another aspect, the first and second rotation axes are substantially parallel to each other.

[0017] According to another aspect, the second end portion of the torque-limiting arm is connected to the suspension link.

[0018] According to another aspect, the second end portion of the torque-limiting arm is rotatably mounted to the suspension link, at or in the vicinity of the frame-mounting portion thereof.

[0019] According to another aspect, the second end portion of the torque-limiting arm is rotatably mounted to the frame.

[0020] According to another aspect, the frame comprises a chassis-mounting portion rotatably mountable to the chassis of the vehicle, wherein, considered in a substantially vertical plane comprising a longitudinal direction of the track assembly, a longitudinal direction of the torque-limiting arm intersects the chassis-mounting portion.

[0021] According to another aspect, the chassis comprises a frame-mounting axle, the second end portion of the torque-limiting arm being rotatably mounted to the framemounting axle.

[0022] According to another aspect, considered relative to a forward displacement direction of the vehicle, the track-engaging wheel is at a front portion of the track assembly.

[0023] According to another aspect, the suspension assembly is at a rear portion of the track assembly.

[0024] According to another general aspect, there is provided a towed vehicle comprising a track assembly as disclosed.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Fig. 1 is a side rear perspective view of a towed vehicle comprising a track assembly comprising an endless track and a plurality of track-contacting wheels;

[0026] Fig. 2 is a side view of a track assembly from the prior art, the endless track thereof being removed, the track assembly comprising a suspension assembly;

[0027] Fig. 3 is a rear perspective view of the track assembly of Fig. 2;

[0028] Figs. 4, 5 and 6 are side views of the track assembly of Fig. 2 schematically representing forces applying to components thereof;

[0029] Fig. 7 is a side view of a track assembly in accordance with an embodiment, the endless track thereof being removed, a first end portion of a torque-limiting arm being connected to a braking system and a second end portion of the torque-limiting arm thereof being connected to a suspension assembly;

[0030] Fig. 8 is a side view of a track assembly in accordance with another embodiment, the endless track thereof being removed, the second end portion of the torque-limiting arm thereof being connected to a frame-mounting axle of a chassis of a vehicle equipped with the track assembly;

[0031] Fig. 9 is a partial side view of a track assembly in accordance with another embodiment, a longitudinal direction of the torque-limiting arm intersecting a framemounting axle of the chassis;

[0032] Fig. 10 is a side view of a track assembly in accordance with another embodiment, the track assembly comprising at least two pairs of mid-rollers carried by two distinct bogies, the second end portion of the torque-limiting arm being rotatably connected to a chassis-mounting portion of a frame mountable to the chassis; and

[0033] Fig. 11 is a side view of a track assembly in accordance with another embodiment, the endless track thereof being removed, the first end portion of the torque-limiting arm being connected to a motor and the second end portion of the torque-limiting arm thereof being connected to the suspension assembly.DETAILED DESCRIPTION

[0034] In the following description, the same numerical references refer to similar elements. Furthermore, for the sake of simplicity and clarity, namely so as to not unduly burden the figures with several references numbers, not all figures contain references to all the components and features, and references to some components and features may be found in only one figure, and components and features of the present disclosure which are illustrated in other figures can be easily inferred therefrom. The embodiments, geometrical configurations, materials mentioned and / or dimensions shown in the figures are optional and are given for exemplification purposes only.

[0035] Moreover, it will be appreciated that positional descriptions such as "above", "below", "forward", "rearward", "left", "right" and the like should, unless otherwise indicated, be taken in the context of the figures only and should not be considered limiting. Moreover, the figures are meant to be illustrative of certain characteristics of the track assembly and of the vehicle equipped therewith and are not necessarily to scale.

[0036] To provide a more concise description, some of the quantitative expressions given herein may be qualified with the term "about". It is understood that whether the term "about" is used explicitly or not, every quantity given herein is meant to refer to an actual given value, and it is also meant to refer to the approximation to such given value that would reasonably be inferred based on the ordinary skill in the art, includingapproximations due to the experimental and / or measurement conditions for such given value.

[0037] In the following description, an embodiment is an example or implementation. The various appearances of "one embodiment", "an embodiment" or "some embodiments" do not necessarily all refer to the same embodiments. Although various features may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, it may also be implemented in a single embodiment. Reference in the specification to "some embodiments", "an embodiment", "one embodiment" or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments.

[0038] It is to be understood that the phraseology and terminology employed herein is not to be construed as limiting and are for descriptive purpose only. The principles and uses of the teachings of the present disclosure may be better understood with reference to the accompanying description, figures and examples. It is to be understood that the details set forth herein do not construe a limitation to an application of the disclosure.

[0039] Furthermore, it is to be understood that the disclosure can be carried out or practiced in various ways and that the disclosure can be implemented in embodiments other than the ones outlined in the description above. It is to be understood that the terms "including", "comprising", and grammatical variants thereof do not preclude the addition of one or more components, features, steps, or integers or groups thereof and that the terms are to be construed as specifying components, features, steps or integers. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element. It is to be understood that where the claims or specification refer to "a" or "an" element, such reference does not mean that there is only one of that element. It is to be understood that where the specification states that a component, feature, structure, or characteristic "may","might", "can" or "could" be included, that particular component, feature, structure, or characteristic is not required to be included.

[0040] The descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only. Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined. It will be appreciated that the methods described herein may be performed in the described order, or in any suitable order.

[0041] Referring now to the drawings, and more particularly to Fig. 1 , there is shown a towed vehicle 100 or a trailer comprising a plurality of track assemblies 10 (two, in the embodiment shown, arranged on opposed lateral sides of the vehicle 100). Certain off-road vehicles, such as agricultural vehicles (e.g., harvesters, combines, tractors, etc.), construction vehicles (e.g., loaders, bulldozers, excavators, etc.), forestry vehicles (e.g., feller-bunchers, tree chippers, loaders, etc.) and military vehicles (e.g., combat engineering vehicles (CEVs), etc.) to name a few, are used in agricultural fields, construction sites and other areas with a variety of ground surfaces which may be soft, slippery and / or uneven (e.g., soil, mud, sand, ice, snow, etc.) to perform various types of work. Some vehicles are provided with track assemblies instead of tire-equipped ground-engaging wheels to enhance floatation and traction of the vehicles on the ground.

[0042] In the embodiment shown, the towed vehicle 100 comprises a front tractormounting portion 102, a chassis 104 at a lower portion of which the track assemblies 10 are mounted and a trailer 106 mounted to the chassis 104, above and supported by the track assemblies 10. As detailed below, each of the track assemblies 100 comprises a frame 12, a plurality of track-contacting wheels 14, 16, 18 including a drive wheel 14 or track-engaging wheel 14 rotatably mounted to the frame 12 and a plurality of mid-rollers 16, and an endless track 20 disposed around the trackcontacting wheels 14, 16, 18, the drive wheel or track-engaging wheel 14 engaging the endless track to drive the endless track 20, the mid-rollers 16 being disposed to roll on a bottom run 22 of the endless track 20. In the embodiment shown, each track assembly 10 also comprises a trailing or rear wheel 18. The terms rear and frontshould be understood relative to a usual forward direction of displacement of the vehicle 100.

[0043] Even though the following description will refer to a towed vehicle, it should be understood that the track assembly of the present disclosure might equip any other type of vehicle.Track assembly with a suspension assembly

[0044] When a vehicle equipped with track assemblies as the one shown in Fig. 1 travels on a road (for instance on a crowned road) or on an agricultural field or another soft and / or uneven ground area, vibrations may occur and load on tracks of the track assemblies may not be evenly distributed. This may create discomfort to a user of the vehicle and sometimes lead to premature failure of components of the vehicle.

[0045] As best shown in Figs. 2 and 3 on which the endless track has not been represented for clarity purposes, to limit the above-mentioned drawbacks, the track assembly 10 might comprise a suspension assembly 30. In the embodiment of the prior art shown in Figs. 2 and 3, the track assembly 10 thus comprises a frame 12, a plurality of track-contacting wheels 14, 16, 18 including a drive wheel (or trackengaging wheel) 14 rotatably mounted to the frame 12 and a plurality of mid-rollers 16 and an endless track (not represented) disposed around the track-contacting wheels. The drive wheel or track-engaging wheel 14 engages the endless track to drive the endless track, while the mid-rollers 16 are disposed to roll on a bottom run of the endless track. The track assembly 10 further comprises a suspension assembly 30 connecting at least one of the mid-rollers 16 to the frame 12 and one of a braking system and a motor (not represented in Figs. 2 and 3) selectively couplable to the track-engaging wheel 14 to respectively brake or drive into rotation the track-engaging wheel 14. In the embodiment shown, and as represented by the arrow D on Fig. 2 representing a forward displacement direction of the vehicle 100 equipped with the track assembly 10, the track-engaging wheel 14 is at a front portion of the track assembly 10 (or mounted at a front portion of the frame 12). In the embodiment shown, and without being limitative, the track assembly 10 comprises a bogie 32 carrying at least two of the mid-rollers 16 and movable relative to the frame 12. The suspension assembly 30 physically connects the bogie 32 to the frame 12. In other words, in theembodiment shown, the bogie 32 is mounted to the frame via the suspension assembly 30.

[0046] Possible embodiments of suspension assemblies are disclosed in WO2021146817 filed by the applicant, the content of which being hereby incorporated by reference in its entirety for all purposes. The present disclosure is not limited to the suspension assemblies described below or in the cited document and any other type of suspension assemblies could be conceived.Endless track and track-contacting wheels

[0047] In the embodiment shown, the front track-engaging wheel 14 and the rear wheel 18 support part of the weight of the vehicle 100 via the endless track and guide and maintain the endless track under tension as the endless track is driven by the track-engaging wheel 14 around the plurality of track-contacting wheels.

[0048] The roller wheels or mid-rollers 16 roll on a lower - or bottom - run of the endless track to apply it on the ground for traction and guide the track as it is driven by the track-engaging wheel 14. When the vehicle is driven, the track-engaging wheel 14 is rotatable by power of a motor configured to impact motion of the endless track. For instance, the endless track is an elastomeric endless track, allowing it to elastically change in shape as it is in motion around the track-contacting wheels.

[0049] In the embodiment shown, at least two of the mid-rollers 16 are carried by the bogie 32 of the track assembly 10. The bogie 32 is a wheel-carrying assembly that comprises a wheel-carrying structure 33 to which are rotatably mounted the mid-rollers 16, the wheel-carrying structure 33 being movable relative to the frame 12. This allows the mid-rollers 16 to move as a “tandem” to conform to a ground unevenness, such as a terrain variation (i.e. , a terrain elevation or depression such as a hill or bump) and / or an object (e.g., a rock) on the ground.

[0050] The track assembly 10 is connected to a fixed structure of the vehicle 100. The fixed structure may be the chassis 104 of the vehicle 100 or any other structure fixed to the chassis 104 of the vehicle 100. More particularly, in this embodiment, the frame 12 comprises a chassis-mounting portion 13 rotatably mountable to a frame-mounting axle of the chassis 104 about a frame-rotation axis X (Figures 4-6).Suspension assembly

[0051] As mentioned above, the track assembly 10 as represented in Figs. 2 and 3 comprises a suspension assembly 30 for absorbing shocks, reducing vibrations, and / or improving ride quality. For instance and without being limitative, the suspension assembly 30 comprises a suspension link or suspension member 34 (or suspension tandem 34) comprising a frame-mounting portion 36 rotatably mounted to the frame 12 about a first rotation axis X1 and a bogie-mounting portion 38 rotatably mounted to the bogie 32 about a second rotation axis X2. It is thus understood that the bogie 32 is mounted to the frame 12 via the suspension link or rear tandem 34. In the embodiment shown, the first and second rotation axes X1 , X2 as well as the framerotation axis X are substantially perpendicular to the longitudinal direction of the track assembly 10 and are therefore substantially parallel to each other.

[0052] In the embodiment shown, the suspension assembly 30 further comprises a resilient member 40 (Fig. 3) mounted for instance between the suspension link 34 and the rear wheel 18. The resilient member 40 (comprising for instance a spring) is configured to change from a first configuration to a second configuration in response to a load and recover the first configuration in response to removal of the load to allow movement of the mid-rollers 16 relative to the frame 12. The suspension link 34 is thus configured to control movement of the bogie 32 and of the mid-rollers 16 mounted thereto relative to the frame 12. Any other configuration of the suspension assembly could be conceived.

[0053] It is understood that when the track assembly 10 moves on the ground and the mid-rollers 16 encounter a bump or other terrain variation, a rock or other object on the ground, or some other ground unevenness, the suspension link 34 can pivot about the first rotation axis X1 to allow the bogie 32 to move substantially upwardly against a spring force exerted by the resilient member 40. Upon release of the load to which it is subjected due to the mid-rollers 16 having cleared the ground unevenness, the resilient member 40 can recover its original configuration, biasing the suspension link 34 and the bogie 32 back to their original positions.

[0054] It is appreciated that the shape, the configuration, and the location of the suspension assembly, the components thereof and the shape, configuration andrelative location of the components of the track assembly can vary from the embodiment shown.Relative movement of the components of the track assembly upon braking of the track-engaging wheel

[0055] In the embodiment shown, the track assembly comprises a braking system 50 (Fig. 8) selectively couplable to the drive (or front) wheel 14 to brake (i.e., reduce a rotation speed of) the track-engaging wheel 14. As detailed below with reference to Figs. 4 to 6, components of the track assembly 10 rotate unfavorably under braking loads (i.e., upon actuation of the braking system 50) and this can result in some wheels losing contact with the track 20 (with the inner face thereof). Figs. 4 to 6 schematically represent the relative movement of the components of a track assembly which does not comprise a torque-limiting arm according to the present disclosure, upon actuation of the braking system 50 (i.e., upon braking of the track-engaging wheel 14).

[0056] The track assembly being displaced in the displacement direction D, as represented in Fig. 4, a braking force is applied by the braking system to the trackengaging wheel 14. The braking forces are then transferred to the frame 12 as a torque, by which, as best shown in Fig. 5, the frame 12 is pivoted about the framerotation axis X in a clockwise direction. As a result of the pivoting of the frame 12 about the frame-rotation axis X, a greater portion of the load comes to the front or trackengaging wheel 14 and is removed from the frame-mounting portion 36 of the rear tandem or suspension member 34. As schematically represented in Fig. 6, a force balance on the rear tandem or suspension member 34 is affected by a lower vertical force applied thereto. A rotation axis of the rear wheel 18 being lower, considered in a direction perpendicular to the displacement direction D, than the first rotation axis X1 by which the frame-mounting portion 36 of the rear tandem 34 is rotatably mounted to the frame 12, a moment is created; when said moment becomes greater than vertical forces applied to the rear tandem 34, the rear tandem 34 is pivoted about the first rotation axis X1 in a counterclockwise direction, causing the mid-rollers 16 to come off the ground and off the inner face of the endless track 20.

[0057] In other words, upon actuation of the braking system on the track-engaging wheel 14, the mid-rollers 16 lose contact with the inner face of the endless track 20,resulting in a loss of stability during heavy braking and reducing significantly a track tension. Similar drawbacks can be expected upon actuation of a motor operatively coupled to the track-engaging wheel 14.Torque-limiting arm

[0058] To limit such a contact loss between the mid-rollers 16 and the inner face of the track or any other drawbacks encountered by the track assembly and the suspension assembly thereof, the track assembly according to embodiments of the present disclosure and as represented in Figs. 7 to 11 comprises a torque-limiting arm (or torque-limiting rod or torque-limiting member) 60, 60’, 260, 460, 660 shaped and dimensioned so that the braking forces - or the torque induced by a motor - are independent from the suspension system upon actuation of the braking system or the motor. In other words, and as detailed below, the torque-limiting arm 60, 60’, 260, 460, 660 is configured to redirect a braking torque created by the actuation of the braking system or the torque induced by the motor in order to uncouple the braking forces or the motor-induced forces, on the one hand, and the suspension movement, on the other hand.

[0059] As detailed below, the torque-limiting arm comprises a first end portion (or front end portion in the embodiment shown wherein the braking system is at a front portion of the track assembly, or proximal end portion, with respect to the braking system) connected to the braking system 50 and a second end portion (or rear end portion in the embodiment shown wherein the braking system is at a front portion of the track assembly, or distal end portion, with respect to the braking system) rotatably connectable, directly or indirectly, to the chassis 104 of the vehicle 100. For instance, the torque-limiting arm comprises an arm body extending along a longitudinal direction. For instance, the torque-limiting arm comprises a rod or a longitudinal member. For instance, the torque-limiting arm is at least partially made of steel or any other suitable material configured to sustain forces involved upon actuation of the braking system or the motor of the vehicle equipped with the track assembly.

[0060] Referring now to Fig. 7, there is shown a torque-limiting arm 60 in accordance with a first embodiment. In the embodiment shown, the first end portion 62 of the torque-limiting arm 60 is connected - for instance coupled - to the braking system 50operatively couplable to the track-engaging wheel at the front portion of the track assembly 10. In the embodiment shown, the first end portion 62 is vertically offset, when the longitudinal direction of the vehicle is substantially horizontal (for instance in an upward direction in the embodiment shown) with respect to an axle of the trackengaging wheel 14. For instance, the first end portion 62 is pivotally mounted to the braking system 50, for instance above the axle of the track-engaging wheel. The first end portion 62 could also be vertically offset in a downward direction with respect to the axle of the track-engaging wheel 14.

[0061] Still referring to Fig. 7, the second end portion 64 of the torque-limiting arm 60 is connected to (for instance secured to) the suspension assembly 30 (for instance to the suspension link 34 thereof). In the embodiment shown, the second end portion 64 is connected to or in the vicinity of the frame-mounting 36 of the suspension member 34, for instance in the vicinity of the first rotation axis X1 . In the embodiment shown, the second end portion 64 is connected - for instance in a pivotable manner - to the suspension link 34, below - when the track assembly in a substantially horizontal direction - the first rotation X1 connecting the suspension link 34 to the frame 12. It is thus understood that the second end portion 64 of the torque-limiting arm 60 is rotatably mounted to the chassis 104 of the vehicle 100 via the suspension link 34 and the frame 12. The present disclosure is not limited to the position of the torque-limiting arm as represented in Fig. 7; the second end portion 64 could for instance be mounted to any other part of the suspension member 34.

[0062] Referring now to Fig. 8, there is shown another possible embodiment of the torque-limiting arm 260. In the embodiment shown, the first end portion 262 of the torque-limiting arm 260 is connected - for instance coupled - to the braking system 50 couplable to the track-engaging wheel 14 at the front portion of the track assembly 10. In the embodiment shown, the first end portion 262 is connected above the axle of the track-engaging wheel 14. For instance, the first end portion 262 is pivotally mounted to the braking system 50. The first end portion 262 could also be vertically offset in a downward direction with respect to the axle of the track-engaging wheel 14.

[0063] Still referring to Fig. 8, the second end portion 264 of the torque-limiting arm 260 is pivotally connected to the frame-mounting axle X of the chassis 104. Forinstance, the second end portion 264 is rotatably mounted to the frame-rotation axis X such that the torque-limiting arm 260 rotates about the frame-rotation axis X. It is thus understood that in the embodiment shown, the second end portion 264 of the torque-limiting arm 260 is rotatably mounted to the chassis 104 of the vehicle 100.

[0064] Referring now to Fig. 9, there is shown another possible embodiment of the torque-limiting arm 460. In the embodiment shown, the first end portion 462 of the torque-limiting arm 460 is connected - for instance coupled - to the braking system 50 couplable to the track-engaging wheel 14 at the front portion of the track assembly 10. In the embodiment shown, the first end portion 462 is connected above - for instance substantially vertically aligned with, considered along the longitudinal direction of the track assembly - the axle of the track-engaging wheel 14. For instance, the first end portion 462 is pivotally mounted to the braking system 50.

[0065] Still referring to Fig. 9, the second end portion 464 is mounted to - for instance in a pivotable manner - a front portion - considered along the longitudinal direction of the track assembly with respect to the forward displacement direction D of the vehicle - of the frame 12. In other words, in the embodiment shown, the second end portion 464 is longitudinally located between the first end portion 462 of the torque-limiting arm 460 and the chassis-mounting portion 13 of the frame 12. Moreover, considered in a plane comprising the longitudinal direction of the track assembly 10 and extending substantially vertically when the vehicle is on a substantially horizontal plane, a longitudinal direction T of the torque-limiting arm 460 intersects the chassis-mounting portion 13 (for instance the frame-rotation axis X) or the frame-mounting axle of the chassis when the track assembly 10 is mounted to the chassis. The present disclosure is not limited to the position of the torque-limiting arm as represented in Fig. 8 or 9; the second end portion 264, 464 could for instance be rotatably mounted to any other part of the frame 12.

[0066] Referring now to Fig. 10, there is shown another embodiment of a track assembly 510. In the embodiment shown, the track assembly 510 comprises at least two pairs of mid-rollers 16, respectively front and rear pairs 21 , 23, considered with respect to the forward displacement direction D of the track assembly 510 when mounted to a vehicle. The track assembly 510 thus comprises front and rear bogies32, 32’ carrying respectively the front and rear pairs 21 , 23 of mid-rollers 16. The track assembly 510 also comprises a frame 12 rotatably mountable to the chassis of the vehicle and front and rear suspension assemblies 30, 30’ connecting respectively the front and rear pairs via the front and rear bogies 32, 32’ to front and rear portions of the frame 12. In the embodiment shown, the track assembly 510 also comprises a braking system 550 couplable to the track-engaging wheel 514 and a torque-limiting arm 660. The first end portion 662 of the torque-limiting arm 660 is mounted to the braking system 550 (for instance above the rotation axis of the track-engaging wheel 514) and the second end portion 664 of the torque-limiting arm 660 is rotatably mounted to the chassis-mounting portion 513 of the frame 512, for instance forwardly with respect to the frame-rotation axis X (or in the vicinity thereof). As apparent from Fig. 10, it is thus understood that the present disclosure is not limited to a track assembly comprising only two mid-rollers 16.

[0067] It is appreciated that the shape, the configuration, and the location of the torquelimiting arm 60, 260, 460, 660 and of the first 62, 262, 462, 662 and second end portions 64, 264, 464, 664 thereof can vary from the embodiments shown. For instance, the second end portion 64, 264, 464, 664 of the torque-limiting arm 60, 260, 460, 660 could be located anywhere with respect to the other components of the track assembly or could even be arranged outside of the track assembly 10 (i.e., outside an inner volume delimited by the endless track 20 and first and second vertical planes containing first and second lateral edges of the endless track 20). It could also be conceived a track system comprising a plurality of torque-limiting arms 60, 260, 460, 660, or a torque-limiting arm 60, 260, 460, 660 that would be formed of a plurality of members connected to each other in a substantially rigid manner. The first and / or second end portions of the torque-limiting arm could also be movable with respect to the other components of the track assembly 10, based on movements of the track assembly 10.

[0068] In the embodiments shown, considered relative to the forward displacement direction D of the vehicle, the track-engaging wheel 14 is at a front portion of the track assembly 10 and the suspension assembly 30 is at a rear portion of the track assembly 10, with respect to the track-engaging wheel 14 and the braking system. It is howeverunderstood that the torque-limiting arm 60, 260, 460, 660 could be integrated into other types of track assemblies.Technical effects of the torque-limiting arm

[0069] In the embodiments shown for instance with reference to Figs. 7 to 10, the braking system 50, 550 is free in rotation around a rotation axis of the track-engaging wheel 14 (defined by the axle of the track-engaging wheel 14) and is at least partially supported by the torque-limiting arm 60, 260, 460, 660. By transmitting the braking torque generated upon actuation of the braking system, the torque-limiting arm 60, 260, 460, 660 reduces the risk or even avoids that the actuation of the braking system affects a behavior of the suspension assembly. The torque-limiting arm 60, 260, 460, 660 thus contributes to keeping the suspension assembly reactive during the actuation of the braking system.

[0070] In other words, the torque-limiting arm 60, 260, 460, 660 makes it possible for the braking torque to be redirected so as to uncouple the braking forces from the suspension movement. The braking forces being redirected towards a neutral point of the track assembly 10, they will therefore not have any effects on the undercarriage movement (i.e., a movement of the different components of the track assembly 10) during actuation of the braking system.

[0071] It is thus understood that the braking system (disk, drum or any other component thereof) is not constrained on the axle where it is applied (i.e., to the axle of the track-engaging wheel, in the embodiments shown).

[0072] The track assembly 10 as disclosed thus makes braking forces independent from the suspension, allowing for better traction and stability upon actuation of the braking system. The track assembly 10 also allows better ground-following properties and reduces and / or removes the braking instabilities.

[0073] Even though in the embodiments shown, the track assembly 10 comprises a braking system selectively couplable with one of the track-contacting wheels, it could also be conceived, as represented in Fig. 11 , a track assembly 10 comprising a motor 51 selectively driving a track-engaging wheel - rotatably mounted to a front or a rear portion of the track assembly 10 - into rotation and a torque-limiting arm 60’ having afirst end portion 62’ rotatably mounted to the motor (for instance above or in the vicinity of the rotation axis of the track-engaging wheel 14) and a second end portion 64’ rotatably connected to the chassis 104 of the vehicle, for instance via the suspension member 34 and the frame 12. The torque-limiting arm 60’ would thus be shaped and dimensioned so that the motor drives the track-engaging wheel into rotation without inducing a torque on the frame 12 holding the motor 51.

[0074] Several alternative embodiments and examples have been described and illustrated herein. The embodiments of the invention described above are intended to be exemplary only. A person of ordinary skill in the art would appreciate the features of the individual embodiments, and the possible combinations and variations of the components. A person of ordinary skill in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. It is understood that the invention may be embodied in other specific forms without departing from the central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. Accordingly, while the specific embodiments have been illustrated and described, numerous modifications come to mind. The scope of the invention is therefore intended to be limited by the scope of the appended claims.

Claims

CLAIMS:1 . A track assembly for a vehicle comprising a chassis, the track assembly comprising: a frame rotatably mountable to the chassis; a plurality of track-contacting wheels including: a track-engaging wheel rotatably mounted to the frame; and a plurality of mid-rollers; an endless track disposed around the track-contacting wheels, the trackengaging wheel engaging the endless track to drive the endless track, the mid-rollers being disposed to roll on a bottom run of the endless track; a suspension assembly connecting at least one mid-roller to the frame; one of a braking system and a motor selectively couplable to the trackengaging wheel to respectively brake or drive into rotation the trackengaging wheel; and a torque-limiting arm comprising: a first end portion connected to said one of a braking system and a motor; and a second end portion rotatably connectable to the chassis.

2. The track assembly of claim 1 , wherein the first end portion is connected in the vicinity of an axle of the track-engaging wheel.

3. The track assembly of claim 1 , wherein the first end portion is vertically offset in an upward direction with respect to an axle of the track-engaging wheel.

4. The track assembly of claim 2 or 3, wherein the first end portion is vertically aligned with the axle of the track-engaging wheel.

5. The track assembly of any one of claims 2 to 4, wherein the first end portion is pivotally mounted to said one of a braking system and a motor.

6. The track assembly of any one of claims 2 to 5, wherein said one of a braking system and a motor is pivotally mounted to the axle of the trackengaging wheel.

7. The track assembly of any one of claims 1 to 6, wherein the torquelimiting arm comprises a rod member extending along a longitudinal direction between the first and second end portions.

8. The track assembly of any one of claims 1 to 7, wherein the torquelimiting arm is at least partially made of steel.

9. The track assembly of any one of claims 1 to 8, further comprising a bogie carrying at least one of the mid rollers and movable relative to the frame, wherein the suspension assembly connects the bogie to the frame.

10. The track assembly of claim 9, wherein the suspension assembly comprises a suspension link comprising a frame-mounting portion rotatably mounted to the frame about a first rotation axis and a bogiemounting portion rotatably mounted to the bogie about a second rotation axis, the bogie being mounted to the frame via the suspension link.

11. The track assembly of claim 10, wherein the first and second rotation axes are substantially parallel to each other.

12. The track assembly of claim 10 or 11 , wherein the second end portion of the torque-limiting arm is connected to the suspension link.

13. The track assembly of claim 12, wherein the second end portion of the torque-limiting arm is rotatably mounted to the suspension link, at or in the vicinity of the frame-mounting portion thereof.

14. The track assembly of any one of claims 1 to 11 , wherein the second end portion of the torque-limiting arm is rotatably mounted to the frame.

15. The track assembly of any one of claims 1 to 11 , wherein the frame comprises a chassis-mounting portion rotatably mountable to the chassis of the vehicle, wherein, considered in a substantially vertical plane comprising a longitudinal direction of the track assembly, a longitudinal direction of the torque-limiting arm intersects the chassis-mounting portion.

16. The track assembly of any one of claims 1 to 11 , wherein the chassis comprises a frame-mounting axle, the second end portion of the torquelimiting arm being rotatably mounted to the frame-mounting axle.

17. The track assembly of any one of claims 1 to 16, wherein, considered relative to a forward displacement direction of the vehicle, the trackengaging wheel is at a front portion of the track assembly.

18. The track assembly of claim 17, wherein the suspension assembly is at a rear portion of the track assembly.

19. A towed vehicle comprising a track assembly as claimed in any one of claims 1 to 18.

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