Track assembly for a work machine and a work machine comprising said track assembly

Abstract

A track assembly (100) of a work machine, the track assembly comprising a supporting element (110) extending along a longitudinal direction, DL, an endless track (120), a sprocket (130) arranged to drive the endless track, and a road wheel module (140) The road wheel module comprises a bogie arm suspension member (150) arranged to be rotatably mounted to the supporting element to allow rotation relative a parallel rotation axis, AP, parallel to the longitudinal direction, DL, and at least two bogie arms (160) rotatably mounted to the bogie arm suspension member to allow rotation relative a transverse rotation axis, AT, transverse to the longitudinal direction, DL. The bogie arms are mounted on opposite sides of the bogie arm suspension member relative the bogie parallel rotation axis, AP, wherein each bogie arm carries at least two road wheels (170) located at opposite sides of the bogie transverse rotation axis, AT.

Description

[0001] TRACK ASSEMBLY FDR A WORK MACHINE AND A WORK MACHINE COMPRISING SAID TRACK ASSEMBLY

[0002] Field of the invention

[0003] The present invention relates to a track assembly for a work machine, a road wheel module used in such track assembly, and a work machine comprising such track assembly. The present invention especially relates to track assemblies associated with forestry vehicles.

[0004] Technical background

[0005] Different types of machines and vehicles are frequently used within different areas such as construction, agriculture, forestry, etc., to conduct work and moving equipment, products etc. For example, within the forestry industry, powerful vehicles are used for harvesting and transporting cut down trees from the forest.

[0006] Some vehicles intended for use for example within a forest area are provided with track assemblies arranged to propel the vehicle. The track assemblies are able to withstand high loads and improve the vehicle abilities to drive in rough conditions, such as soft or loose ground, inclines, uneven surfaces, etc. The track assemblies could have different configurations, but all involves an endless track extending around at least one sprocket and a number of road wheels. Track assemblies offer several advantages over wheel-based systems by distributing machine weight across a larger surface area, improving traction, stability, and reducing ground pressure.

[0007] It is critical to properly distribute load within the track system for ensuring the machine's operational efficiency, safety, and durability. Not doing so may result in e.g., uneven wear and tear on components, loss of stability, inefficient operation, ground damage, and in worst cases, the endless track being forced off the road wheels. To overcome this issue, bogies may be used within track systems to accurately distribute the load within the track system when the work machine is active. Nonetheless, the current track assemblies still experience difficulties with uneven wear and tear on components and unbalanced load distribution when driving through rough driving environments, which may result in a reduced detracking performance.

[0008] Hence, there is still a strong need to address these issues to improve the performance of track assemblies of work machines in order to achieve an improved load distribution and to achieve high resistance against detracking.

[0009] Summary

[0010] It would be advantageous to provide a track assembly, a road wheel module, and a work machine, that at least alleviates some of the above-mentioned drawbacks. This and other objects are achieved by providing a track assembly, a road wheel module, and a work machine, having the features in the independent claims. Preferred embodiments are defined in the dependent claims. Hence, according to the present invention, there is provided a track assembly of a work machine having a frame. The track assembly comprises a supporting element extending along a longitudinal direction, DL, of the work machine, an endless track arranged in the longitudinal direction, DL, and a sprocket connected to the supporting element and arranged to drive the endless track. The track assembly further comprises a road wheel module comprising a bogie arm suspension member arranged to be rotatably mounted to the supporting element to allow a rotation relative to a bogie parallel rotation axis, Ap, parallel to the longitudinal direction, DL. The road wheel module further comprises at least two bogie arms rotatably mounted to the bogie arm suspension member to allow a rotation relative to a bogie transverse rotation axis, AT, transverse to the longitudinal direction, DL. The at least two bogie arms are mounted on opposite sides of the bogie arm suspension member relative the bogie parallel rotation axis, Ap. Furthermore, each bogie arm carries at least two road wheels located at opposite sides of the bogie transverse rotation axis, AT.

[0011] Thus, the present invention is based on the concept or idea of providing a track assembly comprising dual-axle bogie arms. Hence, additional degrees of freedom are introduced into the track assembly system. This is achieved by having the track assembly comprising bogie arms combined with a rotational suspension member, similar to a pendulum axle. The present invention provides for having the bogie arm not directly connected to the frame of the work machine, but instead to a rotational suspension member, thus enabling rotational motion around two axes.

[0012] The present invention is advantageous in that the road wheel module comprises a bogie arm suspension member arranged to be rotatably mounted to the supporting element, and at least two bogie arms rotatable mounted to the bogie arm suspension member. Hence, the present invention enables double-axle bogie arms. This is advantageous in that the added degree of freedom allows the road wheels and the endless track to better adapt to various driving conditions. For example, when the work machine comprising the track assembly enters a side slope or travels over a relatively large obstacle, the track road wheels, and the endless track will be able to distribute the load both in the longitudinal direction and in the lateral direction of the work machine.

[0013] This is further advantageous in that the road wheels will more precisely follow the endless track. This results in a reduced peak load on the track from the road wheels, i.e., a more balanced load distribution over the endless track. Therefore, mechanical wear of the track assembly and its component will be more evenly distributed. This increases the track durability and therefore also the longevity of the track assembly. Also, a more balanced load distribution of the road wheels and the endless track results in a more balanced load distribution of the track assembly and the work machine relative to the ground. This is especially advantageous as the track assembly and the work machine then causes less disruption to the ground. Furthermore, maintaining optimal track alignment of the road wheels relative to the endless track during different driving conditions reduces energy consumption.

[0014] The present invention is further advantageous in that the risk of detracking of the road wheels relative to the endless track is reduced. This is accomplished as the road wheels more precisely follow the endless track, and the track durability is increased. Reducing the risk of detracking is beneficial for a range of reasons e.g., increasing the safety and the overall driving- experience for an operator of the work machine. This holds true as well for the safety and integrity of the surroundings of the work machine, such as humans, animals, and other objects. Further, potential downtime of the work machine is reduced.

[0015] There is provided a track assembly of a work machine. By work machine, it is here meant any type of machine designed to perform a typically labor-intensive task, for example excavators, forklifts, tractors, cranes, loaders, and forestry vehicles, such as harvesters and forwarders.

[0016] According to an embodiment of the present invention, the bogie arm suspension member may comprise a bogie arm rotation restriction arrangement arranged to define a first angular movement range, -α1 through +α1, of the at least two bogie arms relative to the bogie transverse rotation axis, A. Hence, each bogie arm of the at least two bogie arms is restricted to rotate within the first angular movement range -α1 to +α1. This is advantageous in that the risk of mechanical damage of the at least two bogie arms is reduced. This is true as well for the rest of the components of the track assembly. Further, excessive rotation of the bogie arms could lead to a loss of control over the steering and movement of the track assembly and / or the work machine. Hence, the embodiment of the present invention provides for a more stable and safe track assembly and / or work machine, for example reducing the risk of detracking of the road wheels from of the endless track.

[0017] According to an embodiment of the present invention, each of the at least two bogie arms may comprise at least two bogie abutment surfaces, each bogie abutment surface arranged to abut a corresponding restriction surface of the bogie arm rotation restriction arrangement if the bogie arm reaches one of the endpoints, -α1 and +α1, of the first angular movement range, -α1 through +α1. Hence, if a bogie arm reaches one of its angular endpoints, at least one bogie abutment surface of said bogie arm will abut, come into contact, meet, engage with, or the like, a corresponding restriction surface of the bogie arm rotation restriction arrangement. Said contact between a bogie abutment surface and a corresponding restriction surface will restrict the bogie arm to rotate beyond said angular endpoint. The present embodiment is advantageous in that it enables a noncomplex and robust structure to prevent excessive rotation of the bogie arms.

[0018] According to an embodiment of the present invention, the bogie arm suspension member may comprise a bogie arm suspension member rotation restriction arrangement arranged to define a second angular movement range, -α2 through +α2 of the bogie arm suspension member relative to the bogie parallel rotation axis, Ap. Hence, the bogie arm suspension member is restricted to rotate within the second angular movement range -α2 to +α2 This is advantageous in that the risk of mechanical damage of the bogie arm suspension member is reduced. This is true as well for the rest of the components of the track assembly. Hence, the present embodiment provides for a track assembly with an increased longevity. Further, the risk of detracking of the road wheels from the endless track is reduced.

[0019] According to an embodiment of the present invention, the track assembly may comprise restriction surfaces stationary arranged relative to the supporting element, wherein the bogie arm suspension member rotation restriction arrangement may comprise at least two bogie arm suspension member abutment surfaces, wherein each bogie arm suspension mEmber abutment surface is arranged to abut a corresponding restriction surface if the bogie arm suspension member reaches one of the end points, -α2 and +α2, of the second angular movement range, -α2 through +α2. The present Embodiment is advantageous in that it Enables a non-complex and robust structure to prevent excessive rotation of the bogie arm suspension member.

[0020] According to an embodiment of the present invention, the bogie arm rotation restriction arrangement and the bogie arm suspension member rotation restriction arrangement may together be formed as a unified rotation restriction arrangement. The unified rotation restriction arrangement may comprise a plurality of abutment surfaces arranged to restrict the rotation of the at least two bogie arms relative to the bogie transverse rotation axis, A, thus defining the first angular movement range, -α1 through +α1, and to restrict the rotation of the bogie arm suspension member relative to the bogie parallel rotation axis, Ap, thus defining the second angular movement range, -α2 through +α2. Hence, the abutment surfaces of the unified rotation restriction arrangement may be arranged to abut a portion of the at least two bogie arms and the bogie arm suspension member if the at least two bogie arms and the bogie arm suspension member is near or has reached their respective extreme angular movement range. This is advantageous in that the bogie arm rotation restriction arrangement and the bogie arm suspension member rotation restriction arrangement is formed as a single, unified, integrated, coherent, etc., component. This enables a road wheel module with a reduced weight, which may further save energy consumption. The present Embodiment is also favorable as it allows for a less complex road wheel module, which may also result in a reduction of manufacturing cost etc.

[0021] According to an embodiment of the present invention, at least one of α1=40° and α2=20° is fulfilled. Hence, both, or only one of the conditions α1=40° and α2=20° may be fulfilled. This is advantageous in that the def i ned angular movement range of the rotation of the bogie arms, -α1 through +α1, respective of the bogie arm suspension member, -α2 through +α2, allows for an optimal balance between rotational freedom and rotational constraint. Hence, the present Embodiment provides for a track assembly for a work machine adaptable to various driving conditions, whilst imposing rotational constraints to protect its components. Furthermore, the safety and driving-experience of the operator is increased, as for example the risk of detracking and / or tipping of the track assembly and / or the work machine may be reduced.

[0022] According to an embodiment of the present invention, the bogie arm suspension member may comprise spaced-apart bearing areas for the rotation of the bogie arm suspension member relative to the bogie parallel rotation axis and for the rotation of the at least two bogie arms relative to the bogie transverse rotation axis. Hence, the bearing areas of the bogie arm suspension member may support loads and enable the rotation of the bogie arm suspension member and the rotation of the at least two bogie arms. This is advantageous in that loads may be better distributed, avoiding potential high concentrations of stress. Hence, the present embodiment allows for a road wheel module and / or track assembly with an increased durability and longevity.

[0023] According to an embodiment of the present invention, the spaced-apart bearing areas may be joined by at least one internal lubrication channel of the bogie arm suspension member. In other words, the bogie arm suspension member may be at least partially hollow. Hence, the spaced-apart bearing areas may be united by several internal lubrication channels of the bogie arm suspension member, wherein e.g., lubricant may travel between the spaced-apart bearing areas. This is advantageous in that the internal lubricant channel (s) are provided within the suspension member, protected from potential external harm during manufacturing, transportation, and / or operation of the track assembly. Furthermore, the present embodiment allows for an overall weight reduction, as there is no need for additional, external lubrication channels.

[0024] According to an embodiment of the present invention, a first sealable lubrication port of the supporting element may be arranged to be fluidly connected to a second sealable lubrication port of the bogie arm suspension member to deliver a lubricant from the supporting element to the bogie arm suspension member. This is advantageous in that the first and second lubrication ports of the supporting element respective the bogie arm suspension member may be sealable. Hence, if desired, the road wheel module comprising the bogie arm suspension member may be removed from the supporting element without the need of disconnecting a lubricant hose of the track assembly. Hence, the present embodiment allows for a more adaptable road wheel module and track assembly. For example, the road wheel module may be pre-assembled and then fastened to the supporting element. The first sealable lubrication port of the supporting element may then be fluidly connected to the second sealable lubrication port of the bogie arm suspension member in order to deliver a lubricant from the supporting element to the bogie arm suspension member

[0025] According to an embodiment of the present invention, the bogie arm suspension member may be fluidly connected to the at least two bogie arms to deliver a lubricant via the at least two bogie arms to wheel bearings of the road wheels carried by the at least two bogie arms. Hence, the bogie arm suspension member may deliver a lubricant to a respective wheel bearing of the road wheels of the bogie arms. This is advantageous in that the bogie arm suspension member may be arranged to provide lubricant to the bogie arms. The present embodiment may result in a reduced amount of materials and costs when providing lubricant to the bogie arms. Also, there is no need of incorporating additional, external channels in order to provide lubricant from the bogie arm suspension member to the bogie arms. Hence, the present embodiment allows for an increased structural integrity of the wheel module and / or the track assembly, increasing their longevity.

[0026] According to an embodiment of the present invention, the track assembly may comprise a track support beam forming the supporting element, wherein the track support beam may be arranged to be connected to the frame by a suspension arrangement allowing movement, relative to the frame, of the track support beam at least in parallel with the longitudinal direction, Dl. For example, the track support beam may be connected to the frame by a suspension arrangement for allowing movement, relative to the frame, of the track support beam at least in parallel with the longitudinal direction, Di in a vertical plane parallel to the longitudinal direction, DL. This is advantageous in that the movement of the track support beam relative the frame allows for a more versatile track assembly and / or work machine relative different driving conditions. Furthermore, the safety and driving-experience of an operator may be increased, as the frame is not fixedly mounted to the track support beam.

[0027] According to an embodiment of the present invention, each of the at least two road wheels of each bogie arm may comprise a pair of road wheels arranged coaxially each other. In other words, each bogie arm may comprise at least four road wheels. Hence, each bogie arm may comprise two pair of road wheels located at opposite sides of the bogie arm relative to the bogie transverse rotation axis, A. This is advantageous in that the additional amount of road wheels allows for an increased load distribution. Hence, the weight of the track assembly and / or of the work machine may be more evenly distributed across the track, thus reducing the pressure exerted on the ground. This is especially favorable when operating on soft, loose, or uneven surfaces without sinking or damaging the terrain. The present embodiment also provides for an enhanced traction, allowing for that the endless track remains in constant and even contact with the ground. In other words, the maneuverability and control of the track assembly and / or the work machine is improved.

[0028] According to an embodiment of the present invention, the bogie parallel rotation axis, Ap, may intersect with the bogie transverse rotation axis, AT. In other words, the bogie parallel rotation axis, Ap, may intersect with the bogie transverse rotation axis at a specific point, wherein the two axes, Ap and AT, lies in a same plane. This is advantageous in that the intersection of the two axes provides for a structural stability of the road wheel module and precise control of the rotations of the bogie arm suspension member and the at least two bogie arms. Furthermore, the stress and load distribution may be enhanced, improving the durability and longevity of the road wheel module and / or the track assembly.

[0029] According to an example, the bogie arm suspension member may be arranged to be detachably mounted to the supporting element. In other words, the road wheel module comprising the bogie arm suspension member may be detachably mounted to the supporting element via the bogie arm suspension member. This is advantageous in that the road wheel module may be pre-assembled and fastened to the supporting element to form a complete system of the track assembly. This may allow for facilitated manufacturing, transporting, and assembling of the road wheel module, the track assembly, and / or of the work machine as a whole.

[0030] According to an embodiment of the present invention, a portion of the bogie arm suspension member may be arranged to be permanently secured to the supporting element. This is advantageous in that the bogie arm suspension member is securely attached to the supporting element, improving the overall stability and mechanical strength of the track assembly. This may further improve the load and stress distribution in the track assembly, increasing its durability and longevity.

[0031] According to an embodiment of the present invention, at least one of the at least two bogie arms may further comprise a secondary bogie arm rotatably mounted to said bogie arm, wherein at least one road wheel of said bogie arm comprises a pair of road wheels located at opposite sides of the secondary bogie arm relative to an axis parallel to the bogie transverse rotation axis, A. According to an example, each of the at least two bogie arms may comprise said secondary bogie arm. In other words, the road wheel module may comprise at least four bogie arms. Hence, the road wheel module may comprise two bogie arms on each opposite sides of the bogie arm suspension member relative the bogie parallel rotation axis, Ap. The road wheel module according to the present embodiment may be compared to a rocker bogie. The present embodiment is advantageous in that it allows for an increased stability, aiding in maintaining the stability of the track assembly and / or the work machine. Furthermore, it allows for a more versatile track assembly and / or work machine in terms of various driving conditions. According to an embodiment of the present invention, there is provided a road wheel module for a track assembly according to any embodiments of the road wheel module described herein. The road wheel module according to any of the present embodiments described herein is advantageous in that it provides for a dual-axle bogie arm, hence adding degrees of freedom to the road wheels. Hence, the present embodiment enables an improved maneuverability and adaptability to the terrain of the road wheel module. Also, the road wheel module allows for a better weight distribution, which is desirable when carrying heavy or uneven loads. Thus, load handling of the road wheel module may be improved, reducing the risk of mechanical damage of components of the road wheel module.

[0032] According to an embodiment of the present invention, there is provided a work machine comprising at least two track assemblies according to any embodiments of the track assembly described herein. The present embodiment is advantageous in that the work machine comprising the track assemblies according to any of the embodiments described herein allows for withstanding high loads while simultaneously allow for a more versatile and adaptable ability of the work machine to drive in rough conditions, such as soft or loose grounds, uneven terrain, and / or transversing relatively large obstacles.

[0033] According to an embodiment, the work machine may further comprise a control unit and a controllable suspension arrangement arranged to connect each of the track assemblies to the frame and make it possible to adjust the distance between each of the track assemblies and the frame of the work machine. This type of work machine in combination with the claimed track assembly is very advantageous since the alternating positions of the track assemblies in relation to the work machine to improve the versatility of the work machine favors from the increased flexibility in the support of the endless track to reduce wear and pressure on the ground.

[0034] According to an embodiment, the suspension arrangement of each track assembly is configured to make it possible to move the track assembly in a plane substantially parallel to the longitudinal direction of the work machine. This embodiment result in a work machine that is very versatile and adaptable for rough conditions, such as soft or loose grounds, uneven terrain, and / or transversing relatively large obstacles.

[0035] According to an embodiment, the suspension arrangement of each track assembly is configured to make it possible to move the at least two track assemblies in substantially parallel planes. This embodiment improves versatility further.

[0036] According to an embodiment, the suspension arrangement of each track assembly comprises at least a first and a second pendulum arm extending between the frame of the work machine and the support element of the track assembly, wherein at least one of the pendulum arms has an adjustable length to allow the track assembly to be arranged in an adjustable angular position relative the longitudinal direction of the work machine. This embodiment increases the range of movement of the track assemblies and consequently makes it possible to adapt the work machine for even more rough conditions still keeping the pressure and wear on the ground at a reasonable level.

[0037] According to an embodiment of the present invention, each track assembly of the work machine may comprise at least two road wheel modules aligned in the longitudinal direction, DL. In other words, the work machine may comprise at least four road wheel modules. The present embodiment is advantageous in that it provides for a more stable work machine, allowing for a more even weight distribution. Hence, the risk of the work machine of tipping or instability is reduced, especially when turning or driving on loose or uneven terrain. Also, more balanced weight distribution provides for a more evenly distributed mechanical wear of the track assembly and its component, thus increasing their durability and longevity. Furthermore, the traction between the road wheels and the endless track may be increased, allowing for maintaining an optimal track alignment of the road wheels to the endless track. Hence, the risk of detracking the road wheels from the endless track is reduced.

[0038] As used herein, the terms "support element", "supporting element", "track assembly support element" and "track support element" are intended to refer to the same structural element and may be used interchangeably, as will be apparent herein.

[0039] Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings, and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following.

[0040] Brief description of the drawings

[0041] The invention will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments, with reference to the appended drawings, in which:

[0042] Fig. 1 schematically illustrates a track assembly for a work machine according to an exemplifying embodiment of the invention.

[0043] Fig. 2 schematically illustrates a road wheel module according to an exemplifying embodiment of the invention. Fig. 3 schematically illustrates a road wheel module according to exemplifying embodiments of the invention. Fig.4 schematically illustrates a cut -through portion of a road wheel module according to exemplifying embodiments of the invention.

[0044] Figs. 5a-c schematically illustrates a road wheel module according to an exemplifying embodiment of the invention.

[0045] Fig. 6 schematically illustrates a road wheel module according to an exemplifying embodiment of the invention. Fig. 7 schematically illustrates a road wheel module according to an exemplifying embodiment of the invention. Fig. 8 schematically illustrates a work machine comprising a track assembly according to an exemplifying embodiment of the invention.

[0046] Fig. 9 schematically illustrates a track assembly for a work machine according to an exemplifying embodiment of the invention.

[0047] Fig. 10 schematically illustrates a work machine comprising a track assembly according to an exemplifying embodiment of the invention.

[0048] All figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested. Detailed description of the Embodiments

[0049] The present invention will now be described more fully hereinafter with reference to the accompanying figures, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0050] Fig. 1 schematically illustrates a track assembly 100 for a work machine having a frame according to an exemplifying embodiment of the invention. The track assembly 100 in Fig. 1 comprises a supporting element 110 extending along a longitudinal direction, DL, of the work machine and an endless track 120 arranged in the longitudinal direction, DL. The longitudinal direction, DL, may be the driving direction of the work machine. The endless track I2D may comprise rubber. The track assembly 100 further comprises a sprocket 130 connected to the supporting element 110 and arranged to drive the endless track 120, and a road wheel module 140. The road wheel module 140 will be further explained herein.

[0051] Fig. 2 schematically illustrates a road wheel module 140 according to an exemplifying embodiment of the invention. The road wheel module 140 of Fig. 2 is also disclosed in Fig. 1, wherein Fig. 1 discloses two road wheel modules 140 arranged in the track assembly 100. According to Fig. 2, the road wheel module 140 comprises a bogie arm suspension member 150 arranged to be rotatably mounted to the supporting element 110 to allow a rotation relative to a bogie parallel rotation axis, Ap, parallel to the longitudinal direction, DL. In other words, the bogie arm suspension member 150 may rotate relative to the bogie parallel rotation axis, Ap. The bogie arm suspension member 150 may be any element, component, unit, or the like suitable to sustain and distribute loads. The bogie arm suspension member 150 may have the shape of a cross, as disclosed in Fig. 2. It should be noted that other shapes of the bogie arm suspension member 150 are also feasible, such as a T-shape. Furthermore, a portion of the bogie arm suspension member 150 may arranged to be permanently secured to the supporting element 110.

[0052] According to an example, the bogie arm suspension member 150 may be formed as a single, integral, uniform, monolithic, or the like, member. According to another example, the bogie arm suspension member 150 may be formed by a plurality of submembers. In other words, the bogie arm suspension member 150 may be a modular bogie arm suspension member 150. A monolithic bogie arm suspension member 150 may be advantageous by imposing a lower weight to the track assembly 100 compared to a modular bogie arm suspension member 150. Furthermore, a monolithic bogie arm suspension member 150 may comprise fewer joints, connections, couplings, assembly points, or the like, compared to a modular bogie arm suspension member 150, thereby providing increased structural strength and reliability under external forces. However, the modular bogie arm suspension member 150 may be advantageous in that a modular member may exhibit reduced manufacturing complexity and cost, compared to a monolithic member.

[0053] According to Fig. 2, the portion of the bogie arm suspension member 150 arranged to be permanently secured to the supporting element 110 comprises two end portions 115 arranged opposite each other relative to the bogie transverse rotation axis, AT. The two end portions 115 of the bogie arm suspension member 150 are separated by at least a first distance, D1, along the bogie parallel rotation axis, Ap. As a result of that the portion of the bogie arm suspension member 150, which is arranged to be permanently secured to the supporting element 110, comprises the two end portions 115, and that the two end portions 115 of the supporting element 110 is separated by at least the first distance, D1, support is provided to the bogie arm suspension member 150 in regard to handling e.g., side loads of the road wheel module 140, and / or torque around a vertical axis perpendicular to the bogie parallel rotation axis, Ap, and to the bogie transverse rotation axis, AT. According to an example, the bogie arm suspension member 150 may be connected to the supporting element 110 by bolting or welding.

[0054] The road wheel module 140 further comprises at least two bogie arms 160 rotatably mounted to the bogie arm suspension member 150 to allow a rotation relative to a bogie transverse rotation axis, AT, transverse to the longitudinal direction, DL. Hence, the bogie arms 160 may rotate relative to the bogie transverse rotation axis, AT. The bogie arm suspension member 150 may further comprise bearings to allow for the rotation of the at least two bogie arms 160, such as sliding bearings, roller bearings, ball bearings, or the like. The at least two bogie arms 160 are mounted on opposite sides of the bogie arm suspension member 150 relative the bogie parallel rotation axis, Ap. Further, each bogie arm 160 carries at least two road wheels 170 located at opposite sides of the bogie transverse rotation axis, AT. Hence, each bogie arm 160 comprises at least two road wheels 170, wherein each at least two road wheel 170 may be arranged at opposite end portions of each bogie arm 160, as disclosed in Fig. 2. The road wheels 170 of the road wheel module 140 may provide support on an inside of the endless track 120 disclosed in Fig. 1.

[0055] It is therefore understood that each of the at least two bogie arms 160 is rotatably mounted to the bogie arm suspension member to allow an independent rotation relative to each other and relative to the bogie transverse rotation axis, AT. Hence, the at least two bogie arms 160 may rotate relative to the bogie transverse rotation axis, AT, independent to each other. This is further illustrated in an exemplifying embodiment of Fig. 5c, wherein the bogie arm 160 to the right in Fig. 5c is rotated around the transverse rotation axis, AT, independent of a rotation of the bogie arm 160 to the left in Fig. 5c. Hence, the bogie arm suspension member 150 may comprise a first bearing to allow a first rotation of a first bogie arm of the at least two bogie arms 160 relative to the bogie transverse rotation axis, AT, and a second bearing to allow a second rotation, independent to the first rotation, of a second bogie arm of the at least two bogie arms 160 relative to the bogie transverse rotation axis, AT. This is further illustrated in an exemplifying embodiment of Fig. 3 and the associated text, describing how each of the at least two bogie arms 160 may individually be restricted to a first angular movement range, -α1 through +α1, by a corresponding restriction surface 182 of the bogie arm rotation restriction arrangement 180. The restriction surface 182 and the bogie arm rotation restriction arrangement 180 is further described in combination with Fig. 5c.

[0056] The at least two bogie arms 160 are mounted on opposite sides of the bogie arm suspension member 150, relative to the bogie parallel rotation axis, Ap, as explained herein. Furthermore, the bogie arm suspension member 150 is arranged to be rotatably mounted to the supporting element 110 to allow a rotation relative to the bogie parallel rotation axis, Ap. As illustrated in Fig. 1, each of the at least two bogie arms 160 is rotatably mounted to the bogie arm suspension member 150 by at least a second distance, D2, from the bogie parallel rotation axis, Ap, wherein the second distance, D2, extends perpendicular to the bogie parallel rotation axis, Ap. For example, the second distance, D2, may be perpendicularly measured from the bogie parallel rotation axis, Ap, to a coupling point between the bogie arm 160 and the bogie arm suspension member 150. The coupling point between the bogie arm 160 and the bogie arm suspension member 150 may correspond to the bearing of the bogie arm suspension member 150 described herein, allowing for the rotation of the bogie arm 160. Furthermore, a lateral distance in a direction parallel to the bogie transverse rotation axis, A, between the supporting element 110 and the bogie arms 160 may vary based on the rotation of the bogie arm suspension member 150 around the bogie parallel rotation axis, Ap, and / or the rotation of the bogie arm 160 around the bogie transverse rotation axis, AT. However, by rotatably mounting the bogie arm 160 to the bogie arm suspension member 150 by at least the second distance, Dp, a separation between the supporting element 110 and the bogie arm 160 may be achieved regardless of the rotations of the bogie arm suspension member 150 and the bogie arm 160. Hence, each of the at least two bogie arms 160 is arranged beyond, outside, orthe like, the supporting element 110 in a direction parallel to the bogie transverse rotation axis, AT.

[0057] Consequently, the rotation of each of the at least two bogie arms 160 around the bogie transverse axis, Ay, occurs in a respective plane, PBA, perpendicular to the bogie transverse rotation axis, AT. Each plane, PBA, is positioned, in a direction parallel to the bogie transverse rotation axis, Ay, beyond, outside, orthe like, the extent of a vertical projection of the supporting element 110 onto a plane, Pyp, defined by the bogie transverse rotation axis, Ay, and the bogie parallel rotation axis, Ap. In other words, the rotational planes, PBA, of the at least two bogie arms 160 do not intersect or coincide with the vertical projection of the supporting element 110 onto the plane, Pyp. Put it differently, each rotational plane, PBA, is separated from the vertical projection of the supporting element 110 onto the plane, Pyp, by at least a distance. Therefore, the respective rotation of the at least two bogie arms 160 around the bogie transverse rotation axis, Ay, may occur without being physically restricted by the supporting element 110.

[0058] As described herein, each bogie arm 160 carries at least two road wheels 170 located at opposite sides of the bogie transverse rotation axis, AT. In Figs.1-7, it is shown that each of the at least two bogie arms 160 comprises a bent, curved, angled, incline, orthe like, portion. The bent portion is arranged between the opposite sides of the bogie arm 160. Thus, a respective center of the at least two road wheels 170 of each of the at least two bogie arms 160 may be separated from the plane, Pyp, defined by the bogie transverse rotation axis, Ay, and the bogie parallel rotation axis, Ap, by at least a third distance, D3. The third distance, D3, is a vertical distance between the plane, Pyp, defined by the bogie parallel rotation axis, Ap, and the bogie transverse rotation axis, Ay, and the respective center of the at least two road wheels 170 in a direction parallel to a normal of the plane, P. Put it differently, a rotation axis, Aw, of each of the at least two road wheels 170, parallel to the bogie transverse rotation axis, Ay, is separated from the plane, Pyp, by at least the third distance, D3.

[0059] Therefore, the invention allows a relatively large rotation of each of the at least two bogie arms 160 around the bogie transverse rotation axis, Ay, compared to allowing a relatively small rotation of the bogie arm suspension member 150 around the bogie parallel rotation axis, Ap. As is illustrated in Fig. I, the at least two bogie arms 160 would not be physically restricted by abutment with the supporting element 110 during their respective rotation around the bogie transverse rotation axis, Ay. On the contrary, the bogie arm suspension member 150 is arranged to at least partially overlap with the supporting element 110 along the bogie transverse rotation axis, A. Hence, as illustrated in Fig. I, the bogie arm suspension member 150 would be at least partially restricted during the rotation around the bogie parallel rotation axis, Ap, due to contact with the supporting element 110. Limiting the rotation of the bogie arm suspension member 150 around the bogie parallel rotation axis, Ap, to be relatively small may be preferable, since excessive rotation may otherwise lead to increased risk of wear on the endless track 120 and / or the road wheels 170, and / or to an increased risk of detracking. Accordingly, allowing the respective rotation of the at least two bogie arms 160 to be relatively large may be preferable, as said rotation may allow the at least two bogie arms 160 to (individually) adapt to relatively large objects. Relatively large objects may be commonly encountered by a work machine in e.g., forest environments, such as boulders, rocks, trees, tree trunks, tree branches, or the like.

[0060] Such configuration, i.e., allowing a relatively large rotation of the bogie arms 160 around a bogie transverse rotation axis, Ay, and allowing a relatively small rotation of the bogie arm suspension member 150 around the bogie parallel rotation axis, Ap, may be especially advantageous in combination with a work machine comprising a controllable suspension arrangement. An example of such work machine is described in combination with e.g., Figs.8-10. A conventional tracked work machine comprising a suspended chassis may experience increased loads at the ends of the endless track when positioned on uneven ground, as the suspended chassis adapts to the unevenness in order to, for example, maintain an operator cabin in a level orientation. However, a work machine comprising a controllable suspension arrangement and enabling dual-axle bogie arms, as described herein, may provide for an efficient tradeoff between reducing such loads at the ends of the endless track, reducing the risk of wear / detracking of the endless track 120, and enabling the bogie arms 160 to (individually) adapt to relatively large hindrance or objects.

[0061] Additionally, according to Fig. 2 as an exemplifying embodiment, the bogie parallel rotation axis, Ap, intersects with the bogie transverse rotation axis, AT. Hence, the bogie parallel rotation axis, Ap, may intersect with the bogie transverse rotation axis, Ay, at a specific point. Therefore, according to this example, the bogie parallel rotation axis, Ap, and the bogie transverse rotation axis, Ay, may lie in a same plane, P. According to another example, the bogie parallel rotation axis, Ap, and the bogie transverse rotation axis, Ay, does not intersect with each other. Hence, according to this other example, the two axes does not lie in the same plane, P. In other words, there is a distance, D, between a first plane, Pi, containing the bogie parallel rotation axis, Ap, and a second plane, Pp, containing the bogie transverse rotation axis, AT.

[0062] Fig.3 schematically illustrates a wheel module 140 according to exemplifying embodiments of the invention. It should be noted that the wheel module 140 shown in Fig.3 has several features in common with the wheel module 140 shown in Figs. I and 2, and some references may have been omitted in Fig.3 for this reason. It is hereby referred to Figs. I and 2 and the associated text for an increased understanding of some of the features and / or functions of the wheel module 140.

[0063] The bogie arm suspension member 150 of the wheel module 140 disclosed in Fig. 3 may further comprise a bogie arm rotation restriction arrangement 180, not shown, arranged to define a first angular movement range, -oti through +ai, of the at least two bogie arms 160 relative to the bogie transverse rotation axis, A. Hence, the bogie arm rotation restriction arrangement 180 may restrict the rotation of the at least two bogie arms 160 exceeding the first angular movement range, -on through +ai. The bogie arm rotation restriction arrangement 180 is shown in Fig. 5b and 5c.

[0064] Furthermore, each of the at least two bogie arms 160 comprises at least two bogie abutment surfaces 181, not shown, wherein each bogie abutment surface 181 is arranged to abut a corresponding restriction surface 182 of the bogie arm rotation restriction arrangement 150 if the bogie arm 160 reaches one of the endpoints, -α1 and +α1, of the first angular movement range, -α1 through +α1. Hence, if a rotation of the bogie arm 160 relative to the bogie transverse rotation axis, Ay causes the bogie arm 160 to reach one if its angular endpoints, -oti and +ai, a bogie abutment surface 181 of said bogie arm 160 is arranged to abut, meet, engage with, come into contact, or the like with a corresponding restriction surface 180 of the bogie arm rotation restriction arrangement 150. Hence, the bogie arm rotation restriction arrangement 180 may restrict the rotation of the at least two bogie arms 160 exceeding the first angular movement range, -oti through +ai. The bogie abutment surfaces 181 are shown in Fig. 5c. According to Fig.5c, each bogie arm 160 comprisestwo bogie abutment surfaces 181 located on opposite sides ofthe bogie transverse rotation axis, AT. Also, according to Fig. 5c, each bogie abutment surfaces 181 is located on their respective bogie arm 160 facing the bogie arm suspension member 150. It should be noted that the bogie abutment surfaces 181 may vary in shape and location on the bogie arms 160.

[0065] Fig.4 schematically illustrates a wheel module 148 according to an exemplifying embodiment of the invention. It should be noted that the wheel module 140 shown in Fig.4 has several features in common with the wheel module 140 shown in Figs.1-3, and some references may have been omitted in Fig.4 for this reason. It is hereby referred to Figs.1-3 and the associated text for an increased understanding of some of the features and / or functions ofthe wheel module 140.

[0066] According to Fig.4, the bogie arm suspension member 150 comprises spaced-apart bearing areas 210 for the rotation ofthe bogie arm suspension member 150 relative to the bogie parallel rotation axis, Ap, and for the rotation ofthe at least two bogie arms 160 relative to the bogie transverse rotation axis, AT. Hence, the spaced-apart bearing areas 210 enables the rotation of the bogie arm suspension member 150 and of the bogie arms 160. For example, the bogie arm suspension member 150 may have the shape of a cross, wherein the spaced-apart bearing areas 210 are located at each end portion of the cross-shaped bogie arm suspension member 150. It should be noted that other shapes ofthe bogie arm suspension member 150 is feasible.

[0067] Shown in Fig.4 are how the spaced-apart bearing areas 210 are joined by at least one internal lubrication channel 215 ofthe bogie arm suspension member 150. In other words, the bogie arm suspension member 150 is at least partially hollow. The internal lubrication channel 215 may allow lubricant to flow between the spaced-apart bearing areas 210 of the bogie arm suspension member 150. It is to be understood that the spaced-apart bearing areas 210 may be joined by a plurality of internal lubrication channels 215.

[0068] Furthermore, in Fig.4 a first sealable lubrication port 220 of the supporting element 110 is arranged to be fluidly connected to a second sealable lubrication port 230 of the bogie arm suspension member 150 to deliver a lubricant from the supporting element 110 to the bogie arm suspension member 150. In other words, a lubricant can flow from the first sealabl e lubrication port 220 of the supporting element 110, to the second sealable lubrication port 230 of the bogie arm suspension member 150. It should be noted that the supporting element 110 and the bogie arm suspension member 150 may comprise additional sealable lubrication ports. For example, according to Fig.4, the supporting element 110 comprises two first seal able lubrication ports 220, and the bogie arm suspension member 150 comprises two second sealable lubrication ports 230.

[0069] Furthermore, the first and second sealable lubrication ports 220, 230 are independently sealable. This allows for the road wheel module 140 to be disconnected from the track assembly 100 if desired, without disconnecting a lubrication hose of the track assembly. The first and second sealable lubrication ports 220, 230 may be fluidly connected to each other using a sealable element such as an o-ring, or any other suitable seal able olomont.

[0070] The bogie arm suspension member 150 shown in Fig.4 is fluidly connected to the at I east two bogie arms 160 to deliver a lubricant via the at least two bogie arms 160 to wheel bearings of the road wheels 170 carried by the at least two bogie arms 160. According to an Example, a lubricant may be delivered to the wheel bearings of the bogie arms 160 from a first sealable lubrication port 220 of the supporting element 110, via the bogie arm suspension member 150.

[0071] Figs. 5a-c schematically illustrates a wheel module 140 according to an exemplifying embodiment of the invention. It should be noted that the wheel module 140 shown in Figs. 5a-c has several features in common with the wheel module 140 shown in Figs.1-4, and some references may have been omitted in Figs. 5a-c for this reason. It is hereby referred to Figs.1-4 and the associated text for an increased understanding of some of the features and / or functions of the wheel module 140.

[0072] According to Fig.5a, the bogie arm suspension member 150 comprises a bogie arm suspension mombor rotation restriction arrangement IGO arranged to define a second angular movement range, -012 through +ot2, of the bogie arm suspension member 150 relative to the bogie parallel rotation axis, Ap. Hence, the bogie arm suspension member rotation restriction arrangement 190 may restrict the rotation of the bogie arm suspension member 150 exceeding the second angular movement range, -α2 through +α2. The bogie arm suspension member rotation restriction arrangement 190 is shown in Fig.5b and 5c. It should be noted that Fig.5b discloses a road wheel module 140 comprising eight road wheels 170 instead of four road wheels 170 as disclosed in Fig.2, both feasible embodiments of the road wheel module 140.

[0073] According to Figs.5a-c, the track assembly 100 further comprises restriction surfaces 191 stationary arranged relative to the supporting element 110. For example, the supporting element 110 may comprise the restriction surfaces 191. The bogie arm suspension member rotation restriction arrangement 190 comprises at least two bogie arm suspension mombor abutment surfaces 182, wherein each bogie arm suspension mombor abutment surface 182 is arranged to abut a corresponding restriction surface 131 if the bogie arm suspension member 150 reaches one of the end points, -α2 and +α2, of the second angular movement range, -α2 through +α2. Hence, if a rotation of the bogie arm suspension member 150 relative to the bogie parallel rotation axis, Ap, causes the bogie arm suspension member 150 to reach one if its angular endpoints, -α2 and +α2, a restriction surface 191 is arranged to abut, meet, engage with, come into contact, or the like with a corresponding bogie arm suspension member abutment surface 192 of the bogie arm suspension member rotation restriction arrangement 190. Hence, the bogie arm suspension member rotation restriction arrangement 190 may restrict the rotation of the bogie arm suspension member 150 exceeding the second angular movement range, -α2 through +α2. According to Figs.5b and 5c, the bogie arm suspension member abutment surfaces 192 of the bogie arm suspension member rotation restriction arrangement 190 are transverse elements, parallel to the bogie transverse rotation axis, A. Furthermore, the bogie arm suspension member abutment surfaces 192 are, according to said figures, located on opposite sides of the bogie arm suspension member 150 relative to the bogie transverse rotation axis, AT. It should be noted that the bogie arm suspension member abutment surfaces 192 may vary in shape and location on the bogie arm suspension member 150.

[0074] More specifically, according to Fig.5b-5c, the bogie arm rotation restriction arrangement 180 and the bogie arm suspension member rotation restriction arrangement 190 are together formed as a unified rotation restriction arrangement 180, 199, wherein the unified rotation restriction arrangement comprises a plurality of abutment surfaces 200. It should be noted that the plurality of abutment surfaces 200 of the unified rotation restriction arrangement 180,199 may thus be the same surfaces as the restriction surfaces 182 of the bogie arm rotation restriction arrangement and as the bogie arm suspension member abutment surfaces 192. The plurality of abutment surfaces 255 of the unified rotation restriction arrangement 180, 199 is arranged to restrict the rotation of the at least two bogie arms 160 relative to the bogie transverse rotation axis, Ay, thus defining the first angular movement range, -oti through +ai, and to restrict the rotation of the bogie arm suspension member 150 relative to the bogie parallel rotation axis, Ap, thus defining the second angular movement range, -α2 through +α2. In the enlarged view of Fig. 5c, it is shown how an abutment surface 200 of the unified rotation restriction arrangement 180, 199, is sandwiched between a stationary restriction surface 191 and an abutment surface 181 of a bogie arm 160.

[0075] As described herein, each of the at least two bogie arms 160 comprises at least two bogie abutment surfaces 181, wherein each bogie abutment surface 181 is arranged to abut a corresponding abutment surface 200 of the bogie arm suspension member 150. It is understood that the respective abutment surface 181 of the at least two bogie arms 160 do not have to be a separate component projecting from the respective bogie arm 160, as illustrated in Fig.5c. Instead, the abutment surface 181 may be a first surface of the bogie arm 160 itself, arranged to face a first surface of the abutment surface 200 of the bogie arm suspension member 150. In other words, each abutment surface 181 of the at least two abutment surfaces 181 may be integrally formed with a respective bogie arm 199 of the at least two bogie arms 160. This may be achieved by the respective abutment surface 200 of the bogie arm suspension member at least partially overlapping with the respective first surface of the respective bogie arm 160 along a direction parallel to the bogie transverse rotation axis, AT. Furthermore, the stationary restriction surface 191 may also at least partially overlap with the respective first surface of the respective bogie arm 160 along a direction parallel to the bogie transverse rotation axis, AT. Put differently, the stationary restriction surface 191 and the abutment surface 200 of the bogie arm suspension member 150 may extend further along the bogie transverse rotation axis, Ay, compared towhat is illustrated in Fig. 5c, in order to at least partially overlap the respective abutment surface 181 of the respective bogie arm 160 along a direction parallel to the bogie transverse rotation axis, A, wherein the abutment surface 181 is formed by an integrated first surface of the bogie arm 160.

[0076] This may be advantageous in that the bogie arm 160 comprises relatively few elements, components, or the like. Hence, the bogie arm 160 may comprise relatively few joints, connections, couplings, assembly points, orthe like, thereby providing increased structural strength and reliability under external forces. Furthermore, by having the abutment surface 181 to be a first surface of the bogie arm 160 itself, compared to having a separate component projection from the bogie arm 160, a longer lever arm may be achieved between the bogie parallel rotation axis, Ap, and the abutment surface 181, in a direction parallel to the bogie transverse rotation axis, AT. Put it differently, a lateral fourth distance, D, between the bogie parallel rotation axis, Ap, and the abutment surface 181 may be increased if the abutment surface 181 is integrally formed with the bogie arm 160, wherein the fourth distance, DA, extends perpendicular to the bogie parallel rotation axis, Ap. A distance between the bogie transverse rotation axis, Ay, and the abutment surface 181, wherein the distance extends perpendicular to the bogie transverse rotation axis, Ay, is determined based on the length of the bogie arm suspension member 150 along the bogie parallel rotation axis, Ap, and the length of the bogie arm 160 along the bogie parallel rotation axis, Ap.

[0077] This may be advantageous as a longer lever arm between the bogie parallel rotation axis, Ap, and a contact area between the abutment surface 181 of the bogie arm and the abutment surface 200 of the bogie arm suspension member 150 may reduce the reaction force reguiredto resist a given torgue, thereby lowering contact stress and promoting a more uniform load distribution across the abutment surface 181. This may in turn reduce localized wear and improve the durability of both the abutment surface 181 and the bogie arm 160. The same advantages may apply where a longer lever arm between the bogie parallel rotation axis, Ap, and a contact area between the abutment surface 200 of the bogie arm suspension member 150 and the stationary restriction surface 191 is achieved.

[0078] According to an example, at least one of α1=40°and α2=20°is fulfilled. More preferably, at least one of α1=30°and α2=10°is fulfilled. Most preferably, at least one of α1=22° and α2=7° is fulfilled. According to another example, the first angular movement range, -α1 through +α1, and / orthe second angular movement range, -α2 through +α2 may differ between the direction of the rotation, i.e., clockwise, or anti-clockwise. According to yet another example, the first angular movement range, -α1 through +α1, and / orthe second angular movement range, -α2 through +α2, may differ between different road wheel modules 140 of the track assembly 100. These differences may be based on the locations of the road wheel modules 140 relative to the track assembly 100 and / or on expected ground characteristics.

[0079] Fig.6 schematically illustrates a wheel module 140 according to an exemplifying embodiment of the invention. It should be noted that the wheel module 140 shown in Fig.6 has several features in common with the wheel module 140 shown in Figs.1-5, and some references may have been omitted in Fig.6 for this reason. It is hereby referred to Figs.1-5 and the associated text for an increased understanding of some of the features and / or functions of the wheel module 140. According to Fig. 6, each of the at least two road wheels 170 of each bogie arm 160 comprises a pair of road wheels 170 arranged coaxially each other. Hence, according to the example of Fig.5, a road track module 140 comprises at least eight road wheels 170. It should be noted that a track assembly 100 may comprise a combination of road track modules 140 having different amount of road wheels 170. For example, one road track module 140 of the track assembly 100 may comprise four road wheels 170 as shown in Fig. 2, whereas another road track module I4D of the same track assembly 100 may comprise eight road wheels 170 as shown in Fig. 6.

[0080] Fig.7 schematically illustrates a wheel module 140 according to an exemplifying embodiment of the invention. It should be noted that the wheel module 140 shown in Fig.7 has several features in common with the wheel module 140 shown in Figs. 1-6, and some references may have been omitted in Fig.7 for this reason. It is hereby referred to Figs. I-G and the associated text for an increased understanding of some of the features and / or functions of the wheel module 140.

[0081] According to Fig.7, at least one of the at least two bogie arms 160 further comprises a secondary bogie arm 165 rotatably mounted to said bogie arm 160. At least one road wheel I7D of said bogie arm 160 comprises a pair of road wheels 170 located at opposite sides of the secondary bogie arm 165 relative to an axis parallel to the bogie transverse rotation axis, A. As shown in Fig.7, said secondary bogie arm 165 may be mounted to a first end of said bogie arm 160. Said bogie arm 160 may carry a road wheel I7D at a second end of said bogie arm, opposite the secondary bogie arm 165 relative to the bogie transversal rotation axis, AT. According to Fig.7, each of the at least two bogie arms 160 comprises said secondary bogie arm 165. In other words, the road wheel module 140 may comprise at least four bogie arms 160. Hence, the road wheel module 140 may comprise two bogie arms 160 on each opposite sides of the bogie arm suspension member 150 relative the bogie parallel rotation axis, Ap. Hence, each combination of bogie arm 160 and secondary bogie arm 165 may carry three road wheels 170 in total, according to Fig.

[0082] 7. The road wheel module 140 shown in Fig.7 may be compared to a rocker bogie.

[0083] Fig. 8 schematically illustrates a work machine 300 comprising a track assembly 100 according to an exemplifying embodiment of the invention. It should be noted that the track assembly 100 and the wheel module 140 shown in Fig.3 has several features in common with the track assembly 100 and wheel module 140 shown in Figs.1-7, and some references may have been omitted in Fig.8 for this reason. It is hereby referred to Figs.1-7 and the associated text for an increased understanding of some of the features and / or functions of the track assembly 100 and the wheel module 140.

[0084] According to Fig.8, the work machine 300 comprises four track assemblies IDD, but it should be noted that other number of track assemblies IDD are feasible. In more general terms, the work machine 300 comprises at least two track assemblies IDD. It should be noted that the track assemblies IDD disclosed in Fig. 8 are the same track assemblies IDD disclosed in different embodiments throughout the application. The work machine 300 shown herein is a forestry vehicle, more specifically a forwarder. It should be noted that the claimed track assembly 100 is suitable for other machines and vehicles, such as excavators, forklifts, tractors, cranes, loaders, harvesters, or the like.

[0085] Furthermore, the track assembly 100 comprises a track support beam 110 forming the supporting element 110. The track support beam IID may be arranged to be connected to the frame of the work machine 300 by a suspension arrangement, allowing movement, relative to the frame, of the track support beam IID at least in parallel with the longitudinal direction, Dl. The suspension arrangement will be further discussed in connection to Fig.3. The movement of the track assembly 100 relative to the frame can be controlled by actuators and / or be a result of spring action elements. Further, this movement relative the frame can at times be different fortrack assemblies 100 at different sides of the frame and at different ends of a singletrack assembly 100, i.e., the track assembly 100 can be rotated relative to a track assembly rotation axis transverse to the longitudinal direction.

[0086] The work machine 300 is intended for work within forest areas and comprises a front II and rear 12 body unit connected to each other by a pivotable coupling 13 such that the angular position between the front II and rear 12 body unit could be changed to steer the work machine during use.

[0087] Both the front II and rear 12 body unit comprises one track assembly 100 arranged on each side of the work machine body unit to support the work machine body unit and power the work machine during driving. The claimed track assembly and work machine could also be used in vehicles with other configuration like for example with only one work machine body supported by track assemblies.

[0088] In the illustrated work machine, the four track assemblies have substantially the same configuration even though the dimensions and size of the different parts of the track assemblies could be adapted to the specific needs of the respective work machine body unit.

[0089] In the front body unit II, an engine and thereto related systems, are arranged to power the work machine during driving as well as the different functions within the vehicle such as for example a crane 15 for handling logs etc. The engine is either a conventional combustion engine and / or an electrical and / or hydraulic configuration and a larger battery capacity to power the different functions of the vehicle.

[0090] Furthermore, the front vehicle body unit II comprises a cabin 16 for one, or more, operators of the vehicle. Within the cabin the reguired user interfaces for driving the vehicle and the different systems and tools arranged on the vehicle.

[0091] The rear work machine body 12 unit of the illustrated vehicle embodiment is adapted for work within the forest area and comprises a load area 18 for logs, and the crane 15 for loading and / or unloading logs 19 from the work machine 10. The load area 18 is formed by six log supports 20 each formed by a lower part referred to as a bunk connected to the vehicle chassis and an upper preferably adjustable part referred to as a stake. The load area could however be modified in different ways to optimize the load area for different purposes and gods. For example, storage of logs transverse to the longitudinal direction of the vehicle, or dividing the load area into two, or more, smaller compartments arranged along the rear vehicle body unit.

[0092] The illustrated work machine has one track assembly 100 on each side of the respective body unit. The number of track assemblies could however be increased if a longer rear vehicle body unit is desired.

[0093] Each track assembly 100 is connected to the frame of the work machine by a suspension arrangement 40. The suspension arrangement is designed to allow a movement of the track assembly 100 relative to the work machine body 12 in a substantially vertical plane extending parallel to the longitudinal direction of the work machine body unit 12 and the track assembly 100 such that the vehicle body could be maintained in a substantially horizontal orientation even though the ground is inclined. Fig. 9 schematically illustrates a track assembly 100 for a work machine 300 according to an exemplifying embodiment of the invention. It should be noted that the track assembly 100 shown in Fig.9 has several features in common with the track assembly 100 in Figs.1-8, and some references may have been omitted in Fig.9 for this reason. It is hereby referred to Figs.1-8 and the associated text for an increased understanding of some of the features and / or functions of the track assembly 100.

[0094] The suspension arrangement 40 for each track assembly 100 comprises a first and a second pendulum arm connecting the track assembly to the work machine. In the illustrated embodiment the first and second pendulum arms are referred to as front 41 and a rear 42 pendulum arm to facilitate the understanding of the description. The front 41 and rear 42 pendulum arm are turnably connected to the work machine and the track assembly support element to allow the track assembly 100 to move in the vertical plane. The front 41 and rear 42 pendulum arm are both turnable around axes transverse to the longitudinal direction of the work machine and the track assembly.

[0095] The front pendulum arm has an elongated substantially straight arm section 44 intended to extend in a plane substantially parallel to the track assembly 100 plane of movement. In the end of the elongated arm section 44 that is intended to be turnable fitted to the frame. An attachment element 45 is extending in a direction substantially transverse from the arm section 44 towards the frame. In the opposite end of the arm section 44, a similar attachment element 46 is extending transverse to the arm section 44 towards the track support element 110. In both the frame and track support element the attachment elements 45, 46 are fitted via suitable bearing to provide a reliable and robust fitting for a long period of time.

[0096] The rear pendulum arm 42 have a similar configuration as the front pendulum arm but the elongated arm section 47 is divided into a first 48 and a second arm segment 43 movably connected to each other to make it possible to adjust the length of the elongated pendulum arm section 47 by adjusting the position of the two arm segments 48, 43 in relation to each other.

[0097] The possibility to adjust the length of the arm section 47 is important for the movement of the track assembly 100 in relation to the work machine body, and necessary to allow the track assembly 100 to move free in the vertical plane into angled positions in relation to the respective body unit.

[0098] In the end of the first pendulum arm segment 48 that is intended to be turnable fitted to the frame an attachment element 50 is extending in a direction substantially transverse form the first arm segment 48 towards the frame, and in the opposite end of the elongated arm section, i.e. the second arm segment 43, a similar attachment element 51 is extending transverse to the second arm segment 43 towards the track assembly support element. In both the frame and track assembly support element the attachment elements 50, 51 are fitted via suitable bearing to provide a reliable and robust fitting for a long period of time. The first 48 and second arm segment 43 are turnably connected to each other by a suitable bearing element 52.

[0099] In an alternative configuration the front pendulum arm, or both pendulum arms, have an adjustable length to allow the track assembly to move in different angles in relation to the work machine body. The suspension arrangement 40 furthermore comprises a control unit 60 and means to hydraulically, or electrically, operate the position of the forward 41 and rear 42 pendulum arm to control the position of the track assemblies 100 in the vertical plane in relation to the work machine.

[0100] Fig.10 schematically illustrates a track assembly 100 for a work machine 300 according to an exemplifying embodiment of the invention. It should be noted that the track assembly 100 shown in Fig.10 has several features in common with the track assembly 100 shown in Figs.1-9, and some references may have been omitted in Fig.10 for this reason. It is hereby referred to Figs.1-9 and the associated text for an increased understanding of some of the features and / or functions of the track assembly 100.

[0101] In Fig.10, a front view of the work machine with the track assemblies in different vertical positions are illustrated. In the left illustration, the work machine is operating on substantially horizontal ground and the track assemblies 100 are arranged at the same distance from the work machine to maintain the work machine body in the desired horizontal position.

[0102] In the illustration to the right, the track assemblies are arranged in different positions to compensate for the inclined ground conditions to maintain the work machine in the desired substantially horizontal position. The positioning of the track assemblies is preferably monitored and operated automatically by the control unit 60.

[0103] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, the supporting element 110, the road wheel module 140, the bogie arm suspension member 150, the bogie arms 160, etc., may have different shapes, dimensions and / or sizes than those depicted / described.

[0104] Additionally, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

Claims1. A track assembly (100) of a work machine having a frame, the track assembly comprising:a supporting element (110) extending along a longitudinal direction, DL, of the work machine;an endless track (120) arranged in the longitudinal direction, DL;a sprocket (130) connected to the supporting element and arranged to drive the endless track; anda road wheel module (140) comprising:a bogie arm suspension member (150) arranged to be rotatably mounted to the supporting element to allow a rotation relative to a bogie parallel rotation axis, Ap, parallel to the longitudinal direction, DL; andat least two bogie arms (160) rotatably mounted to the bogie arm suspension member to allow a rotation relative to a bogie transverse rotation axis, AT, transverse to the longitudinal direction, DL;wherein the at least two bogie arms are mounted on opposite sides of the bogie arm suspension member relative the bogie parallel rotation axis, Ap;wherein each bogie arm carries at least two road wheels (170) located at opposite sides of the bogie transverse rotation axis, A.

2. The track assembly according to claim 1, wherein the bogie arm suspension member comprises a bogie arm rotation restriction arrangement (180) arranged to define a first angular movement range, -α1 through +α1, of the at least two bogie arms relative to the bogie transverse rotation axis, AT.

3. The track assembly according to claim 2, wherein each of the at least two bogie arms comprises at least two bogie abutment surfaces (181), each bogie abutment surface arranged to abut a corresponding restriction surface (182) of the bogie arm rotation restriction arrangement if the bogie arm reaches one of the endpoints, -α1 and +α1, of the first angular movement range, -α1 through +α1.

4. The track assembly according to any of the preceding claims, wherein the bogie arm suspension member comprises a bogie arm suspension member rotation restriction arrangement (190) arranged to define a second angular movement range, -α2 through +α2, of the bogie arm suspension member relative to the bogie parallel rotation axis, Ap.

5. The track assembly according to claim 4, comprising restriction surfaces (191) stationary arranged relative to the supporting element, wherein the bogie arm suspension member rotation restriction arrangement comprises at least two bogiearm suspension member abutment surfaces (192), wherein each bogie arm suspension member abutment surface is arranged to abut a corresponding restriction surface if the bogie arm suspension member reaches one of the end points, -a? and +ot2, of the second angular movement range, -α2 through +α2.

6. The track assembly according to any of claim 2 or 4, wherein the bogie arm rotation restriction arrangement and the bogie arm suspension member rotation restriction arrangement are together formed as a unified rotation restriction arrangement comprising a plurality of abutment surfaces (200) arranged to:restrict the rotation of the at least two bogie arms relative to the bogie transverse rotation axis, A, thus defining the first angular movement range, -α1 through +α1, andrestrict the rotation of the bogie arm suspension member relative to the bogie parallel rotation axis, Ap, thus defining the second angular movement range, -α2 through +α2.

7. The track assembly according to any of claims 2 to 6, wherein at least one of α1=40°and α2=20°is fulfilled.

8. The track assembly according to any of the preceding claims, wherein the bogie arm suspension member comprises spaced-apart bearing areas (210) for the rotation of the bogie arm suspension member relative to the bogie parallel rotation axis, Ap, and for the rotation of the at least two bogie arms relative to the bogie transverse rotation axis, AT.

9. The track assembly according to claim 8, wherein the spaced-apart bearing areas are joined by at least one internal lubrication channel (215) of the bogie arm suspension member.

10. The track assembly according to claim 9, wherein a first sealable lubrication port (220) of the supporting element is arranged to be fluidly connected to a second sealable lubrication port (230) of the bogie arm suspension member to deliver a lubricant from the supporting element to the bogie arm suspension member.

11. The track assembly according to claim 10, wherein the bogie arm suspension member is fluidly connected to the at least two bogie arms to deliver a lubricant via the at least two bogie arms to wheel bearings of the road wheels carried by the at least two bogie arms.

12. The track assembly according to any of the preceding claims, comprising a track support beam (110) forming the supporting element, wherein the track support beam is arranged to be connected to the frame by a suspension arrangement allowing movement, relative to the frame, of the track support beam at least in parallel with the longitudinal direction, DL.

13. The track assembly according to any of the preced i ng claims, wherein each of the at least two road wheels of each bogie arm comprises a pair of road wheels (170) arranged coaxially each other.

14. The track assembly according to any of the preceding claims, wherein the bogie parallel rotation axis, Ap, intersects with the bogie transverse rotation axis, A.

15. The track assembly according to any of the preceding claims, wherein a portion of the bogie arm suspension member is arranged to be permanently secured to the supporting element.I6. The track assembly according to any of the preceding claims, wherein at least one of the at least two bogie arms further comprises a secondary bogie arm (165) rotatably mounted to said bogie arm, andwherein at least one road wheel of said bogie arm comprises a pair of road wheels located at opposite sides of the secondary bogie arm relative to an axis parallel to the bogie transverse rotation axis, AT.

17. The road wheel module (140) according to any of claims 1 to 16, for the track assembly according to any of claims 1 to 16.

18. A work machine (300) comprising at least two track assemblies according to any of claims 1 to 16.

19. The work machine according to claim 18, further comprising a control unit (60) and a controllable suspension arrangement (40) arranged to connect each of the track assembly to the frame and make it possible to adjust the distance between each of the track assemblies and the frame of the work machine,wherein the suspension arrangement of each track assembly is configured to make it possible to move the track assembly in a plane substantially parallel to the longitudinal direction of the work machine.

20. The work machine according to claim 18, further comprising a control unit (60) and a controllable suspension arrangement (40) arranged to connect each of the track assembly to the frame and make it possible to adjust the distance between each of the track assemblies and the frame of the work machine,wherein the suspension arrangement of each track assembly is configured to make it possible to move the at least two track assemblies in substantially parallel planes.

21. The work machine according to claim 18, further comprising a control unit (60) and a controllable suspension arrangement (40) arranged to connect each of the track assembly to the frame and make it possible to adjust the distance between each of the track assemblies and the frame of the work machine,wherein the suspension arrangement of each track assembly is configured to make it possible to move the track assembly in a plane substantially parallel to the longitudinal direction of the work machine,wherein the suspension arrangement of each track assembly is configured to make it possible to move the at least two track assemblies in substantially parallel planes.

22. The work machine according to any of claims 18 to 21, wherein the suspension arrangement of each track assembly comprises at least a first (41) and a second (42) pendulum arm extending between the frame of the work machine and the support element of the track assembly, wherein at least one of the pendulum arms has an adjustable length to allow the track assembly to be arranged in an adjustable angular position relative the longitudinal direction of the work machine.

23. The work machine according to any of claims 18 to 22, wherein each track assembly comprises at least two road wheel modules aligned in the longitudinal direction, DL.

Images