PRIORITY DOCUMENT

[0001] The present application claims priority from Australian Provisional Patent Application No. 2021903777 titled “ROAD WHEEL ARM” and filed on 23 November 2021, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to a road wheel arm. In a particular form the present invention relates to an adjustable road wheel arm for use with tracked vehicles.

BACKGROUND

[0003] Tracked vehicles use endless tracks rather than tyres to contact terrain over which they are driven. The endless tracks are configured to travel over a drive sprocket, a plurality of road wheels and a tensioning wheel, and have an external surface that comes in to contact with the terrain and an internal surface that comes in to contact with the drive sprocket, road wheels and tensioning wheel. Many tracks will also feature a plurality of guide horns that project from the internal surface and locate within guide slots provided in the drive sprocket, road wheels and tensioning wheel in order to guide the track during movement of the vehicle.

[0004] Road wheels are attached with respect to the vehicle via road wheel arms, where the road wheel arms are typically formed as a unitary body comprising a spindle providing a support surface for accommodating a hub on which a road wheel is mounted and rotates with respect thereto. The road wheel arms are pivotally connected with respect to the vehicle via a torsion spring and bearing arrangement. The road wheel arm is also configured to accommodate a damping arrangement, such as a hydropneumatic damper extending between the road wheel arm and the vehicle.

[0005] The external surface of the track will often be configured to accommodate track pads that are replaced as they are worn out. If the camber or toe of the road wheel results in a misalignment with the track, uneven and/or undesirable wear of the track pads and/or guide horns may occur. This misalignment may occur for a number of reasons, including poor vehicle manufacturing tolerancing, and the road wheel arm flexing in response to variances in the weight of the vehicle.

[0006] Tracked vehicles may also be able to be equipped with a variety of different track types, where the dimensions vary between tracks, for example the thickness of the track between the external and internal surface. This variation in thickness may result in an undesirable variation of the position of the road wheel and road wheel arm with respect to the vehicle. This may also result in an undesirable variation in the ride height of the vehicle.

[0007] It is against this background that the present disclosure has been developed.

SUMMARY

[0008] According to a first aspect, there is provided a road wheel arm assembly for supporting a road wheel for a tracked vehicle, comprising a road wheel arm comprising a first end configured to pivotally rotate with respect to the vehicle around a first axis, and a second end configured to accommodate a removable spindle, and a removable spindle configured to rotatably support the road wheel, comprising a spindle shaft having a shaft axis that defines the axis of rotation for the road wheel.

[0009] In one form, the second end of the road wheel arm comprises a spindle receiver having a receiver axis, wherein the spindle receiver is configured to receive the spindle.

[0010] In one form, the spindle further comprises a base having a base axis and being configured to be received by the spindle receiver, such that the base axis and receiver axis are coincident, and wherein the spindle shaft extends from the base in a first direction.

[0011] In one form, the spindle further comprises a locating projection extending from the base in a second direction, wherein the spindle receiver and locating projection comprise complimentary surfaces, such that when the spindle is received by the spindle receiver, the spindle is prevented from rotating with respect to the road wheel arm.

[0012] In one form, the shaft axis and the base axis are non-coincident so as to adjust any one or a combination of camber, caster or toe of the road wheel.

[0013] In one form, the locating projection comprises a triangular cross-sectional shape.

[0014] In one form, the locating projection comprises a cross-sectional shape of a curvilinear triangle.

[0015] In one form, the locating projection comprises a cross-sectional shape of a Reuleaux triangle.

[0016] Unlike a circle, this shape prevents rotation of the locating projection relative to the hole in the spindle receiver, while load is still equally distributed on all three sides without having comers providing stress concentration points. [0017] According to a second aspect, there is provided a road wheel arm assembly for supporting a road wheel for a tracked vehicle, comprising a road wheel arm comprising a first end configured to pivotally rotate with respect to the vehicle around a first axis, and a second end configured to accommodate either of at least two interchangeable spindles, each spindle configured to rotatably support the road wheel, and comprising a spindle shaft having a shaft axis that defines the axis of rotation for the road wheel.

[0018] In one form, the second end of the road wheel arm comprises a spindle receiver having a receiver axis, wherein the spindle receiver is configured to receive either of the at least two interchangeable spindles.

[0019] In one form, each spindle further comprises a base having a base axis and being configured to be received by the spindle receiver, such that the base axis and the receiver are coincident, and wherein the spindle shaft extends from the base in a first direction.

[0020] In one form, each spindle further comprises a locating projection extending from the base in a second direction, wherein the spindle receiver and locating projection comprise complimentary surfaces, such that when either spindle is received by the spindle receiver, the spindle is prevented from rotating with respect to the road wheel arm.

[0021] In one form, the shaft axis and the base axis of the first spindle are coincident, such that the shaft axis is coincident with the receiver axis, and wherein the shaft axis and the base axis of a second spindle are non-coincident, such that the shaft axis is non-coincident with the receiver axis, so as to adjust any one or a combination of camber, caster or toe of the road wheel.

[0022] In one form, the vehicle may be configured in at least two alternate configurations, wherein the first spindle may be used with the vehicle is in a first configuration and the second spindle may be used when the vehicle is in a second configuration.

BRIEF DESCRIPTION OF DRAWINGS

[0023] Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein:

[0024] Figure 1 is a perspective view of a road wheel arm assembly, according to an embodiment;

[0025] Figure 2 is a front exploded view of the road wheel arm assembly of Figure 1;

[0026] Figure 3 is a rear exploded view of the road wheel arm assembly of Figure 1; [0027] Figure 4 is a top view of the road wheel arm assembly of Figure 1 ;

[0028] Figure 5 is a side view of the road wheel arm assembly of Figure 1 ;

[0029] Figure 6 is a front view of the road wheel arm assembly of Figure 1 ;

[0030] Figure 7 is a top view of a road wheel arm assembly, according to an alternate embodiment;

[0031] Figure 8 is a side view of the road wheel arm assembly of Figure 7 ; and

[0032] Figure 9 is a front view of the road wheel arm assembly of Figure 7.

DESCRIPTION OF EMBODIMENTS

[0033] Referring to Figures 1 to 6, there is shown a road wheel arm assembly 1 comprising a road wheel arm 100 and a number of interchangeable spindles 200, 300 being configurable to adjust the camber, toe or caster angle, or any combination thereof, of a road wheel carried by the spindles 200, 300.

[0034] In the embodiment shown, the road wheel arm 100, also known as a swing arm, has a first end 101 configured to pivotally connect with respect to the vehicle via a torsion sleeve 110. The torsion sleeve 110 is configured to be accepted by a bearing arrangement (not shown) provided on the vehicle, providing support for pivotal motion of the road wheel arm 100 around a first axis 103 with respect to the vehicle. The torsion sleeve 110 is further configured to accommodate a first end of a torsion bar (not shown), wherein a second end of the torsion bar is connected with respect to the vehicle, the purpose of the torsion bar being to act as a spring, forcing the road wheel arm 100 toward the vehicle track, so that the vehicle track maintains contact with the terrain.

[0035] The road wheel arm 100 is also configured to connect to the vehicle via a damping arrangement, such as a hydropneumatic damper (not shown) acting between an intermediate portion 120 of the road wheel arm 100 and the vehicle.

[0036] The second end 102 of the road wheel arm 100 comprises a spindle receiver 130 having a second axis 133, configured to removably accommodate the interchangeable spindle 200 in such a manner that the spindle 200 is prevented from rotating with respect to the road wheel arm 100.

[0037] As best shown in Figures 2 and 3, the spindle receiver 130 and spindle 200 comprise complimentary features that allow for the spindle 200 to correctly locate with respect to the road wheel arm 100 (the importance of which will be detailed below). [0038] It can be seen that the spindle 200 comprises a circular base section 201 having a base axis 202, from which a spindle shaft 203 extends in a first direction, where the spindle shaft 203 provides a support surface for accommodating a hub on which a road wheel is mounted and rotates with respect thereto. It will be further appreciated that the orientation of the spindle shaft 203 defines a shaft axis 204 around which the road wheel rotates. The spindle receiver 130 comprises a circular socket 132 located around the receiver axis 133, in which a portion of the base 201 of the spindle 200 is received, where it will be appreciated that the base and receiver axes 202, 133 are coincident.

[0039] The spindle 200 also comprises a locating projection 205 extending in a second direction from the base 201, the locating projection 205 has an approximately triangular section configured to extend through a complimentarily shaped through hole 131 provided by the spindle receiver 130. As best shown in Figures 1 and 2, the spindle 200 is inserted into the spindle receiver 130, by correctly orienting the locating projection 205 with respect to the through hole 131. Once fully inserted, a spindle may be secured to the road wheel arm via a bolt (not shown) received in a threaded bolt hole 206 in the locating projection 205, which bears against the road wheel arm 100 when tightened.

[0040] As previously alluded to, the road wheel arm assembly 1 is configured to adjust camber, toe or caster, or any combination thereof, of the road wheel supported by the spindle 200. This is achieved by providing a number of different interchangeable spindles with varying axes of alignment.

[0041] With reference to Figures 4 to 6, it can be seen that in this example the shaft axis 204 is nonparallel with the base axis 202. In this particular configuration, it will be appreciated that this misalignment of the shaft and base axes represents an adjustment to the toe of the road wheel. It will however be appreciated that in alternate embodiments, this misalignment of the shaft and base axes allows for the spindle to be configured to adjust the camber of the road wheel, or a combination of camber and toe, if required.

[0042] With reference to Figures 7 to 9, where a road wheel arm assembly 2 is shown with an alternate spindle 300.lt can be seen that in this example the shaft axis 304 is parallel with, but separated by a predefined distance from the base axis 302. In this particular configmation, it will be appreciated that this separation of axes represents an adjustment to the caster of the road wheel arm assembly 1, effectively allowing for an adjustment in the effective length of the road wheel arm 100. Again, it will be appreciated that in an alternate embodiment, a spindle may be configured to adjust any one or a combination of caster, camber or toe of the road wheel. It will be appreciated that the approximately triangular shape of the locating projection and through hole 205, 131 of the spindle 200 and road wheel arm 100, assists in correctly orienting the spindle 200 with respect to the road wheel arm 100, with the shape assisting in the transferring of forces from the spindle to the road wheel arm, while also preventing rotation of the spindle 200 with respect to the road wheel arm 100. While it will be appreciated that the approximately triangular shape allows the spindle 200 to be inserted in three possible orientations with respect to the road wheel arm 100, alignment markings (not shown) provided on both the road wheel arm 100 and spindle 200 will ensure that correct orientation is achieved.

[0043] The cross-sectional shape of the locating projection 205 may also be referred to as a curvilinear triangle or a Reuleaux triangle, where, it will be appreciated, that unlike a circle, this shape prevents rotation of the locating projection 205 relative to the through hole 131, while load is still equally distributed on all three sides without having corners providing stress concentration points.

[0044] While in the embodiment shown, an approximately triangular shaped locating projection 205 has been employed, it will be appreciated that alternately shaped locating projections having cross-sectional shapes that prevent rotation of the spindle with respect to the road wheel arm, are also intended to fall within the scope of this disclosure. It will also be appreciated that any other means that prevents rotation of the spindle with respect to the road wheel arm is also intended to fall within the scope of this disclosure.

[0045] It will be appreciated that by providing a road wheel arm assembly with a road wheel arm capable of receiving a number of different interchangeable spindles with varying axes of alignment, that the same road wheel arm can always be used, but with different spindles provided depending on the use case for the vehicle.

[0046] It will be appreciated that the vehicle may have a typical or default configmation (such as a typical or default weight or weight range and a typical or default track thickness or thickness range) and that when in this configmation, the base and receiver axes correspond to the correct or desired axis of rotation for the road wheel. Accordingly, a default spindle may be used where the base and shaft axes me coincident. It will further be appreciated that when variations me made to the vehicle configmation, that various alternate spindles may be used, having non-coincident base and shaft axes configured to maintain the correct or desired axis of rotation for the road wheel.

[0047] In an example of this solution in use, it is envisaged that the road wheel arm assembly 1 may be used on a vehicle platform that may have a variety of configurations, such that in one configuration the vehicle may have a default weight of approximately 35 tonnes, and then in another configuration the vehicle may weigh approximately 50 tonnes. It will be appreciated that this additional weight may cause the road wheel arms to elastically deform or flex in such a way that the orientation of the second end of the road wheel arm varies from the correct or desired axis of rotation. In order to accommodate this change in orientation, each spindle can be swapped out for one that provides the correct or desired axis of rotation for the road wheel. [0048] In another example of this solution in use, it is envisaged that the road wheel arm assembly 1 may be used on a vehicle platform that may be equipped with a variety of different track types, where the dimensions vary between tracks, for example, the thickness of the track between the external and internal surface. This change in track thickness may result in an undesirable variation in the ride height of the vehicle. In order to accommodate this change in ride height, each spindle can be swapped out for one that provides a change in caster, thereby providing the correct or desired ride height for the vehicle. It will be appreciated that these are only some of the possible use cases in which this road wheel arm assembly may be employed and that a variety of alternative spindle configmations may be employed, comprising adjustments to any one or all of the camber, caster or toe of the road wheel as required.

[0049] Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0050] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0051] In some cases, a single embodiment may, for succinctness and/or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0052] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.