The present invention relates to an axle assembly for a vehicle, a steering mechanism, a vehicle and a trailer. In particular, embodiments of the present invention relate to an axle assembly incorporating one or more electric motors and a steering mechanism.

There is a need in modern society for goods to be delivered to, and collected from, urban and suburban environments and rural areas. In order to minimise the logistical effort and environmental damage associated with such deliveries, it is preferable for deliveries to be undertaken in as few journeys as possible. These tasks are therefore suited to large goods vehicles, such as lorries, due to their large load capacities. However, conventional lorries are not well suited to some urban, suburban, and rural environments, as their considerable length and width, and their fixed rear axles make them difficult to manoeuvre in the restricted spaces which often exist in such areas. For example, stationary and slow-moving vehicles, road furniture, and varying widths of road can all restrict the space available for manoeuvre.

The large internal combustion engines often used to move the considerable weight of lorries also generate a considerable amount of noise and air pollution, which is particularly undesirable in built up and residential areas.

Attempts have been made to improve lorries in this respect. For example, some existing chassis arrangements provide steerable rear axles for lorries provided with internal combustion engines. However, such arrangements are limited in the effectiveness of their steering, and they still have many of the drawbacks associated with the use of an internal combustion engine. It will be appreciated that the terms "goods" and "deliveries" are used in a general sense in this case, and these terms also refer to, for example, the collection of waste, and the transport of passengers. Similarly, discussion of lorries can refer to any large load-carrying vehicle which could conceivably be used on a road.

Embodiments of the present invention seek to ameliorate one or more problems associated with the prior art.

Accordingly an aspect of the invention provides an axle assembly for a vehicle, the axle assembly comprising: a first electric motor; a driveshaft coupled to the first electric motor, the first electric motor being configured to drive rotation of the driveshaft; a first hub configured to be attached to a first wheel of the vehicle; and a first gearbox mounted at least partially within the first hub and coupled to the driveshaft, wherein the first gearbox is configured to convert rotation of the driveshaft into rotation of the first wheel attached to the first hub and the driveshaft includes a first pivotable link between the first electric motor and the first hub such that the first hub is steerable with respect to the first electric motor.

The first gearbox may be a reduction gearbox. The first gearbox may have two reduction stages.

The first gearbox may be an epicyclic gearbox.

The first gearbox may be substantially mounted within the first hub. The first hub may include a first hub casing which is configured to be attached to a first wheel rim and which is configured for rotation with respect to the first electric motor. The first pivotable link may be a double Hooke's joint or a constant velocity joint.

The axle assembly may further comprise a first upright assembly, wherein the first hub is mounted to the first upright assembly, and the first upright assembly may be rotatable with respect to the first electric motor such that the first upright assembly is steerable with respect to the first electric motor.

The axle assembly may further comprise a first ram, wherein the first ram may be coupled at a first end to a mounting positioned relative to the first electric motor and may be coupled at a second end to a mounting positioned relative to the first hub, such that extension and retraction of the first ram may drive rotation of the first hub with respect to the first electric motor about the first pivotable link in a steering movement. The axle assembly may further comprise: a second electric motor; a further driveshaft coupled to the second electric motor, the second electric motor being configured to drive rotation of the further driveshaft; a second hub configured to be attached to a second wheel of the vehicle; and a second gearbox mounted at least partly within the second hub and coupled to the further driveshaft, wherein the second gearbox is configured to convert rotation of the further driveshaft into rotation of the second wheel attached to the second hub and the further driveshaft includes a second pivotable link between the second electric motor and the second hub such that the second hub is steerable with respect to the second electric motor. The first and second wheels may form a pair of wheels located on opposing sides of the vehicle.

The driveshaft and further driveshaft may have respective longitudinal axes which are parallel to each other.

The first and second motors may be configured to be operated independently from each other. The axle assembly may further comprise a locking system configured, when in a locked configuration, to inhibit, constraint, or substantially prevent, movement of the first hub with respect to the first electric motor about the pivotable link. The locking system may be further configured, when in the locked configuration, to inhibit, constraint, or substantially prevent, movement of the second hub with respect to the second electric motor about the pivotable link.

The subframe may be configured to support at least part of the axle assembly with respect to another part of the vehicle.

The subframe may include one or more beams configured to support at least part of the axle assembly and at least one bridge member, wherein the at least one bridge member may be configured to brace the first and second electric motors against movement with respect to each other.

Another aspect of the present invention provides an axle assembly for a vehicle, the axle assembly comprising: a first and a second electric motor; a first and a second axle tube; and a bridge member, wherein the first electric motor is substantially supported by the first axle tube, the second electric motor is substantially supported by the second axle tube, and the bridge member is attached to the first and second axle tubes to secure the first and second motors with respect to each other. More than 50% of the weight of the first electric motor may be supported by the first axle tube and more than 50% of the weight of the second electric motor is supported by the second axle tube.

The bridge member may be a beam which extends between the first and second axle tubes.

Another aspect of the present invention provides a steering mechanism for a vehicle, the steering mechanism including a locking system, the locking system comprising: a first locking element and a co-operative locking element, the first locking element being configured to engage the co-operative locking element in a locked configuration, wherein the steering mechanism includes: an axle member coupled by a pivotable link to an upright assembly, such that the upright assembly is steerable with respect to the axle member about the pivotable link, wherein: the first locking element is secured with respect to the axle member and the co-operative locking element is secured with respect to the upright assembly such that the first locking element and co-operative locking element are moveable with respect to each other between a locked and an unlocked configuration and steering movement of the upright assembly with respect to the axle member is inhibited, constrained, or substantially prevented with the first locking element and the co-operative locking element in the locked configuration.

Another aspect provides a steering mechanism for a vehicle, the steering mechanism comprising: an axle member coupled by a pivotable link to an upright assembly, such that the upright assembly is steerable with respect to the axle member about the pivotable link, a steering ram configured to drive steering of the upright assembly about the pivotable link, the steering ram having first and second ports for the delivery of fluid into and out of the steering ram to control the operation of the steering ram, and a locking system including a locking valve which is configured to be actuated between: a first mode of operation in which the delivery of fluid into and out of first and/or second port of the steering ram is inhibited or substantially prevented such that steering movement of the upright assembly with respect to the axle member is inhibited, constrained, or substantially prevented; and a second mode of operation in which the delivery of fluid into and out of the first and/or second ports of the steering ram is substantially permitted such that steering movement of the upright assembly with respect to the axle member is permitted. The locking system may further comprise a first locking element and a cooperative locking element, the first locking element being configured to engage the co-operative locking element in a locked configuration, wherein the first locking element is secured with respect to the axle member and the cooperative locking element is secured with respect to the upright assembly such that the first locking element and co-operative locking element are moveable with respect to each other between a locked and an unlocked configuration and steering movement of the upright assembly with respect to the axle member is inhibited, constrained, or substantially prevented with the first locking element and the co-operative locking element in the locked configuration.

At least one of the locking element and co-operative locking element may be resiliently biased towards the locked configuration. At least one of the locking element and co-operative locking element may be configured to be actuated between the locked and unlocked configurations by a pneumatic system. Another aspect of the present invention includes a vehicle including an axle assembly and/or a steering mechanism.

The vehicle may be a heavy goods vehicle. Another aspect of the present invention provides a trailer for a vehicle including an axle assembly and/or a steering mechanism.

Another aspect of the present invention provides an axle assembly for a vehicle, the axle assembly comprising: a first electric motor; a driveshaft coupled to the first electric motor, the first electric motor being configured to drive rotation of the driveshaft; a first hub configured to be attached to a first wheel of the vehicle; and a first gearbox mounted at least partially within the first hub and coupled to the driveshaft, wherein the first gearbox is configured to convert rotation of the driveshaft into rotation of the first wheel attached to the first hub and the driveshaft includes a first pivotable link between the first electric motor and the first hub such that the first hub is steerable with respect to the first electric motor; and a locking system configured, when in a locked configuration, to inhibit, constrain, or substantially prevent, movement of the first hub with respect to the first electric motor about the first pivotable link, wherein the locking system is actuated to the locked configuration for normal vehicle travel and to an unlocked configuration to manoeuvre the vehicle at slow speeds.

Another aspect provides a steering mechanism in combination with an axle assembly for a vehicle. Embodiments of the present invention are described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows an axle assembly incorporating aspects of an embodiment of the invention;

Figure 2 shows another view of an axle assembly which incorporates aspects of an embodiment of the invention;

Figure 3 shows a view from a side of an axle assembly which incorporates aspects of an embodiment of the invention;

Figure 4 shows a view from the rear of an axle assembly which incorporates aspects of an embodiment of the invention;

Figure 5 shows a view from above an axle assembly which incorporates aspects of an embodiment of the invention; Figure 6 shows a view from below an axle assembly which incorporates aspects of an embodiment of the invention;

Figure 7 shows a cutaway view of part of an axle assembly which incorporates aspects of an embodiment of the invention;

Figure 8 shows another view of an axle assembly which incorporates aspects of an embodiment of the invention;

Figure 9 shows a further view of an axle assembly which incorporates aspects of an embodiment of the invention; Figure 10 shows a cutaway view of a hub assembly which incorporates aspects of an embodiment of an invention; Figure 1 1 shows a cutaway view of a hub assembly which incorporates aspects of an embodiment of an invention which shows an example of torque transfer through a reduction box;

Figure 12 shows a vehicle of some embodiments;

Figure 13 shows a locking system of some embodiments. The vehicle With reference to figure 12, an embodiment of the present invention includes a vehicle 100. The vehicle 100 may comprise a heavy goods vehicle such as a lorry or truck. The heavy goods vehicle may be an articulated or non- articulated vehicle. In some embodiments, the vehicle is a refuse truck. The vehicle 100 has a plurality of ground engaging wheels 102 which are mounted in pairs. One or more pairs of ground engaging wheels 102 may be driveable to move the vehicle 100 across the ground surface. As such, the one or more driveable ground engaging wheels 102 are mechanically coupled to an engine 103 of the vehicle 100. The engine 103 may be an internal combustion engine or may be an electric engine which includes one or more electric motors or may be a hybrid engine (which includes an internal combustion engine and one or more electric motors).

Typically, the foremost pair of ground engaging wheels 102 is steerable such that they may be used to steer the vehicle 100 along a desired course through the use of a steering wheel or other input mechanism coupled to the steerable ground engaging wheels 102.

Embodiments relate to an axle assembly 10 which forms part of the vehicle 100 and which may be located at or towards the rear of the vehicle 10 such that the axle assembly 10 provides rear wheel steering.

Embodiments of the axle assembly 10 are shown in figures 1 to 1 1 . The axle assembly 10 is mountable to a chassis of the vehicle 100 and a load bearing assembly which supports the axle assembly 10 with respect to the vehicle chassis is referred to herein as the subframe 1 1 . In some embodiments, the subframe 1 1 forms part of the axle assembly 10.

In some embodiments, the axle assembly 10 and/or subframe 1 1 are configured to be fitted to a trailer for a vehicle 100.

It will also be appreciated that elements of the depicted and described axle assembly 10 may be adapted for fitment to a vehicle 100 of different configurations. In the figures, parts of the axle assembly 10 labelled, for example, '12a' and '12b' are parts which are similar to one another (e.g. they perform a similar function), but which are used on different parts of the axle assembly 10. These parts may be identical, symmetrical, or adapted in other ways for their respective position in the assembly 10 as parts sharing the same reference numeral.

The subframe

In some embodiments, the subframe 1 1 may include two chassis mounting parts 12a and 12b, and the chassis mounting parts 12 have mounting portions 14a, 14b which are configured to engage another part of the vehicle 100. The two mounting portions 14a, 14b may be mounting plates 14a and 14b. In other embodiments, only one such chassis mounting part 12 is provided and in other embodiments, more than two chassis mounting parts 12 are provided. The mounting portions 14a, 14b may be secured to the other part of the vehicle 100 by any suitable means, such as the depicted fixings 13 (which may be a plurality of bolts). In addition, one or more further elements may be provided for securing and/or fitting the mounting portions 14a, 14b to the other part of the vehicle 100, such as gaskets, bushes, or similar. The mounting portions 14a, 14b may face or otherwise be positioned towards a vehicle (or 'upper') side of the axle assembly 10 and generally away from a ground surface (or 'lower') side of the axle assembly 10.

The chassis mounting parts 12 may include a number of mounting points for suspending or otherwise attaching other parts of the axle assembly 10.

In some embodiments, for example, a support part 15a, 15b may extend from each respective mounting portion 14a, 14b towards a ground surface (i.e. generally downwardly). The support parts 15a, 15b may each comprise a pair of members forming a V-shaped support part with the pair of members converging towards the ground surface side of the axle assembly 10 to an intersection of the pair of members (the intersections of the support parts 15a, 15b may be generally the closest portions of the support parts 15a, 15b to the ground surface).

The chassis mounting parts 12 may each include a lower pivot mount 20. These lower pivot mounts 20 may be generally located at the intersection of the pair of members forming each respective support part 15a, 15b, or otherwise towards the ground surface side of the axle assembly 10 with respect to the mounting portions 14. Each lower pivot mount 20 may be configured to be coupled to a respective lower arm 28a, 28b such that the lower arm 28a, 28b is pivotable with respect to the chassis mounting part 12 to which it is coupled. In some embodiments, each of the chassis mounting parts 12 includes a respective suspension element mounting portion 16. Each suspension element mounting portion 16 may be configured to be coupled to a respective first suspension element 17a,b. The suspension mounting portions 16 are generally located towards the vehicle side of the axle assembly 10 between the mounting portions 14 and the lower pivot mounts 20 (if provided).

In some embodiments, the chassis mounting parts 12 include respective upper pivot mounts 18, which may be formed integrally with the suspension element mounting portions 16. The upper pivot mounts 18 may be configured to be coupled to an upper wishbone 22. The upper pivot mounts 18 are generally located towards the vehicle side of the axle assembly 10 between the mounting portions 14 and the lower pivot mounts 20 (if provided).

In embodiments, the chassis mounting parts 12 are configured to allow any suitable direction of movement. In some embodiments, the upper and lower pivot mounts 18,20 allow movement of part of the axle assembly 10 with respect to the chassis mounting parts 12 towards or away from the ground surface (i.e. generally vertically). This movement may, for example, be controlled by the suspension elements 17 (which may include the first suspension elements 17a, 17b coupled to the chassis mounting parts 12 of some embodiments).

In some embodiments, the upper wishbone 22 comprises wishbone arms 23a and 23b, which are coupled to the chassis mounting parts 12a and 12b at open end pivots 26a and 26b, and converge at their opposite ends to form a closed end pivot 25. The closed end pivot 25 is configured to be coupled to another part of the axle assembly 10.

As discussed above, in some embodiments, the lower pivot mounts 20 are configured to be coupled to lower arms 28. Each of the lower arms 28 may be mounted by respective first pivoting ends 30 to the respective lower pivot mounts 20. Each lower arm 28 may be an elongate arm and, at an end which is opposite the first pivoting end 30 of each lower arm 28, there may be a second pivoting end 32. The lower pivot arms 28, therefore, may each comprise first and second pivoting ends 30,32 separated by an arm member 31 extending therebetween.

The second pivoting end 32a, b of each lower pivot arm 28 is configured to be coupled, through a pivotable coupling, to a part of the subframe 1 1 . This part of the subframe 1 1 may comprise one or more beams 40 (each lower pivot arm 28 may, in some embodiments, be coupled to a respective beam 40).

Each suspension element mounting portion 16 is configured to be coupled to a respective first suspension element 17a, 17b which may be in the form of an air bag. Each first suspension element 17a, 17b may be coupled at a first end thereof to a respective one of the suspension element mounting portions 16 and at a second end to a respective one of the beams 40. Each first suspension element 17a, 17b may, therefore, be sandwiched between one of the suspension element mounting portions 16 and one of the beams 40.

Each beam 40 is generally disposed parallel to a longitudinal axis of the vehicle 100. As such, for ease of reference, the beams 40 are referred to herein 'longitudinal beams' 40. In some embodiments, the longitudinal beams 40a, 40b form part of the subframe 1 1 . The longitudinal beams 40a,40b (of which there may be two) may be arranged such that they extend past an axle axis which is substantially perpendicular to the longitudinal axis of the vehicle 100 and which passes generally through a centre of wheel hubs of the axle assembly 10 (when the wheel hubs are in a substantially the straight ahead orientation).

In some embodiments, three or more such beams 40 are provided and, in some embodiments, a single beam 40 is provided which includes all of the mounting points and the like of the two beams 40a, 40b described herein in relation to some other embodiments.

The remote ends of each of the longitudinal beams 40a and 40b may include a mounting point for a respective suspension element 17. Each mounting point for a suspension element 17 may be configured to be mounted, or otherwise coupled to, a respective suspension element 17. Thus, each longitudinal beam 40a,40b may have a first mounting point for coupling to a first suspension element 17a, 17b, and a second mounting point for coupling to a second suspension element 17c, 17d - which may be of a similar or identical form to the first suspension elements 17a, 17b.

The longitudinal beams 40a, 40b, therefore, may form part of a suspended cradle which is configured to support other elements of the axle assembly 10 as described herein.

In some embodiments, the longitudinal beams 40a,40b include a widened part towards the centre of their longitudinal lengths. This widened part of each longitudinal beam 40a, 40b provides a surface which faces towards the vehicle side of the axle assembly 10 and on which one or more other parts of the axle assembly 10 may be supported. The axle axis may be located on the vehicle side of the longitudinal beams 40a and 40b between the longitudinal beams 40a, 40b and another part of the vehicle 100.

In some embodiments, one or more cross members 60,65,70 (see figures 2, 4, 5, 6 and 7) extend between the two longitudinal beams 40a, 40b and may be secured to both beams 40a, 40b. The cross member or members 60,65,70 may extend generally parallel to the axle axis. In some embodiments, there are two cross members 60,65,70 and in some embodiments there are three cross members 60,65,70 which extend laterally between the longitudinal beams 40a and 40b - a first cross member 60, a second cross member 65 and a third cross member 70.

The cross members 60,65,70 may each be in the form of beams, and may include mounting points for other components of the axle assembly 10. One cross member (such as the first cross member 60) may be located towards a first end of the axle assembly 10. One cross member (such as the second cross member 65) may be located generally between the axle axis and the ground surface (i.e. generally beneath the axle axis). One cross member (such as the third cross member 70) may be located generally towards a second end of the axle assembly 10.

Each cross member 60,65,70 may be joined or otherwise attached to at least one other cross member 60,65,70 by a cross member link (not shown). In some embodiments, the first cross member 60 may be joined to the second cross member 65 by a longitudinal cross member link (i.e. a link member generally perpendicular to the axle axis). The cross member link may be located at least partially between a component of the axle assembly 10 and the ground surface so as to provide additional support for that component (which may include one or more electric motors 215, for example). In some embodiments (see figures 4 and 6, for example), one or more of the cross members 60,65,70 (the second cross member 65 and the third cross member 70, for example) include one or more mounting points for anti-roll bar mounting brackets 80a and 80b (in some cases there are two such mounting points provided). The anti-roll bar mounting bracket or brackets 80a and 80b may be arranged to retain respective anti-roll bar bushes 81 a and 81 b which are, in turn, mounted to a U-shaped anti-roll bar 82 and to attach the anti-roll bar 82 to the subframe 1 1 of the axle assembly 10. At respective free ends 83a and 83b of the anti-roll bar 82, there may be mounting points 84a and 84b for respective anti-roll bar drop links 85a and 85b. Each drop link 85a, 85b mounts to another part of the vehicle 100 at a respective side of the vehicle 100, such that a load is induced in the respective sides of the anti-roll bar 82 when there is a vertical displacement of one side of the vehicle 100 relative to the other.

The subframe 1 1 may include one or more damper mounts (not shown) which are each configured for pivotable attachment to a respective damper 41 (or other suspension element). The or each damper 41 may form part of the subframe 1 1 and/or axle assembly 10 and is coupled at a first end to a one of the damper mounts. The or each damper 41 is also coupled (at a second end thereof) to another part of the vehicle 100 by another pivotable mount. The or each damper by comprise an elongate body which extends between the two ends of which and which is configured to extend and retract. The or each damper 41 further includes a mechanism for resisting the extension and retraction thereof to dampen movements between the rest of subframe 1 1 (and axle assembly 10), and the rest of the vehicle 100.

As will be appreciated, the subframe 1 1 and its various components provide support for other parts of the axle assembly 10. The subframe 1 1 is permitted a degree of freedom of movement with respect to the rest of the vehicle 100 to allow raising or lowering of another part of the vehicle 100 with respect to the subframe 1 1 . Drive train

In some embodiments, the or each longitudinal beam 40 (or some other part of the subframe 1 1 ) supports a drive train 200 which forms a subassembly of the axle assembly 10.

The drive train 200 includes at least two electric motors 215a and 215b (see figures 2, 4, 5 and 7, for example), each of which is configured to drive a respective ground engaging wheel 102 which may be a wheel 400a and 400b (see figure 7). In some embodiments, two or more electric motors 215 are provided to drive each respective wheel 400. However, in embodiments, there is no mechanical coupling configured to transmit mechanical power between a shaft driving rotation of one of a pair of wheels 400 and a shaft driving rotation of the other of the pair of wheels 400. In some embodiments, the electric motor or motors 215a for driving rotation of one wheel 400a generally face the opposite direction to the electric motor or motors 215b for driving rotation of another wheel 400b. The drive train 200, therefore, may include two substantially identical parts - a first part to drive rotation of one wheel 400a and a second part to drive rotation of another wheel 400b. One of these parts is described below but, as will be appreciated, this description applies equally to both parts of the drive train 200.

In some embodiments (such as that shown in Figure 7), an output shaft 225 of the electric motor 215 is mechanically coupled to a secondary drive shaft 250 via a pivotable joint 240 which may be a universal joint (which may be a Hooke's joint or a double Hooke's joint, or a constant velocity joint). The coupling is such that rotation of the output shaft 225 of the motor 215 causes rotation of the secondary drive shaft 250. In some embodiments, the output shaft 225 of the electric motor 215 is coupled by a primary coupling 230 to a primary drive shaft 226 (see figure 7, for example). The primary coupling 230 may include a first socket configured to receive a portion of the output shaft 225 and a second socket configured to receive a portion of the primary drive shaft 226. The primary coupling 230 may, therefore, be configured to transmit rotational movement of the output shaft 225 to the primary drive shaft 226 via the first and second sockets.

The primary drive shaft 226 may be mechanically coupled to the pivotable joint 240 and the secondary drive shaft 250 may also be coupled to the pivotable joint 240 such that the secondary drive shaft 250 is pivotable about the pivotable joint 240 with respect to the primary drive shaft 226. As will be appreciated, depending on the form the of the pivotable joint 240, the pivotable movement of the secondary drive shaft 250 with respect to the primary drive shaft 226 may be about one or more axes.

Thus, in such embodiments, rotation of the output shaft 225 of the electric motor 215 causes rotation of the primary coupling 230 and primary drive shaft 226. This causes rotation of the pivotable joint 240 which, in turn, drives rotation of the secondary drive shaft 250.

The primary drive shaft 226 may be mounted on one or more bearings (such as the bearing 218) for rotation with respect to an axle tube 245 (and the electric motors 215). In some embodiments, more than one such bearing is provided and the output shaft 225, primary coupling 230, and/or the primary drive shaft 226, may be mounted on one or more bearings. The secondary drive shaft 250, which may pass through an upright assembly 255, is coupled to a hub assembly 260, and is configured to deliver mechanical power to the hub assembly 260.

An example of a hub assembly 260 of some embodiments is shown in Figure - 10.

The hub assembly 260 may include a gearbox 300 (which may be a reduction gearbox or may be geared in an overdrive configuration or a one-to-one configuration) and, in some embodiments, the gearbox 300 is a double reduction epicyclic gearbox. The gearbox 300 is configured to convert rotational movement of an input driveshaft (such as the secondary driveshaft 250) into rotational movement of a wheel 400 associated with the gearbox 300. The gearbox 300 may be at least partially housed in a hub casing 308 of a hub 307 of the hub assembly 260. As such, the secondary driveshaft 250 (or another driveshaft coupled thereto) may pass through a part of the hub casing 308 and into the hub 307. In some embodiments, the secondary driveshaft 250 (or another driveshaft coupled thereto) may pass through a driveshaft tube 306 which is supported by the hub casing 308 of the hub 307. The driveshaft tube 306 may be supported by a bearing 303. In some embodiments, the driveshaft tube 306 is coupled to the upright assembly 255 and may be integrally formed therewith.

In some embodiments, there may be a bearing disposed within the driveshaft tube 306 to support the driveshaft 250 therein.

The secondary driveshaft 250 (or other driveshaft which extends into the hub 307) may be coupled to another driveshaft within the hub casing 308. In any event, in some embodiments, the secondary driveshaft 250 (whether via one or more other driveshafts or not) is mounted with respect to a first sun gear 320 of the gearbox 300 such that rotation of the secondary driveshaft 250 causes rotation of the first sun gear 320. The first sun gear 320 may be configured to mesh with a first set of planetary gears 322. The first set of planetary gears 322 may be mounted on a primary planet carrier 324, and the first set of planetary gears 322 may be configured to mesh with a first ring gear 326. The first ring gear 326 may be fixed against rotation with respect to the upright assembly 255, and may be integrally formed with a gearbox casing 325 mounted within the hub casing 308. The gearbox casing 325 may be fixed against rotation with respect to the upright assembly 255, and may be mounted with a bearing 304 within the hub casing 308. The gearbox casing 325 may be integrally formed with the driveshaft tube 306 or it may be formed separately and joined by any suitable means or the gearbox casing 325 may not be joined to the driveshaft tube 306.

The primary planet carrier 324 may be coupled for rotation with a second sun gear 330, and the second sun gear 330 may be integrally formed with the primary planet carrier 324. In some embodiments, the primary planet carrier 324 is configured to drive rotation of the second sun gear 330.

The second sun gear 330 may be configured to mesh with a second set of planetary gears 332, which may be mounted on a secondary planet carrier 334. The second set of planetary gears 332 may be surrounded by, and configured to mesh with, a second ring gear 336 (which may be fixed against rotation with respect with respect to the upright assembly 255). The second ring gear 336 may be integrally formed with the primary ring gear 326 or it may be formed separately.

The secondary planet carrier 334 may be coupled for rotation with a hub drive part 338 which may be a drive plate, and the secondary planet carrier 334 may be integrally formed with the drive plate 338. In some embodiments, the secondary planet carrier 334 is configured to drive rotation of the hub drive part 338. It will be understood that, in accordance with some embodiments, the gearbox 300 need not be an epicyclic gearbox but could take a number of different forms. For example, the gearbox 300 may be a mesh transmission.

In some embodiments, the gearbox 300 is not a hub mounted gearbox and is, in fact, mounted inboard with respect to the hub casing 308 and/or wheel 400. In such embodiments, the gearbox 300 may be attached to the axle tube 245 and/or the electric motor 215 and/or the subframe 1 1.

The hub drive part 338 may be coupled to drive the hub casing 308, such that rotational movement of the hub drive part 338 causes rotational movement of the hub casing 308.

The hub casing 308 may, in some embodiments, include a fixing point or points for the mounting a brake disc 265 (or part of another braking mechanism), and the brake disc 265 is mounted to the hub casing 308 such that rotational motion of the hub casing 308 results in rotational movement of the brake disc 265 (see figures 1 and 7 - 9, for example).

The brake disc 265 may form part of a brake assembly 270 which may be an air brake system. In embodiments, the brake assembly 270 includes a spring chamber 280. The spring chamber 280 is positioned generally adjacent the brake disc 265 and may have a longitudinal axis which is substantially perpendicular to the axle axis. As will be appreciated, the brake assembly 270 may also include brake pads which are configured to apply a clamping force to the brake disc 265 to slow and/or stop the rotation thereof. The brake pads are associated with a brake actuation mechanism configured to drive the operation of the brake pads with respect to the brake disc 265. The spring chamber 280 may form part of the brake actuation mechanism and may house a spring configured to apply a force to the brake pads, wherein a force applied to the brake pads is controlled by a pneumatically or hydraulically operated arrangement which acts against a biasing force of the spring. In addition or as an alternative, in some embodiments, the brake actuation mechanism includes a pneumatic or hydraulic arrangement to apply a force to the brake pads. The hub casing 308 may be provided with a flange 309 in some embodiments (see figure 10). The flange 309 is configured to be fixed to a wheel rim 415. The wheel rim 415 is configured, in such embodiments, have a tyre 410 mounted thereon, and collectively, the wheel rim 415 and tyre 410 may be referred to as a wheel 400.

In use of some embodiments, the electric motor 215 applies torque to the primary driveshaft 226 (in some embodiments, this torque may be applied through the output shaft 225, which is transferred to the primary driveshaft 226 through the primary coupling 230). The primary driveshaft 226 transfers the torque through the pivotable joint 240 to the secondary driveshaft 250, which transfers the torque to the gearbox (e.g. to the first sun gear 320).

In some embodiments, the torque is transferred to the first sun gear 320 of the gearbox 300. As the first sun gear 320 turns, the torque is transferred through the first set of planetary gears 322, and it will be appreciated that if the first sun gear 320 turns clockwise, the first set of planetary gears 322 will turn anticlockwise, and will cause the primary planet carrier 324 to turn clockwise. Similarly, if the first sun gear 320 is driven anticlockwise the first set of planetary gears 322 will turn clockwise, and the primary planet carrier 324 will turn anticlockwise. It will be appreciated that the relationship between the gears 320,324 produces a reduction ratio, such that the primary planet carrier 324 has a slower rate of turn than the first sun gear 320, but a greater torque. The gearbox 300, therefore, includes a primary reduction stage which may or may not be implemented in the above manner.

In some embodiments, the torque output from the primary planet carrier 324 is the input to the secondary sun gear 330, which operates in the same way as the primary reduction stage (via the second set of planetary gears 332), and results in a further reduced rate of turn and increased torque of the secondary planet carrier 334. The gearbox 300, therefore, includes a secondary reduction stage which may or may not be implemented in the above manner.

The torque is transferred from the secondary planet carrier 334 (at least in some embodiments) to the hub casing 308, through drive plate 338, and to the wheel 400.

In some embodiments, the torque applied at the secondary driveshaft 250 is about 1200Nm, and after the primary reduction stage (which in this case has a reduction ratio of approximately 3: 1 (or about 2.8: 1 )) the resultant torque is about 3369Nm. This about 3369Nm torque is then the input torque for the second reduction stage (which has a reduction ratio of approximately 3: 1 (or about 3.2: 1 )), and this results in a torque output of about 10771 Nm. The overall reduction ratio achieved by the gearbox 300 may be approximately 9: 1 (or about 8.96: 1 ), though it will be understood that other ratios could be achieved using a similar or different gearbox 300. The bridge member

As will be appreciated, in some embodiments, the drive train 200 may be supported by the subframe 1 1 and the axle tubes 245 (one for each part of the drive train 200) may join to both the subframe 1 1 and the drive train 200.

The axle tubes 245 each define a generally cylindrical internal volume, which are each configured (in some embodiments) to house at least part of the output shaft 225 and/or the coupling 230 and/or primary drive shaft 226 and/or the pivotable joint 240 and/or the secondary drive shaft 250 . Each of the axle tubes 245 extends generally parallel to the axle axis and may be generally coaxial therewith. The axle tubes 245 may have an inboard portion (towards the electric motor 215) and an outboard portion (towards the wheel 400). The inboard portion of each axle tube 245 is mounted, in some embodiments, so that it is directly supported by the subframe 1 1 . In other words, a part of the subframe 1 1 is between the inboard portion of each axle tube 245 and a ground surface. The outboard portion may extend outward of the subframe 1 1 such that it is not directly supported by the subframe 1 1 .

In some embodiments, each of the axle tubes 245 has a coupling portion adjacent its inboard end, which in some embodiments may be a flange formation. The coupling portions may mount to a respective motor casing 220 of a respective electric motor 215 (see figure 9). In embodiments, the coupling portions are joined to the motor casings using fixings, which in some cases may be bolts. The axle tubes 245 may support a substantial part of the weight of the motors 215. In embodiments, the axle tubes may support all of the weight of the motors 215. In other embodiments, the axle tubes 245 may support over 80% of the weight of the motors 215. In some embodiments, the axle tubes may support over 50% of the weight of the motors 215. In some embodiments, the axle tubes 245 may support over 30% of the weight of the motors 215. Each of the axle tubes 245 may include a mounting point 246 for a suspension element, such as damper 41 . The or each damper 41 may, therefore, in some embodiments be attached to the subframe 1 1 or, in other embodiments, may be attached to a one of the axle tubes 245 (which may be supported by and attached to the subframe 1 1 ). Adjacent respective inboard sides, each of the axle tubes 245 is mounted by a first (e.g. lower) part thereof to a respective longitudinal beam 40 of the subframe 1 1 , and at a second (e.g. an upper) part thereof, the axle tubes 245 may be configured for attachment to another part of the subframe 1 1 (which may be a bridge member 500 (see figure 9)).

In some embodiments, the bridge member 500 extends across the two electric motors 215a and 215b, and forms a structural link between the two axle tubes 245a and 245b. This structural link provides support for the axle assembly 10 and inhibits movement of first and second parts of the drive train 200 in a manner such that the respective parts of the axle axis (one part of the axle axis being associated with each part of the drive train 200) remain parallel and aligned with each other. In other words, in some embodiments, the bridge member 500 braces the electric motors 215 against movement with respect to each other). This may be advantageous in some embodiments because the axle assembly does not include a conventional differential mounted within a casing to join the axle tubes on each side of the vehicle 100 - which would otherwise provide structural support for the axle assembly 10. In some embodiments, the bridge member 500 forms a structural link between the two axle tubes 245a and 245b, and the axle tubes 245 may support a substantial part of the weight of the motors 215 (and/or gearboxes 300 if inboard). It will be appreciated that the bridge member 500 may therefore support a substantial part of the weight of the motors 215 and may hold the motors 215 in a predetermined position with respect to each other.

The bridge member 500 may provide an upper part (i.e. toward the vehicle side of the axle assembly 10) of a support structure and may form part of the subframe 1 1 . In some embodiments, the bridge member 500 is an elongate beam with a substantially straight main body whose longitudinal axis is generally parallel to the axle axis. The bridge member 500 may include, in some embodiments, angled parts at either end of the main body. The angled parts are configured to be attached or otherwise coupled to the axle tubes 245. As such, the two angled parts of the bridge member 500 may carry respective mounting formations 505 which are configured to mate with corresponding respective mounting formations of the axle tubes 245.

In some embodiments, the bridge member 500 may include mounting points for other components of the axle assembly 10. In some embodiments, a pivot mount 510 is provided as part of the bridge member 500 and the pivot mount 10 may be configured for attachment to the closed end pivot 25 of the upper wishbone 22. The pivot mount 510 may be provided as part of the main body of the bridge member 500 and may be substantially centrally located along a length of the bridge member 500 between the two ends thereof.

The bridge member 500 may be made from any suitable material, and in embodiments, the bridge member 500 is made from Austempered Ductile Iron (ADI). In some embodiments, the bridge member 500 also provides a further mounting point 515 for a bracing member 520 (for example, see figure 8). The bracing member 520 may be attached to the bridge member 500 by the mounting point 515 and may extend in a direction generally perpendicular thereto. The bracing member 520 may also extend generally towards the ground surface and around one or more components of the axle assembly 10 located between the bridge member 500 and the ground surface (and/or between the bridge member 500 and the first cross member 60). In some embodiments, the bracing member 520 extends between the bridge member 500 and the first cross member 60 of the subframe 1 1 (the first cross member 60 may include an attachment formation for securing the bracing member 520 thereto). The bracing member 520 may include one or more mounting points for other components and, in some embodiments, a mounting point 525 for a steering element is provided on the bracing member 520.

In some embodiments, the bridge member 500 is coupled to the cross member link and may be integrally formed therewith.

Steering mechanism

In some embodiments, the outboard portions of the axle tubes 245 are each configured to receive a respective first kingpin 1 12 (see figure 7). The first kingpin 1 12 may be formed from separate or coupled upper and lower sections - the upper section being received by an upper part of the axle tube 245 (i.e. a part of the axle tube 245 away from the ground surface) and the lower section being received by a lower part of the axle tube 245 (i.e. a part of the axle tube 245 towards the ground surface). In some embodiments the first kingpin 1 12 may be mounted substantially vertically (i.e. generally perpendicular to the ground surface and axle axis). A longitudinal axis of the first kingpin 1 12 (which may be a substantially vertical longitudinal axis of the first kingpin 1 12) may intersect a pivotable joint 240.

The upright assembly 255 may, in some embodiments, further include an upright assembly kingpin mount 152, 154 (see figure 4, for example) which may comprise a first kingpin mount 152 and a second kingpin mount 154. The upright assembly kingpin mount 152,154 is configured for engagement with the first kingpin 1 12 such that the upright assembly 255 is pivotable with respect to the outboard portion of the axle tube 245 (about the longitudinal axis of the kingpin 1 12). This arrangement may be repeated in relation to both axle tubes 245 and upright assemblies 255 of the axle assembly 10.

In some embodiments, the first and second kingpin mounts 152, 154 are configured for engagement with different parts of the first kingpin 1 12 (which may be the upper and lower sections thereof respectively).

In some embodiments, the upright assembly kingpin mount 152,154 may be provided with bearings which the mount to rotate about the first kingpin 1 12. In other embodiments, the first kingpin 1 12 may be configured for rotation with the upright assembly kingpin mount 152, 154 with respect to the axle tube 245.

In some embodiments, the first kingpin 1 12, upright assembly kingpin mounts 152, 154 and/or the axle tube 245 are associated with a locking system 469 (see figure 7) configured to inhibit, constrain, or substantially prevent rotation of the upright assembly 255 with respect to the axle tube 245 about the first kingpin 1 12.

The upright assembly 255 may include at least one mounting point 290 for a steering mechanism (for example, see figure 8). The steering mechanism is configured to steer the two wheels 400 which are coupled to the axle assembly 10 and which may form a part thereof. The at least one mounting point 290 is mounted on an arm which extends away from the axle axis to a position to a first side of the electric motors 215 (a second side of the electric motors 215 opposing the first side across a width of the electric motors 215).

The steering mechanism may, in some embodiments, comprise a hydraulically and/or a pneumatically actuated ram 450 and/or a link from a mechanical steering rack (such as a rack and pinion steering rack), which may be actuated by any suitable steering actuator. Optionally, the steering mechanism may include a biasing mechanism which is configured to bias the wheels into the 'straight ahead' position (i.e. such that they are positioned to rotate about an axis which is perpendicular to the longitudinal axis of the vehicle 100).

In some embodiments, the steering mechanism includes a pair of steering rams 450a and 450b (see figure 8). Each of the steering rams 450a, 450b is attached to the mounting point 525 of the bracing member 520 at one end (but may be attached to some other part of the axle assembly 10). The attachment of the steering rams 450 to the mounting point 525 is a pivotable attachment. The other end of each steering ram 450 is attached to the mounting point 290 of a respective one of the upright assemblies 255. The attachments of the steering rams 450 to the mounting points 290 are pivotable attachments.

In some embodiments, each steering ram 450 has an actuator body 451 , an actuator arm 455, and first actuator connecting part 456, and a second actuator connecting part 452. The first actuator connecting part 456 may be configured for movement with the actuator arm 455 and the second actuator connecting part 452 may be configured for movement with the actuator body 451 - the actuator arm 455 being configured for telescopic movement with respect to the actuator body 451. In some embodiments, therefore, the first actuator connecting part 456 of each steering ram 450 is connected to the mounting point 290 of a respective one of the upright assemblies 255. The second actuator connecting part 452 may be connected to the mounting point 525 of the brace member 520. In other embodiments, the steering rams 450 are connected the other way around - with the second actuator connecting part 452 connected to the mounting point 290 of a respective one of the upright assemblies 255 and the first actuator connecting part 456 connected to the mounting point 525 of the brace member 520, for example.

In use, as the actuator arm 455 moves outwardly from the actuator body 451 , it pushes the part of the upright assembly 255 adjacent the first side of the electric motors 215 outwards (i.e. in a direction away from the electric motors 215). This results in the upright assembly 255 pivoting about the first kingpin 1 12. This, in turn, causes a corresponding movement of the wheel 400 which is attached to that upright assembly 255.

Similarly, as the actuator arm 455 moves inwardly with respect to the actuator body 451 , it pulls the part of the upright assembly 255 adjacent the first side of the electric motors 215 inwards (i.e. in a direction towards the electric motors 215). This results in the upright assembly 255 pivoting about the first kingpin. This, in turn, causes a corresponding movement of the wheel 400 which is attached to that upright assembly 255. It will be appreciated that, when the vehicle 100 is undertaking a conventional turning manoeuvre, the two wheels 400 should perform complementary movements. In other words, as a front of one of the wheels 400 moves outward of the vehicle 100, a front of the other of the wheels 400 should move inward of the vehicle 100. Therefore, the two steering rams 450 are also configured to operate in a complimentary manner in some embodiments.

As such, in embodiments, as the two steering rams 450 are hydraulically or pneumatically linked such that extension of one steering ram 450 (i.e. movement of the actuator arm 455 outwardly from the ram actuator body 451 ) occurs at the same time as retraction of the other steering ram 450 (i.e. movement of the actuator arm 455 inwardly with respect to the ram actuator body 451 ).

As will be appreciated, the steering rams 450 may each include a cylinder in which a piston is housed. The piston may be mechanically coupled to the actuator arm 455. A first port 4502 may be provided to provide fluid communication with the cylinder on a first side of the piston and a second port 4503 may be provided to provide fluid communication with the cylinder on a second side of the piston. The delivery of fluid through the first port 4502 of each steering ram 450 and the recovery of fluid from the second port 4503 causing movement of the piston within the cylinder in one direction and the delivery of fluid through the second port 4503 and the recovery of fluid from the first port 4502 causing movement of the piston within the cylinder in another direction. Thus, achieving inward and outward movement of the actuator arm 455 from the actuator body 451 .

The complementary operation of the two steering rams 450 may be achieved hydraulically or pneumatically by providing a fluid communication channel (e.g. a pipe or tube) linking the first port 4502 and second port 4503 of one steering ram 450 with the second port 4503 and first port 4502 of the other steering ram 450, respectively. In some embodiments, the fluid communication channel may not be provided in the configuration described above. Instead, the steering rams 450a and 450b may be hydraulically or pneumatically coupled to respective control systems which are partially or completely independent from each other. Each control system may be configured to control the supply and receipt of fluid from each steering ram 450 to control their operation. For example, in embodiments, each steering ram 450 may have a separate controller, and in embodiments each steering ram 450 may have a separate sensor to provide feedback. Such control systems allow for a degree of redundancy. For example, if the control system for one of the steering rams 450 fails, the other steering ram 450 may still be operational under the control of the other control system.

In some embodiments, a steering link bar 460 is provided. The steering link bar 460 is an elongate bar which is coupled to both of the upright assemblies 255 by respective link bar connections 465 (which may be connections via the first kingpin 1 12 and the link bar connections 465 may be coupled for pivotable movement about the first kingpins 1 12). The steering link bar 460 extends between the two upright assemblies 255 and is configured to constrain movement of the two upright assemblies 255 about their respective first kingpins 1 12 to complementary movement.

As will be appreciated, therefore, in some embodiments, if one of the steering rams 450a fails, the force from the other steering ram 450b will still provide a steering force to the upright assembly 255 to which the functioning steering ram 450b is not attached (and vice versa). This provides a degree of redundancy.

In embodiments, the steering link bar 460 and/or the link bar connections 465 may be adjustable to allow the wheels 400 to be aligned with respect to each other. In yet further embodiments, there may be more than one steering ram 450 acting on each upright assembly 255.

In some embodiments, there is no steering link bar 460 provided. In such embodiments, each upright assembly 255 (and hence each wheel 400) may be independently steered. This may be of use in some manoeuvres.

In some embodiments, a locking system 469 is provided. The locking system 469 is configured to restrict, constrain, or substantially prevent rotational movement of the upright assemblies 255 about the longitudinal axes of their respective first kingpins 1 12. The locking system 469 may constrain the upright assemblies 255 such that the wheels 400 are directed in the straight ahead position. An embodiment of such a locking system is shown in Figure 7.

The locking system 469 may include a part associated with each upright assembly 255. Each such part may include a locking element 470 mounted on or with respect to the bridge member 500 (or axle tube 245) and a co- operative locking element 473 mounted on or with respect to the upright assembly 255. The locking element 470 is configured for movement between a locked position (or configuration) and an unlocked position (or configuration) with respect to the co-operative locking element 473. In the locked position, the locking element 470 extends into engagement with the co-operative locking element 473 and inhibits the movement thereof with respect to the bridge member 500. In the unlocked position, the locking element 470 is retracted from such engagement to permit movement about the longitudinal axis of the first kingpin 1 12. Thus, in use, locking element 470 and co-operative locking element 473 may engage to prevent rotational movement of the upright assembly 150, and therefore the wheel 400. In some embodiments, the locking element 470 may be a pin which is resiliently biased towards the locked position. A biasing member 471 may be provided to apply a biasing force on the pin. The biasing member 471 may be a spring. Movement of the pin against the biasing force may be achieved by using a pneumatic or hydraulic system of the vehicle 100 (which may be part of the air braking system).

In some embodiments, the co-operative locking element 473 may be an aperture defined by a part of the upright assembly 255 and may be provided with a lead in, channel, or guide, to aid engagement of the locking member 470 in the straight ahead position (even if the upright assembly 255 is at least partly out of this position when engagement commences). The locking element 470 may be shaped in a similar or co-operative manner (e.g. with a tapered end portion for engagement with the co-operative locking element 473).

It will be appreciated that, in some embodiments, the locking system 469 will be configured such that movement of the upright assembly 255 is restricted (constrained or substantially prevented) generally automatically on the failure of a vehicle system such as the pneumatic system of the vehicle 100 (which may be the air braking system) - such an event may occur in response to a security or safety alert generated in or by the vehicle 100.

The locking system 469 may include a locking element 470 and co-operative locking element 473 associated with each wheel 400 (i.e. with each upright assembly 255 of the axle assembly 10). In some embodiments, more than one locking element 470 and co-operative locking element 473 is provided for each wheel 400 (i.e. for each upright assembly 255 of the axle assembly 10).

In some embodiments, (see figure 13, for example) the locking system 469 is at least partially provided by the or each steering ram 450. In particular, in some embodiments, the locking system 469 is actuated from the unlocked configuration to the locked configuration by hydraulic or pneumatic locking of the or each steering ram 450 (e.g. one or both of the pair of steering rams 450a, 450b). This locking may be achieved by using a locking valve 4501 of the locking system 469. The locking valve 4501 may be associated with the steering ram 450. The locking valve 4501 is configured to selectively inhibit or substantially prevent the movement of fluid through the first 4502 and/or second port 4503 of the steering ram 450 to lock the steering ram 450 in a particular position/configuration. The locking valve 4501 is, therefore, configured to be actuatable between a first mode of operation (corresponding with the locked configuration of the locking system 469) in which the steering ram 450 is locked and a second mode of operation (corresponding with the unlocked configuration of the locking system 469) in which the locking valve 4501 does not inhibit or substantially prevent the passage of fluid into or out of the steering ram - which is, as such, unlocked.

Accordingly, the locking valve 4501 may be associated with one or both of the first and second ports 4502,4503 of the steering ram 450. In some embodiments, the locking valve 4501 is connected to the first and/or second ports 4502,4503 of the locking valve 4501 in a hydraulic/pneumatic circuit between the steering ram 450 and a part of the control system for the steering mechanism.

In some embodiments, the locking valve 4501 is further coupled to a steering actuator which is configured to control the supply of fluid to and from the first and/or second ports 4502,4503 of the steering ram 450 to control the operation of the steering ram 450 (and provide steering). Therefore, in the second mode of operation, the locking valve 4501 may act to allow the substantially free passage of fluid therethrough from the steering actuator to the steering ram 450. In the first mode of operation, the locking valve 4501 may inhibit or substantially prevent the passage of fluid between the steering ram 450 and the steering actuator.

In some embodiments, two steering rams 450a, 450b are provided. In some of these embodiments, one steering ram 450a may be actuated to provide steering and the other steering ram 450b may be associated with the locking valve 4501 . Accordingly, in some embodiments, one of the steering rams 450b may be a locking ram 450b which does not provide a steering force but which is configured to lock the steering.

In some embodiments, the locking system 469 is configured to enter the locked configuration when fluid pressure to the first or second port 4502,4501 from the control system for the steering mechanism is lower than a threshold pressure. The locking valve 4501 may be configured to actuate, therefore, from the first to the second mode of operation based on a fluid pressure in the steering system.

In some embodiments, the control system for the steering mechanism includes a separate control for the locking valve 4501 , such that the locking valve 4501 (and, hence, the locking system 469) is actuatable via the separate control. The separate control may include, for example, a pilot line which is coupled to the locking valve 4501 . The separate control may be pneumatic, hydraulic, or electric. The separate control may be actuated by an operator (e.g. using a switch) or may be automatically actuated dependent on an aspect of the operation of the vehicle 100 (e.g. the vehicle speed). In some embodiments, the locking valve 4501 is an over-centre valve.

In some embodiments, the locking system 469 is actuated to the locked configuration for normal vehicle travel (e.g. to drive the vehicle 100 along a road) but actuated to the unlocked configuration to manoeuvre the vehicle 100 (or parts thereof) at slow speeds.

Although the provision of a brake assembly 270 has been described, in some embodiments, and in some situations, the electric motors 215 may be used to provide at least some braking for the vehicle 100. The braking provided by the electric motors 215 may be used to charge an energy storage device of the vehicle 100 (such as a battery). It will be appreciated that, in use, aspects of embodiments of the invention seek to provide significant advantages over prior axle assemblies. The reduction gearboxes increase the amount of torque to be transferred to the wheels 400 of the vehicle 100, and this mean that compact electric motors 215 can be used to drive the wheels 400. This reduces noise and air pollution, and allows electric motors 215 to be used without compromising the load space of the vehicle 100, or compromising operational performance of the vehicle 100.

It will also be appreciated that each wheel 400 of the axle assembly 10 of some embodiments has a drive system which can be operated independently of the other wheel 400 of the axle assembly 10. This allows 'torque vectoring' to be implemented in some embodiments: the drive to each wheel 400 can be adapted according to the situation and the torque applied to each wheel 400 may be different. For example, vehicle stability and traction can be increased by managing the drive to each wheel 400, and it can also be used to assist with a steering operation of the vehicle 100. This can reduce tyre scrub, and therefore tyre wear.

It will be appreciated that in some embodiments, one or more sensors may be provided. In some cases, the or each sensor may be configured to sense the angle of the upright assembly 255 relative to the associated axle tube 245 (i.e. the angle of rotation about the longitudinal axis of the kingpin 1 12), and each upright assembly 255 may have at least one such steering angle sensor. In use, a signal from the angle sensor may be used to as feedback to the steering mechanism. Such feedback may be used as an input to part of a control system of the steering mechanism, for example as an influence on the actuation of steering rams 450, or the engagement or disengagement of steering locking system 469.

It will be appreciated that where a steering link bar 460 is provided, it may be possible to provide only one such steering angle sensor, as one upright assembly 255 is linked to the other upright assembly 255, so angular movement in one upright assembly 255 can be derived from the angular movement of the other upright assembly 255. However, some embodiments comprising a steering link bar 460 may include more than one steering angle sensor, to allow redundancy (each steering angle sensor being associated with a different upright assembly 225 and/or multiple steering angle sensors being associated with a single upright assembly 225).

In some embodiments, other sensors may be incorporated into the steering system. For example, there may be one or more linear movement sensors (such as a linear potentiometer) configured to sense movement in one or both of the steering rams 450. Similarly, in some embodiments, one or more pressure sensors may be provided to sense the pneumatic and/or hydraulic pressure in a part or parts of one or both of the steering rams 450.

It will also be appreciated that the drivetrain 200 may include sensors. For example, in some embodiments there may be one or more sensors provided which are configured to sense the speed of a rotating part of the drivetrain 200. In some embodiments, such speed sensors may be used in the control system of the drivetrain 200, such as for control of the motors 215a,b, and/or for control of a braking assembly 270 of the vehicle 100.

It will be appreciated that, in some instances, a first art of an assembly has been described in detail, wherein the assembly will include a second part which is substantially identical to the described first part (e.g. the first part may be a part of the drivetrain 200 associated with a first of a pair of wheels and the second part may be a part of the drivetrain 200 associated with the second of the pair of wheels). For ease of reference components of the two parts may be referred to as first and second components to differentiate between the components of the two parts. It will be appreciated that the combination, in some embodiments of the invention, of a hub mounted gearbox and an electric motor goes against a significant prejudice in the art against such a combination - particularly with a steerable hub. This has significant advantages with respect to the weight distribution and/or maintenance and/or positioning of components and/or versatility of the assembly.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.