GB2574475A

GB2574475A - Wheel assembly

Info

Publication number: GB2574475A
Application number: GB1809466.4A
Authority: GB
Inventors: John Kaye Michael; Robert Yarrow Andrew
Original assignee: Design Prototype Manufacture and Supply Ltd
Current assignee: Design Prototype Manufacture and Supply Ltd
Priority date: 2018-06-08
Filing date: 2018-06-08
Publication date: 2019-12-11
Anticipated expiration: 2038-06-08
Also published as: GB201809466D0; GB2574475B

Abstract

A wheel assembly (10) centered on a rotational axis (12). The wheel assembly (10) comprises a shaft (14) rotatable about the rotational axis (12) and a wheel (16) carried on the shaft (14). There is also provided a brake assembly (18) comprising a first brake plate (26) carried on the shaft (14), a first non-rotatable housing (20), and a second brake plate (22). The second brake plate (22) is non-rotatable about the rotational axis (14) and the second brake plate (22) is moveable axially along the rotational axis (12) between a first configuration in which the non-rotatable second brake plate (22) is urged into engagement with the rotatable first brake plate (26) a second configuration in which the non-rotatable second brake plate (22) is spaced apart from the rotatable first brake plate (26).

Description

WHEEL ASSEMBLY

The present disclosure relates to a wheel assembly.

In particular the disclosure is concerned with a wheel assembly for a vehicle, where the wheel assembly is configured for travelling on railway track.

Background

Wheels with brakes are provided for manual handling equipment, for example rail handling equipment for moving and positioning of railway track, and trollies for transport of equipment on a railway track. This generally takes the form of a mechanical and manually operated brake on some, but not all, of the wheels of the vehicle. Such mechanically operated brakes are advantageous as rail handling equipment, and trollies for carrying of equipment on rails, operate in harsh environments and must operate with the minimum of maintenance.

The brakes tend to have a pad which abuts an external diameter of the wheel to slow the vehicle and/or hold the vehicle in position. Hence the brake pad acts on the same wheel surface that bears on the railway track.

A problem with these devices arises if debris gets between the brake pads and the wheel, increasing wear and reducing effectiveness which may result in the rail vehicle from moving after the brake has been applied. Also any wear or damage suffered by the wheel from rolling on the track will reduce its effectiveness as a braking surface.

Hence a system for ensuring that vehicles are sufficiently and effectively braked to increase safety of users of the track and the equipment is highly desirable.

Summary

According to the present disclosure there is provided apparatus as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

Accordingly there may be provided a wheel assembly (10) for a rail vehicle, wherein the wheel assembly (10) is centred on a rotational axis (12), and comprises : a shaft (14) rotatable about the rotational axis (12); a wheel (16) configured for use on railway track and carried on the shaft (14); a brake assembly (18) comprising : a first brake plate (26) carried on the shaft (14); a first non-rotatable housing (20) which supports a second brake plate (22), wherein the second brake plate (22) is nonrotatable about the rotational axis (14) and the second brake plate (22) is moveable axially along the rotational axis (12) between : a first configuration in which the nonrotatable second brake plate (22) is urged into engagement with the rotatable first brake plate (26); and a second configuration in which the non-rotatable second brake plate (22) is spaced apart from the rotatable first brake plate (26).

The brake assembly may comprise an actuator (28) coupled to the second brake plate (22) operable to move the second brake plate (22) between the first configuration and the second configuration.

The actuator (28) may comprise an electro-magnet (30), and the second brake plate (22) comprises, or is mounted to, a magnetic material such that when the electromagnet (30) is operating the second brake plate (22) is drawn towards the electromagnet (30).

A resilient biasing member (32) may be provided between the electro-magnet (30) and the second brake plate (22) in order to bias the second brake plate (22) towards the first configuration or the second configuration.

The electro-magnet (30) may be operable to receive : a first control signal from a switch (34) to turn the electro magnet (30) on; and a second control signal from a switch (34) to turn the electro magnet (30) off.

The wheel (16) may extend along the rotatable axis (12) and has a cavity (36) in which the brake assembly (18) is located.

The wheel (16) may have a frusto-conical main body portion (52) which increases in diameter from a first end (54) to a second end (56), and a flange (58) which extends from the second end (56) in a direction away from the rotational axis (12).

The cavity (36) may be provided in the frusto-conical main body portion (52) and may open onto the first end (54).

There may be provided a vehicle (50) comprising a wheel assembly (10) according to the present disclosure.

The vehicle (50) may comprise : a support frame (50) to which the wheel assembly (10) is coupled such that: when the second brake plate (22) in the first configuration the wheel (16) is braked; and when the second brake plate (22) is in the second configuration the wheel (16) is rotatable to allow the vehicle to travel.

All wheels of the vehicle (50) may be a wheel assembly according to the present disclosure.

The vehicle may be a rail handling device (80), and comprise a leg (60) which extends from the support frame (50) to support a lifting beam (62) and a chain hoist (64) slideably mounted on the lifting beam (62) such that the chain hoist (64) is operable to move along the lifting beam (62).

The chain hoist (64) may be manually operated by a handle (66). The handle (66) may be rotatable about a chain hoist rotational axis (68) such that the chain hoist (68) is operable to raise/lower a chain when the handle (66) is rotated about the chain hoist rotational axis (68). The chain hoist rotational axis (68) may be located at distance (h) from the wheel assembly rotational axis (12) such than an operator can operate the handle (66) while standing substantially upright.

The distance h may be no less than 0.6m and no more than 1.1m.

The vehicle may comprise a support platform (70) carried on the support frame (50).

There may also be provided a vehicle system comprising at least two vehicles (50) according to the present disclosure. Each wheel assembly (10) may be operable to simultaneously receive a control signal from a switch (34) on one of the vehicles so as to lock/unlock each wheel assembly (50) of each vehicle (50) at the same time.

Hence there is provided a wheel assembly for a vehicle, and a vehicle comprising the wheel assembly. The vehicle may be for use on a railway track. Since the brake assembly is fitted to an interior region of the wheel it is inherently less likely to be contaminated with debris and/or damaged, and hence is more likely to operate successfully than examples of the related art.

Also since the brake of the present disclosure employs a dedicated rotor brake plate and stator brake plate which bear on each other (rather than employing an external surface of the wheel as one of the braking surfaces), the components of the brake will maintain their desired configuration, material properties and/or surface finish for longer, and hence successfully operate for longer than example devices of the related art.

The wheel assembly may be provided as all of the wheels on the vehicle, and operated centrally by a single switch. Hence all of the wheels of the vehicle may be braked at the same time and released (i.e. allowed to rotate) with a single action of an operator. In the event that the brake mechanism of any one of the wheel assemblies should fail, then the vehicle will still be braked as effectively as an example device of the related art.

Brief Description of the Drawings

Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

Figure 1 shows an example of a rail carrier vehicle comprising a wheel assembly according to the present disclosure;

Figures 2, 3 show different views of the vehicle shown of Figure 1;

Figure 4 shows a side view of a trolley unit for use on a railway track which includes a wheel assembly according to the present disclosure;

Figure 5 shows an exploded view of a wheel assembly according to the present disclosure;

Figure 6 shows a side view of the exploded view shown in Figure 5;

Figure 7 shows a cross-sectional view of the arrangement shown in Figure 6.

Figure 8 shows a cross sectional view of the wheel assembly in a locked configuration; and

Figure 9 shows a cross sectional view of the wheel assembly in a locked configuration.

Detailed Description

A wheel assembly 10 of the present disclosure may be fitted to a vehicle. In particular it may be fitted to a rail vehicle or other equipment for travelling on rail. Alternatively it may be fitted to any other kind of land vehicle and/or other wheeled device, which may include, by way of non-limiting example, tool carts, trolleys, material handling tools, and scaffolding.

Shown in Figures 1 to 3 is a vehicle 50 which is a rail handling device 80 which comprises the wheel assemblies 10 of the present disclosure. This vehicle 50 may comprise a pair of support frames 50 which each have a wheel assembly 10 according to the present disclosure provided at either end. The rail handling device 80 may further comprise a shelf 102 for supporting articles (i.e. rail sections 100 and/or turnouts) to be carried by the rail handling device 80, which may extend from the support frame 50. The shelf 102 may extend part of the way between the support frames 50 (as shown) or be provided as a beam which spans the full distance between the support frames 50.

A leg 60 may extend away from each support frame 50. The legs 60 are joined by a support beam 62 which carries a chain hoist 64. The chain hoist 64 is slideably mounted on the support beam 62 such that the chain hoist 64 is operable to move along the lifting beam 62. The chain hoist 64 is for lifting sections of rail 100 into position.

All of the wheels of the vehicle may be wheel assemblies according to the present disclosure. Alternatively at least one of the wheels of the vehicle may be a wheel assembly according to the present disclosure. In one example two of the wheels of the vehicle may be a wheel assembly according to the present disclosure. In alternative examples a plurality, but not all, of the wheels of the vehicle may be wheel assemblies according to the present disclosure.

The chain hoist 64 may be powered. That is to say, it may comprise an electrical motor operable by a user to wind up and lower the chain.

In another example, as shown in the figures, the chain hoist 64 may be manually operated by a handle 66. The handle 66 is rotatable about a chain hoist rotational axis 68 such that the chain hoist is operable to raise/lower a chain (and hence the load it is attached to) when the handle 66 is rotated about the chain hoist rotational axis 68. That is to say, the handle 66 is connected to an internal mechanism, which may be known in the art, for winding up and lowering a chain, where the chain holds a grip (or hook, or claw) 110 for lifting items, for example rail track sections 100. The chain hoist rotational axis 68 is located at a distance h from the wheel from a rotational axis 12 of the wheel assembly 10 such that an operator can operate the handle 66 whilst standing substantially upright.

The height h of the chain hoist rotational axis 68 is determined in dependence upon the wheel diameter, the position of the wheel on the support frame 50, the length of the leg 60, the thickness of the support beam 62 upon which the chain hoist 64 is mounted, and the distance of the chain hoist rotational axis 68 relative to the support beam 62, and the likely relative height of the wheels 10 relative to the rail on which they sit, and the likely terrain which the rail handling device will be used in.

The distance h may be no less than 0.6 metres and no more than 1.1 metres. For example the distance h may be about 0.75 metres. Alternatively the chain hoist rotational axis 68 may be at least 0.6 metres but no more than 1.1 metres above the rail head (i.e. the highest point of the rail on which the wheel 16 sits). For example the chain hoist rotational axis 68 may be about 0.75 metres above the rail head. This covers a range of heights (e.g. slightly above waist height) which results in comfortable operation for an average sized operator.

Alternatively, as shown in Figure 4, a wheel assembly of the present disclosure may be included on a trolley type vehicle, where the vehicle comprises a support frame 50, i.e. supports for carrying the wheel assemblies 10, and a platform 70 fitted to the top of the support frame 50.

Figures 5, 6 and 7 show an exploded view, side view and section respectively of the wheel assembly 10. Figures 8, 9 show a cross sectional view of the wheel assembly shown in Figures 5, 6, 7.

The wheel assembly 10 is centred on a rotational axis 12. The wheel assembly 10 comprises a shaft (or axle) 14 rotatable about the rotational axis 12. A wheel 16 is carried on, and fixed to, and rotatable with, the shaft 14. The shaft 14 may be fixed to the wheel 16 by any suitable means, for example bolts (as shown in Figures 8, 9). However any other appropriate fixing means (for example welding, bonding, friction, interference bond) may be used instead. The wheel 16 extends along the rotatable axis 12 and has a cavity 36 in which a brake assembly 18 is located/housed. The cavity 36 is open on one side 54.

In the example shown the wheel 16 is configured for use on a railway track, and hence has a frusto-conical main body 52 which increases in diameter from a first end 54 to a second end 56. A flange 58 extends from the second end 56 in a direction away from the rotational axis 12. That is to say, the flange extends perpendicular to the rotational axis 12 of the wheel assembly.

The cavity 36 is provided in the frusto-conical main portion 52 and opens onto the first end 54.

The brake assembly 18 comprises a first brake plate 26 carried on, fixed to, engaged with and rotatable with the shaft 14. Put another way, the first brake plate 26 is directly coupled to the shaft 14. Hence the first brake plate 26 is a rotor (i.e. is rotatable about the rotational axis 12). Thus the first brake plate 26 (rotor) is attached to the wheel 16 via the shaft 14, and hence the first brake plate 26 rotates with the wheel 16. As shown in Figures 8, 9 the first brake plate 26 may be carried on a hub 27, where the hub 27 is keyed to the shaft 14. The brake assembly 18 further comprises a first nonrotatable housing 20 which supports the shaft 14. The housing 20 also supports a second brake plate 22. The second brake plate 22 is non-rotatable about the rotational axis 14. That is to say, the second brake 22 is a stator. The second brake plate 22 is movable axially along the rotational axis 12.

The second brake plate 22 is configured to move axially along the rotational axis 12 between a first configuration (Figure 8) and a second configuration (Figure 9). In the first configuration the non-rotatable second brake plate 22 is urged into engagement with the rotatable first brake plate 26, hence locking/braking the wheel 16 relative to the housing 20. In the second configuration the non-rotatable second brake plate 22 is spaced apart from the rotatable first brake plate 26, hence allowing the wheel 16 to rotate around the rotational axis 12 relative to the housing 20.

The brake assembly 18 comprises an actuator 28 coupled to the second brake plate 22. The actuator 28 may be of any as suitable kind, for example any suitable electrically operated magnetic device. The actuator 28 is operable to move the second brake plate 22 between the first configuration (locked/braked) and the second configuration (unlocked/unbraked). The actuator 28 may comprise an electromagnet 30. The second brake plate 22 may comprise, or is mounted to, a magnetic material such that when the electromagnet is operating the second brake plate 22 is drawn towards the electromagnet 30. Hence the second brake plate 22 may comprise a pad for engagement with the first brake plate and a magnetic material to which the pad/friction material is mounted or attached. Alternatively the brake plate 22 may be of a uniform composition which comprises a magnetic material.

The second brake plate 22 and actuator 28 are coupled together by a pin 29, or plurality of pins 29, which extend through the second brake plate (stator) 22, the actuator 28 and the housing 20 such that the actuator 28 and second brake plate (stator) 22 are carried on the non-rotatable housing 20. The second brake plate 22 is slideable relative to the pin 29 such that it may move along the pin 29 in an axial direction along the rotational axis 12. The actuator 28 is fixed to the housing 20 and/or pin 29 such that it may not move relative to the rotational axis either in a radial or axial direction. Hence during operation of the actuator 28, only the second brake plate 22 moves along the rotational axis 12.

A resilient biasing member 32 is provided between the electromagnet 30 and the second brake plate 22 in order to bias the second brake plate towards the first configuration or the second configuration. The resilient biasing member 32 may be provided as a coiled spring or other resilient biasing means.

The resilient biasing member 32 may be located in a passage 33 in the actuator, or may be fitted to the surface of the actuator 28. Hence the resilient biasing member 32 may be provided to bias the second brake plate towards the first configuration in which the non-rotatable second brake plate 22 is urged into engagement with the rotatable first brake plate 26, thereby locking the wheel assembly. Alternatively the resilient biasing member may be provided in order to bias the second brake plate 22 towards the second configuration in which the non-rotatable second plate 22 is spaced apart from the rotatable first brake 26, and hence allows the wheel to rotate relative to the housing 20.

The electromagnet 30 is in communication with a switch 34. The electromagnet 30 is operable to receive a first control signal from a switch 34 to turn the electromagnet 30 on. The electromagnet is also operable to receive a second control signal from the switch 34 to turn the electromagnet 30 off. The switch 34 may comprise, or be in communication with, a power supply (not shown), which may be a 24 volt power supply. The configuration of the switch 34, power supply and actuator 28 may be of a conventional kind and need not be described in detail.

As shown in Figures 1 to 3 the switch 34 may take the form of a handle attached to the frame of the vehicle, for example the support beam 62. Alternatively, as shown in Figure 4, the switch 34 may take the form of a press bar on the handle of the vehicle. Alternatively the switch 34 may take the form of any convenient switch device suitable for the application. Notably however the switch 34 is located away from the wheel assembly 10 and at a height convenient for an operator to operate the switch. The switch 34 may be hardwired into the coil/actuator 28, or may be wirelessly linked to it. The power supply for the electro-magnet and/or switch may also be provided at a convenient location on the vehicle, although are not shown in Figures 8, 9 for sake of clarity.

In the example shown bearings are provided at either end of the shaft 14 for coupling to the housing 20 and to a portion of the support member 50. The wheel assembly 10 may be coupled to the support frame 50 and the vehicle to which it is attached in any appropriate manner, for example by coupling to the housing 20, or directly supporting bearings which carry the shaft 14.

In use the brake of the wheel assembly 10 is operated by pressing the switch 34 to move the second brake plate 22 towards or away from the first brake plate 26.

Hence in one configuration the switch may be operated to unlock the brake when it is required for the vehicle to be moved, and releasing the switch 34 relocks the wheel assembly so the vehicle cannot move. This type of arrangement is known as a “dead man’s handle. That is to say, the power source (e.g. battery) is used to release the brake. Hence in the event of a user failing to make a positive act to unlock the brakes, or if the power source fails or becomes disconnected, then the brake will be engaged.

Hence in this example the second brake plate 22 (stator) does not rotate with the wheel 16 but does retract under magnetic force from the electromagnet 30 to release the first brake plate 26 (rotor) allowing the first brake plate 26 to rotate.

In an alternative configuration, the brake may be unlocked until the switch 34 is operated, and releasing the switch unlocks the brakes again.

Either configuration may be used depending on the application.

In examples where more than one or all of the wheels of the vehicle are wheel assemblies 10, then all wheels may be operable to lock and unlock with the same press or release of the button 34. That is to say wheel units can be configured to operate such that pairs of brakes (e.g. two brakes, four brakes etc) are engaged simultaneously.

In other applications, only some of the wheels may be operable to lock and unlock with the same press or release of the button 34, for example where the brake on each wheel is operated according to a schedule. The schedule may be to operate each or some of the brakes in turn depending on the braking requirements or to minimise wear on each of the wheel assemblies.

In other examples, multiple rail vehicles (in particular trolley units) may form a vehicle system. At least two vehicles in the system comprise a wheel assembly of the present disclosure, and are linked together such that they can be simultaneously controlled. Such trolley systems may be termed “link trolleys”. Hence all of the said wheel assemblies may be operable to lock and unlock with the same press and/or release of a control button 34. That is to say, the electromagnet 30 of each wheel assembly is operable to simultaneously receive a control signal from a switch 34 on one of the vehicles so as to operate the electromagnet 30 of each wheel assembly and thereby lock/unlock each wheel assembly of each trolley at the same time. Put another way, in this example, each wheel assembly 10 is operable to simultaneously receive a control signal from a switch 34 on one of the vehicles so as to lock/unlock each wheel assembly 50 of each vehicle 50 at the same time.

Hence there is provided a wheel assembly for use on a vehicle, where the vehicle may be configured for use on a railway track or other vehicle.

The location of the brake assembly inside the wheel means the brake assembly components are inherently protected from debris and other materials which may affect their performance, and hence the brake of the wheel assembly of the present disclosure is more likely to operate reliably than examples of the related art.

Also since the wheel assembly comprises a pair of brake plates which are pressed together and released to operate the brake, this system is inherently more reliable than conventional wheel assemblies for use on rail vehicles where brake pads are applied to the wheel itself, which have the demerit as previously discussed.

Additionally since the brake assembly is electro-mechanical, operation and release of the brake is inherently simpler for a user and more inclined to result in a positive brake or release than a device of the related art.

Since the brake assembly is electromechanical, all of the wheels, or several of the wheels of the vehicle, may be provided with a brake assembly which may be simultaneously braked, which is inherently more convenient and safer than examples of the related art in which each wheel much be braked independently and by an independent physical act of the user braking each in turn.

The chain hoist of the present disclosure replaces a conventional lifting mechanism used for rail handling equipment, namely a ratchet lever hoist. Chain hoists are inherently more compact than ratchet lever hoists and hence enable the rail handling assembly to be reduced in height, thus making it easier to configure the lifting equipment to be a comfortable height for a user.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1 A wheel assembly (10) for a rail vehicle, wherein the wheel assembly (10) is centred on a rotational axis (12), and comprises :

a shaft (14) rotatable about the rotational axis (12);

a wheel (16) configured for use on railway track and carried on the shaft (14);

a brake assembly (18) comprising :

a first brake plate (26) carried on the shaft (14);

a first non-rotatable housing (20) which supports a second brake plate (22), wherein the second brake plate (22) is non-rotatable about the rotational axis (14) and the second brake plate (22) is moveable axially along the rotational axis (12) between :

a first configuration in which the non-rotatable second brake plate (22) is urged into engagement with the rotatable first brake plate (26); and a second configuration in which the non-rotatable second brake plate (22) is spaced apart from the rotatable first brake plate (26).

2 A wheel assembly (10) as claimed in claim 1 wherein the brake assembly comprises an actuator (28) coupled to the second brake plate (22) operable to move the second brake plate (22) between the first configuration and the second configuration.

3 A wheel assembly (10) as claimed in claim 2 or claim 3 wherein the actuator (28) comprises an electro-magnet (30), and the second brake plate (22) comprises, or is mounted to, a magnetic material such that when the electro-magnet (30) is operating the second brake plate (22) is drawn towards the electromagnet (30).

4 A wheel assembly (10) as claimed in claim 2 or claim 3 wherein a resilient biasing member (32) is provided between the electro-magnet (30) and the second brake plate (22) in order to bias the second brake plate (22) towards the first configuration or the second configuration.

5 A wheel assembly (10) as claimed in claim 4 wherein the electro-magnet (30) is operable to receive :

a first control signal from a switch (34) to turn the electro magnet (30) on;

and a second control signal from a switch (34) to turn the electro magnet (30) off.

6 A wheel assembly (10) as claimed in any one of the preceding claims wherein the wheel (16) extends along the rotatable axis (12) and has a cavity (36) in which the brake assembly (18) is located.

7 A wheel assembly (10) as claimed in any one of the preceding claims wherein the wheel (16) has a frusto-conical main body portion (52) which increases in diameter from a first end (54) to a second end (56), and a flange (58) which extends from the second end (56) in a direction away from the rotational axis (12).

8 A wheel assembly (10) as claimed in clam 7 when dependent on claim 6 wherein the cavity (36) is provided in the frusto-conical main body portion (52) and opens onto the first end (54).

9 A vehicle (50) comprising a wheel assembly (10) as claimed in any one of claims 1 to 8.

10 A vehicle (50) as claimed in claim 9 wherein the vehicle (50) comprises :

a support frame (50) to which the wheel assembly (10) is coupled such that:

when the second brake plate (22) in the first configuration the wheel (16) is braked; and when the second brake plate (22) is in the second configuration the wheel (16) is rotatable to allow the vehicle to travel.

11 A vehicle (50) as claimed in claim 10 wherein all wheels of the vehicle (50) are a wheel assembly as claimed in claims 1 to 8.

12 A vehicle (50) as claimed in any one of claims 9 to 11 wherein the vehicle is a rail handling device (80), and comprises a leg (60) which extends from the support frame (50) to support a lifting beam (62);

a chain hoist (64) slideably mounted on the lifting beam (62) such that the chain hoist (64) is operable to move along the lifting beam (62).

13 A vehicle (50) as claimed in claim 12 wherein the chain hoist (64) is manually operated by a handle (66);

the handle (66) rotatable about a chain hoist rotational axis (68) such that the chain hoist (68) is operable to raise/lower a chain when the handle (66) is rotated about the chain hoist rotational axis (68);

and the chain hoist rotational axis (68) is located at distance (h) from the wheel assembly rotational axis (12) such than an operator can operate the handle (66) while standing substantially upright.

14 A vehicle (50) as claimed in claim 13 wherein the distance h is no less than 0.6m and no more than 1.1m.

15 A vehicle (50) as claimed in any one of claims 9 to 11 wherein :

the vehicle comprises a support platform (70) carried on the support frame (50).

16 A vehicle system comprising at least two vehicles (50) as claimed in any one of claims 9 to 15 when dependent on claim 3 wherein :

each wheel assembly (10) is operable to simultaneously receive a control signal from a switch (34) on one of the vehicles so as to lock/unlock each wheel assembly (50) of each vehicle (50) at the same time.