WO1994008801A1

WO1994008801A1 - A wheeled vehicle and a castorable wheel

Info

Publication number: WO1994008801A1
Application number: PCT/GB1993/002102
Authority: WO
Inventors: David R. Barnes; David Michael White
Original assignee: Feron Investments Limited
Priority date: 1992-10-12
Filing date: 1993-10-11
Publication date: 1994-04-28
Also published as: AU5153293A; EP0662881A1

Abstract

The invention provides a wheeled vehicle having a front end, a rear end and a longitudinal axis. At least one castored front wheel arrangement (10) is arranged at or adjacent the front end of the wheeled vehicle and at least one castored rear wheel arrangement is arranged at or adjacent the rear end of the wheeled vehicle. Means (22; 26) are provided for bringing the plane of the or each wheel (12) of the at least one front wheel arrangement (10) into parallel alignment with the longitudinal axis on forward or rearward movement of the wheeled vehicle. The invention also provides a castorable wheel arrangement for attachment to the frame of a wheeled vehicle having a longitudinal axis. The arrangement incorporates at least one wheel (12) and means (22, 26) for, in use, bringing the plane of the wheel or wheels (12) into parallel alignment with the longitudinal axis of the wheeled vehicle on forward or rearward movement of the wheeled vehicle.

Description

A Wheeled Vehicle and a Castorable Wheel Arrangement Therefor

The invention relates to a wheeled vehicle particularly, but not exclusively, to a trolley of the type commonly utilised in supermarkets and other shops, stores or the like, and to a castorable wheel arrangement therefor. The invention is also applicable to any trolley having a load-bearing capacity and to be steered by the user of .e trolley or, indeed, to any type of wheeled vehicle or cart.

For the avoidance of doubt, the term "wheeled vehicle" as used hereinafter is intended to include all types of wheeled vehicles including trolleys, wheelchairs, pushchairs, carts, etc.

It is quite common for the user of a supermarket or other trolley to find that the steering of the trolley is problematic. This is often because the front wheels of the trolley tend to remain aligned with the existing direction of travel of the trolley and steering away from that original direction is difficult. Also, the effort required to steer a supermarket or other trolley increases with the load carried by the trolley. Thus, it is quite possible for the body of a trolley to be turned so that the longitudinal axis of the trolley lies at an angle to the original direction of travel but that the trolley continues to maintain its original direction of travel without being steered. Naturally, this is undesirable. The above described difficulties in steering supermarket and other trolleys are enhanced when the user of the trolley requires to steer the trolley by use of only one hand, for example, when carrying a small child.

It is an object of the present invention to provide a wheeled vehicle which exhibits improved steering characteristics. It is a further object of the invention to provide a wheeled vehicle which can be steered by the user with only one hand.

The invention provides a wheeled vehicle having a front end, a rear end and a longitudinal axis, at least one castored front wheel arrangement being arranged at or adjacent the front end and at least one castored rear wheel arrangement being arranged at or adjacent the rear end, wherein means are provided for bringing the plane of the or each wheel of the at least one front wheel arrangement into parallel alignment with the longitudinal axis on forward or rearward movement of the wheeled vehicle. This arrangement allows the wheeled vehicle to be steered by moving the at least one rear wheel arrangement to the right or left, thereby inclining the longitudinal axis to the previous direction of travel, whereupon the front wheels will automatically align themselves with the longitudinal axis^*Of the wheeled vehicle and the direction of travel of the wheeled vehicle will thereby be changed. The steering movement is easily carried out by the user of the wheeled vehicle using, if necessary, only one hand. Further preferable and advantageous features of the invention are set out in sub-claims 2 to 17.

A second aspect of the invention provides a castored wheel arrangement for attachment to the frame of a wheeled vehicle having a longitudinal axis, wherein the arrangement incorporates at least one wheel and means for, in use, bringing the plane of the wheel or wheels of the arrangement into parallel alignment with the longitudinal axis of the wheeled vehicle on forward or rearward movement of the wheeled vehicle.

The invention also provides apparatus for converting a standard wheeled vehicle into a wheeled vehicle having the features described above, comprising means for inclining rearwardly the axis of the or each wheel of the at least one front wheel arrangement about which the wheel pivots. It is envisaged that standard trolleys existing in many supermarkets can easily be converted to incorporate the features of the invention by means of this apparatus. Advantageous features of the apparatus according to the invention are set out in sub-claims 24 to 33.

Embodiments of each aspect of the invention will now be described with reference to the accompanying drawings wherein:

Figure 1 shows a typical front wheel arrangement as utilised in known or standard supermarket trolleys;

Figure 2 shows the front wheel arrangement of Figure 1 modified in accordance with the present invention;

Figure 3 shows a schematic diagram of a first alternative front wheel arrangement embodying the present invention;

Figures 4a and 4b illustrate a second alternative embodiment of the present invention;

Figures 5a and 5b illustrate an enhanced embodiment of the invention illustrated in Figures 4a and 4b; Figure 6 illustrates a third alternative embodiment of the invention;

Figure 7 illustrates an alternative version of the embodiment illustrated in Figure 6;

Figures 8 and 9 schematically illustrate alternative castored wheel arrangements suitable for attachment to a trolley to produce a trolley according to the invention;

Figures 10a and 10b illustrate a further modified embodiment of the present invention;

Figures 11a, lib and lie illustrate a hand grip for use on a trolley modified in accordance with the present invention;

Figure 12 illustrates a fourth embodiment of the' invention;

Figure 13 illustrates schematically apparatus for converting a standard trolley to a trolley incorporating the invention;

Figure 14 is a schematic diagram of the bending apparatus forming part of the apparatus of Figure 13; and Figures 15a and 15b illustrate the operation of the clamping means of the apparatus illustrated in Figure 13.

In the drawings, Figure 1 shows a standard castored front wheel arrangement 10 as is commonly found on supermarket trolleys. The wheel 12 is freely rotatable about a horizontal axis 14 to allow forward or rearward motion of the trolley. The axis 14 is located in a housing 16 which, in turn, is pivotably connected by means of a swivel joint 18 to the lower portion of the trolley frame 20. The axis 14 about which the wheel 12 is freely rotatable is off-set rearwardly with respect to the axis 22 about which the housing 16 is pivotable to allow steering of the front wheel 12 of the trolley. Pivoting of the housing 16 results in the rotation of the axis 14 in a horizontal plane about the axis 22.

Normally, the remainder of the trolley will be of standard configuration. Two similar front wheel arrangements are located side by side at or adjacent the front end of the trolley and two rear wheel arrangements will be located at or adjacent the rear end of the trolley. The longitudinal axis of the trolley extends from a point midway between the two rear wheel arrangements to a point midway b- sen the two front wheel arrangements. The front wheel arrangements will normally be arranged closer together than the rear wheel arrangements to allow stacking of a plurality of identical trolleys in a convenient and efficient manner. Above the front and rear wheel arrangements, a load carrying basket or platform will normally be arranged. A handle for steering by the user will normally extend across substantially the entire width of the trolley at the rear end thereof at a convenient height. These features do not affect the invention and will not be described further.

Figure 2 shows the front wheel arrangement 10 of Figure 1 adapted to incorporate the features of the present invention. In Figure 2, the axis 22 about which the housing 16 and wheel 12 are pivotable for steering purposes is inclined rearwardly at an angle of substantially 5" to 6', although the angle of inclination can be anywhere in the range 2^* to 16^*. The inclination of this axis 22 to the vertical means that, as the wheel 12 pivots about the swivel joint 18, the bulk of the trolley is raised and lowered. However, when the housing 16 is free to pivot about the swivel joint 18, it will always turn, under the influence of gravity acting on the bulk of the trolley and its load, towards the position in which the bulk of the trolley is at its lowest possible position, i. e. the position shown in Figure 2. In this position, the wheel 12 is in parallel allignment with the longitudinal axis of the trolley. This is the point of greatest stability.

A trolley having this feature is steered in the following manner: after moving in a forward direction, it is desired to change the steering direction to the right. The user then swings the rear end of the trolley to the left so that the longitudinal axis of the trolley is pointing in the desired direction of travel. The wheels 12 of the front wheel arrangements maintain their original position and are thus inclined to the longitudinal axis of the trolley. However, this relative pivoting of the swivel joints 18 causes a slight raising of the bulk of the trolley and its load. However, as the trolley is moved forwards, this height is reduced by the automatic pivoting of the swivel joints 18 as they tend to bring the front wheels 12 into parallel alignment with the longitudinal axis of the trolley. Thus the desired change of direction of movement is achieved. The rear wheels, being castorable and closer to the centre of gravity of the trolley, are also aligned with the longitudinal axis of the trolley on forward movement.

The inclination of the axis 22 is achieved in the embodiment shown in Figure 2 merely by means of the configuration of the trolley frame 20. However, other ways of achieving the inclination of the axis are possible. An alternative arrangement is shown in Figure 3 in which the inclination of the axis 22 is achieved by the provision of wedge-shaped washers 24 located beneath the swivel joint 18. As before, the weight of the trolley acts in a downward direction to bring the wheel into the position shown in Figure 3, i. e. with the wheel 12 in parallel alignment with the longitudinal axis of the trolley, after the front wheel arrangements have been previously pivoted away from this position in the same manner as described above. (It should be noted that the swivel joint is illustrated schematically). Clearly, there are a number of alternative ways of arranging for the bulk of the trolley to be raised slightly when the front wheels 12 of the front wheel arrangements are pivoted away from the position in which they are in parallel alignment with the longitudinal axis of the trolley. One way to achieve this would be to provide a spring or other resilient biasing means adapted to bring the wheel into parallel alignment with the longitudinal axis of the trolley.

A further alternative arrangement is shown in Figures 4a and 4b. In this embodiment, a rising cam 26 is arranged between the housing 16 and the trolley frame. In effect, the rising cam 26 takes the place of the swivel joint 18 shown in the previous figures. The upper portion 26a of the rising cam 26 is fixedly attached to the trolley frame and the lower portion 26b is fixedly attached to the housing 16, the portions 26a, 26b of the rising cam being connected so as to allow relative rotation between the two parts about a fixed, vertical axis 22. Figure 4a shows the relative positions of the parts 26a, 26b when the wheel is in parallel alignment with the longitudinal axis of the trolley and is suitably arranged for forward movement of the trolley. The upper portion 26a of the rising cam 26, and therefore the bulk of the trolley and its load, is in its lowest possible position. However, when the wheel 12 is pivoted away from this position, the lower portion 26b of the rising cam 26 is rotated relative to the upper portion 26a which causes an increase in the height of the upper portion 26a and the remainder of the trolley above floor level. Figure 4b shows the extreme position of the wheel 12 having been rotated through 180' to achieve the maximum possible increase in- height of the bulk of the trolley above floor level. In this position, the trolley can move in a rearward direction if desired. However, at any point between the two positions shown in Figures 4a and 4b, the weight of the bulk of the trolley will act so as to drop the bulk of the trolley to the lowest position possible, i. e. that shown in Figure 4a and therefore the wheel 12 will be rotated to bring it into parallel alignment with the longitudinal axis of the trolley as shown in Figure 4a. A modified version of the embodiment shown in Figures 4a and 4b is shown in Figures 5a and 5b. In this embodiment, a helical spring 28 acts between the upper portion 26a of the rising cam 26 and a washer 30 fixed on the trolley frame. This increases the downward force acting upon the upper portion 26a and thereby increases the tendency of the wheel 12 to become aligned with the longitudinal axis of the trolley. The alignment is thus achieved quickly and reliably.

As is clear from Figures 4 and 5, no rearward inclination of the axis about which the housing 16 pivots is required to achieve the desired effect. However, when the axis 22 about which the housing 16 pivots is inclined to the vertical, it is envisaged that the angle of inclination of this axis 22 can be made variable. By increasing the rearward angle of inclination of the axis 22, the raising of the bulk of the trolley above the floor can be increased for any given angle of pivoting of the housing 16. Thus, for a given angle of pivoting of the housing 16, the force acting to return the wheel 12 to a position in which it is in parallel alignment with the longitudinal axis of the trolley is increased. Two alternative arrangements allowing for an increase in the angle of inclination with an increase in the load carried by the trolley are shown in Figures 6 and 7. In Figure 6, the swivel joint 18 is connected to the trolley frame 20 by means of a connector 32 which is rigidly connected to the swivel joint 18 and pivotably connected about an axis 34 to the trolley frame 20. A spring 36 or other suitable resilient means act between the connector 32 and the trolley frame 20 to bias the connector 32 into a configuration wherein the angle of inclination a achieves a desired minimum, for example 5^*. An increase in the load carried by the trolley will act to urge the trolley frame 20 and the axis 34 downwards, thereby resulting in the connector 32 rotating about the axis 34 in an anticlockwise direction so as to increase the angle of inclination a. Suitable stops (not shown) can be provided to limit the angle of inclination a to a desired maximum, for example 16^*. Unloading of the trolley will allow the trolley frame to return to its previous position under the influence of the spring 36 and the angle of inclination a will then return to the desired minimum value of 5^*. When the trolley is in a loaded state, the tendency of the front wheels 12 to bring themselves into parallel alignment with the longitudinal axis of the trolley will be enhanced.

Figure 7 shows an embodiment very similar to that shown in Figure 6, but with the connection between the connector 32 and the trolley frame 20 formed by a resilient member 34a deformable to allow relative rotation between the connector 32 and the frame 20. As previously described, an increase in the load carried by the trolley will rotate the connector 32 in an anticlockwise manner so as to increase the angle of inclination a of the axis 22.

Figures 8 and 9 illustrate further ways of achieving the desired result, i. e. of inclining the axis 22 rearwardly to the vertical, by modifying only the castored wheel arrangements and making no modifications whatsoever to the remainder of the trolley frame. Figure 8 illustrates a modified castor arrangement 10a wherein the swivel joint 18a (illustrated schematically) between the housing 16a and the trolley frame 20a is adapted so that the axis 22a is inclined to the vertical. The swivel joint 18a is comprised of two freely rotatable portions 18a', 18a'' relatively rotatable about the axis 22a, the upper portion 18a' , being shaped so that rigid attachment to the trolley frame 20a creates a rearward inclination of the axis 22a. The shaping of the upper portion 18a can also be such that a lateral inclination of the axis 22a is achieved. The effect of this is explained in relation to Figure 10.

Figure 9 shows a further modification of a castored front wheel arrangement 10b suitable for attachment to a standard trolley frame. Again, the upper portion 18b' of the swivel joint 18b is shaped so that attachment thereof to the trolley frame creates a rearward inclination of the axis 22b about which the housing 16b is pivotable. Again, a lateral inclination can also be achieved if desired.

Figures 10a and 10b illustrate a further improvement relating to the invention described above. Figure 10a shows, in side view, a schematic diagram of a trolley wherein the axis 22 about which the front wheels 12 pivot is inclined rearwardly to the vertical. Figure 10b is a schematic diagram of the front view of the same trolley from which it can be seen that the axis 22 about which each of the front wheels 12 pivots is also inclined to the vertical in a lateral direction. The preferred angle of inclination in this direction is in the range 1^* to 5^*. The lateral inclination of the axes 22 (Fig 10b) towards one another improves the steerability of the front wheels and thus enhances the steerability of the trolley as a whole. In particular, the performance of the trolley is enhanced during cornering, i. e. when the front wheels 12 are pivoted away from parallel alignment with the longitudinal axis of the trolley.

The improved performance with this "tow in-tow out" effect is surprising since, if each wheel were allowed to act independently on straight, forward movement, the result would be that the two front wheels 12 would tend to steer slightly towards one another, ie. the wheels would each aim towards a point on the longitudinal axis of the trolley but some distance in front of the trolley. However, since the trolley as a whole can only move in one direction, the wheels steer along a compromise course, ie. parallel to the longitudinal axis of the trolley, when the trolley is moved in a forward direction. It will be understood that this effect can only be satisfactorily achieved when two front wheel arrangements are present and the lateral inclination of axes 22 is the same for each wheel.

The effect on the steering performance is explained below.

When a trolley without this "tow in-tow out" feature is steered around a corner, the inside front wheel will turn at a different radius to that of the outside wheel. The inside wheel will therefore pivot more sharply than the outside wheel. Because of the rearward inclination of the axes about which the wheels are pivoted, the trolley is lifted as each wheel pivots. However, each wheel will lift the trolley to a different degree. Hence there is a tendency for one of the front wheels (namely the wheel on the outside of the turn) to be lifted off the ground. This affects the steering potential and stability which then relies mainly upon the inside front wheel.

The problem can be solved by angling each wheel outwardly in a lateral direction from its point of attachment as well as rearwardly. Viewed from the rear therefore the right-hand wheel is angled to the right and the left-hand wheel is angled to the left at the same angle of 1^* to 5^*. The result of this is that, when the trolley is being steered around a bend, the outside front wheel tends to lift the trolley and the inside front wheel tends to reduce the lift. This is the opposite effect to the lift effect caused by the rearward inclination of the wheels and, if the degree of lateral inclination is calculated correctly (and this is different for each type of trolley), compensates for the "differential lift" and keeps both front wheels on the ground retaining the improved steering characteristics and stability.

The improvements described above mean that a trolley incorporating any one of the above designs will require to be steered in a completely different manner from that normally used by current users of supermarket trolleys. Currently, users of supermarket trolleys tend to apply a turning force to the handlebar of the trolley so as to swing the front wheels around and align the longitudinal axis of the trolley with the desired direction of travel. The modifications described above will enable the trolley to be steered more easily by swinging the rear wheels of the trolley away from the intended direction of travel (i. e. to the right when a turn to the left is desired and to the left when a turn to the right is desired) and pushing the trolley forward so as to align the front wheels with the longitudinal axis of the trolley. It is therefore necessary to assist users of the trolley to adopt a different steering procedure and this can be done by encouraging the user to grip the centre of the handlebar of the trolley rather than the ends. To this end, it is proposed that a handle grip be positioned centrally of the handlebar and a suitable hand grip is illustrated in Figures 11a, lib and lie. As can be seen, the hand grip 40 is generally C-shaped in cross-section having a longitudinal opening by means of which an existing handlebar of a trolley may be introduced to the interior of the hand grip 40. By manufacturing the hand grip 40 of a resilient material such as a plastics material, the hand grip 40 can be attached to the handlebar of an existing trolley. Protrusions 42 are arranged about the upper and lower portions of the circumference of the hand grip 40 to provide finger grooves for the user. The outer surface of the hand grip 40 diametrically opposite the longitudinal opening is substantially free of shapings so that an area 44 is provided upon which an advertising message may be displayed.

A hand grip 40 such as that described above is of particular use when a standard trolley, i. e. a trolley not incorporating the features described above, is converted into a trolley falling within the scope of the present invention. The hand grip 40 is then attached to the handlebar of the existing trolley in order to inform the user of the modified trolley that it should be steered in the manner described above.

A trolley incorporating the invention is adaptable in various ways which will enhance the performance of the trolley. One such modification is the provision of a third front wheel arrangement between the two more usual front wheel arrangements and the central front wheel arrangements will also incorporate the feature of the inclined axis 22. This modification is illustrated in Figure 12. Such an arrangement assists with the performance of the trolley when travelling over inclined surfaces such as those found in supermarket car parks.

As briefly mentioned above, it is envisaged that it will be possible to modify existing supermarket trolleys which do not incorporate the features of the invention prior to modification such that, after modification, the features of the invention are incorporated. The invention therefore also provides apparatus for converting some types of standard or existing trolleys into trolleys which fall within the scope of the present invention. Apparatus for carrying out this modification is schematically illustrated in Figures 13 to 15.

In Figure 13, the modification apparatus 50 is shown schematically in operation. The apparatus 50 comprises clamping apparatus 52 and bending apparatus 54. The clamping apparaus 52 comprises two sets of clamping heads 56, each pair of clamping heads 56 being configured so as to receive therebetween one of the front wheel arrangements of a standard trolley. Pneumatic or hydraulic cylinders 58 are provided to allow the pairs of clamping heads 56 to be moved towards one another and thereby to clamp the front wheel^' arrangement therebetween. The clamping heads 56 are arranged so as to be fully adjustable to allow for various different styles and shapes of trolleys to be accommodated.

On operation of the pneumatic or hydraulic cylinders 58, the clamping heads 56 are moved towards one another so that each of the front wheel arrangements of the trolley is clamped between a pair of clamping heads 56. The remainder of the trolley frame 20, which is engaged with the bending apparatus 54, is then deformed in a controlled manner by means of the bending apparatus 54 to achieve the desired inclination of the axis 22 about which the housing 16 of the front wheel arrangement pivots. The bending means 54 is illustrated more clearly in Figure 14.

As can be seen from Figure 14, the bending means 54 comprises upwardly extending members 60 in which are located grooves 62 for receiving the relevant portions of the trolley frame 20. The bending means 54 also comprises a pneumatic or hydraulic cylinder 64 adapted to move the upwardly extending members 60 in a controlled manner and in a downward direction so as to deform the trolley frame 20 with respect to the clamped front wheel arrangements. The controlled deformation of the trolley frame 20 results in the desired inclination of the axis about which the housings 16 of the front wheel arrangements pivot.

Figures 15a and 15b illustrate the operation of the clamping means which are shown in the open position (Figure 15a) and in the closed position (Figure 15b). As can be seen, the clamping heads 56 are closed by means of the hydraulic or pneumatic cylinders 58 so as to rigidly clamp the front wheel arrangements of the trolley therebetween. It is also envisaged that the lateral inclination of the axes about which the front wheels 16 are pivotable can be introduced to a standard trolley during this clamping procedure. To this end, the clamping heads 56 can be inclined to the vertical at the required angle so that a permanent deformation of the trolley frame 20 can be achieved.

Apparatus of the type described above can be adapted, with modifications obvious to one skilled in the art, to apparatus for converting any type of wheeled vehicle.

Claims

Claims:

1. A wheeled vehicle having a front end, a rear end and a longitudinal axis, at least one castored front wheel arrangement being arranged at or adjacent the front end and at least one castored rear wheel arrangement being arranged at or adjacent the rear end, wherein means are provided for bringing the plane of the or each wheel of the at least one front wheel arrangement into parallel alignment with the longitudinal axis on forward or rearward movement of the wheeled vehicle.

2. A wheeled vehicle as claimed in claim 1, wherein the axis about which the or each wheel of the at least one front wheel arrangement pivots is inclined to the vertical.

3. A wheeled vehicle as claimed in claim 2, wherein the angle of inclination lies in the range 2^* to 16^*.

4. A wheeled vehicle as claimed in claim 3, wherein the angle of inclination is substantially 5^* to 6^*.

5. A wheeled vehicle as claimed in claim 2 or 3, wherein the angle of inclination is variable.

6. A wheeled vehicle as claimed in claim 5, wherein the angle of inclination is dependent upon the load carried by the wheeled vehicle.

7. A wheeled vehicle as claimed in any one of claims 2 to 6, wherein the axis about which the or each wheel of the at least one front wheel arrangement pivots is inclined rearwardly to the vertical.

8. A wheeled vehicle as claimed in claim 1, wherein the or each front wheel arrangement comprises rising cam means.

9. A wheeled vehicle as claimed in claim 8, wherein the rising cam means is at its most stable when the or each wheel of the at least one front wheel arrangement is in parallel alignment with the longitudinal axis.

10. A wheeled vehicle as claimed in any one of the preceding claims, wherein the or each wheel of the at least one front wheel arrangement is biassed into parallel alignment with the longitudinal axis.

11. A wheeled vehicle as claimed in claim 10, wherein the or each wheel of the at least one front wheel arrangement is biassed into parallel alignment with the longitudinal axis by means of a spring.

12. A wheeled vehicle as claimed in any one of the preceding claims, wherein two castored front wheel arrangements are provided, each front wheel arrangement comprising a single wheel.

13. A wheeled vehicle as claimed in claim 12, wherein the axis about which the wheel of each respective front wheel arrangement pivots is inclined in a lateral direction.

14. A wheeled vehicle as claimed in claim 13, wherein the angle of lateral inclination of each respective axis lies in the range 1" to 5^*.

15. A wheeled vehicle as claimed in claim 12, wherein a further front wheel arrangement is provided between the two said front wheel arrangements.

16. A wheeled vehicle as claimed in any one of the preceding claims and further comprising a handlebar extending substantially across the entire width of the rear end of the wheeled vehicle, wherein a hand grip is arranged substantially centrally of the handlebar.

17. A wheeled vehicle as claimed in any one of the preceding claims, wherein the wheeled vehicle is a trolley.

18. A wheeled vehicle substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.

19. A castored wheel arrangement for attachment to the frame of a wheeled vehicle having a longitudinal axis, wherein the arrangement incorporates at least one wheel and means for, in use, bringing the plane of the wheel or wheels of the arrangement into parallel alignment with the longitudinal axis of the v/heeled vehicle on forward or rearward movement of the wheeled vehicle.

20. A castored wheel arrangement as claimed in claim 19, wherein the axis about which the or each wheel is pivotable is inclined to the vertical.

21. A castored wheel arrangement as claimed in claim 20, wherein, in use, the axis is inclined rearwardly to the vertical at an angle in the range 2' to 16^*.

22. A castored wheel arrangement substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.

23. Apparatus for converting a standard wheeled vehicle into a wheeled vehicle as claimed in claim 17, comprising means for inclining rearwardly the axis of the or each wheel of the at least one front wheel arrangement about which the wheel pivots.

24. Apparatus as claimed in claim 23, wherein the angle to which the or each axis is inclined lies in the range 2^* to 16^*.

25. Apparatus as claimed in claim 23 or 24, wherein the angle to which the or each axis is inclined is substantially 5' to 6^*.

26. Apparatus as claimed in any one of claims 23 to 25, wherein clamping means are provided for rigidly clamping the at least one front wheel arrangement in a fixed position, and bending means are provided for bending the remainder of the wheeled vehicle with respect to the clamped front wheel arrangement or arrangements.

27. Apparatus as claimed in claim 26, wherein the clamping means are operated pneumatically.

28. Apparatus as claimed in claim 26, wherein the clamping means are operated hydraulically.

29. Apparatus as claimed in any one of claims 26 to 28, wherein the bending means are operated pneumatically.

30. Apparatus as claimed in any one of claims 26 to 28, wherein the bending means are operated hydraulically.

31. Apparatus as claimed in any one of claims 26 to 30, wherein the clamping means comprise clamping heads for engagement with the at least one front wheel arrangement of the wheeled vehicle, the clamping heads being capable of being inclined to the vertical to allow for the front wheels of the wheeled vehicle being inclined in a lateral direction.

32. Apparatus as claimed in any one of claims 26 to 30, wherein the clamping means comprise clamping heads for engagement with the at least one front wheel arrangement of the wheeled vehicle, the clamping heads being operable so as to incline the front wheels of the wheeled vehicle in a lateral direction.

33. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.