GB1579922A - Jockey wheels for attachment to trailer units - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO JOCKEY WHEELS FOR ATTACHMENT TO TRAILER UNITS (71) We, G. A. NORMAN LIMITED, a British Company of Mowbray Drive, Blackpool, Lancashire, and FRANK ASPIN, a British subject of 36 Riley Avenue, St.

Annes-on-Sea, Lancashire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to jockey wheels for attachment to trailer units, and in this specification the term "trailer unit" is intended to include within its scope such things as caravans, to which the invention is particularly applicable.

It is common practice for trailer units such as caravans or boat trailers, to incorporate a nose wheel or jockey wheel at the front. When the caravan or trailer is being towed, the jockey wheel is held out of contact with the ground and is inoperative; but when the unit is uncoupled from its towing vehicle the jockey wheel engages the ground and the front of the trailer is supported by this wheel.

The invention provides an assembly comprising a jockey wheel carried on a support which can be attached to a trailer unit, characterised by the provision of handoperable means for extending and retracting the wheel relative to the support, means for transmitting a hand-powered drive to the wheel from a power input on the assembly, and means allowing hand-steering movement of the wheel relative to the support and hence to the trailer unit to which the support is to be attached.

The required hand steering movement may be obtained by so mounting the wheel on the support that a castor action of the wheel about the support is obtained. Alternatively or additionally the assembly may incorporate, or may be adapted to receive, an elongate steering handle such as a tiller by which handsteering movement of the wheel can be controlled.

The means for transmitting a hand-powered drive to the wheel may comprise an endless chain or toothed belt connecting two sprockets, one secured to the wheel and the other being rotatably mounted at said power input on the assembly, said other sprocket incorporating, or being adapted to receive, a handle by means of which it can be rotated.

The transmission from one sprocket to the other would normally incorporate some form of reduction gearing. For example, the sprocket on the wheel could be several times the size of the other sprocket. Alternatively, or additionally, the chain or toothed belt could be trained around one or more intermediate sprockets whose sizes had been worked out to give the necessary overall reduction between the sprocket on the wheel and the drive input sprocket.

The means for extending and retracting the wheel could comprise a co-operating hand rotatable screw-and-nut mechanism, and in one particularly advantageous form the support could comprise a hollow tube in which slides a hollow rod fixed to the wheel, the screw being hand-rotatable and extending down inside the hollow rod, and the nut being fixed to the supporting tube and moving between the limits of a slot cut in the hollow rod.

In this last mentioned case, and where the drive input sprocket and the sprocket on the wheel are connected by a toothed belt or chain, the chain could also pass through the hollow rod as it travels from one sprocket to the other.

If a belt or chain is used, and extension or retraction of the wheel causes the distance between the two sprockets to vary, means such as a spring loaded jockey sprocket would be provided to take up or pay out the slack in the chain. Preferably, however, extension or retraction of the wheel does not cause the distance between the two sprockets to be varied-for example, in the case just outlined where the wheel is fixed to one end of a hollow rod, the drive input sprocket could be fixed to the other end of the rod.

Two assemblies embodying the invention will now be described, by way of example only and with reference to the accompanying drawing.

The drawing consists of the following Figures: Figure 1 shows first assembly diagrammatically and in perspective; Figure 2 shows, to an enlarged scale and in cross-section, parts of the wheel extending and retracting mechanism of Figure 1, Figures 3 and 4 are respective side and end elevations of a second assembly embodying the invention, Figure 4 being in section; Figure 3A shows in perspective the clamp of the assembly of Figures 3 and 4; and Figures 5, 5a, 5b and Sc shows to an enlarged scale a nut used in the assembly of Figures 3 and 4.

In the first assembly, shown in Figures 1 and 2, a wheel 11 incorporating a treaded rubber tyre 12 and is freely rotatable in bearings 13, the inner races of the bearings being secured to a shaft 14, which is itself bolted between the limbs of a forked structure 15. This structure 15 consists simply of two sheet steel plates welded on opposite sides of the axis of an elongate hollow steel rod 16, the plates projecting at right angles to the axis of the rod.

At the other end of the rod is welded another forked structure 17, again consisting essentially of two steel plates welded one on either side of the axis of the rod 16 and projecting at right angles from it. The forks 15 and 17, in this particular embodiment of the invention, project in opposite directions from the axis of the rod.

Mounted between the arms of the fork 17 is a drive input sprocket 18. This sprocket 18 runs in bearings and is carried on a shaft which projects from the fork 17, and the projecting part of the shaft has a crank arm 19 fixed to it. An endless chain 21 connects the sproket 18 to a chain wheel 22 (bolted to the wheel 11) via a succession of jockey sprockets 23, 24, 25, 26. The difference in size between the drive input sprocket 18 and the chain wheel 22 gives the necessary reduction gearing and, when a drive handle (not shown) is inserted into the crank 19, rotation of that crank will cause a powered drive to be transmitted to the wheel 11.

The rod 16, at opposite ends of which the wheel 11 and the input drive sprocket 18 are rotatably mounted, is itself mounted in an elongate tube 27. This tube 27 is in turn surrounded by an outer tube 28 which constitutes a support for the wheel. The tube 28 is freely rotatable relative to the tube 27, but is prevented from moving axially relative to tube 27. Thus, tube 28 can be rigidly secured or clamped to a trailer and tube 27, together with rod 16, can rotate inside it to allow steering movement of the wheel relative to the trailer. A tiller bar 29 is detachably mounted in the fork structure 17 to control such movements.

The wheel 11 can be extended and retracted relative to tube 28 by means of a co-operating screw-and-nut mechanism. The screw 31 passes down the inside of the hollow rod 16 and can rotate freely inside the rod. It is however held against axial movement relative to the rod. The nut 32 is secured to the tube 27 and engages the screw 31 through an axially elongate slot 33 which is cut in the walls of the hollow rod 16. Thus, hand-rotation of the screw 31 causes the nut 32, and hence the tubes 27 and 28, to move along the screw within the axial limits of the slot 33; and if the tube 28 is clamped to a trailer, the screw 31 and rod 16 to which it is attached will of course move axially together relative to the tubes 27 and 28. Thus the wheel 11 can be extended and retracted by rotating the screw 31, and when the assembly is clamped to a trailer the attitude of the trailer relative to the ground on which it stands can thereby be varied.

It will be appreciated that the embodiment just described allows a trailer unit, such as a caravan, to be steered, manoeuvred and altered in attitude, relative to the ground on which it stands, all by hand. This can prove extremely useful where trailer units such as caravans have been uncoupled from their towing vehicles and have then to be hand-manoeuvred into position within the confines of a strictly limited space.

It will also be appreciated that modifications can be made to this embodiment without departing from the scope of the invention as defined in the claims. For example, although the axis of rotation of wheel 11 is spaced from its steering axis (i.e. the axis of the rod 16), thus giving a castor effect, the axis of rotation of the wheel could lie on the extended axis of the rod 16. This could in certain embodiments, make for easier mannoeuvreability in use. The remaining drawings Figures show an embodiment of the invention in which this has been done.

It will be appreciated readily that the embodiment of Figures 3, 3A, 4, and 5 to 5c, embodies many similar parts to the embodiment of Figures 1 and 2, and works in substantially the same way. In Figures 3, 3A, 4, and 5 to 5c, parts which correspond to the parts in Figures 1 and 2 have therefore been given the same reference numerals, and accordingly the following description will be restricted to the important differences between the two assemblies.

A first difference, as has been noted above, is that the wheel 11 has its axis of rotation on the extended axis of the rod 16. This makes for easier hand-manoeuvrability of the assembly, since less steering effort is required and the caster effect is not present and does not have to be overcome. It will be noted also that a chain guard 1 lea shrouds the wheel on its chainwheel side, and that this chain guard is provided with a "window" aperture to give access to a threaded adjusting mechanism indicated generally by the numeral 1 lc in order that slackness developing in the chain can be taken up. The housing for the main wheel spindle is, of course, elongate in the appropriate direction to allow such adjustment to take place.

In Figure 3 a mounting bracket 28a partly surrounds the outermost tube 28 and incorporates a screw clamp 28b. The bracket 28a can be mounted on the front of a trailer unit, such as a caravan, and the screw clamp 28b clamps the tube 28-and hence the whole assembly-firmly against the bracket 28a whilst still allowing the wheel 11, 12 to be raised and lowered relative to the trailer unit.

The screw 28b of the clamp bears against the inside of the clamp body 28a, as shown in Figure 3A, forcing the clamping jaw upwards against the tube 28 so as to grip that tube within the body of the clamp. As Figure 3A also shows, the tube 28 can be moved up and down within the clamp body 28a, and can then be held in a desired position by tightening the screw 28b.

If the tube 28 is moved fully up into the clamp body 28a, and the screw 28b tightened, the wheel 11, 12 can be raised (using the cooperating screw and nut mechanism 31, 32) until the flat wheel supporting plate contacts the bottom of the tube 28. In that position, as Figure 3A indicates, the flat wheel supporting plate will have been drawn up inside the "U-shaped" extended portion of the clamp body 28a, and the flat base of the "U" will prevent the wheel supporting plate-and hence the wheel itself-from swinging about its steering axis.

In this second embodiment of the invention, the arrangement of the nut 32 also differs from that of the first embodiment. In the first embodiment, it will be recalled that the nut 32 was welded to the inside of the intermediate tube 27; in the second embodiment, as shown in Figure 4, the nut is simply located in a correspondingly-shaped hole bored in the wall of the intermediate tube 27, and the shape of the nut itself is shown in detail in Figures 5a, 5b and 5c. It will be appreciated from these Figures that the generally circular button-shaped part of the nut locates in the aforesaid bored hole, whilst the chamfered screw-threaded part of the nut projects to the right in Figure 4 and receives the screw 31. As Figure 4 shows, the nut 32 in this embodiment does not extend by as great an amount as the corresponding nut of the first embodiment.

Finally, it will be seen from Figure 4 that a circlip 28c holds the tubes 27 and 28 together once they have been assembled and prevents the tube 28 from moving axially relative to tube 27 whilst still allowing the two tubes to rotate relative to one another; and an elongate strengthening rib is welded to the flat plate which supports the wheel 11, 12 of the unit on the tube 16.

WHAT WE CLAIM IS:- 1. An assembly comprising a jockey wheel carried on a support which can be attached to a trailer unit, characterised by the provision of hand-operable means for extending and retracting the wheel relative to the support, means for transmitting a handpowered drive to the wheel from a power input on the assembly, and means allowing hand-steering movement of the wheel relative to the support and hence to the trailer unit to which the support is to be attached.

2. An assembly according to claim 1, in which the required hand-steering movement is obtained by so mounting the wheel on the support that a castor action of the wheel about the support is obtained.

3. An assembly according to claim 1 or claim 2, in which the assembly incorporates or is adapted to receive an elongate steering handle by which hand-steering movement of the wheel can be controlled.

4. An assembly according to any preceding claim, in which the means for transmitting a hand-powered drive to the wheel comprises an endless chain or toothed belt connecting two sprockets, one secured to the wheel and the other rotatably mounted at said power input on the assembly, said other sprocket incorporating, or being adapted to receive, a handle by means of which it can be rotated.

5. An assembly according to any preceding claim, in which the means for extending and retracting the wheel comprises a cooperating hand-rotatable screw-and-nut mechanism, the said support comprising a hollow tube in which slides a hollow rod fixed to the wheel, the screw being handrotatable and extending down inside the hollow rod, and the nut being fixed to the supporting tube and moving between the limits of upper and lower detents in the hollow rod.

6. An assembly according to claim 6, when dependent on claim 4, in which the toothed belt or chain passes through the hollow rod as it travels from one sprocket to another.

7. An assembly according to any of the preceding claims, in which, when the wheel is retracted up into a fully off the ground position, it is automatically prevented from swinging freely about its steering axis.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. the assembly, since less steering effort is required and the caster effect is not present and does not have to be overcome. It will be noted also that a chain guard 1 lea shrouds the wheel on its chainwheel side, and that this chain guard is provided with a "window" aperture to give access to a threaded adjusting mechanism indicated generally by the numeral 1 lc in order that slackness developing in the chain can be taken up. The housing for the main wheel spindle is, of course, elongate in the appropriate direction to allow such adjustment to take place. In Figure 3 a mounting bracket 28a partly surrounds the outermost tube 28 and incorporates a screw clamp 28b. The bracket 28a can be mounted on the front of a trailer unit, such as a caravan, and the screw clamp 28b clamps the tube 28-and hence the whole assembly-firmly against the bracket 28a whilst still allowing the wheel 11, 12 to be raised and lowered relative to the trailer unit. The screw 28b of the clamp bears against the inside of the clamp body 28a, as shown in Figure 3A, forcing the clamping jaw upwards against the tube 28 so as to grip that tube within the body of the clamp. As Figure 3A also shows, the tube 28 can be moved up and down within the clamp body 28a, and can then be held in a desired position by tightening the screw 28b. If the tube 28 is moved fully up into the clamp body 28a, and the screw 28b tightened, the wheel 11, 12 can be raised (using the cooperating screw and nut mechanism 31, 32) until the flat wheel supporting plate contacts the bottom of the tube 28. In that position, as Figure 3A indicates, the flat wheel supporting plate will have been drawn up inside the "U-shaped" extended portion of the clamp body 28a, and the flat base of the "U" will prevent the wheel supporting plate-and hence the wheel itself-from swinging about its steering axis. In this second embodiment of the invention, the arrangement of the nut 32 also differs from that of the first embodiment. In the first embodiment, it will be recalled that the nut 32 was welded to the inside of the intermediate tube 27; in the second embodiment, as shown in Figure 4, the nut is simply located in a correspondingly-shaped hole bored in the wall of the intermediate tube 27, and the shape of the nut itself is shown in detail in Figures 5a, 5b and 5c. It will be appreciated from these Figures that the generally circular button-shaped part of the nut locates in the aforesaid bored hole, whilst the chamfered screw-threaded part of the nut projects to the right in Figure 4 and receives the screw 31. As Figure 4 shows, the nut 32 in this embodiment does not extend by as great an amount as the corresponding nut of the first embodiment. Finally, it will be seen from Figure 4 that a circlip 28c holds the tubes 27 and 28 together once they have been assembled and prevents the tube 28 from moving axially relative to tube 27 whilst still allowing the two tubes to rotate relative to one another; and an elongate strengthening rib is welded to the flat plate which supports the wheel 11, 12 of the unit on the tube 16. WHAT WE CLAIM IS:-

1. An assembly comprising a jockey wheel carried on a support which can be attached to a trailer unit, characterised by the provision of hand-operable means for extending and retracting the wheel relative to the support, means for transmitting a handpowered drive to the wheel from a power input on the assembly, and means allowing hand-steering movement of the wheel relative to the support and hence to the trailer unit to which the support is to be attached.

2. An assembly according to claim 1, in which the required hand-steering movement is obtained by so mounting the wheel on the support that a castor action of the wheel about the support is obtained.

3. An assembly according to claim 1 or claim 2, in which the assembly incorporates or is adapted to receive an elongate steering handle by which hand-steering movement of the wheel can be controlled.

4. An assembly according to any preceding claim, in which the means for transmitting a hand-powered drive to the wheel comprises an endless chain or toothed belt connecting two sprockets, one secured to the wheel and the other rotatably mounted at said power input on the assembly, said other sprocket incorporating, or being adapted to receive, a handle by means of which it can be rotated.

5. An assembly according to any preceding claim, in which the means for extending and retracting the wheel comprises a cooperating hand-rotatable screw-and-nut mechanism, the said support comprising a hollow tube in which slides a hollow rod fixed to the wheel, the screw being handrotatable and extending down inside the hollow rod, and the nut being fixed to the supporting tube and moving between the limits of upper and lower detents in the hollow rod.

6. An assembly according to claim 6, when dependent on claim 4, in which the toothed belt or chain passes through the hollow rod as it travels from one sprocket to another.

7. An assembly according to any of the preceding claims, in which, when the wheel is retracted up into a fully off the ground position, it is automatically prevented from swinging freely about its steering axis.

8. An assembly as substaantilly described

herein, with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings.

9. An assembly according to claim 8 when modified substantially as described herein with reference to and as illustrated in the remaining Figures of the accompanying drawings.