GB2046190A - Improvements in and Relating to Attachments for Trailer Units - Google Patents

Abstract

An attachment for trailer units, e.g. caravans, is disclosed comprising a jockey wheel 11 carried on a support 16, the support in use being attached to a trailer unit so that the wheel 11 projects beneath the support and engages the ground on which the trailer unit stands, the attachment including a chain or toothed belt 21 for transmitting a hand power drive to the wheel from a power input such as a handle 33. The attachment also includes means such as a tiller bar 28 allowing a hand steering movement of the wheel 11 relative to the support and hence relative to the trailer unit to which the support is attached in use. The support comprises a first portion 16 which is adapted to be secured to the trailer unit, and a second portion 15 which carries the wheel 11 and which is slidable up and down relative to the first portion. the support also includes means to clamp the second portion to the first at selected positions within its range of sliding movement. <IMAGE>

Description

SPECIFICATION Improvements In and Relating to Attachments for Trailer Units The invention relates to attachments for trailer units.

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 at the front. When the caravan or trailer is being towed, the nose wheel-commonly known as 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.

When the unit is being manoeuvred in a confined space-for example when it is first being backed out of the drive of a house in order to be coupled to its towing vehicle-difficulty can be experienced, because such units as caravans are extremely heavy and the jockey wheel itself is usually relatively small and a considerable mechanical disadvantage has to be overcome. In addition, many jockey wheels are mounted to give a castor effect and this leads to a self-steering tendency when the user attempts to manoeuvre his caravan if it is unattached to any towing vehicle.

The invention provides an attachment comprising a jockey wheel carried on a support, the support itself in use being attached to a trailer unit so that the wheel projects beneath the support and engages the ground on which the trailer unit stands, the attachment including means for transmitting a hand-powered drive to the wheel from a power input on the attachment, the attachment also including means allowing hand-steering movement of the wheel relative to the support (and hence to the trailer unit to which the support is attached in use), the support comprising a first portion, which is adapted to be secured to the trailer unit, and a second portion, which carries the wheel and which is slidable up and down relative to the first portion, the support also incorporating means to clamp the second portion to the first portion at selected positions within its range of sliding movement, and the arrangement being such that the amount by which the wheel projects beneath the support in use can be varied only by releasing said clamping means and sliding the wheel-carrying portion of the support up or down within the clamp.

Preferably the attachment incorporates, or is adapted to receive, an elongate steering handle such as a tiller-by which the required handsteering movement of the wheel can be controlled. The elongate steering handle may be telescopic, or foldable, or both.

The means for transmitting a hend-powered drive to the wheel may comprise an endless chain or toothed belt connecting two sprockets, one sprocket being secured to the wheel and the other being rotatably mounted at said power input on the attachment, 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 the 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 of the wheel and the drive input sprocket.

In any event, intermediate sprockets may be positioned between the wheel sprocket and the drive sprocket, to keep the chain or toothed belt in a properly tensioned state. Such sprockets may be spring-loaded in a direction tending to increase the tension in the chain or toothed belt.

In one particularly simple and advantageous form of the invention, the wheel-carrying portion of the support comprises two hollow tubes rotatably mounted one within another, the outer tube being slidable within and engageable by the clamping portion of the support, the inner tube carrying the wheel at one end and the drive input and steering means at the other end and being capable of rotational steering movement within the outer tube irrespective of whether or not the outer tube is clamped.

In such an arrangement, and where the driving sprocket and the driven sprocket are connected by a chain or toothed belt, the chain or belt can pass along the interior of the inner hollow tube as the chain or belt travels from one sprocket to the other.

One attachment embodying the invention is shown, by way of example only, in the accompanying drawings. It will now be described with reference to those drawings, in which: Figure 1 shows the attachment in side elevation; Figure 2 shows the attachment in end elevation; and Figures 3 and 3A show in perspective two different clamps, either of which could form part of the attachment.

Figure 1 is sectioned, and Figure 2 is partly sectioned.

A wheel 1 1 incorporates a treaded rubber tyre, which may be solid or pneumatic, and is rotatably mounted on a stub axle 12. The stub axle 12 is welded to a generally trapezoidal plate 1 3 which is itself carried at one end of a circular-cylindrical elongate hollow tube 14. This hollow tube 14 is co-axially and rotatably mounted within a coextensive further circular cylindrical hollow tube 15. The tube 15 is slidable axially up and down within the gripping jaws of a clamp assembly, which is referenced generally 16 and whose construction and operation will be described later.

At the top end of the tube 14 (i.e. the end remote from the wheel 11) there is joined to the tube a prefabricated hollow square steel box 17.

This box 17 incorporates a drive input in the form of a shaft 18 which is rotatably journaled in the walls of the box 17 and which carries, inside the box, a first toothed drive sprocket 19.

An endless chain 21 is trained around the drive sprocket 1 9 and runs down the interior of the hollow tube 14 and around a chain wheel 22 which (as Figure 2 shows) is secured to the wheel 1 Auxiliary sprockets 23, 24, 25 are mounted at spaced points on the attachment in order to guide the chain 21 and to tension it.

As Figure 2 shows, a chain guard 26 shrouds the chain wheel. It is removably secured at 27 to the bottom part of the tube 14. It has been removed from the attachment shown in Figure 1, for the sake of clarity.

An aperture cut into the bottom portion of the chain guard 26 gives access to a mechanism 26A, 268 for adjusting the position of the wheel 11 in the plate 13, thereby enabling the tension of the chain 21 to be varied. As Figure 2 shows, the component 26 is an elongate plate which at one end is drilled through to fit closely over the wheel spindle 27: at the other end, it is bent over at right-angles to the main body of the plate, and is drizzled and tapped to take the correspondinglythreaded screw and nut which together constitute the component 26B.

As shown in Figure 2, the through-bore in the plate 13 which receives the stub axle 12 is elongated to allow the mechanism 26A, 26B to work. With the main stub axle securing nuts slackened, the screw of the screw-and-nut component 26B is rotated in its threaded bore in the plate 26A, causing the plate 26A to advance or retract the stub axle 12 until the desired tension in the chain 21 is achieved. At that point, the nut of the screw-and-nut component 26B is tightened, locking the screw of that component in position in its bore to fix the position of the stub axle 12. The main wheel-securing nut can then be tightened to grip the stub axle 12 firmly in position relative to the plate 13.

In order for the chain 21 to pass from the drive box 1 5 into the interior of the hollow tube 14, a circular hole "H" (Figure 1) is cut out of the floor of the box 17.

An elongate tiller bar 28 is pin-jointed to a boss on one side of the box 1 7, and projects from the box. As Figure 1 shows, the tiller bar 28 passes through an accurately machined bore towards the top of the hollow tube 14, and so effectively secures the box 1 7 to the top end of the tube 14. If the securing pin 28A is removed, and the bar 28 withdrawn, the box 17 can be removed, for maintenance; but with the bar 28 and pin 28A in place the box 17 is firmly secured to the hollow tube 14 which is in turn welded to the wheel carrying plate 13, movement of the tiller 28 in an arc about the axis of the tube 14 will cause steering movements of the wheel 11.

Because the tube 14 is freely rotatably mounted within the tube 15, the wheel 11 can be steered irrespective of whether or not the tube 1 5 is held in the clamp 16.

Hard annular nylon collars 29,31 are provided respectively at the top and the bottom ends of the tube 15. They space the tube 15 from the box 17 at the top end and-in conjunction with a steel collar 32 welded to the tube 14-they space the tube 15 from the wheel carrying plate 13 at the other end. The collars themselves are a freelyrotatable fit around the outer circumference of the tube 14.

A handle 33 is secured to the shaft 18, so that when the handle 33 is turned the shaft 18 rotates and-via the sprocket 19, the chain 21 and chain wheel 22-transmits a powered drive to the wheel 11. Although the handle 33 is shown permanently secured to the shaft 18, it could be releasable from the shaft 18. For example the portion of the shaft 1 8 which projects from the drive box 1 7, and which receives the boss of the handle 33, could be of square cross-section, with the interior of the boss of the handle being bored out to match.

Figure 3 shows in detail the construction of the clamp 16. The main body 34 of the clamp is prefabricated and incorporates lugs 35 by which the clamp-and hence the entire attachment- can be releasably secured to a trailer unit (not shown). Welded within the main body 34 is the cylindrical fixed jaw 36A of the clamp. The tube 1 5 is a sliding fit within this cylindrical jaw 36A.

The movable jaw 368 of the clamp fits on one end of the cylindrical jaw 36A.

A clamping screw 37 is a threaded fit within the movable jaw 368. Rotation of the clamping screw causes one end 37A of the screw to bear against or be released from the main body 34 of the clamp, so causing the jaw 368 to be brought respectively into or out of gripping engagement with the tube 15.

When the clamp 16 is released, the tube 1 5- and hence the entire assembly of wheel 11, the plate 13, inner tube 14 and drive box 17-can be slid axially up and down within the clamp, and can then be clamped at any desired operating position. With the clamp secured by its lugs 35 to a trailer unit such as a caravan, the wheel 11 can quickly be brought into a ground engaging position, the clamp 16 locked, and the combination of hand-steering and hand-wheelrotating facilities can be used to drive the trailer unit slowly and carefully.

The attachment can thus be used to manoeuvre a relatively large caravan, say, within the confined space of a garage, a camp site, or a drive running alongside a house. The whole attachment is so light and simple, and takes up so little room, that the manoeuving has been completed (for instance when the caravan is hitched to its towing vehicle) the clamp 16 can be released, the wheel 11 slid as far up off the ground as it will go, the clamp 16 secured again to hold the wheel 11 permanently off the ground, and the caravan towed away.

There is therefore no need to remove the attachment from the caravan whilst the caravan is being towed.

Similarly, once the caravan has been moved into a desired position, the normal jockey wheel with which it is already fitted can be lowered in order to support the front end of the caravan on the ground. The attachment can then be raised into its highest position, as just outlined, and secured by the clamp 16 until it is next needed.

In Figure 3A, the clamp of Figure 3 has been modified. Parts of Figure 3A which correspond to those shown in Figure 3 have been given the same reference numbers. The movable clamping jaw 36B pivots about the left-hand side of the clamp as a whole, and the end 37A of the screw 37 makes screw-threaded engagement with a bore 38 formed in the fixed jaw 36A of the clamp.

In this embodiment, the jaw 368 can be swung fully back from the fixed jaw 36A, so that the tube 15 (and the parts carried by it) can be inserted into and removed from the clamp in directions transverse to the axis of the tube 1 5.

In another embodiment of the invention, not illustrated in the drawings, the clamp 16 is a double clamp in which the bolt-on lugs 35 and the clamping components 37, 37A, 38 are replaced by an "overcentre" quick-reiease clamp.

The main action of the Figure 3A clamp in holding the tube 15 is as previously described, but instead of the lugs 35 having to be bolted onto the trailer unit the "overcentre" quick-release part of the clamp secures the whole attachment to its trailer unit as well as securing the tube 15 within the clamp.

This clamp, like the clamp of Figure 3A, gives the advantage that, once the attachment has been used, it can at once be released entirely from the trailer unit and can then be stowed in the unit itself-or for example in the garage from which the trailer unit has just been manoeuvred outuntil the attachment is next needed. It does not then have to ride permanently on the unit adjacent the existing conventional jockey wheel, and the overall nose weight of the unit is thus not increased beyond its designed original weight.

Claims (11)

Claims

1. An attachment which comprises a jockey wheel carried on a support, the support in use being attached to a trailer unit so that the wheel projects beneath the support, the attachment including means for transmitting a hand power drive to the wheel from a power input on the attachment, the attachment also including means allowing hand steering movement of the wheel relative to the support, and the wheel being lockably adjustable relative to the support so that the wheel can be clamped at any one or a range of distances from the support.

2. An attachment as claimed in cl 1 in which the support comprises a first portion which is adapted to be secured to the trailer unit, and a second portion which carries the wheel and which is slidable up and down relative to the first portion, the support also incorporating means to clamp the second portion to the first portion at selected positions within its range of sliding movement.

3. An attachment as claimed in claim 2 in which the arrangement is such that the amount by which the wheel projects beneath the support in use can be varied only by releasing said clamping means and sliding the wheel carrying portion of the support up or down within the clamp.

4. An attachment as claimed in any one of claims 1 to 3 in which the attachment is aaddapted to receive an elongated steering handle by which the required hand steering movement of the wheel can be controlled.

5. An attachment as claimed in claim 4 in which the handle is telescopic or foldable or both.

6. An attachment as claimed in any one of claims 1 to 5 in which means for transmitting a hand power drive to the wheel comprises an endless chain or toothed belt connecting two sprockets, one sprocket being secured to the wheel and the other being rotatably mounted at said power input on the attachment and being adapted to receive a handle by means of which it can be rotated.

7. An attachment as claimed in claim 6 in which the transmission from one sprocket to the other incorporates reduction gearing.

8. An attachment as claimed in either of claims 6 or 7 in which intermediate spring-loaded sprockets are positioned between the wheel sprocket and the drive sprocket to keep the chain or toothed belt in a tensioned state.

9. An attachment as claimed in any preceding claim in which the wheel carrying portion of the support comprises two hollow tubes rotatably mounted one within another, the outer tube being slidable within and engageable by the clamping portion of the support, the inner tube carrying the wheel at one end and the drive input and steering means at the other end and being capable of rotational steering movement within the outer tube irrespective of whether or not the outer tube is clamped.

10. An attachment as claimed in claim 9 in which the driving sprocket and the driven sprocket are connected by a chain or toothed belt which passes along the interior of a hollow inner tube.

11. An attachment for a trailer unit substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2, Figure 3 or Figure 3A of the accompanying drawings.