This invention relates to towing devices particularly but not exclusively for trailers including caravans or the like.

Conventional towing devices comprise a ball and socket joint. The ball is rigidly connected to the underside of a car via bolts and the socket is rigidly connected to a trailer. The socket is placed over the ball to provide a joint which allows relative lateral movement of the car and trailer so as to aid manoeuvering of the car and trailer around corners. A pin passes through the wall of the socket and below the ball to prevent the socket from becoming detached from the ball .

The known joint is problematic in that when the car is towing the trailer along a straight road the trailer tends to move laterally relative to the car owing to the action of wind or uneven road surfaces on the trailer .

The present invention has been made from a consideration of this problem .

For the purposes of the present invention the term vehicle is used to describe any vehicle such as a tractor , car , lorry , articulated lorry and so forth which may be used for towing and the term trailer is used to describe any item which may be towed

such as a trailer , caravan and so forth .

According to the present invention there is provided a towing device comprising a towing member adapted to be connected to a vehicle, a member to be towed adapted to be connected to the trailer , characterised in that the towing device comprises means for resisting relative lateral movement of the towing member and the towed member .

I n a preferred embodiment of the invention means are provided for rigidly connecting the towing member to the towed member . At least a part of one of the members is movable so as to allow relative lateral movement of the vehicle and trailer when the towing device is in use. The towing member comprises means for rigidly connecting the towing member to the towed member , at least a part of the towing member being movable so as to allow relative lateral movement of the vehicle and trailer when the towing device is in use and the towing member further comprising means for resisting the said lateral movement.

Preferably the means for resisting the said lateral movement are provided on the said one member . The means for resisting the relative movement may comprise one or more springs and/or one or more releasably engageable parts. The releasably engagable parts, may be biased towards one another , and may comprise teeth which releasably engage the teeth of other such parts.

The means for rigidly connecting the towing member to the towed member may comprise a pin passing between the towed member and the towing member . For example a pin may pass through the wall of the socket and be received in a bore within the ball . Alternatively the rigid connection may be provided by providing at least one barrier integral with or adapted to be connected to one member which in use will restrict the lateral travel of the other member . For example a hole may be provided in one of the members through which at least a part of the other member will pass , the hole being of similar dimension to the part of the other member passing through it so as to provided a snug fit .

Alternatively a square ball and a correspondingly sized socket may be used .

A lid or pin may be provided over the ball and socket joint to restrict the upward travel of the socket from the ball and hence prevent the socket from becoming detached from the ball .

The towing device may comprise two releasably engageable parts such as two sets of opposing teeth at least one of the parts being urged towards the other part .

I n order that the invention may be more readily understood specific embodiments thereof will now be described by way of

example only with reference to the accompanying drawings in which: -

Figure 1 is a diagrammatic part sectional side elevation of one embodiment of the invention in use;

Figure 2 is a magnified part sectional side elevation of the towing device of Figure 1 ;

Figure 3 is a rear part sectional elevation of the towing member of Figure 1 ;

Figure 4 is a rear part sectional elevation of a second embodiment of a towing member of the present invention ;

Figure 5 is a part sectional perspective view of the towing member of Figure 4;

Figure 6 is a rear elevation of a further embodiment of the towing member of the invention;

Figure 7 is a side elevation of the towing member of Figure

6;

Figure 8 is a side elevation of a further towing member ;

Figure 9 is a side elevation of a still further towing device; and

Figure 10 is a side elevation of another towing device.

Referring to Figures 1 to 3 a vehicle 10 is connected to a trailer 15 via towing device 20. The towing device 20 comprises a towing member 22 and a towed member 24. The towing member 22 comprises an open box 26 the rear wall of which is integral with an upstanding plate 30. The box 26 is secured to the rear of the vehicle 10 via bolts 28 through upstanding plate 30. The lower part of an L shaped member 32 is received in the box .

Tightly sprung coil springs 38,40 are received in the box 26 on either side of the horizontal limb 42 of the L shaped member 32. The springs 38,40 are biased to resist lateral movement of the L shaped member 32 within the box 26.

A ball 34 is integral with the top of the vertical limb 41 of the L shaped member . A bore 36 extends into the ball 34 from the side of the ball 34 which is remote from the upstanding plate 30.

The towed member 24 comprises a socket 44 defined by a wall 46. The socket 44 is adapted to receive the ball 34 when the towing device 20 is in use. A pin 48 extends through wall

46 of towing device 24 and is received in bore 36 so as to provide a rigid connection between the towing and towed members 22,24 when the pin 48 is in position. This prevents relative lateral movement of the towing and towed member 22, 24. The towed arm 30 extends rearwardly from the socket 44, to the underside of trailer 15.

I n order to detach the trailer 15 from vehicle 1 0 the pin 48 is removed from the bore 36 and the socket 44 is withdrawn from the ball 34.

Referring now to Figures 4 and 5 there is shown a second embodiment of a towing member 60 of the present invention for use in conjunction with a towed member 24 similar to that previously described .

The towing member 60 comprises a box 62 the rear upstanding wall 64 of which is taller than the front upstanding wall 66 such that upstanding plate 68 extends above the top 70 of the box 62.

Plate 68 is adapted to be secured to the rear of a vehicle 10 via bolts 72.

A toothed ring 78 is integral with the underside of the top 70 of the box 62. An orifice 74 passes through the top 70 and the centre of the toothed ring 78. A ball 76 is integral with the top of a rod 72. Rod 72 extends downwardly from ball 76 through

orifice 74 and into box 62.

A second toothed ring 80 is non-rotatably mounted around the part of the rod 72 immediately below the first toothed ring whilst being vertically movable such that the sets of teeth 80 , 84 of the two rings 78 , 82 may releasably engage one another . This may be achieved by forming the rod 72 into a non circular shape such as a hexagon or elipse and providing a correspondingly sized orifice through the centre of the second toothed ring 82.

The second toothed ring 82 is biased towards the first toothed ring 78 via coil spring 86. The tension of the spring 86 is maintained via tightening nut 90 which bears against the spring 86 via washer 88.

The base 90 of rod 72 rests on the base of the box 92. Alternatively a collar may be provided around a part 98 of the rod which extends above the top 70 of the box so as to support the rod 72 whilst still allowing rotation thereof .

I n use the pin 48 of towed member 24 is received in a bore 94 in the ball 76 in a similar manner to that described with reference to the first embodiment of the invention .

Referring to Figures 6 and 7 there is shown a third towing member 100. The towing member 100 is similar to that described

with reference to Figures 4 and 5 except that the rod 72 is supported by a collar .

The upper toothed ring 78 is integral with the collar 1 02. The manner of operation of the towing member 100 is also much the same as that previously described with reference to Figures

4 and 5.

However , here the towing member 100 is not attached to the towed member 26 by a pin being inserted though a bore in the towing ball 76. A cage 1 04 is provided around the top of the rod 72. The cage 104 comprises a base 1 06 which is fixed to the rod 72 and an upstanding rear wall 108 which is located on the side of the rod which is adjacent the towing vehicle . The sides of the cage 1 04 may be closed or open as desired . The roof and front of the cage are defined by a lid 1 1 0 . The lid 1 1 0 is preferably attached to the top of the rear wall 108 at pivot 1 12.

The lowermost part of the lid 1 10 may be releasably secured to the free end 1 14 of the base 106 by two locks 1 16.

In order to connect the towed member 24 to the towing member 100 the lid 110 is raised and the wall 46 of the towed member 24 is located over the ball 76. The lid 1 1 0 is then closed and locked to the base 1 06 of the cage via the two locks 116. It can be seen that an aperture 118 is provided in the lid through which the arm of the towed member 24 extends when in

use. The part of the arm of the towed member 24 over which the aperture extends in a snug fit inside aperture 1 18 so as to provide a rigid connection before the towed and towing members . The height of the wall 108 is selected such that it bears against the top of the wall 46 of the towing member when in use such that the ball 76 and socket 44 remain engaged .

Referring to Figure 8 a cage 120 may have side walls only one of which 1 22 is shown . Here a pin would be passed through keyholes 124 in the side walls. The pin extends over the top of the wall 46 of the towed member so as to prevent the socket 44 from disengaging the ball 76. The top of the cage is open here although it is possible to provide a lid . A fitting 126 for an adjusting bar is provided on the underside of the base of the cage 120.

Referring to Figure 9 there is shown a further embodiment of the invention having particular but not exclusive application to articulated vehicles.

Here a vertical rod 128 depends from a trailer . A pin which is key shaped in underplan view extends from the base of the rod 128. A radially extending disc 130 is fixed to the rod

128. This may be achieved in one example by forming the rod 128 into a non-circular shape such as a square, hexagon or elipse and providing a correspondingly sized orifice through the

centre of the disc 130.

A second disc 132 is secured to the rod 128 below the first disc 130 . The second disc 132 is parallel with the first disc 1 30. The second disc 132 is mounted in such a manner that is is non-rotatable relative to the rod 128 but may move vertically relative to the rod 128. A coil spring 134 is provided between the two discs 1 28 , 130. A set of teeth 1 36 are provided on the underside of the second disc 132. These teeth 136 resiliently releasably engage a further set of teeth 138 provided on the top

T O of a third disc 140 under the action of the spring 134 , the third disc 140 being fixed to the top of the tractor unit .

I n use while the vehicle travels along a straight road the two sets of teeth 136 ,138 engage one another thus preventing relative lateral movement of the tractor unit and trailer . As the 15 vehicle turns a corner this causes the upper disc 132 to move upwardly and also rotates relative to the lower disc 140 about the axis of the rod 128.

Referring now to Figure 10 there is shown a further embodiment of the invention with particular but not exclusive 20 application to articulated vehicles .

A rod 142 depends from the underside of the base of a trailer . A pin 144 which is key shaped in underplan view extends

from the base of the rod . I n use th is is located in the so called fifth wheel of the trailer unit in a conventional manner . A disc 1 46 extends in a radial direction from the rod 142. This disc 146 is fixed to the rod 142 such that there is no relative movement of the dies 146 and the rod 142.

Brake shoes 148 , 1 50 operated by way of an hydraulic system move inwardly to engage the periphery of the disc 146 when desired , such as when the vehicle is travelling along a straight road . The system is operated either manually by the driver or automatically .

Alternatively the disc 146 may be maintained for any desired length of time in a set position by way of a disc brake system

I t wil l be seen that the present invention allows relative lateral movement between the vehicle 1 0 and trailer 1 5 on cornering whilst resisting lateral movement while the vehicle 1 0 and trailer

1 5 are travelling along a straight road . This controlled resistance to lateral movement may be prov ided by the springs , releasably engageable teeth which are biased together or by other suitable means .

It is to be understood that the above described embodiments are by way of illustration only . Many modifications and variations are possible.

For example the towing device could be used on an articulated tractor and trailer .