GB2358164A - Stowing and deploying a trailer for towing vehicles - Google Patents

Abstract

A repair vehicle has a deployable trailer movable between stowed and deployed positions by, e.g., a screw 25 engaged by a nut 27 on the end of a towing member 1 of the trailer. The towing member is engaged with a coupling on the back of the vehicle once the trailer is deployed so that towing forces are not transmitted through the deployment mechanism 25, 27. The trailer is "T" shaped, is designed to support the front wheels of a vehicle being towed, has self-steering wheels and is telescopically adjustable laterally against, or assisted by resiliency (Figs 1 and 2). A locking pin may be used to secure the trailer coupling (Fig. 3).

Description

2358164 THE TOWING OF VEHICLES This invention relates to the towing of

vehicles and in particular the recovery from a road of a broken-down vehicle.

The towing of a broken-down vehicle has altered dramatically over the years. Initially tow ropes were the standard method which was later improved by use of a rigid tow bar. In such cases however the broken-down vehicle . required a driver to steer the broken- down vehicle whilst it was being towed.

Later developments included the use of an A frame. This is a frame where the legs of the "A" were fitted to the bumper, or later the suspension, of the vehicle to be towed. At the point of the "A" a tow hitch is positioned to be fitted to a tow bar of a towing vehicle. An advantage of such a system is that a driver is not needed in the towed vehicle. A disadvantage is that the bodywork or suspension of the towed vehicle may be damaged.

Another arrangement which avoids the risk of damage to the towed vehicle is to support the front wheels of the broken-down vehicle on a trailer, often called a "car ambulance", which is pivotally attached to the towing vehicle in the usual way for a trailer. Such car ambulances work well in towing a broken-down vehicle. However, it is very inconvenient for a roadside patrol vehicle permanently to have to tow a trailer, especially as it is often the case that broken-down vehicles can be repaired quickly on the roadside and so there is no need for the trailer to remove the vehicle.

As a result a type of trailer known as "Stow and ToW was developed. This was a trailer which is carried in a disassembled form in the repair vehicle.

Once the repair man realises that he cannot effect a quick roadside repair, he assembles the trailer and winches the front wheels of the broken down vehicle on to it, to tow the vehicle to a convenient repair centre.

2 A problem with such Stow and Tow trailers, however is that their ppits are heavy to manhandle during assembly, and then assembly is very tIr e consuming; it often takes over one hour to complete the assembly ofrthe trailer and to get the broken-down vehicle onto the trailer. During all that ticr e, the occupants of the recovery vehicle and the repairman are exposed to tl e damages of passing traffic.

A further form of recovery vehicle is one having a support for the tr.,. ont wheels of the vehicle to be recovered which is mounted on an arm pivotalbly connected to the bed or chassis of the recovery vehicle. In this case, when a vehicle is to be recovered, the arm is pivoted so the support rests on the flod r, and the front wheels of the vehicle to be recovered are pulled onto e support. The arm is then pivoted to lift the front wheels of the vehicle to. t e recovered above the ground. In this case, the weight of the recoverE d vehicle must be borne by the rear axle of the recovery vehicle. Also, e weight of the recovered vehicle will give a moment of force about the rear ax e of the recovery vehicle. Therefore, the recovery vehicle must be a hEt'y duty vehicle.

According to a first aspect of the invention there is provided a method in which a repair vehicle is able to drive to a repair site without any trailer, the trailer being accommodated in a stowed position on board the repair vehicli:-, and at the repair site means are provided to deploy a trailer out from ll---e stowed position to a towing position behind the rear of the repair vehicle, Cir d thereafter to couple a towing end of the trailer to the rear of the repair vetli:.ic e so that the towing forces are transmitted to the repair vehicle directly rather than via the said means, the coupling between the trailer and the repe ir vehicle allowing free movement of the trailer relative the repair vehicle so th;t it can follow the repair vehicle when towed.

3 The advantages of such an arrangement are that the trailer is normally stowed within the repair vehicle and so, when driving to a repair site, the repair vehicle need not be hampered by the trailer. At the repair site, however, the trailer is already assembled and simply deployed from the rear of the vehicle. This can be achieved automatically, relatively quickly and need not involve any heavy lifting. Also by ensuring that the trailer is coupled to the vehicle directly for towing, all the large towing forces need not be accommodated by the means for deploying the trailer and so those means can as a result be made relatively light-weight and compact.

Once the trailer has been used and is no longer needed, it can be thereafter retracted into the vehicle to its stowed position.

According to a second aspect of the invention, a repair vehicle having a chassis and bodywork mounted on the chassis, comprises deployment and retraction means for a trailer mounted within the bodywork of the repair vehicle and attached to the chassis, the trailer carried by these extension and retraction means normally stowed by those.means within the bodywork but movable by those means to the rear of repair vehicle to a towing position and from that position to the stowed position, and coupling means for attaching a towing end of the trailer and the chassis so that towing forces are taken directly by the chassis to the repair vehicle.

The trailer for use in the invention can be of generally conventional construction and will be of the type designed to support the front wheels of a broken down vehicle. This will generally involve a main towing frame generally of M shapes, which comprises a lengthwise member constituting the stem of the "-F" which has a towing end at the base of the stem where it is coupled to the vehicle, and a transverse member constituting the cross-part of the "T" and joined to the end of the lengthwise member away from the towing end. The transverse member will have a pair of wheels at or near its ends 4 and have means, such as wheel pans, on to which the front wheels of a broken down vehicle can rest for towing.

The wheels of the trailer should be mounted in a self steering mari n z.r j so that the trailer can follow the towing vehicle around corners when the fc it wheels of a broken down vehicle are supported by the trailer. Suitable Self steering arrangements are known.

It is not essential but may be desirable in some circumstances for ithe trailer to be stowed in a compacted condition width-wise. Thus when lhe trailer is in the towing position it may be desirable for it to be widE! 0 accommodate the broken-down vehicle than the width available within 11 e bodywork of the repair vehicle. As will be appreciated this will often def)( pr d upon the size of the repair vehicle.

If the trailer needs to be brought to a compacted condition for stowing, s this can be achieved by giving the transverse member resiliency along, i. i length, e.g. by providing parts which are capable of resiliently telescoping or e into the other to reduce the width of the trailer, and cam means on the veh lcle to reduce the width of the trailer as it enters the bodywork of the vehicleiffir stowing, the inherent resiliency causing the trailer to resume its full width Is it is moved to its towing position. To prevent changes in width during towino, it is preferred that the width of the trailer be fixed by manually operable locNir 9 means which are operated to lock the transverse member to its fully op(, n position for towing and are released before the trailer is brought to the stowdl d position.

The means for retracting and extending the trailer may comprise a nit, which forms a third aspect of the invention, that comprises frame means to: be attached to a structural part of the vehicle, translation means movable along the frame in one direction, which is to be a fore and aft direction when Ithe frame is mounted on the vehicle, coupling means for attaching a trailer to the translation means, and coupling means for fixing the towing end of the trailer directly to the structural part, such as the chassis of the vehicle, when the translation means reaches the limit of its travel corresponding to the towing position.

In order that the unit can remain relatively compact it is desirable that its overall length in the said one direction be roughly the same as the extent of movement of the translation means, which in turn is fixed by the extent of movement required between the stowed and towing positions of the trailer.

Therefore, it is preferred not to use an hydraulic pistonlcylinder arrangement which would require that overall length to be almost double that required in order to accommodate the pistonlcylinder arrangement in its extended position. Instead it is preferred to use an arrangement such as a rack and pinion, or more preferably a rotatable screw and a trunnion which works along the screw as the latter is rotated. Such an arr angement can be relatively simple since a small electric motor and reduction gear can be used to operate the screw.

The trailer should be attached to the vehicle at its towing end by means of a universal pivot to allow the usual relative movement between the trailer and vehicle during towing. In addition a hole may be provided through this pivot and a pin provided which is passed through that hole to lock into engagement with means attached to the chassis of the vehicle when the translation means are in a fully extended position with the trailer in its towing position, e.g. by means of a simple electronically operated solenoid. In this way, towing forces will then be directly passed via the pin to the chassis of the vehicle. This allows the unit itself to be relatively light-weight since it does not need to be strong enough in itself to take all of the towing forces.

An important advantage of such a compact and light-weight unit is that it can readily be fitted to existing vehicles, particularly if they have a chassis, 1 6 and accommodated within normal sized bodywork so that there remaiins sufficient space for the tools which need to be carried and room 'for passengers from the broken down vehicle during towing. Such vehicles pte often referred to as double cab vehicles and examples are LDV Convoy 3."F, E0 Doublecab, Voltswagon T4 2.5 Tdi Doublecab and Ford Transit TI, Doublecab.

The trailer may have its own braking system. This can be achieved,Iby the provision of a telescoping arrangement for the trailers such that braking of the vehicle causes compression of such parts of the trailer and the movement causing that compression is used to move and apply the brakes to the whee s of the trailer.

Such an arrangement can be improved according to the further featwre of the invention by providing the wheels of the trailer with disc brakes r cl providing a hydraulic pistonlcylinder unit associated with the telescopIr 9 i arrangements on the trailer, the unit acting as a pump to pass hydraulic. fip cl to the disc brakes to activate them when the trailer compresses as a result of braking of the vehicle.

The invention will now be described by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a plan view of a trailer; Figure 2 shows a view of the mounting of a wheel to the base of the trailer; i Figure 3 shows a view of the coupling between the trailer and the chassis of a recovery vehicle; and Figure 4 shows a cross-sectional side view of a deployment means.

7 As shown in plan view in Figure 1, the trailer according to one example of the present invention is of a generally T-shape. The stem of the Tshape forms a towing member 1 that is retractable and fixable to the towing vehicle.

The cross-member 2 of the T-shape includes a wheel 3 at either end, and pans 4 to receive the wheels of a broken down vehicle that is to be recovered.

The wheels 3 and pans 4 are each mounted to a member 5 that is mounted telescopically on the cross-member 2 of the trailer, allowing the relative distance between the wheels 3 and the relative distance between the pans 4 to be varied. This is advantageous as it allows the trailer to be used to recover vehicles of different widths. For vehicles of different widths, the space between the front wheels of the vehicle will be different. Therefore, by varying the width between the pans 4 of the trailer that support the wheels of the vehicle during recovery, different width vehicles may be recovered using the same trailer. Without this feature, it would be necessary to increase the width of the pans 4 to allow these to align with the wheels of the vehicle, therefore increasing the size and weight of the trailer. Further, as described below, the telescopic arrangement assists in the stowing of the trailer when not in use.

Each wheel 3 is connected to the member 5 by a pivotal coupling 6 that enables the wheels 3 to self-steer. The longitudinal plane of the wheels 3 are angled inwardly at a small camber angle to help reduce wear of the tyres, and to assist with the self-centring of the wheels. Each wheel 3 is mounted on an axle which is supported by a first support 10 of the pivotal coupling 6. This is coupled to a second support 11, provided co-axialiy with the first support 10, and attached thereto by a king pin, allowing relative rotational movement between the first and second supports 10, 11. The second support 11 is fixed to the member 5. The axis of the pivotal connection between the first and second support 10, 11 is angled outwardly, such that the theoretical extension of the axis intersects the ground at a point to the inside the wheel 3. This arrangement is similar to the self-centring arrangement of vehicles, such as 8 lorries. The abutting surfaces of the first and second supports 10,11. is angled. In this way, the relative rotation of the first and second supports 10, 11 causes the second support 11 to be lifted away from the first suppc irt 10. The weight of the trailer and the vehicle supported by the trailer cau(,s this lifting to be resisted, thereby encouraging the supports 10, 11 to rota:e back to their lowest position, in which the wheels 3 are centred. This liffir g and reverting action is similar to that achieved with a rising butt hinge of a door.

A locking mechanism is provided on the hinge to stop the relat.Ke rotation of the supports 10,11. This is especially useful when the tow Irg vehicle is reversing, in which case turning or steering of the wheels of the trailer is not desirable.

The towing member 1 is receivable through a bush 20 mounted on he chassis of the towing vehicle, and into a receiving housing 26 in the towi n vehicle extending upwardly at an angle of about 150 to the horizontal. This angle is dependent o the length of the towing member 1 and the height of 1,hlm towing vehicle. The receiving housing 26 includes a threaded rod 25. The end of the towing member 1 includes a plate 27 including an interncidly threaded hole 28 which receives the threaded rod 25. The threaded rod 4 is driven by a motor, typically a 12v motor. By rotating the threaded rod 25, t; he plate 27, and therefore the entire towing member 1, is driven along the threaded rod 25, thereby retracting or deploying the towing member 1 fri) the housing 26 depending on the direction of rotation of the threaded rod 21 The speed of rotation of the threaded rod 25, and the pitch of the threads,,. i3 selected such that towing member may be retracted or deployed within a acceptable time period, typically around 1 minute.

A threaded system as described is preferred for the deployment of t.h trailer since this does not require any additional length. In particular, th 9 length of the threaded rod 25 can be substantially the same length as the towing member 1, and this will allow the complete retraction and deployment of the towing member 1. If systems such as hydraulic systems were used, this would require additional space, and in particular additional length, to accommodate the retraction and deployment means. However, other means may be used that fit into the available space for allowing the deployment and retraction of the towing member 1, for example using a rack and pinion. In some cases, the vehicle may have sufficient room to accommodate a hydraulic or other system.

Especially in view of the compact size of the deployment means, this does not have sufficient strength to support the weight of the trailer and the vehicle being recovered. Therefore, according to the present invention, the trailer, once deployed, is attached to the vehicle by a means other than the deployment means. As shown best in Figure 3, the end of the towing member 1 is provided with a ring connector 30 within which a ball connector 31 having an axial opening 34 is provided. When the towing member 1 is fully deployed, this opening 34 will align with a though opening 35 in the bush 20. A pin (not shown) is provided through the opening 35 in the bush 20 and through the opening 34 in the ball connector 31, thereby securing the towing member 1 in place. As the ball connector 31 is able to rotate relative to the ring connector 30, some movement of the towing member 1 is possible, in particular pivotal movement relative to the vehicle to allow the trailer to follow the towing vehicle around bends, and to allow the trailer to be at a different angle to the towing vehicle when not on fiat ground. When the trailer is fully deployed, the plate 27 contacts the rear of the bush 20 or the chassis of the vehicle. Therefore, when the trailer is pulled by the towing vehicle, the forces through the towing member 1 are coupled directly to the chassis of the vehicle, either by the coupling of the end of the towing member to the bush 20 via the pin, or through the contact between the plate 27 and the bush 20 or chassis of tt e vehicle or both, and not through the lightweight deployment means.

As best shown in Figure 3, the ring connector 30 is loosely mounted n the end of the towing member 1, allowing some relative movement betwqE n i the ring connector 30 and the towing member 1. A spring 32 biases the ring connector 30 towards an extended position from the towing member 1. The ring connector 30 is held captive within the towing member 1, for example; t y the provision of a flange around the ring connector 30 that abuts against.an inwardly turned flange of the end of the towing member 1. As also shown. i i Figure 3, the towing member 1 includes an elongate actuating member 3. When the trailer is being towed by a towing vehicle, the towing forces wili.'b applied to the towing member 1 through the ring connector 30, thereby pulling the ring connector 30 outwardly from the towing member 1 into its exten e J position. When the towing vehicle slows down, the forces transmitted throg 1 the ring connector 30 and the towing member 1 will be reduced, causing 1h ring connector 30 to move against the bias of the spring 32 and into t h R towing member 1. As the ring connector 30 is moved into the towing merriEr 1, the connector 30 will contact and move the actuating member 33. This movement of the actuating member 33 causes actuation of a braking systorn to brake the wheels 3 of the trailer. For example, this braking system mayble a hydraulic braking system in which the movement of the actuating merrioE,!,r 33 causes the release of hydraulic brake fluid from a source through pipes' to cause the application of brakes, such as disk brakes, to each of the wheels! 3, This ensures that when the recovery vehicle slows or brakes, the wheels 3; of the trailer are also braked, thereby ensuring that the trailer slows together Vvith the recovery vehicle.

As described above, the cross-member of the T-shaped trailer include telescoping sections to allow the width of the trailer to be varied as requir(A. The cross-member includes a biasing means to bias the telescoping sections into an extended position. This allows the trailer to be easily extended in the width wise direction. One or more locking pins are provided to fix the telescopic sections in the desired position.

To further reduce the space required for the trailer when stowed, the trailer is stored in a position where the telescopic sections are contracted as far as possible. A system is provided to automatically contract the trailer as it is retracted into the recovery vehicle, and to automatically extend the trailer as it is deployed. In one example, this is achieved by providing a pin on the extension sections 5 and an inwardly directed track or guide on the chassis of the recovery vehicle. As the trailer is retracted into the vehicle, the pin engages and runs along the track or guide, causing the member 5 to be slid along the main cross-member 2 against the action of the bias means to reduce the width of the trailer as it is retracted. When the trailer is deployed, the pins again run along the tracks or guides to extend the width of the trailer.

The bias means in the cross-member may be in the form of gas struts or springs.

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Claims (24)

1. A method in which a repair vehicle is able to drive to a repair $ile without any trailer, the trailer being accommodated in a stowed position, cn board the repair vehicle, and at the repair site means are provided to deploy a trailer out from the stowed position to a towing position behind the rear of 9he repair vehicle, and thereafter to couple a towing end of the trailer to the rear (if the repair vehicle so that the towing forces are transmitted to the rep a r vehicle directly rather than via the said means, the coupling between h trailer and the repair vehicle allowing free movement of the trailer relative th repair vehicle so that it can follow the repair vehicle when towed.

2. A method according to Claim 1, in which the trailer is deployp automatically, relatively quickly and without the need for any heavy lifting.

3. A method according to Claim 1 or Claim 2, in which, after the trailer i no longer needed, it is retracted into the vehicle to its stowed position.

4. A repair vehicle having a chassis and bodywork mounted on th,' chassis, further comprising deployment and retraction means for a trai lelr mounted within the bodywork of the repair vehicle and attached to th, 6> chassis, the trailer carried by these extension and retraction means normallY stowed by those means within the bodywork but movable by those means to the rear of repair vehicle to a towing position and from that position to th.l stowed position, and coupling means for attaching a towing end of the trailer 13 and the chassis so that towing forces are taken directly by the chassis to the repair vehicle.

5. A repair vehicle according to Claim 4, in which the trailer is of the type 5 to support the front wheels of a broken down vehicle.

6. A repair vehicle according to Claim 5, in which the trailer has a main towing frame generally of 'T' shapes, which comprises a lengthwise member constituting the stem of the "-r' which has a towing end at the base of the stem where it is coupled to the vehicle, and a transverse member constituting the cross-part of the 'T' and joined to the end of the lengthwise member away from the towing end.

7. A repair vehicle according to Claim 6, in which the transverse member will have a pair of wheels at or near its ends and have means, such as wheel pans, on to which the front wheels of a broken down vehicle can rest for towing.

8. A repair vehicle according to any one of Claims 4 to 7, in which the wheels of the trailer are mounted in a self steering manner so that the trailer can follow the towing vehicle around corners when the front wheels of a broken down vehicle are supported by the trailer.

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9. A repair vehicle according to any one of Claims 4 to 8, in which.: tie transverse member of the trailer has resiliency along its length allowin( gi t ie trailer to be compacted widthwise for storage, and allowing variation inAie width of the trailer to accommodate vehicles to be recovered of different widl h.

10. A repair vehicle according to Claim 9, in which the trailer includes pp Is which are capable of resiliently telescoping one into the other to reduce t ie width of the trailer.

11. A repair vehicle according to Claim 10, in which the vehicle incluo, S means to reduce the width of the trailer as it enters the bodywork of 11 e vehicle for stowing, the inherent resiliency causing the trailer to resume its f 111 width as it is moved to its towing position.

12. A repair vehicle according to any one of Claims 8 to 11, in which', to prevent changes inwidth during towing, a manually operable locking mean,s is provided to lock the transverse member to its desired position for towing 01 d are released before the trailer is brought to the stowed position.

13. A repair vehicle according to any one of Claims 4 to 12, in which Ihe trailer is attached to the vehicle at its towing end by means of a universal pivDt. 1 to allow the usual relative movement between the trailer and vehicle dtiritg towing.

14. A repair vehicle according to Claim 13, in which a hole is provided through this pivot and a pin provided which is passed through that hole to lock into engagement with means attached to the chassis of the vehicle when the translation means are in a fully extended position with the trailer in its towing 5 position.

15. A repair vehicle according to Claim 14, in which the pin is provided through the hole by an electronically operated solenoid.

16. A repair vehicle according to any one of Claims 4 to 15, in which the trailer has its own braking system.

17. A repair vehicle according to Claim 16, in which the trailer includes a telescoping arrangement such that braking of the vehicle causes compression of such parts of the trailer and the movement causing that compression is used to move and apply the brakes to the wheels of the trailer.

18. A unit comprising frame means to be attached to a structural part of a repair vehicle, translation means movable along the frame in one direction, which is to be a fore and aft direction when the frame is mounted on the vehicle, coupling means for attaching a trailer to the translation means, and coupling means for fixing the towing end of the trailer directly to the structural part, such as the chassis of the vehicle, when the translation means reaches the limit of its travel corresponding to the towing position.

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19. A unit according to Claim 18, in which the translation means COMpr.i; 6 S a rotatable screw and a trunnion which works along the screw as the latter is rotated, the trunnion being connected to the trailer for deploying and retracting the trailer from the towing vehicle.

20. A unit according to Claim 19, in which a small electric motor an reduction gear is provided to operate the screw.

21. A repair vehicle according to any one of Claims 4 to 17, including th 10 unit of any one of Claims 18 to 20.

22. A repair vehicle according to any one of Claims 4 to 17 or 21, used. i accordance with the method of any one of Claims 1 to 3.

23. A method of driving a repair vehicle with a trailer stowed on board h repair vehicle, and deploying the trailer at a repair site, substantially as described with respect to the accompanying drawings.

24. A repair vehicle, substantially as shown in or as described with respib( t 20 to the accompanying drawings.