GB2238773A - A recovery vehicle - Google Patents

Abstract

A vehicle recovery vehicle comprising a chassis 1; a supported lift towing boom 5 mounted on the chassis 1 for pivotal movement about a pivot 7 and including a body Portion 9 and a folding boom 11 movable relative to the body portion 9 between an inoperative position and an operative position; means 21 for swinging the supported lift towing boom 5 about its pivot 7; and linkage means 33, 37, 43 which reacts, on movement of the towing boom 5, to adjust the angle of inclination of the folding boom 11 relative to the body portion 9 of the towing boom 5 so that the relative angle of the folding boom end is maintained constant during raising or lowering of the towing boom portion. The link can be a pivoted rod (33), a bell crank lever (37) and a pistol rod (43) acting on for anvil (13). The means (21) can be a hydraulic cylinder. <IMAGE>

Description

A RECOVERY VEHICLE This invention relates to a recovery vehicle, and in particular to a recovery vehicle for medium and heavy duty work which can recover and tow heavy trucks and other vehicles which have become immobilised.

Such recovery vehicles are designed to be capable of recovering heavy vehicles, for example tanks and armoured cars, from ditches, mud and the like, normally using a winch. Additionally, the vehicles should be able to support tow an immobilised vehicle, for transportation either over open country or on the open road, using a pivoting and lifting or supported lift towing boom which engages under the front or rear end of the immobile vehicle. In this way, the front or rear end of the immobilised vehicle can be lifted clear of the ground and the vehicle can be towed like a trailer.

A recovery vehicle of the general type described above is disclosed in our own specification GB-A-2061193. While this vehicle is most satisfactory and extremely compact, considering its recovery capacity, there is now a demand for an even more compact recovery vehicle. Further, it is desired to reduce the weight of the towing boom (as utilised in this prior art vehicle), which of necessity must be very strong and is therefore very heavy. By reducing the size and weight of the towing boom the size of the overall vehicle is thereby reduced.

A recovery and towing vehicle which is more compact than that disclosed in GB-A-2061193 is described in another of our own patent specifications, EP-B-0153187. The vehicle described in this specification includes a towing boom which is moved up and down arcuate slideways to raise the front or rear end of an immobilised vehicle off the ground.

Although this type of recovery vehicle has been most successful in the field, it is essential that the slideways are kept clean and free from dirt. This can prove very difficult to accomplish under the circumstances in which the vehicle is used and if the slideways do become engrained with dirt, the sliding action is greatly impaired.

In the light of the foregoing, a recovery vehicle comprising a short towing boom which can lift the front or rear end of an immobilised vehicle off the ground to a reasonable height for towing purposes would be a marked improvement over the prior art. However, if a vehicle is equipped with a towing boom which is short and which therefore has a small radius of rotation, the result when the towing boom is raised is that a folding boom (forming the end of the towing boom for supporting the front or rear end of an immobilised vehicle) changes its angle of inclination and ends up pointing skywards. This is clearly unsatisfactory and the present invention has been devised to overcome this problem.

According to the present invention there is provided a recovery vehicle comprising a chassis; a supported lift towing boom mounted on the chassis for pivotal movement about a pivot and including a body portion and a folding boom movable relative to the body portion between an inoperative position and an operative position; means for swinging the supported lift towing boom about its pivot; and linkage means which reacts, on movement of the towing boom, to adjust the angle of inclination of the folding boom relative to the body portion of the towing boom.

Preferably, the towing boom also includes an anvil against which the folding boom bears, and the linkage means adjusts the position of the anvil as the towing boom is moved about its pivot. Preferably, the anvil is pivotally mounted on the body portion. Preferably, the folding boom is also pivotally mounted on the body portion. Preferably, the pivots for the anvil and folding boom are aligned on the body portion. They may be provided by a common pivot pin.

Preferably the folding boom, in it operative position, retains a substantially fixed inclination during motion of the towing boom. In a preferred embodiment of the invention, the substantially fixed inclination of the folding boom is manually adjustable. Such adjustment would normally be effected before an immobilised vehicle is supported on the towing boom.

Preferably the linkage means is pivotally attached to the chassis, to the body portion of the towing boom and to the anvil. In one specific embodiment, the linkage means includes a first rod, extending between a pivot on the chassis and a pivot on one arm of a bell crank lever pivotally mounted on the body portion of the towing boom, and a second rod extending between a pivot on the second arm of the bell crank lever and a pivot on the anvil. This arrangement ensures that when the body portion of the towing boom is moved, a reaction force is applied to the anvil by the second rod while the said first rod of the linkage means remains pivotally fixed to a mounting on the chassis of the vehicle.

It will be appreciated that if the length of the first rod is manually adjustable, the fixed orientation of the folding boom may be adjusted. Of course, an alternative way of adjusting the fixed orientation of the folding boom would be to move the mounting of the first rod on the chassis or on said one arm of the bell crank lever (i.e. the location of the pivot). Other alternative possibilities will of course be appreciated by a man skilled in the art.

A specific embodiment of the present invention is now described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a vehicle according to the present invention; and Figure 2 is a perspective view, with parts omitted for the sake of clarity, from the rear and to one side of part of the vehicle of Figure 1.

Referring to the drawings, the recovery vehicle has a main chassis 1 on which a cab 3 is mounted at one end thereof. At the opposite end of the chassis 1, a supported lift towing boom 5 is pivotally supported by bearing means securely mounted on the chassis 1 which allows the towing boom 5 to pivot about axis 7.

The supported lift towing boom 5 includes a body portion 9, a folding boom 11 and an anvil 13 for adjusting the angle of the folding boom 11 relative to the body portion 9 when the latter is pivoted about its axis 7. The folding boom 11 is moved by a piston and cylinder device 15 between a generally horizontal operating position as shown in the drawings and a generally upright transport position. The folding boom 11 may be increased in length by means of an extension boom or beam 17 which is movable by a piston and cylinder device 19 within the folding boom 11. The extension boom or beam 17 is designed for sliding beneath an immobilised vehicle so that with loose cross beams and forks etc. it can be attached to an axle or recovery eyes of the vehicle for recovery purposes.

The complete towing boom 5 is swung about axis 7 by means of a pair of hydraulically operated piston and cylinder devices 21 (i.e. rams), one device acting on each side of the towing boom 5. When the towing boom 5 has been raised by the rams 21, it can be locked in the raised position by means of bolts or pegs passing through apertures in a support frame 23 and engaging a locking bar 25 permanently attached to the body portion 9. Two support frames 23 are provided, one on each side of the towing boom 5, permanently attached to substantially vertical housings 27 which accommodate stiff leg spades 29 slidable therein.

The leg spades 29 are controlled by hydraulic piston and cylinder devices (not shown) and are designed to engage the ground under the recovery vehicle during use to add stability to the vehicle when an immobilised vehicle is being lifted or dragged towards the vehicle by a winch rope.

As will be appreciated, the distance of the end of the folding boom 11 from the axis of rotation 7 of the complete towing boom 5 is relatively small in comparison to many prior art recovery vehicles. Accordingly, if the relative angle of inclination of the folding boom 11 to the body portion 9 of the towing boom 5 were to remain constant during a lifting process, the folding boom 11 would be inclined at a steep angle to the horizontal and extend skywards when the towing boom 5 reaches its maximum raised position. Accordingly, a linkage means has been provided which enables the folding boom 11 to pivot about an axis 31 when the towing boom 5 is moved, such that the folding boom 11 remains substantially horizontal throughout the lifting operation.

The linkage means comprises a first rod 33 having one end pivotally mounted about axis 35 on the body of the vehicle, a bell crank lever 37 having two arms 39,41 and a second rod 43 extending between the bell crank lever 37 and the anvil 13. The first rod 33 has its other end pivotally connected to one arm 39 of the bell crank lever 37, and the second rod 43 has one end pivotally connected to arm 41 of the bell crank lever 37 and its other end pivotally connected to a knuckle 45 extending from the anvil 13 on the opposite side of an axis 31 about which the anvil 13 is pivotally mounted on the body portion 9 of the towing boom.

This axis 31 is the same axis about which the folding boom 11 is pivotally connected to the body portion 9 of the towing boom, and may be provided by a common pivot pin. The bell crank lever 37 sits in a recess 47 in the body portion 9 of the towing boom 5 and is able to swing about a pivot 49 attached to the body portion 9.

In use, as the hydraulic rams 21 raise the towing boom 5, the towing boom 5 swings about axis 7 and the folding boom 11 is raised. As the towing boom 5 moves, the first rod 33 receives a reaction force due to its pivotal connection at 35 to the vehicle body which causes the bell crank lever 37 to swing about axis 41, thus urging the second rod 43 to move in substantially the opposite direction relative to the upward movement of the body portion 9 of the towing boom 5. The second rod 43 thus bears down on the knuckle 45 of the anvil 13 to force the anvil 13 to swing clockwise about axis 31 as shown in the drawings, effectively away from the folding boom 11.The folding boom 11, which bears on the anvil 13 due to its own weight (and that of any immobilised vehicle mounted thereon) follows the anvil 13 and thereby adjusts its inclination relative to the body portion 9 of the towing boom 5, thus retaining its substantially horizontal, original orientation. On lowering of the towing boom 5, the reverse happens such that the anvil 13 is urged anti-clockwise and towards the folding boom 11 and thus raises the free end of the folding boom 11 in relation to the body portion 9 of the towing boom 5.

By choosing the position of axis 35 and the lengths of the first rod 33 and the second rod 43, the specific inclination of the folding boom 11 relative to ground level can be chosen. In this regard, if axis 35 is fixed, the length of the first rod 33 could be adjusted by having reversed screw threads on the ends of the rod for engaging cooperating threads in the mounting means attached to the ends of the rod 33. Thus on rotating the rod 33 in a chosen direction, the effective length of the rod can be increased or decreased as required. Alternatively or additionally, the relative positions of the body portion 9 and folding boom 11 could be adjusted by making the location of the pivot in the arm 39 of the bell crank lever 37 adjustable.

This could be achieved with a screw device or hydraulically, or in any other way.

A winch 51 is mounted centrally on the vehicle and is provided with a cable or rope path which may pass through the body portion 9 of the towing boom 5 for attachment to an immobilised vehicle to aid in the recovery of that vehicle, in which case the rod 43 at least would have to be replaced by spaced twin link rods. As shown, however, a twin capstan winch 51 is used with the rope 53 exiting from one side of the vehicle, passing around a match block 55 and leading back to a fixture on the opposite side of the vehicle body.

Alternatively, guides can be provided on the side of the chassis of the recovery vehicle to enable the winch to be utilised to pull vehicles or other items situated in front of the vehicle itself.

Furthermore, the recovery vehicle is provided with a small crane 57 mounted behind the cab 3 for loading and unloading items onto the vehicle, such as complete engines.

A distinct advantage of the present invention is that a user needs only to control a single set of hydraulic rams (in this case devices 21) to raise and lower the towing boom 5 with the folding boom 11 having a preferred orientation, rather than having to control two sets of rams if the linkage means were not present (since this would mean that a second set of rams would be required in place of the linkage means to control the angle of inclination of the folding boom 11).

It will of course be understood that the present invention has been described above purely by way of example and that modifications of detail can be made within the scope of the present invention.

Claims (11)

1. A recovery vehicle comprising a chassis; a supported lift towing boom mounted on the chassis for pivotal movement about a pivot and including a body portion and a folding boom movable relative to the body portion between an inoperative position and an operative position; means for swinging the supported lift towing boom about its pivot; and linkage means which reacts, on movement of the towing boom, to adjust the angle of inclination of the folding boom relative to the body portion of the towing boom.

2. A recovery vehicle as claimed in claim 1, wherein the towing boom includes an anvil against which the folding boom bears, and the linkage means adjusts the position of the anvil as the towing boom is moved about its pivot.

3. A recovery vehicle as claimed in claim 2, wherein the folding boom and the anvil are pivotally mounted on the body portion.

4. A recovery vehicle as claimed in claim 3, wherein the anvil and the folding boom pivot about a common pivot pin.

5. A recovery vehicle as claimed in any preceding claim, wherein the linkage means is positioned such that the folding boom, in its operative position, retains a substantially fixed inclination during motion of the towing boom.

6. A recovery vehicle as claimed in claim 5, wherein the substantially fixed inclination of the folding boom is adjustable.

7. A recovery vehicle as claimed in any preceding claim, wherein the linkage means is pivotally attached to the chassis, to the body portion of the towing boom and to the anvil.

8. A recovery vehicle as claimed in claim 7, wherein the linkage means includes a first rod extending between a pivot on the chassis and a pivot on one arm of a bell crank lever pivotally mounted on the body portion of the towing boom, and a second rod extending between a pivot on the second arm of the bell crank lever and a pivot on the anvil.

9. A recovery vehicle as claimed in claim 8, wherein the first rod is manually extendable to adjust the inclination of the folding boom.

10. A recovery vehicle as claimed in claim 8, wherein the location of the pivot on the chassis or the pivot on said one arm of the bell crank lever is adjustable.

11. A recovery vehicle substantially as hereinbefore described with reference to and as shown in the accompanying drawings.