The present invention concerns a device to be mounted on piece lifts wherein the device comprises two support legs being located at an angle with respect to each other and with a cross brace between each leg, wherein the legs are rotationally and securably hinged to a securing location on a vehicle, and wherein the length of the legs may be extended individually.

The problem being present as a basis for the instant invention is the support against a foundation, usually the ground, at the end of a vehicle lifting heavy pieces such as timber logs, concrete blocks, rocks etc. by the aid of a lift (piece lift) . Vehicles that shall lift heavy objects e.g. timber lorries, rescue cars, vehicles to be used in rock mines, development sites, road work etc. have got a lifting crane (piece lift) mounted at the rear of the vehicle or at one end of a hanger which is to be attached to a towing vehicle. At heavy loads it may consequently be a problem that the vehicle or the hanger is not heavy enough at the opposite end to create a sufficient counterweight for the object to be lifted, or the vehicle/hanger is not sufficiently stable in the side direction to be able to lift the relevant object.

This problem has previously been solved by equipping such crane lorries/hangers with simple hydraulically extendable support legs as an extra support at the end of the vehicle by placing the one support leg on the ground as a stabilizer for heavy loads as described supra. The problem with this prior art is that even if a single support leg admittedly may provide a support for heavy loads, the construction with an extendable leg is not sufficiently robust and does not give sufficient stability since such a support leg firstly is dependent on the strength in its rotating securing point on the crane vehicle, secondly not often or rarely has a level foundation as a support surface and consequently will have to be extended at an angle to the foundation (e.g. at construction sites, when lifting timber in forests, etc.), and thirdly the larger this angle is towards the foundation, the larger load will have to be carried by the securing point of the support leg, and this may have as a consequence that the securing point of the support leg breaks or is damaged, that the position of the crane vehicle is displaced, that the crane vehicle is overturned or that a suitable foundation simply is not present at the relevant area (soft woods ground, slippery foundation (ice), bog, sand, skew foundation, etc.), or that the lag fails at a swing angle of the crane at over 90° .

There are previously known devices to ameliorate these problems.

In US patents 4.708.362 and 6.142.488 there are disclosed devices/support legs that may support and/or stabilize camping homes that may be disconnected from a towing vehicle. Largely such devices as these are not suitable to be used for crane lorries since they may not be manipulated automatically (i.e. hydraulically/pneumatically) and they are generally too weak for being suitable for the indicated work and loads.

Consequently there exists a need for an improvement in such previously known support devices consisting of only one support leg or consisting of weak support constructions.

The present invention concerns such an improved support leg for vehicles with piece lifts.

The invention will be more closely described infra with reference to the enclosed figures wherein: Figs. 1, 2 and 3 show simple support legs for vehicles with piece lifts according to the prior art, as well as an illustration of the problem that is the basis for the present invention by too poor stability in such legs.

Fig. 4 shows an embodiment of the improved support legs according to the present invention.

Fig. 5 shows the improved support legs according to the invention in an inoperative condition at the end of a lorry with a piece lift.

The contents of figs. 1-3 showing a support leg for a piece lift according the prior art, is self-explanatory since it here is shown how the support leg may be displaced from its supporting position, or simply is not able to be used if the ground in which it is to be used, is too uneven.

Fig. 4 shows the device according to the present invention with the improved support legs, wherein the device comprises two support legs 1,2 being situated at an angle relative to each other, with a cross strut 3 between each of the legs 1,2, wherein the legs 1,2 are rotationally mounted hinged and may be locked in position to a securing point 4 in a vehicle, and wherein the length of the legs 1,2 may be individually extended.

The advantages in such an assembly of the support legs for piece lifts according to the present invention as disclosed are many. Among such advantages there may be mentioned especially that the assembly prevents damages, the formation of cracks etc. in the construction. It ensures better and more securing points for the legs so that the vehicle/hanger will be better prevented from sliding e.g. in a steep downhill slope or on ice. It will also improve the crane safety when parked because the vehicle/hanger will be more stable. The angled support legs 1,2 will initially give a broader area that the support may be distributed over. In its simplest form the support legs will have s cross strut/beam 3 running between them for bracing and enhancing the construction of the device, wherein this cross strut/beam is securely fastened to the legs 1,2. Such a cross strut/beam 3 will also have the effect that the load on the rotational hinge 4 more difficultly will form a moment arm in relation to the hinge 4 so that the hinge will not become overloaded. Such an overload/moment arm may arise if the rotational hinge 4 will come to lie outside any of the support points of the legs 1,2 against the foundation. This also makes the device according to the present invention more flexible and creates more opportunity for selecting the location of the support legs 1,2 than with only one leg according to the prior art which is dependent on the attack point of the forces against the securing hinge passing mainly through the axis of the support leg. When the cross strut/beam/brace 3 is of a fixed length, the legs 1,2 may be inter-independently secured to the rotational hinge 4.

In an alternative embodiment the length of the cross brace may be adjusted while the legs 1,2 are individually and independently rotatable around the rotational hinge 4. This will make the device according to the invention even more flexible concerning its use in e.g. uneven terrain. Also the space being necessary for mounting/transport on the vehicle/hanger may be smaller since the legs 1,2 then may be collected so they form a smallest angle to each other. A preferred angle interval with a separation between the legs 1,2 will be 10-90°. Normally the angle between the legs 1,2 will be 10-45°. Angles that may be used between the legs 1,2 may be 10°, 15°, 20°, 25°, 30° or 35°, which also are selected angles between the legs 1,2 when they are mounted with a fixed angle between themselves. The legs 1,2 in the support device according to the invention are to be extendable. In this capacity it is preferred that the legs are telescopically extendable. The extension may be performed mechanically or hydraulically, preferably hydraulically. In such a hydraulic control of the extension of the legs 1,2 there may be used a conventional coupling of the hydraulic parts in the legs. From a safety point of view it is preferred that there is present a check valve on the return cylinders in case a pressurized pipe or hose is to break or the whole crane collapses.

To ensure a better and more stable connection between the ground and the legs 1,2, the ends of the legs 1,2 may be equipped with supporting cups 5 preferably being secured to the legs 1,2 through the aid of ball joints 6.

When transporting the support legs according to the invention, the whole device may be rotated about the rotational joint 4 so that the legs 1,2 become elevated to lie at a distance from the ground with the legs pointing in the same direction or against the driving direction of the vehicle.