The present invention relates to a device for an anti-skid device preferably of a kind comprising a pulley provided with chain pieces which is brought to rotate when bearing on the side of a vehicle wheel, whereby the chain pieces, when the wheel and there- by the pulley rotate, are successively thrown in between the wheel and the ground.

Anti-skid devices of the above-mentioned kind are known particu¬ larly for heavy trucks, but also for ordinary trucks. To achieve a proper function of the anti-skid device it is necessary that the point where the pulley is in contact with the vehicle wheel can be adjusted vertically and horizontally and that the proper pressure between the pulley and the wheel can be achieved.

In SE 8501021-3 an anti-skid device for smaller trucks is dis¬ closed and which device has a certain adjustability but comprises many parts. In addition, when to bring the pulley from a resting position to a working position, a relatively large space is required, because the pulley must be brought to a resting posi¬ tion where the chains are well above the ground.

According to the European patent with publ. No. 162823 a special shelf provided for buses and similar vehicles with limited space is described. The shelf collects the chains and keeps them free of the ground. The construction comprises additional parts to be located and adjusted into the system in order to obtain the desired function. The shelf is probably also collecting dirt. Characteristic of the mentioned designs is that they are rela¬ tively complicated and expensive and can be adapted only to larger vehicles.

The object of the present invention is to provide an anti-skid device of the above-mentioned kind which can easily be adapted to and mounted on heavier trucks as well as smaller vans and cars, and which device, without any need for large space, admits moving

the pulley to a resting position where the chains are caught and kept well above the ground.

Another object is to achieve a construction that is resistant to moist and dirt.

A further object is to achieve a simple construction.

These objects are achieved with the present invention in a pre¬ ferred embodiment in which a fixing device, fixed to the vehicle, carries an arm flexible essentially in one plane to the end of which the pulley is rotatably attached, the arm comprising a number of positioning elements each consisting of a body of a shape permanent material with at least a first and a second con¬ tact surface arranged at a distance from each other in a way that permits the first contact surface of a positioning element to be brought in a position-stable contact with the second con- tact surface on a nearby located element, whereby the position¬ ing elements at their one end are kept together by a contracting means and enclose at least one resilient means which in a first position, when the resilient means is in a curved resting posi¬ tion, brings the elements to diverge from each other and in a second position, when a first pulling means acts against the force of the resilient means, brings the contact surfaces of the ele¬ ments to interact and create a position-stable stack.

In another embodiment of the invention there is a second pulling means going through the wedge-shaped part of the positioning elements and which pulling means when activated keeps the wedge- shaped parts of the positioning elements together so that a curved arm is obtained.

The mentioned embodiments have the positioning elements, the contracting means and the spring means encapsulated in an elastic tight cover. Furthermore, there are means that catch and fix the chains in the resting position of the device. Common to all the

embodiments is that the fixing device, which fixes the arm to the vehicle, is adjustable so that the proper contact point between the pulley and the wheel can easily be obtained.

The invention will now be described with reference to the accom- panying drawings.

Fig. 1 shows the device in a resting position;

Fig. 2 shows an enlarged cut-out portion of the interiour of the device in a resting position;

Fig. 3 shows the device in a working position;

Fig. 4 shows a device with two pulling means in a working position;

Fig. 5 shows the same device in a resting position.

Figs. 1 and 2 show the device 1 mounted on a vehicle shaft with the fixing device 2 attached to the axle tube 3 inside the wheel 9. It is also possible to mount a fixing device of another kind to the points where the springs or the shock absorbers are fixed. However, this is not shown in any figure.

The fixing device has an elongated means 4 consisting of a tube or a bar. The means 4 is fixed to the axle tube 3 of the vehicle with two clamping means 5 and 6, which when tightly fixed fasten the means 4 and press the lower parts 7 and 8 of the clamping means against the shaft tube of the vehicle. Thus, when the clamping means 5 and 6 are loose the means 4 is adjustable horizontally as well as vertically and is also turnable, and when the clamping means are tightly fixed the means 4 is fastened to the axle tube of the vehicle. Thus, the contact point between the pulley 16 and the vehicle wheel 9 can easily be adjusted.

At the end of the elongated means 4 which is directed towards

the wheel 9, a plate 13 is attached. In this plate 13 the arm 10 is turnably mounted. In the plate there is also a bowden cable 14 attached in which runs a pulling means 15. The pulling means is connected to a power generating device mounted on the vehicle (not shown). Around the arm a preferably u-shaped magnetic means 18 is provided by which the chains are caught when the device is in its resting position. The magnetic device 18 is provided with a clamp 19 positioned between the pulley and the outer positioning element.

The arm 10 comprises a number of positioning elements 20, made of a shape permanent material. The positioning elements are at their one end kept together by a contracting means 21. Through all the positioning elements runs at least one spring means 22, which by resting against the plate 13 and the attachment of the pulley 16 in the neutral position of the device becomes curved as does the entire device, in that the positioning ele¬ ments, as viewed from the contracting means 21, diverge from each other. The positioning elements have mating warts 24 and cavities 25 in the surfaces facing each other. From the power generating device mentioned above goes at least one pulling device 15 through holes in the positioning elements and the end of which is fixed in the positioning element, the end of the pulling device being an abutment for the device 1 in the means 4.

In another preferred embodiment (not shown) the first pulling device is a strong ribbon, for instance a textile ribbon, which is attached to the last-mentioned positioning element and which ribbon goes along and outside the ends of the positioning ele¬ ments that are directed from the contracting means 21 , to the earlier mentioned power generatingdevice in the vehicle. The arm 10, comprising the positioning elements 20, the contracting means 21, the first pulling device 15 and the spring element 22, is encapsulated in an elastic cover 26 preventing moist and dirt to come through and jeopardize the function. The pulley

16 with its chain pieces 17 is rotatably mounted on the outer positioning elements of the arm 10. In this element the clamp 19 is also mounted.

In Fig. 1 the device is shown in its resting position when the spring means 22 is in its neutral position. The arm 10 then becomes curved so that the pulley 16 is turned and lifted upwards to a height such that the chains 17 will be at an adequate distance from the ground. In this position the pulling means 15 is released allowing the arm to take on this shape. The magnetic means 18 which is provided in the outer positioning element and partial¬ ly embraces the arm will catch the swinging chains when the vehicle moves and prevent them from producing undue sound.

In Fig. 2 the device is shown in its working position. When acti¬ vating the pulling device 15 by the power generating device in the vehicle the spring means 22 will be contracted so that the surfaces of the positioning elements will be pressed against each other. The warts 24 and the cavities 25 are mating each other and a twist and bend resistant and thereby stable stack is obtained. The pulley 16 will then be pressed against the side of the vehicle wheel at a point 27 located on a line between the centre of the shaft and the contact point between the wheel and the ground 28 or close behind. The pulley will then be rotated by the vehicle wheel 9 and the chains are thrown in between the wheel and the ground and skidding is hindered. It is im- portant that the contact point between the pulley and the vehicle wheel is so located that no unwanted power play occurs in the device, i.e. pulling forces in the chains. The determining of the right contact point as already mentioned is performed by adjusting the fixing device 2.

Figs. 3 and 4 show the principle of another embodiment of the arm where the positioning elements 40 are given another shape in that one part 41 has essentially plane parallel surfaces which when pressed together by a first pulling device 44 create an essen-

tially straight stack as shown in Fig. 3. The other part 43 of the positioning elements has surfaces converging towards the end of the elements, which surfaces when pressed together by a second pulling device 42 form a curved stack as is evident from Fig. 4.

The invention described is adapted to act as a device for moving an anti-skid device for a vehicle between a resting position and a working position but can of course be adapted to act in other tasks, e.g. moving a tool or the like into different positions relative to a fixed point.