In the current state of the art these bars are produced either as a single piece of large dimensions, or as a number of folding segments hinged end-to-end to each other.

Both configurations described above have however limits and drawbacks: that described first has the drawback of its large dimensions, and the second that of a fragility at the joints between the various segments, which compromises how long it can be reliably used.

Furthermore, in neither case is there any means of damping the axial stresses acting on the towbar when being used to tow a vehicle.

To avoid all these drawbacks, the inventor of the present innovation has devised a towbar whose straight part is composed of a plurality of elements which connect coaxially together and can slide telescopically one inside the other, and at least two consecutive elements of these elements are connected together by an elastic element, preferably a helical torsion spring, capable of damping the abovementioned axial stresses to which the said towbar is subject when in use.

The subject of the invention is therefore a towbar as described in the preamble of the appended Claim 1,

characterized by the characterizing part of the same claim.

A preferred illustrative embodiment of a towbar according to the invention will now be described in greater detail, and the description will also refer to the accompanying drawings, which show: in Figure 1 a side view with partial cutaway of the said illustrative embodiment of a towbar according to the invention comprising three coaxial segments; and 'in Figure 2 a cross section through the bar shown in Figure 1.

As can be seen clearly in Figure 1, the towbar 1 of the invention comprises a straight part whose ends have two hooks 2,3 of known type, their configuration being such that they can be coupled to the towing hooks (not shown) of two vehicles positioned one behind the other.

The inside of the said hooks 2,3 can also be coated with a damping and soundproofing material such as any of the rubbers or other elastomers in order to prevent troublesome noises caused by shocks during operation (this provision is not shown in the figures).

The abovementioned straight part 11 comprises two consecutive segments 5,6 capable of sliding telescopically one inside the other. In order to prevent unwanted relative rotations, the inventor envisages that the hollow cross section of the said two consecutive segments 5,6, and in general that of all the segments 4,5,6 making up a towbar 1, are of polygonal shape, preferably quadrilateral as shown in Figure 2.

Between the said two consecutive segments 5, 6 is a helical torsion spring 7 which is coaxially external to

them and connected to them by the two final turns 7s, 7t situated at its two ends.

The fact that the spring 7 is positioned externally to the consecutive segments 5,6 means that its structure can also be used to resist bending stresses to which the towbar 1 may be subjected.

This spring 7, as stated, provides progressive damping of axial shocks and stresses acting on the towbar 1.

A number of additional coaxial segments, only one 4 in the case considered, can also be attached coaxially and reversibly (for example by means of a quick-fitting through bolt 8) to one end of one 5 of the said two consecutive segments 5,6, in such a way that the total length of the towbar 1 can be extended telescopically by a predetermined length.

Two devices 2,3 for hitching the bar to towing hooks or other parts of a motor vehicle are also attached to the ends of the towbar 1, on the outermost end parts of the assembly made up of the coaxial segments 4,5,6 (the extra segment 4 being optional only).

If a number of holes 9i are made in the said segment 4 which is connected to the two consecutive segments 5,6 for insertion of one of the said bolts 8, this segment 4 can be slid telescopically inside that segment 5 which is to be connected to it, before securing it with a bolt 8, thus giving the towbar 1 the most appropriate length for each particular application. (As mentioned, if the length of the said segments 5,6 is sufficient, the extra segment 4 need not be present).

The said hitching devices 2,3 should also preferably be made with a tubular part 2t, 3t that fits coaxially and telescopically onto the end of the segment 4,6 to

which it is to be fixed, before securing it with a through bolt 8 of the type described above.

It is therefore possible to fit different forms of hitching device to suit the particular application, e. g. two hooks 2,3 as indicated in the figures, suitable for towing vehicles provided with hitching parts or devices of a variety of shapes.

As far as the said helical torsion spring 7 is concerned, its two final turns 7s, 7t may be fastened by various different systems to each of the two consecutive segments which slide telescopically, in such a way as appropriately to damp their relative sliding velocity: for example, they may be fixed to collars welded or fastened to the said segments 5,6 (this embodiment not shown).

A solution preferred by the inventor is to weld or otherwise fix to each of the said two consecutive segments 5,6 one end of each of a number of long elements lOe (two in total in the figure but four or more are also possible) which run all the way through the helical spring 7 parallel to its longitudinal axis L-L and which terminate at the other end which is wrapped transversely around one of its said two final turns 7s, 7t. This solution has been found to be the most economical without in any way reducing the functional reliability of the towbar 1 of the invention.

All the component parts of the invention can however have shapes, positions and fixing methods different from those illustrated in the figures.

It should be added that each of the component segments of a towbar according to the invention can be made in one piece or from a number of parts fixed together, and can be made from the most suitable materials such as metals (steel, aluminium) and their alloys.