The invention relates to a device in combination with a trailer. A major problem in connection with the use of trailers has been the fastening of the trailer to the drawhook of the towing car, especially when the terrain is uneven. The problem is caused by the fact that in practice it is very difficult to bring the drawbar of the trailer to the location of the drawhook of the towing car. It happens very often that when it is attempted to bring the drawhook of the towing car to the location of the drawbar of the trailer, sheet damages will ensue. Repair costs for these sheet dam- ages can in some cases be very high. The problem is even more marked when the terrain is uneven, as has already been mentioned above. The reason for the above fact is that it is difficult to exactly control the movements of a heavy towing car or trailer; for ex- ample, when rolling away from a stump with roots or a similar obstacle, the car or trailer will very easily and quickly move several dozen centimetres, and in that connection there is a high probability of sheet damage. In the above situations it is possible that in addition to sheet damage, injuries will ensue, especially when it is attempted to prevent sudden imminent sheet damage.

The object of the invention is to provide a device with which the above-mentioned drawbacks can be eliminated. This has been achieved by means of the device of the invention, which is characterized in that it comprises a telescopic part, in the one end of which first means are provided for fastening the telescopic part pivotally to the trailer substantially at the point of the longitudinal symmetry axis of the trailer,

and in the other end of which second means are provided for astening the part pivotally to the drawhook of the towing car, and that the first means further incorpor¬ ate a locking device which is adapted to lock the telescopic part in a position parallel with the drawbar of the trailer when the telescopic part is in said position.

The advantage of the invention is above all the fact that it enables the towing car and the trailer to be brought to the same level without any risk of sheet damage. By means of the invention, the towing car and the trailer can be brought to the same level in a very- simple, quick and natural way, i.e. by driving the towing car forward. This being the case, even a person having no experience with a trailer and with the prob¬ lems arising in connection therewith succeeds more easily than heretofore in using the trailer. The device of the invention is light and thus affects neither the load capacity nor the driving-qualities of the combina- tion. A further advantage of the invention is its simplicity, on account of which putting into use and working the invention will be advantageous.

The invention will be explained in more detail in the following by means of the advantageous embodi- ments shown in the accompanying drawing, in which

Figure 1 is a schematic side view of an auxili¬ ary device of the invention when the"trailer and the towing car are being coupled,

Figure 2 shows the situation of Figure 1 in a top view,

Figure 3 is a top view of another embodiment of the invention when the trailer and the towing car are being coupled,

Figure 4 is a top view of a third embodiment of the invention, and

Figure 5 is a side view of one detail of the embodiment of Figure 4.

The first embodiment of the invention is pres¬ ented schematically in Figures 1 and 2. Reference number 1 denotes the towing car and reference number 2 the trailer. The drawhook of the towing car 1 is indi¬ cated at reference number 3 and the drawbar of the trailer at reference number 4, respectively. The front wheel of the trailer is denoted by reference number 5. The above-mentioned facts are quite conventional technology to a person skilled in the art, wherefore they will not be explained more closely in this connec¬ tion.

According to the essential idea of the inven- tion, the auxiliary device comprises a telescopic part 6, in the one end of which first means 7 are provided for fastening the telescopic part pivotally to the trailer 2 substantially at the point of the longi¬ tudinal symmetry axis of the trailer, and in the other end of which second means 8 are provided for fastening the part 6 pivotally to the drawhook 3 of the towing car. Furthermore, the first means 7 incorporate a locking device which is adapted to lock the telescopic part 6 in a position parallel with the drawbar 4 of the trailer when the telescopic part 6 is in said position.

The auxiliary device of the invention functions in principle in the following way. The towing car 1 is backed close to the drawbar 4 of the trailer 2 in such a way that the drawhook 3 is so close to the drawbar, for example about one metre away from the drawbar, as to enable fastening of the telescopic part 6 with one end thereof to the drawhook 3. The above situation is shown in Figures 1 and 2. In the next step, the towing car 1 is moved forward, upon which the trailer moves forward behind the towing car and simultaneously turns

so as to make the telescopic part 6 to have the direc¬ tion of the drawbar 4. After the telescopic part 6 has turned to the same directional position as the drawbar 4, it locks into this position by means of the locking device. The locking device may be of any type known per se. When the telescopic part locks into the directional position of the drawbar, the towing car and the trailer are located in sequence in the same directional posi¬ tion in the same line. The driving distance during which the telescopic part 6 turns to the direction of the drawbar 4 is very short, for example 0-3 metres. In the next step,, the towing car 1 is backed straight backwards, and the elements 6a and 6b of the telescopic part are pressed one within the other. Backing is con- tinued until the trailer 2 moves slightly. At this stage, the drawbar 4 is precisely at the point of the drawhook 3 and thus cannot touch the car. Finally, the telescopic part 6 is detached from the drawhook 3 and the drawbar 4 is fastened to the drawhook 3. After the electric conductors have been connected, the combina¬ tion is ready for driving.

The basic idea of the auxiliary device of the invention can be modified in different ways. Figure 3 shows another advantageous embodiment of the invention. The embodiment of Figure 3 corresponds in broad outline to the embodiment of Figures 1 and 2, and therefore the same reference numbers are used at corresponding points in Figure 3 and in Figures 1 and 2.

The essential feature in the embodiment of Fig- ure 3 is that the telescopic part 6 is furnished with a joint 9, which enables elements 6a and 6b, nested one within the other, to turn relative to each other in a substantially horizontal position when the telescopic part 6 is in a fully extended position. The joint 9 is - of advantage especially in situations where it is

difficult to get the towing car close to the trailer in front of said trailer and there is room around the trailer.

The telescopic part 6 can be fastened to the trailer 2 with one end thereof in several ways. In the embodiments of Figures 1-3, part 6 is fastened to the body of the trailer 2. This is not, however, the only possibility, as it is possible to fasten the telescopic part also for example to the drawbar 4 of the trailer. A solution of this kind is presented in Figures 4 and 5.

The embodiment of Figures 4 and 5 corresponds in its essential principle to the embodiments of Figures 1-3, wherefore the same reference numbers are used at corresponding points in Figures 4 and 5 and in Figures 1-3. In the embodiment of Figures 4 and 5, the tele¬ scopic part 6 is fastened to the drawbar 4 by means of a turnable slide bush 10 functioning as said first means 7. In this embodiment, the slide bush 10 is so installed that it can turn substantially around the vertical axis, and this enables the telescopic part 6 to turn in the horizontal plane. The slide bush 10 is furnished with a locking device which locks the bush in a direction parallel with the drawbar when the bush turns in the direction in question. The element 6b of the telescopic part 6 can also slide within the slide bush in parallel with its longitudinal axis.

The above embodiments are not intended to limit the invention, but the invention can be modified fully freely within the scope of the claims. This being the case, it is evident that the auxiliary device of the invention or its details can be different from those presented in the figures. The number of the elements of the telescopic part, nested one within the other, has by no means been limited to two, but for example the

use of three elements is fully possible, etc. The locking devices, joints, fastening and bearing means can naturally be any devices known per se. The dimen¬ sioning of the auxiliary device of the invention, i.e. its length etc. can of course be chosen completely freely according to current need.