Background Art Coupling of the kind stated above are well-known in the art. They are used both for single-axle trailers and for trailers with two or more wheel axles. In the latter case, the drawbar is flexibly mounted on the trailer, and an operator uses a resilient actuator arranged between the trailer and the drawbar to balance the drawbar in the correct horizontal position so as to allow it to be in- serted in the catching mouth of the coupling to complete the connection. The actuator is then to be released so that the drawbar, by virtue of its own weight, will bear downwards against the lower receiving surface of the coupling.

Furthermore, in prior-art coupling of this kind there is a play between the drawbar eye and the coupling in the vertical direction. The play allows the drawbar to be angled up and down within an angle range of at least 20 degrees. This mobility is necessary for the coupling to work properly during driving of the vehicle.

If the drawbar eye is not pressed down toward the lower receiving surface of the coupling with sufficient force, which will be the case, in particular if the op-

erator, for instance, omits to release the actuator balancing the drawbar, said play will cause wear in the coupling and inconvenience the driver, who will experience jerks while driving.

Different solutions have been proposed to reduce the play. Spacing elements of resilient material such as rubber have been inserted in the catching mouth to reduce the play. However, such elements may have a detrimental effect on the drawbar's angular freedom and will be sub- ject to rapid material fatigue. More complex solutions include arranging a ring around the coupling bolt which is spring-loaded downwards towards the drawbar eye, and arranging a hydraulic piston which presses the drawbar eye towards the coupling bolt in the horizontal plane.

The major disadvantage of these and similar solutions is that they require an existing coupling to be replaced by a completely new coupling.

Summary of the Invention An object of the present invention is to reduce the play between a coupling eye and a coupling mouth, in the connected state, without affecting in a negative manner the drawbar's angular freedom. A further object of the invention is for it to be mountable on an existing coupling without the need for any major constructional modifications.

These objects are achieved by the damping element stated by way of introduction being plate-like and having at least one first supporting portion adapted to bear against a surface in the coupling mouth oriented essen- tially towards the coupling eye, at least one second sup- porting portion adapted to bear mainly against the upper side of the coupling eye, and at least one resilient, yielding portion adapted to connect the supporting por- tions with each other to bridge a distance between the coupling mouth and the coupling eye.

Thus, when the damping element is in place in a connected coupling, the supporting portions will be in contact with the upper inside of the coupling mouth and the upper side of the coupling eye. The resilient, yielding portion will be slightly pressed against its spring action, so as to exert a downward force on the coupling eye. This spring-like force takes up the main vertical forces that are generated during driving in connection with a relative pendulous motion between the coupling eye and the coupling mouth.

Plate-like here means primarily a plate-shaped, flattened element, the damping element extending in the longitudinal direction between the supporting portions thereof. The damping element does not take up the whole space of the distance between the coupling eye and the coupling mouth, which means that the damping element affords the drawbar the required angular freedom. More- over, owing to the plate-shape, it is easy to design the damping element in such manner that it fits all existing coupling without the need for any major constructional modifications.

The object is achieved also by a trailer coupling provided with a damping element as stated above.

Preferably, the damping element has an opening, or alternatively a hole, which at least partly or, alter- naively, completely surrounds the engagement means. An advantage thereof is that it allows supporting portions in the coupling mouth to be located adjacent the engage- ment means and, thus the damping element to maintain its intended position in the coupling mouth.

Preferably, the resilient, yielding portion has a main extension which is angled relative to the main ex- tension of the supporting portions, the angle differing from 90 degrees. This affords the resilient, yielding portion satisfactory resiliency.

Suitably, the damping element has a third supporting portion, which is adapted to bear against either the cou-

pling mouth or the coupling eye. This means that the damping element can be arranged using more contact points, that the damping element thus maintains its in- tended position and that the play between the coupling mouth and the coupling eye can be more reliably reduced.

According to a preferred embodiment, the resilient, yielding portion has a ridge-shaped extension, the ridge forming the intermediate portion of said three supporting portions. For example, the third supporting portion of the damping element is adapted to bear against an inner surface of the coupling mouth, said ridge being adapted to bear against the upper side of the coupling eye. The resilient, yielding portion thus both serves as one of the supporting portions and exhibits good resilience acting to reduce the play in the desired manner.

Preferably, the damping element has a mounting por- tion adjacent to one of the supporting portions of the damping element, said mounting portion being adapted to be attachable in either the coupling mouth or the cocu- pling eye. At least one of the supporting portions of the damping element is arranged in a movable manner, which allows said supporting portions to move along surfaces of the coupling eye and/or. the coupling mouth.

The risk of permanent deformations of the damping element is thereby reduced. This means that essentially vertical forces are taken up by the variation in length of the damping element, essentially horizontally by its spring action. Moreover, the damping element can be mounted and dismounted in a simple manner with only few attachment points in said mounting portion.

According to a particularly preferred embodiment, the damping element has a mounting portion which is attachable in the coupling mouth so that the first sup- porting portion is locked relative to the coupling mouth, while said second and third supporting portions are adapted to bear against respectively the coupling eye and the coupling mouth in a movable manner.

The mounting portion of the damping element is adapted to be attached to a coupling eye guide portion in the coupling mouth, said guide portion extending back- wards as seen in the driving direction of the towing ve- hicle. For instance, the mounting portion of the damping element is adapted to clasp said guide portion by clamp- ing fit. This allows mounting and dismounting of the damping element to be carried out in a simple manner.

The plate-shaped damping element may consist of a plurality of parts, which in some applications may fa- cilitate mounting and manufacture.

According to a preferred embodiment, the plate- shaped damping element is made of compression-moulded metal, which means that the damping element can be manu- factured in a cost-effective way while maintaining the required material properties.

Brief Description of the Drawings The present invention will now be described in more detail with reference to the accompanying drawings, which by way of example illustrate preferred embodiments of the invention.

Fig. 1 is a schematic view of a trailer coupling and a damping element according to a first embodiment of the invention.

Fig. 2 is a detailed schematic view of the damping element in Fig. 1.

Fig. 3 is a schematic view of a trailer coupling in a connected state, a damping element according to a second embodiment of the invention being arranged in the coupling mouth.

Description of Preferred Embodiments Fig. 1 shows a trailer coupling 1 of a type known per se, for example 795V supplied by VBG AB, comprising a coupling eye 2 arranged at the front end of a trailer drawbar 3, a coupling mouth 4 arranged at the rear of a

towing vehicle and an engagement means 5 arranged in the coupling mouth 4. The coupling mouth 4 is adapted to re- ceive the coupling eye 2 for the purpose of interconnec- tion. The engagement means 5 is insertable in a recess 6 in the eye 2, which allows it to carry out the connection when the coupling eye 2 is inserted in the coupling mouth 4. A damping element 7 according to a first embodiment of the invention is insertable in the coupling mouth 4.

The damping element 7, which appears more clearly in Fig. 2, is preferably made of compression-moulded metal and has a flattened plate shape with a first supporting portion 8 at one end as seen in its longitudinal direc- tion and a second supporting portion 9 located a distance from the edge of the damping element 7. In the example shown, the damping element 7 further has a third sup- porting portion 10 at its other end, which means that the second supporting portion 9 is located between the first 8 and the third 10 supporting portion. The sup- porting portions 8, 9, 10 are joined, from first to last, by a resilient, yielding portion 11 extending in the longitudinal direction of the damping element 7. Again with reference to the embodiment shown, the resilient, yielding portion 11 has a ridge-like extension and thus forms the second supporting portion 9. Furthermore, the damping element in Fig. 2 is bent adjacent to the first supporting portion 8 to facilitate mounting of the damping element 7 in the coupling mouth 4.

As shown in Fig. 3, which illustrates a second embodiment of the damping element 7, as inserted in the coupling mouth 4, the damping element 7 has a shape that is adapted to fit in the coupling mouth 4. In this em- bodiment, there is no bending adjacent to the first sup- porting portion 8 due to the shape of the coupling mouth 4 in Fig. 3. Moreover, a mounting portion 12 adjacent to the first supporting portion 8 is adapted to be attached to a guide portion 13 in the coupling mouth 4, for ex- ample by means of clamping. Suitably, said guide portion

13 adapted to guide the coupling eye 2 extends backwards as seen in the driving direction of the vehicle and con- sists, in the example shown, of an upper lip 14 in the coupling mouth 4. It should be noted that the mounting portion 12 in the second embodiment of the invention, as shown in Fig. 3, clasps the edge of the upper lip 14.

Furthermore, the second supporting portion 9 may bear against the upper side of the coupling eye 2 and the third supporting portion 10 against the upper inside of the coupling mouth 4. The resilient, yielding portion 11 has an extension which is angled relative to the essen- tially horizontal inside of the coupling mouth, the angle differing from 90 degrees.

In the example shown in Fig. 2, the damping element 7 according to the invention has a hole 15 adapted to surround the engagement means 5. The shape of the hole 15 may vary, however, depending on the cross section of the engagement means 5. The resilient, yielding portion 11 with its ridge-shaped extension may extend on both sides of the engagement means 5 to ensure satisfactory resil- iency in the connected state.

In the following, the functioning of the damping element will be described.

When the damping element 7, as shown in Fig. 3, is inserted in a connected coupling, the mounting portion 12 will keep the damping element 7 in position in the cou- pling mouth 4. When the coupling eye 2 is inserted in the coupling mouth 4, with the damping element in its in- tended position, the damping element 7 is slightly com- pressed, which gives it a cushioning function. The second and the third supporting portion 9, 10 will then be pres- sed towards the upper side of the coupling eye 2 and the inside of the coupling mouth 4, respectively, while being free to move in the horizontal direction to avoid defor- mation of the damping element 7 due to different forces acting on the supporting portions 8, 9, 10.

When the damping element 7 is in its intended po- sition during driving and the coupling eye 2 moves, for example, in the vertical direction upwards relative to the coupling mouth 4, the following will occur : The coupling eye 2 exerts an upward force on the second sup- porting portion 9, which force is taken up by the second and the third 10 supporting portion by the intermediary of the resilient, yielding portion 11. Preferably, the surface extension of the damping element 7 between its supporting portions 8, 9, 10 and the resilient, yielding portion 11 described above is such that it allows the damping element 7 to take up the essentially vertical forces occurring between the coupling eye 2 and the coupling mouth 4, for example during driving. The damping element 7 thus provides a damping capacity without re- stricting the vertical mobility required between the coupling eye 2 and the coupling mouth 4. In view of the required mobility, it should be noted that, in terms of volume, the damping element 7, as shown in Fig. 3, does not occupy the whole space between the coupling eye 2 and the coupling mouth 4. Furthermore, the resilient, yield- ing portion 11 will, in the inserted state, be slightly compressed so as to exert a downward force on the cocu- pling eye 2.

Owing to its design, the damping element 7 can be maintained in position also when the trailer has been disconnected or when the engagement means 5 is elevated and disengaged.

It will be appreciated that the embodiment of the invention described above can be modified and varied by a person skilled in the art without departing from the inventive idea defined in the claims. For example, the damping element 7 described above can with relatively simple means be adjusted to be attachable to the coupling eye 2 and to maintain that position when the vehicle is not connected. Moreover, the damping element 7 can be

made of different materials, such as plastic or other materials having the appropriate resiliency properties.

Furthermore, the surfaces of the damping element 7 around the engagement means 5 may be adjusted in such manner relative to the engagement means 5 that they will cooperate therewith during the connecting procedure when the engagement means 5 is lowered, so that the resilient portion 11 will be slightly compressed and the damping element 7 with its damping function thereby achieves the aim of the invention. The surfaces of the damping element 7 around the engagement means 5 may, for example, be pro- vided with flanges and/or the engagement means 5 may be provided with radially projecting parts, so as to allow interaction with the engagement means 5 as described above.

In addition, surface portions of the damping element 7 adjacent to the hole 15 may be designed to have pro- jecting parts positioned around the inside of the hole 6 of the coupling eye 2 in such manner that said projecting portions take up the play that normally occurs between the coupling eye 2 and the engagement means 5.

The damping element 7 may further consist of several parts, either as separate components or as combined com- ponents. The mounting of the damping element 7 in the coupling mouth 4 may be carried out in various ways, for example by means of a groove intended therefor in the coupling mouth 4 or by means of riveting, bolting or welding.