The invention relates to an actuator assembly for a drivebridge that is meant to be used particularly in connection with a trailer of a truck or a like and, which consists of a frame part that is coupled with a frame structure of the trailer in a turnable manner at a first link point, when viewed from the side. The frame part is arranged turnable by means of actuator means, such as one or several hydraulic cylinders or like, by twisting the same with regard to the first link point, first of all to a standby position, against an inclined surface existing in the frame structure of the trailer, and on the other hand to a drive position, as an extension, being essentially parallelly with the inclined surface.

A traditional way to carry out an actuator assembly as mentioned above, is e.g. as shown in figure 1 such that the frame part, acting as a lower part of a drivebridge, is coupled by a link mechanism by a lower edge of its end surface with a head of a push arm of a hydraulic cylinder. This kind of a solution operates in practice so, that a hydraulic cylinder, which is first of all in its standby position in a so called lengthened position and on the other hand visible under the structures of the inclined surface of the trailer, pulls the frame part to a drive position so that it is essentially parallel with the inclined surface, whereafter the hydraulic cylinder is in a so called shortened position, whereby its push arm is drawn inside. The biggest problem involved with this type of a solution is the fact that the hydraulic cylinder is under all circumstances continuously underneath the structures of the inclined surface of the trailer. Since, in addition to the above, it is also in the so called lengthened position during the standby position and on the other hand at the lowest point of the trailer regarding its ground clearance, it is continuously exposed to strokes, dents and getting dirty, when the trailer is moving. A consequence of the above is that, despite decent service and maintenance, particularly the push arm of the hydraulic cylinder gets easily damaged, thus making slower or even preventing proper use of the drivebridge. On the other hand, a traditional solution, being carried out in the way described above, is disadvantageous particularly with a view to the power transmission of the hydraulic cylinder, since the need for power of a link mechanism, that is coupled only at the lower edge of the end of the moveable frame part, is the highest possible due to very short lever arms .

It is the aim of the actuator assembly according to the present invention to achieve a decisive improvement in the problems described above and thus to raise essentially the level of prior art. In order to carry out this aim, the actuator assembly according to the invention is mainly characterized by that the actuator assembly is carried out by a link arm mechanism that is formed of at least two parts and coupled with the frame part in a turnable manner in at least two points, thus enabling opening of the frame part to its drive position by using push force of the hydraulic cylinder or like belonging to the actuator means .

As the most important advantages of the actuator assembly according to the invention may be mentioned the simplicity and reliability of its construction and use. By virtue of the actuator assembly according to the invention, it is possible to carry out use of a moveable frame part, thanks to a link arm mechanism with at least two parts, so that the hydraulic cylinder belonging to the actuator means and moving the same, is, when the trailer is being moved, in a standby position of the drivebridge in a so called shortened position, in which case it can be kept protected from the environmental conditions thanks to its push arm being drawn inside. On the other hand, an advantage of the actuator assembly according to the invention is the fact that the components thereof may be placed thanks to the operating principle depicted above furthermore in a way that the frame part is being moved from the standby position to the drive position by the hydraulic cylinder by pushing the same so to say from above with regard to the first link point. Thanks to an advantageous link arm mechanism of the actuator assembly according to the invention, having at least two parts, it is also possible to exploit significantly longer lever arms compared to existing solutions, thanks to which the hydraulic cylinder may be dimensioned clearly smaller than at present. The actuator assembly according to the invention has also such an advantage, that it does not require extra service and maintenance measures thanks to the fact that its components are both during a standby and drive positions placed totally internally, protected by the structures of the inclined surface of the frame structure and the frame part.

Advantageous embodiments of the actuator assembly according to the invention have been described in the dependent claims related to the same.

In the following description, the invention is being illustrated in greater detail with reference to the appended drawings, whereby in

figure 1 is shown a traditional drivebridge with its actuator assembly during a standby and a drive position,

figure 2 is shown a motion series of the functioning of the actuator assembly according to the invention, when moving the same from its standby position to a drive position, and

figure 3 is shown a top view of an advantageous embodiment of the actuator assembly according to the invention.

The invention relates to an actuator assembly for a drivebridge that is meant to be used particularly in connection with a trailer of a truck or a like and, which consists of a frame part 1 that is coupled with a frame structure R of the trailer in a turnable manner, when viewed from the side, at a first link point N. The frame part 1 is arranged turnable by means of actuator means T, such as one or several hydraulic cylinders or like, by twisting w the same with regard to the first link point N, first of all to a standby position I, against an inclined surface V existing in the frame structure of the trailer, and on the other hand to a drive position II, as an extension, being essentially parallelly with the inclined surface V. The actuator assembly is carried out by a link arm mechanism that is formed of at least two parts and coupled with the frame part 1 in a turnable manner in at least two points X, Y, thus enabling opening of the frame part 1 to its drive position II by using push force F of the hydraulic cylinder Tl or the like belonging to the actuator means T.

With reference particularly to the first and last views of figure 2, the actuator means T belonging to the actuator assembly, such as one or several hydraulic cylinders Tl or like, being turnable on the first hand with regard to the frame structure R and on the other hand with regard to the frame part 1, and the link arm mechanism 2, 3 are being positioned, when viewed from the side, both during the standby and drive position I, II in a totally invisible manner internally with respect to the structures of the inclined surface V and the frame part 1.

As shown in the enclosed drawings, the frame part 1 is coupled at an end of the inclined surface V that exists in the frame structure by means of a joint, hinge assembly or like that forms the first link point N. Furthermore as an advantageous embodiment, the first link arm 2 belonging to the actuator assembly comprises a fixed support arm, such as a rod or like, which is connected in a turnable manner on the first hand at an end Ml of a push arm T2 of a hydraulic cylinder Tl and on the other hand essentially at an end surface X of the frame part 1, at a distance from the first link point N.

A second link arm 3 for its part comprises an arm mechanism, the length of which is changeable, such as a telescope structure or like, which is coupled in a turnable manner on the first hand at the end Ml of the push arm T2 of the hydraulic cylinder and on the other hand in connection Y with the upper edge of the frame part 1 (in its standby position I), on the opposite side of a fastening point X of the first link arm with regard to the hydraulic cylinder Tl.

Particularly with reference to the advantageous embodiment, shown in figure 3, the second link arm 3 is carried out by two parallel shock eliminators 3a or like. With further reference to this view, in. connection with the second link arm 3 there has been arranged limiting means 4 that transmit at least pulling, such as one or several wire ropes, chains or like, in order to restrict the maximum movement length of the second link arm 3.

Furthermore as an advantageous embodiment, the actuator assembly has been carried out by one uniform entirety, which is being placed, when viewed, from above, essentially symmetrically at the center of the inclined surface V, belonging to the frame structure R, and the frame part 1. Furthermore in the inclined surface V, belonging to the frame structure, and at a corresponding point in the frame part 1, there has been arranged lead-through openings Ll, L2 in order to enable free movement of the parts belonging to the actuator assembly.

It is clear that the invention is not limited to the embodiments shown or described above, but it can be modified within its basic idea in very many ways. It is first of all naturally possible to carry out the actuator assembly by two separate units, being placed at opposite sides. The link arm mechanism may on the other hand be carried out differing from what is being represented in the foregoing e.g. by changing the articulation point of the fixed link or its place with regard to the second link arm. On the other hand, the second link arm mechanism may also be carried out by most heterogeneous structures, its most important characteristic being, however, first of all the fact that its length can be changed and on the other hand that it is under certain circumstances, however, able to transmit tension. Furthermore it is naturally clear that an actuator assembly according to the invention may be exploited in connection with a drivebridge, being used in connection with whatever kind of a vehicle.