The present invention relates to an assembly for control- ling the track width of steering skis in a track-belt- driven motorized snowmobile, said snowmobile incorporat¬ ing a front axle/tie-rod with the steering skis attached to both ends thereof.

The track width of steering skis in snowmobiles conven¬ tionally is arranged in a fixed manner. As snowmobiles are used in varied applications, different versions of snowmobiles have to be manufactured with different fixed track widths of steering skis. Furthermore, different terrain conditions may curtail the use of a snowmobile with a fixed track width. For instance, a snowmobile with a narrow track width of the steering skis is much more agile in a terrain with densely growing wood than a snowmobile having steering skis with a wide track width. By contrast, in a rugged terrain, a snowmobile with steering skis of wide track width is more stable to handle and exhibits less tendency to flip over than a snowmobile with a narrow track.

Known from prior art is an assembly according to US patent publication No. 3,847,239 for controlling the steering ski track of a snowmobile. In this assembly the track width of the steering skis is not varied, but rather, with the rotation of the handlebar the steering ski track is shifted as a whole to the outer-bend side thus stabilizing the turning behavior of the snowmobile. However, this arrangement does not make the snowmobile capable of negotiating tight places.

It is an object of the present invention to provide an assembly for controlling the track width of steering skis in a snowmobile, said assembly being capable of offering

an essential improvement to the control of the steering characteristics of a snowmobile with a simultaneous broadening of the operating possibilities of a snowmobile. It is a further object of the invention to provide an assembly for stepless control of the steering ski track width even during driving, said assembly being characterized by simple construction resulting in cost- advantageous manufacture and maintenance.

The goal of the invention is achieved by means of an assembly characterized by what is stated in the charac¬ terizing part of claim 1.

In the assembly according to the invention, the length of the front axle/tie-rod is steplessly controllable and the assembly incorporates an actuator for the length control of the front axle/tie-rod. With the help of the actuator, the length of the front axle/tie-rod, and thus, the track width of the steering skis can be readily varied. The major benefit of the invention is therein that the track width of the steering skis can be controlled in a step¬ less manner during driving thus permitting the steering ski track width to be set according to the intended use and driving conditions of the snowmobile.

In a preferred embodiment of the invention, the front axle/tie-rod with the steering skis attached thereto are supported to the chassis of the snowmobile by means of a trapezoidal link system formed by support rods, steering rods and pivotal joints. Such a link system has proven highly functional in use.

In a further preferred embodiment of the invention, the front axle/tie-rod incorporates a center support rod having actuated rods extending distally outward from said center support rod and at least partially entering tele- scopically into said center support rod, whereby the

steering skis are attached to the ends of said actuated rods. The assembly has a simple and highly functional construction. Alternative arrangements can be used in different applications.

The invention is next examined with reference to attached drawings, in which:

Figure 1 is a top view of an embodiment of the assembly according to the invention and the steering skis of a snowmobile; and

Figure 2 is a top view of the assembly illustrated in Fig. 1 and the steering skis of a snowmobile rotated to an other position; and

With reference to Fig. 1, the steering skis 3 of a snowmobile are shown controlled to a narrow track width. Accordingly, the length-wise steplessly controllable front axle/tie-rod 1 is shown in its shortest position.

The length of the front axle/tie-rod 1 is made adjustable by means of an actuator 2 adapted to the center part of the tie-rod. The actuator itself is a conventional type of actuator powered by the engine of the snowmobile.

The front axle/tie-rod 1 having the steering skis 3 attached to its both ends by means of pivotal joints 8 is supported to the chassis of the snowmobile with the help of support rods 4. When required, auxiliary links can be used so arranged that no hindrance to the lateral move¬ ment of the steering skis 3 and to a small movement of the front axle/tie-rod 1 in the longitudinal direction of the snowmobile. The steering of the snowmobile takes place via the steering arms/rod 5 and 6 and the pivotal joints 7 and 8.

With reference to Fig. 2, the steering skis 3 of the snowmobile are shown controlled to a wide track width. Accordingly, the length-wise steplessly controllable front axle/tie-rod 1 is shown in its longest position. In the embodiment illustrated in the diagrams, the front axle/tie-rod 1 comprises a center support rod 9 having actuated rods 10 extending distally outward from said center support rod and at least partially entering tele- scopically into said center support rod, whereby the steering skis 3 are attached to the ends of said actuated rods by means of balljoints 8. The support to the steering skis is implemented by means of support rods 4. Furthermore, when required, auxiliary links can be used so arranged that no hindrance to the lateral movement of the steering skis 3 and to a small movement of the front axle/tie-rod 1 in the longitudinal direction of the snow¬ mobile. The support rods 4 and the steering rods 6 with the pivotal joints 7 and 8 form a trapezoidal link system. This system facilitates the control of the track width of the steering skis 3 without altering the align¬ ment of the steering skis 3 of the snowmobile.

To those versed in the art it is obvious that the inven¬ tion is not limited by the preferred embodiment described above, but rather, can be widely varied within the inven¬ tive spirit of the invention disclosed in the appended claims.