At present, belt drive devices mentioned above are commonly used in cable production lines, for instance. Flat transmission belts, i. e. belts whose both surfaces are smooth, are commonly used as cable driving belts, for ex- ample. Drive belts in which the surface that is being pressed against the cable is shaped in a suitable manner are also used in the field.

The tightness of drive belts must be adjustable as required by the process, in other words the belts must have a correct tightness during each process. The tightness of the belts is adjusted automatically by hydraulic or pneumatic cylinders, for example. The belt must also be prevented from slip- ping off the wheel. This can be performed by adjusting the axial angle of the stretching roller with respect to the direction of movement of the belt. The ad- justment of the axial angle of the stretching roller has earlier been performed by stopping the belt drive device for the adjustment, since the adjustment must be performed in a danger area. The adjustment of the prior art has been per- formed by winding eccentric sleeves arranged between a bearing arranged inside the stretching roller and the axle. It is to be noted that for reason of safety, the arrangement cannot be used when the shelters are opened.

A drawback of the prior art is that the effect of adjustment is not immediately visible but it is commonly noticed that readjustment is necessary, in which case the drive belt must be stopped to enable additional adjustment to be performed. These procedures must sometimes be carried out several times consecutively. A further problem is that if the adjustment is performed without a cable, the rotation force caused by the torsional movement of the cable starts moving the belts when the device is then run with a cable. The belts move in such a manner that the top belt moves in one direction and the

lower belt in the other direction. This also results in stopping the drive device, readjusting, restarting, etc.

An object of the invention is to provide an arrangement by which the drawbacks of the prior art can be eliminated. This is achieved by the arrange- ment of the invention, which is characterized in that the adjustment means are arranged on the side of the opposite end of the axle with respect to the stretching roller.

Above all, an advantage of the invention is that adjustment can be performed considerably faster than in the prior art. This is due to the fact that the adjustment of the axial angle of a stretching roller can be performed while the drive belt device is running and the stretching roller is rotating. The ad- justment of the axial angle of the stretching roller can thus be performed while the device is running. To perform the adjustment is perfectly safe since the shelters need not be opened and no procedure needs be performed in the danger area. A further advantage of the invention is that it is simple, so it is inexpensive to implement; compared with the prior art, implementation causes no considerable extra costs.

The invention will be described in closer detail in the following by means of an example of a preferred embodiment shown in the accompanying drawing, in which Figure 1 is a schematic side view of a belt drive device, and Figure 2 is a view of an arrangement of the invention seen in a per- pendicular direction with respect to the rotation axle of a stretching roller.

Figure 1 schematically shows a belt drive device. The belt drive de- vice comprises two continuos drive belts 1 which are used by means of drive rollers 2. The drive rollers 2 are used by means of a suitable power source, for example an electric motor. The drive belts 1 are arranged to travel at a dis- tance from each other as continuous loops round stretching rollers 6, whereby a cable or the like 3 is arranged to travel between the drive belts in such a manner that the drive belts are pressed against the cable or the like, drawing it along as they travel. The drive belts 1 are made to be pressed against the ca- ble or the like 3 by means of press rolls 4 which are pressed against the inner surfaces of the drive belts 1 at the point of the cable or the like 3. In the situa- tion of Figure 1, the direction of movement of the cable or the like is from the right to the left. The direction of movement is marked in Figure 1 by means of an arrow.

The above matters are known to those skilled in the art, so they will not be discussed here in further detail.

Figure 2 schematically shows an arrangement of the invention. The adjustment of an axial angle of a stretching roller 6 is arranged to be per- formed by adjustment means 8 which affect the end of an axle 7 which is op- posite to the end on which the stretching roller 6 is fastened. In the example of Figure 2, the adjustment means 8 comprise eccentric sleeves 8a, 8b. The ad- justment of the stretching roller is performed by rotating the sleeves, whereby the position of the axle 7 and simultaneously the position of the stretching roller 6 are changed. According to the basic idea of the invention, the eccentric sleeves 8a, 8b are arranged on the side of the opposite end of the axle 7 with respect to the stretching roller 6. This can be clearly seen in Figure 2. In Fig- ure 2, reference number 10 refers to a part which belongs to a belt stretching leverage and which is supported to a frame 13 of the drive device. The part 10 which belongs to the belt stretching leverage is arranged to rotate round an axle 15 schematically shown in Figure 2 by means of a cylinder device 14, whereby the belt becomes stretched or loosened, depending on the rotation direction of the part 10. The arrow in the figure illustrates how the part 10 ro- tates round the axle 15. In Figure 2, reference number 16 refers to an opening which serves as a play which enables the axle 7 to move when the belts are being stretched. Reference number 6 in Figure 2 refers to a schematic stretching roller. The axle 7 and the stretching roller 6 are attached to each other by means of a suitable bearing device (not shown in Figure 2). The cyl- inder device 14 can be a hydraulic or pneumatic cylinder, for instance, as de- scribed above. Further, it is to be noted that instead of the cylinder device 14, any other suitable device, for instance mechanical solutions, etc., can naturally be used.

As can been seen from the example in Figure 2, the position of the axial angle of the stretching roller can be adjusted with respect to the direction of movement of the belt by winding the eccentric sleeves 8a, 8b round the centre axis of the axle 7. Hence, the axle 7 rotates according to how the thick- est and thinnest points of the eccentric sleeves 8a, 8b are located with respect to each other. Adjusting the axial angle aims to keep the belt in the correct position while the device is running. In addition, surfaces 11,12 which serve as joint points are arranged in the structure. In the example of Figure 2, the surfaces 11,12 operating as joint points are formed of compatible arched

surfaces which are arranged in connection with the part 10 which operates as the supporting part of the axle and the axle 7, and the part 10 and the outer eccentric sleeve 8a, respectively. When the eccentric sleeves 8a, 8b rotate, the axle 7 rotates on the joint points formed by the surfaces 11,12, and as a result, the position of the stretching roller 6 pivoted at the end of the axle is changed.

Since the adjustment means of the stretching roller 6 are arranged at the end of the axle 7 away from the stretching roller in the arrangement of the invention, a considerable advantage can be gained. This is the fact that the position of the axial angle of the stretching roller can be adjusted"from behind"with no need to enter the dangerous operating area where for instance the rotating stretching roller and moving drive belt are located. Above all, an advantage of the structure shown in Figure 2 is thus that the stretching roller can be adjusted safely from behind the belt drive device, in which case the danger area needs not be entered at all when the device is being adjusted.

The position of the axial angle of the stretching roller can thus be adjusted while the device is running, if necessary, which makes repeated readjusting unnecessary, contrary to the prior art.

The example of the invention shown in the figures is by no means intended to restrict the invention, but the invention can, of course, be freely modified within the scope of the claims. It is thus obvious that the arrangement of the invention or its details do not have to be identical to those shown in the figures but various solutions are feasible. In the example of the figures, the adjustment means, in this case the eccentric sleeves are, for example, ar- ranged on the same axle as the stretching roller. This is not the only feasible solution, however, but the invention can also be applied differently in accor- dance with the basic idea of the invention. The adjustment means can also be arranged on a different axle than the stretching roller. Instead of the axle 7, the adjustment means 8, for example the eccentric sleeves 8a, 8b, can be ar- ranged on a different axle, for example on the axle 15. In the example of Fig- ure 2, the adjustment means can be preferably arranged at the right-hand end of the axle 15. The surfaces operating as joint points are then arranged on the axle 15 and in the part 10 as described above in connection with the axle 7. It is essential to place the adjustment means on the side of the opposite end of the axle with respect to the stretching roller. Also other means than the eccen- tric sleeves used in the example of the figure can be used as the adjustment means. The surfaces operating as joint points can also be implemented in various ways; they can be directly formed on the axle and in the outer eccen- tric sleeve, respectively, etc.