The invention relates to a roller device of the kind stated in the introductory portion of claim 1.

The synchronized rollers may e.g. be such crimper rollers which are used in many agricultural machines and which may be equipped with longitudinal rubber edges which in operation intermesh without touching. The deep toothing and the coarse gear wheels ensure that the rollers can be lifted suitably from each other while the gear wheels are still correctly intermeshed. In such cases where the rollers are lifted out of engagement by a large material lump they must be steered back into engagement without causing damage.

In practice, use is e.g. made of rollers with five rubber edges and correspondingly gear wheels with five teeth. However, due to the polygon effect, gear wheels that coarse periodically are not in sufficiently firm engage¬ ment to ensure that the rollers are not damaged in the given situation.

It is the object of the invention to provide a roller device of the kind ensuring that the rollers pass into correct engagement with each other without risk of damage after having been forced so far apart by material lumps that they have passed out of engagement.

The object is achieved by the roller device being designed as stated in the characterizing portion of claim 1, in that by such a construction an engagement is obtained which is similar to the one obtained by using single gear wheels having the same number of teeth as in the set according to the invention while maintaining the freedom

of movement of the gear wheel axes relative to each other which is made possible by the large tooth height.

The angular displacement can be as stated in claim 2 corresponding to 1/n of the tooth pitch.

For most practical purposes each set may suitably comprise two gear wheels as stated in claim 3.

The relative axial disposition of the gear wheels in a set is not decisive; but in practice it is often expedient that the gear wheels are positioned close to each other as stated in claim 4.

In the following the invention will be explained in more detail, reference being made to the drawing in which

Fig. 1 shows a side view of the one pair of gear wheels in one embodiment of the roller device according to the invention with two gear wheels in each set,

Fig. 2 shows a section along the line A-A in fig. 1,

Fig. 3 shows a perspective view of one end of the roller device, and

Fig. 4 shows the two rollers seen from one end.

In the drawing 10 and 11 are two gear wheels which as shown at 12 are welded firmly onto each side of a spacer ring 13 displaced one half tooth pitch corresponding to an angular displacement of 360°/2z, where z is the number of teeth, here five. This gear wheel pair and the second gear wheel pair cooperating therewith are, as shown in fig. 3, positioned on the end of each separate one of a pair of cooperating crimper rollers 15 and 16. As also shown in

fig. 4 these crimper rollers are each equipped with a number of longitudinal edges 18 of rubber or a like resilient material corresponding to the number of teeth on each of the gear wheels 10 and 11, i.e. in the present case five. These edges may be attached to the rollers in an arbitrary suitable way, e.g. by means of bolts. The roller shafts rest in two end plates one of which 19 is shown in fig. 3. The lower roller 17 is in a conventional manner provided with stationary axis, while the shaft of the upper roller 16 is movable at both ends in a slit 20 and being influenced by a spring 21 to abut against the bottom of the slit, in which position the rubber edges of the two rollers intermesh as shown in fig. 4. The gear wheels must synchronize the rotary movements of the rollers in such a way that the rubber edges do not get into contact, which would expose them to risk of damage. As such crimper rollers are often pressed rather far apart by passing material lumps against the effect of the springs 23, the gear wheels must, as in the case shown with five tooth, necessarily have coarse teeth, i.e. large tooth height and correspondingly large tooth pitch. This, if as in the usual way only one gear wheel was provided on each roller, would give the teeth on the two wheels so great freedom of movement relative to each other when the rollers and consequently the gear wheels are pressed apart, that the desired safeguard against contact between the roller edges is not achieved. However, when there are two gear wheels being firmly attached to each other and displaced by one half tooth pitch or in the case shown 180°/5 = 36° relative to each other, on each crimper roller, the same effect is obtained as with single gear wheel having double the number of teeth, i.e. in this case ten teeth. Such gear wheel pairs cannot assume relative positions in which the two crimper rollers are in mutual contact.

Both the gear wheels 10 and 11 and the spacer ring 13 are provided with inwardly directed, radial protrusions 15 contemplated for cooperation with outwardly directed, radial protrusions on a not shown central means being attached to the crimper roller or its shaft through rubber elements not shown acting as shock absorbers.

The details of the shown and described roller device can be changed in various ways within the scope of the invention. E.g. the two gear wheels must not necessarily be positioned close to each other, but merely have to be secured against rotation relative to each other. Further¬ more, both the number of gear wheels in each set and the number of teeth on each gear wheel are variable.