The output rollers of paper machines typically consist of several roller shells and a roller core mounted with bearings on the shells. Between the shells, a clutch is provided to transmit rotation to the next shell and to couple the shells to- gether, with rolling contact bearings on either side of the clutch.

A drawback with current clutches is that the clutch housing, which may consist of a common protective casing for both the clutch and the bearings, is unpro- tected and therefore susceptible to damage caused by dirt, bearing grease etc.

For example, when the bearings are being greased, no protection is provided around the bearings; instead, the lubricant, e. g. grease, goes directly into the end ring seal or penetrates into the space inside the roller from the other side of the bearing. Grease causes fast fatigue of the rubber in the end ring seal so that it soon cracks, and it also produces deformations of the rubber, which means that some grease may get directly to the product or to the shell surface. The roller shell and the product itself may thus gather some of the dirt accumulated in the clutch bellows, and this leads to problems and damage in the nip and elsewhere.

Patent specification EP-B1-0 494 437 discloses a sealing structure for the roller bearing of a spreader roll wherein the bearings are protected against grease or oil entering from outside by means of radial discoid sealing plates and 0-rings placed against the bearings. The O-ring is fitted inside the circumference of the sealing ring, and the inside of the sealing ring has e. g. a concave curved cross- sectional form. In this way, the flow of oil released from bearing grease is stopped, and no oil will leak out when the roller is stationary.

The solution of the aforesaid specification is not very well suited for the sealing of the clutch/bearing housing because it cannot prevent grease and dirt from leaking from the clutch space onto the product itself or onto the roller shell.

The object of the present invention is to eliminate the drawbacks of prior-art technology and achieve a sealing structure for the clutch/bearing housings of rollers to prevent grease from getting from the clutch space onto the product or onto the roller shell. The fundamental idea of the solution of the invention is that the clutch housing is provided with a guard ring parallel to the roller shell and placed in the gap between the shell parts. In addition, second 0-rings are fitted to the ends of the radial sealing plates. By these means, grease and dirt are prevented from getting onto the product itself or onto the roller shell.

The invention affords the advantage that no grease or dirt can get into the pro- duction process. In addition, the end ring seal can be protected against grease, and the"pocket"of the end ring seal can be protected with a guard ring to pre- vent dust produced in the production process from accumulating in the pocket, where it would gradually form larger particles, which could get onto the product and cause damage e. g. to the nip rollers.

In the following, the invention will be described in detail by the aid of an exam- ple with reference to the attached drawing, wherein the figure illustrates the sealing of the clutch/bearing housing of an output roller with a sealing structure according to the invention.

The figure represents the shell parts 1a and 1b and the shaft 2 of an output roller. The shell parts 1a and 1b are provided with roller bearings or ball bear- ings 3a and 3b supporting them on the shaft 2. A clutch 4 is provided between the bearings 3a and 3b. Both the clutch and the bearings are placed in a com- mon protective casing surrounding them. The protective casing comprises two parts 5a, 5b, between which there is a gap 5c corresponding to the gap 1c be- tween the shell parts. The clutch space is additionally provided with end rings 6a, 6b, which are attached to the shell parts via fixing parts 7, with an end ring seal 8 between them.

The bearings are protected by 0-rings 11 placed against the bearings and by radial discoid seating plates 12, inside which the 0-rings are fitted. In addition, the clutch space is provided with a guard ring 13 parallel to the roller shell, placed in the gap 5c between the shell parts. Moreover, second 0-rings 14 are fitted at the ends of the radial sealing plates. By these means, grease dirt and are prevented from getting from the clutch space onto the product itself or onto

the roller shell. Instead of 0-rings, it is also possible to use a corresponding seal made of a sealing material, e. g. vulcanized rubber, felt or other material used for sealing.

It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the example described above, but that they may be varied within the scope of the claim presented below.