| 摘要 |
The rack (10) of the mechanism has a cross-shaped or hollow oval body (11), projecting ribs (13, 13a) and a cogged portion extending in the longitudinal direction and having teeth (9). The teeth (9) of the rack are guided by guide rollers (12) and thereby held in engagement with a gearwheel. To prevent dried grease from accumulating in front of the rollers during the displacement backwards and forwards and blocking the movement of the said rollers, one or more tracks (S) are formed in that side of the rack which faces away from the cogged portion. The guide flanges (14) of the roller therefore also have a shape corresponding to that of the tracks. As a result, the rollers come into more forceful, frictional engagement with the track and are as a result forced to rotate during the movement backwards and forwards, and, at the same time, the roller and the track scrape against one another during the displacement of the rack, preventing dried grease from accumulating in front of the rollers. <IMAGE>
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