| 摘要 |
1464479 Ratchet mechanism EATON GmbH & Co KG 27 Nov 1975 [5 Dec 1974] 48904/75 Heading F2Q A stepped drive for a toothed wheel 1 comprises a pawl 11 which is adapted to be swung into engagement with teeth 2 on the wheel 1, effect a driving step under the influence of a spring 21, at the end of which step it is held in engagement with the teeth 2 by a fixed abutment 3 in order to prevent over-run of the wheel 1, and thereafter is swung clear of the teeth 2 again. The pawl 11 is mounted at its upper end on an eccentric 14 which is integral with a pinion 12 which is caused to rotate about an axis 13 by teeth 24 formed on one edge of an opening 23 in a stressing lever 20. A driving motor 30 drives cams 26 through gearing 29, 25 and the engagement of the cams 26 with stressing lever 20 cause the lever 20 to pivot about a shaft 4, carrying toothed wheel 1, thereby stressing the spring 21 until the cams 26 release the lever 20 whereupon the stressing lever 20 moves clockwise under the influence of the spring 21 causing clock-wise rotation of pinion 12 and a driving step of pawl 11. Between the eccentric 14 and the pawl 11 there is a friction coupling which may comprise a spring-pressed ball, Fig. 2, or a resilient detent finger 19, Fig. 3. When the pawl 11 is clear of the teeth 2, the wheel 1 may be rotated by hand in the direction of the arrow 6, rotation in the opposite direction being prevented by a spring-pressed pawl 7. |
