| 摘要 |
992,718. Ratchet mechanisms. CLARY CORPORATION. April 4, 1962 [April 12, 1961], No. 12950/62. Heading F2Q. Intermittent rotary drive mechanism for a tape feed sprocket 17 comprises a pawl 18 which is oscillated about a shaft 14 by an actuator 37 and carries at one end teeth 65 adapted to co-operate with teeth 66 on the sprocket and carries at the other end larger teeth 68 which are adapted to co-operate with teeth 67 on a cam 20 coaxially mounted on the shaft 14. For a forward direction of drive, the cam 20 is urged by a spring arm 72, Fig. 2, in the direction of an arrow C, Fig. 7, and on the initial movement of the pawl 18 it slides along teeth 67 of the cam 20 in the direction of an arrow F, the teeth 65 moving out of engagement with teeth 66 and into engagement with adjacent teeth 66 under the influence of a spring 70. On the return movement of the pawl 18 it is maintained in contact with the teeth 67 of the sprocket, by the combined effect of the cam 20 and the spring 70, thereby effecting one step of movement of the sprocket 17. The actuator 37 comprises a rocking lever 43, Fig. 5, carrying an eccentric roller 41 which is adapted to be driven by continuously rotating rolls 38, 40 when a brake 52 is released by an electromagnetic device 56, 58. The sprocket 17 is held resiliently in each position by rollers 34 carried by spring-pressed arms 27, Fig. 6. For reverse operation, a button 80 is pressed to effect spring-urging of the cam 20 in the opposite direction, shown by an arrow B in Fig. 10. |
