| 摘要 |
An expanded interval drive mechanism for a program timer includes a lift cam which periodically engages a pawl lifter to move the pawl lifter so as to lift the drive pawl away from the ratchet teeth. The ratchet teeth are at two levels. Where the ratchet teeth are at the lower level, operation of the pawl lifter prevents the drive pawl from engagement with the lower level ratchet teeth. However, the higher level ratchet teeth are always engaged by the drive pawl regardless of the operation of the pawl lifter. Therefore, an expanded interval is achieved in the region having the lower level ratchet teeth.
|
