| 摘要 |
The impulse drive mechanism has a drive pawl which is periodically retracted sufficiently to engage a tooth at maximum tooth spacing to advance the sequence control cam a maximum step. If a lesser step is desired (can be used) the ratchet tooth spacing is decreased and the masking device which incorporates a follower engaging the cam on the inside of the ratchet is moved into position to prevent engagement of the pawl with a tooth at greater spacing. The cam drum can be advanced in small angular increments when only tolling time and the angular increment can be increased to accomodate sequential switching during the advance step if required. |
