| 摘要 |
An add and subtract relay for a pinball machine or the like having an add solenoid and a subtract solenoid mounted side by side with respective drive pawls and associated ratchet wheels, the teeth of both of the ratchet wheels being faced in the same direction. The wheels are axially detented together with one of them being axially shiftable with respect to the frame for operating a switch when the wheels are rotated out of, and into, a relative reference phase position. As an added feature the wheels have telescoping concentric shafts with cooperating discs at the ends of the shafts with indicia to provide constant indication of offset in terms of the number of steps of phase position. Each solenoid has a return spring so that the drive pawl advances the engaged ratchet wheel forwardly one step upon deenergization of the solenoid. A cam is provided adjacent each drive pawl for crowding the pawl inwardly against the ratchet wheel as it approaches the end of its forward stroke to block the ratchet wheel against unwanted rotation in either direction. |
