A solenoid-operated plunger device comprising a frame and a solenoid coil contained within the frame. Two or more movable plungers, separated by a barrier, are located within the solenoid coil. The plungers project the ends of the solenoid coil, and are slidable within the solenoid coil on parallel axes....http://www.google.com.au/patents/US4503411?utm_source=gb-gplus-sharePatent US4503411 - Dual plunger solenoid device
