Patent ID: 7932794

Claim:
An actuator of an electromagnetic type comprising: an electric motor; a gear drive, including a worm shaft adapted to be rotated by the motor, and a rider nut that is in threaded engagement with, and around, the worm shaft and that has a guide finger and a cursor spindle; a lever having a fork and fixed to a drive shaft that extends at a right angle to the worm shaft, the lever being so positioned as to locate the guide finger in the fork between two predetermined positions on the worm shaft, whereby to rotate the drive shaft between two predetermined positions (I and O); a first auxiliary interrupter for breaking the power supply to the electric motor at the end of the stroke of the cursor; and transmission means for transmitting the movement of the cursor at the end of the stroke of the first auxiliary interrupter, whereby to put it in a switching position, the said transmission means comprising a pair of coupled-together control levers, one said control lever being coupled to a movable contact of the first auxiliary interrupter, each of the control levers being pivoted about a pivot pin which is orthogonal to the worm shaft, and each said control lever having a guide edge, the arrangement of the levers and the profiles of their guide edges being such as to enable the cursor to slide on the guide edges regardless of the position on the worm shaft, by causing the control levers to stop or pivot simultaneously, whereby the simultaneous pivoting movement of the levers puts the auxiliary interrupter into a switching position.