Push-pull actuator for key switches

A push-pull actuator for switches, the actuator comprising:

• a mushroom knob, the mushroom knob being movable longitudinally between a rest position and an operating position;
• a first spring, the first spring biasing the mushroom knob toward the rest position;
• an actuating plunger, the actuating plunger movable between an ON position and an OFF position;
• a second spring, the second spring biasing the actuating plunger in a predetermined direction toward one of the ON positions and the OFF position;
• at least one detent, the detent selectively maintaining the actuating plunger in one of the ON position and the OFF position against the bias of the second spring, the mushroom knob being movable with respect to the actuating plunger for disengaging the detent means at least when the plunger is in one of the ON position and the OFF posiiton, the mushroom knob being movable into direct contact with the actuating plunger so as to allow movement of the actuating plunger in the direction of biasing of the second spring when the second spring fails to bias the actuating plunger;
• wherein the mushroom knob includes an inclined surface and the at least one detent comprises a spring loaded latch, the spring loaded latch having a recess;
• and
• the actuating plunger having a projection, the projection extending into the recess such that the actuating plunger is engaged by the latch when the actuating plunger is in the ON position.