Actuator for a frictional engaging device

An actuator for frictional engaging devices controlled by electric signals from a control device and disposed in a power transmission device, comprising:

• a torque generating mechanism which converts electric energy into torque,
• at least two movably mounted frictional engaging devices having respective initial first positions,
• a torque-thrust conversion mechanism which converts torque generated from said torque generating mechanism into an augmented thrust force for moving said at least two frictional engaging devices from said respective initial first positions to different second positions respectively, said torque-thrust conversion mechanism having a given initial position,
• a connecting means which transmits said augmented thrust force generated from said torque-thrust conversion mechanism to each respective one of said at least two frictional engaging devices, and
• first spring means for urging at least one of said at least two frictional engaging devices to be in a compressed condition,
• whereby said torque-thrust conversion mechanism can move said at least two frictional engaging devices from said respective initial first positions to the second positions respectively by rotation in one rotational direction from said given initial position.