Abstract: An actuating mechanism for a vacuum interrupter incorporates a pivotable bell crank mechanism and a displacement structure for imparting movement of the bell crank mechanism to a coupling structure which is connectable to a contact stem carrying the movable contact of the interrupter for moving the contact into and out of engagement with another contact of the interrupter. After movement of the coupling structure for a sufficient distance in a direction which causes closure of the contacts the displacement structure is capable of being moved for a further distance to disengage it from a cooperating surface of the coupling structure. On the return movement the displacement structure is traveling at high velocity when it re-engages the cooperating surface of the coupling structure which produces a rapid acceleration of the latter and hence, in use, of the movable contact of the interrupter to the open position.