PURPOSE: To quickly move a movable jaw member by engaging a slide rod and the movable jaw member mounted thereon in a disengageable manner and providing a one-way actuator for movement from a first position to a second position.

CONSTITUTION: An actuating lever 32 for a one-way actuator is engaged with a slide rod 14 by the operation of a trigger 42 to move a movable jaw member 12 to a fixed jaw member 26 and fasten and hold two workpieces to be adhered or soldered between these jaw members. During forward movement of the movable jaw member 12, a brake lever 50 prevents the backward movement of the slide rod 14, and the trigger 42 is released in the meantime the brake lever 50 is engaged with the slide rod 14. To release the workpieces, the brake lever 50 is pushed to an arrow mark 64 to compress a spring 58, disengage the slide rod 14 from the brake lever 50 and manually separate the movable jaw member 12 from the fixed jaw member 26 together with the slide rod 14.