ACTUATOR AND CLAMP DEVICE USING SAME

摘要

A first piston (20) for high load is inserted into a housing (18) so as to be movable vertically, and a second piston (22) for low load is inserted into a cylindrical hole (40) of the first piston (20) so as to be movable vertically. An output portion (22b) projects from the second piston (22) to above the housing (18). A first spring (24) for high load and a second spring (26) for low load are mounted in a spring chamber (44) defined by both pistons (20) and (22). Both springs (24) and (26) are mounted so as to urge the first piston (20) and the second piston (22) upward. A switching mechanism (27) disposed in the pressure fluid chamber (46) at a side opposite to the spring chamber (44), connects the first piston (20) selectively to the housing (18) or the second piston (22).