| 摘要 |
<p>A three-position actuator having a moving member consisting of a piston capable of sliding and reciprocating within a predetermined distance inside a casing in an axial direction and a piston rod moving integrally with this piston and having part thereof projecting outside the casing, said moving member moving to one of the sides when a fluid flows into a first fluid chamber through a first port formed in the casing, and to the other end when the fluid flows into a second fluid chamber through a second port formed in the casing; characterized in that a pair of stoppers are fixed inside the casing with a predetermined gap between them in the axial direction, a pair of spring receptacles and a spring positioned between these spring receptacles, pressing one of the spring receptacles to one of the stoppers and pushing the other of the spring receptacles to the other of the stoppers are disposed between the pair of stoppers, a pair of engagement portions are formed projectingly on the moving member with a predetermined gap between them in the axial direction so that one of the engagement portions engages with one of the spring receptacles from the opposite side of the spring while one of the spring receptacles is in contact with one of the stoppers and the other of the engagement portions engages with the other of the spring receptacles from the opposite side of the spring while the other of the spring receptacles is in contact with the other of the spring receptacles.</p> |
