| 摘要 |
A reciprocating actuator comprising a body (1) having a piston hole (2), a valve hole (3) and a rod insertion hole (4) formed therein concentrically continuously, a main pump port (9) open to the piston hole, a sub pump port (10) and a tank port (11) both open to the valve hole, an auxiliary port (23) open to the rod insertion port, a piston (5) slidably inserted into the piston hole and defining at ends thereof a piston contracting chamber (8) having a small pressure receiving area and a piston expanding chamber (7) having a large pressure receiving area, respectively, the both chambers communicating with the main pump port, a rod connected to the piston and inserted into the rod insertion hole, a first valve disc (15) inserted into the valve hole in such a manner as to be brought into abutment with the piston at one end thereof, defining the piston expanding chamber at the end where the piston is brought into abutment therewith and a spring chamber (25) at the other end, respectively, and set in a first position where the piston expanding chamber is caused to communicate only with the tank port and a second position where the piston expanding chamber is caused to communicate only with the sub pump port, a first spring (19) for biassing the first valve disc to the first position, an oil path (24) for connecting the auxiliary port to the spring chamber, and a switching means for causing the piston contracting chamber to communicate with the auxiliary port when the piston is in an expanded stroke end position, wherein the main pump port and the sub pump port are connected to a discharge path (13) of a fluid pressure pump (12).
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