| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an automatic booster automatically continuing the reciprocating operation by operating a fluid pressure by providing a booster cylinder and an automatic changeover valve which changeovers the moving direction of a piston by the pressure generated by the movement of the piston. SOLUTION: When a changeover valve 6 is changed over to an operating position A and a spool 5 of an automatic changeover valve 8 is held in an extension position, pressure governing ports 33, 34 are communicated with a tank port 31 and a pump port 30 respectively and the piston 4 in a booster cylinder 10 starts to move in the extension direction. When the pressure of a spool drive pressure chamber 13 increases along with it to be at a prescribed pressure or more, the spool 5 moves in the right direction, the pressure governing ports 33, 34 are communicated with the pump port 30 and a tank port 32 respectively, and the piston 4 starts to move in the contraction direction. Along with it, the pressure in the spool drive chamber 23 increases to be a prescribed pressure or more, the spool 5 is extended to be changed over to the extension position and the changeover piston 4 starts to move in the extension direction.</p> |
