| 摘要 |
PURPOSE:To simplify the construction and decrease the troubles by connecting a pilot operating change-over valve to pilot oil passages of a change-over valve for driving a cylinder and connecting pilot check valves to pilot oil passages of the pilot operating change-over valve. CONSTITUTION:A pilot operating change-over valve 12 is connected to pilot oil passages 17 and 18 of a change-over valve 11 for driving a cylinder and on the way of pilot oil passages 19 and 20 of the pilot operating change-over valve 12, there are installed pilot check valves 21 and 22 which provide communication between high pressure oil passages 15 and 16 and the pilot oil passages 19 and 20, when pilot ports 25 and 26 are held in communication with each other by means of a piston 5 through a cylinder 1 at a termination of the piston movement in one direction. Accordingly, since any limit switch or electric circuit is not required at all, the whole constrution can be simplified and decreased in size and troubles can be almost avoided.
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