| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic system for realizing miniaturization, light weight, and simplification, and having energy saving and proper performance speed changing functions, a and a hydraulic cylinder used to the system. SOLUTION: A hydraulic cylinder consists of the combinations of double and single acting cylinders 1 and 2. The sum of the pressure receiving surfaces A and B of the cylinders 2 and 1 respectively is equalized to the other side pressure receiving surface C of the cylinder 1. At the time of high-speed fast- feeding action, the suction and exhaust ports 16 and 17 of a bidirectional discharge type pump 21 are communicated to the oil entrance 3 of the cylinder 2 and the cylinder chamber 26 on the surface C side of the cylinder 1 respectively, to directly communicate between the oil entrances 11 and 12 of the chamber 26 and a cylinder chamber 27 via an opening/closing valve 19. At the time of low-speed large-load action, the port 16 of the pump 21 is communicated to the entrances 3 and 11 of the cylinders 2 and 1 respectively, to communicate the port 17 to the port 12 of the chamber 27.
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