| 摘要 |
PURPOSE:To prevent excessive acceleration when the cylinder expands or contracts by providing a check valve, a balance piston and a changeover value. CONSTITUTION:At the time when a hydraulic cylinder 2 expands, a changeover valve 19 is in the left direction, and pressurized oil of a pump 4 enters in the cylinder 2 from an inlet port 5 through a check valve 10. At the time of contracting of the cylinder 2, the valve 19 is in the right direction, and pressurized oil of the pump 4 is circulated to a tank 6. On the other hand, discharged oil of the cylinder 2 flows to the tank 6 through an outlet port 3, a stationary orifice 15, a vacant chamber 14, a variable orifice 17, passages 12 and 19 and a discharge port 8. Upon this occasion, a pressure difference is caused in the outlet port 3 and the chamber 14 by an orifice 15, and the oil pressure of the outlet port 3 presses a balance piston 13 in the right-hand direction. The oil pressure within the chamber 14, in cooperation with a spring 18, presses the piston 13 to the left hand, and while balancing the pressing forces in the left and right hands of the piston 13, the orifice 17 formed by a cutout port 16 and the passage 12 is adjusted. Thus, even when an excessive load is applied to the cylinder 2, and the oil pressure at the outlet port 3 is increased, the orifice 17 is adjusted by the movement of the piston 13, and the cylinder 2 moves at a predetermined speed. |
