| 摘要 |
PURPOSE:To prevent a pressure oil leakage from the cylinder chamber by a method wherein the pressure in an annnular groove at the inner circumferential surface of the cylinder and in the cylinder chamber are made to be equal and a pressure oil is applied to the outer circumferential surface of the cylinder so as to prevent an expansion of the cylinder. CONSTITUTION:In an auxiliary pipe 17 are installed a pressure regulator valve 22 and a pressure relief valve 40. The pressure regulator valve 22 may provide a linear movement proportional to a volume of oil to be fed to a flow rate adjusting valve 13 to a ram 4 due to no passage of the pressure oil between the cylinder chamber 8 and the annular groove 20 under a movement of the spool rod 31 so as not to generate a differential pressure between the inner pressure P1 and P2 in the cylinder chamber 8 and the annular groove 20. The pressure relief valve generates a pressure Pa having a specified ratio in respect to a pressure P in the annular groove 20 of the cylinder 2 i.e. a cylinder chamber 8 in the annular groove 44 of the outer cylinder 42, thereby an expansion of the cylinder 2 may be prevented. |
