| 摘要 |
PURPOSE:To eliminate the necessity for increasing the diameter of a cylinder and reduce its weight, by isolating the cylinder of a steel post constructed in a tunnel into two chambers, flowing pressurized oil to be supplied to and discharged from each cylinder and allowing a constructional load to be supported with a pressure chamber having a larger receiving area of pressure. CONSTITUTION:A hydraulic pressure source 33 is connected to a pump while another pressure source 31 is connected to a tank, and if high pressurized oil is supplied to a circuit 32, the oil is guided to a pressure chamber D, and an upper staged cylinder 26 is extended to discharge working fluid in a pressure chamber C to the pressure source 31 through a circuit 30. When the upper staged cylinder 26 reaches its maximum extension, a reverse flow of oil in the pressure chamber D is blocked by a check valve 36, and the oil in said chamber D is enclosed till its pressure reaches the preset level of a relief valve 37. While after extension of the cylinder 26, a check valve 38 is opened, and the high pressurized oil of the power source 33 is guided to a pressure chamber B through a circuit 35, then an intermediate cylinder 24 is extended by the pressure acting on a pressure receiving area D4, thus a constructional load is supported by the pressure chamber B. The high pressure of oil is introduced from the pressure source 31 while the other pressure source 33 is connected to the tank side at compressive operation. |
