| 摘要 |
PURPOSE:To limit a piston pressure without any pressure reducing valve by dividing an oil pressure chamber into two portions and providing a changeover valve, which feeds oil pressure into both chambers when the oil pressure is below the predetermined level and into one chamber when the oil pressure is above the predetermined level. CONSTITUTION:Two oil pressure chambers, 9, 12 separated liquidtight by O-ring 17 mounted on the outer circumference of a piston 7, are provided between the outer wall surface of the piston 7 and the wall surface of the chamber of a motor casing 1, and oil conduits 6, 16 are respectively connected to oil chambers 9, 12. A changeover valve 13 is disposed in way of the oil conduit 16, so as to communicate the oil chamber 12 to the oil conduit 6 or oil tank, and the pilot oil conduit 15 of the changeover valve 13 is connected to the oil conduit 6. |
