| 摘要 |
There is an improvement in operational efficiency of an oil pressure cylinder of an oil pressure device having a multi-stage arm. The present invention is characterized by being provided with a multi-stage arm driving mechanism configured to contract the multi-stage arm by extending the oil pressure cylinder and to extend the multi-stage arm by contracting the oil pressure cylinder; an oil pressure circuit configured to extend and contract the oil pressure cylinder; the oil pressure circuit having a control valve to control the flow of pressurized oil into the oil pressure cylinder; a counterbalance valve provided in a first flow path between a bottom side fluid chamber of the oil pressure cylinder and the control valve; a relief valve wherein a first side is connected to a flow path between the bottom side fluid chamber and the counterbalance valve, among the first flow path, and a second side connected to a second flow path; and a conversion valve configured to flow pressurized oil in the second flow path to a low pressure side when the oil pressure cylinder is extended. |
