Pump system, charge relief mechanism and oil pressure control mechanism

摘要

A charge relief mechanism for setting an oil pressure of a charge line which replenishes operating oil to a pair of operating oil lines fluidly connecting a hydraulic pump body and a hydraulic actuator, includes: an oil pressure setting line; and a charge relief valve inserted in the oil pressure setting line. The charge relief valve includes a relief valve body provided with a large diameter hole, a small diameter hole, and a check valve seat formed between the large diameter hole and the small diameter hole. The large diameter hole is provided with a check valve body which is seatable on the check valve seat and is movable in the axis line direction, and a slip-out prevention member for preventing the check valve body from being separated from the large diameter hole while allowing the check valve body to selectively communicate or block between the large diameter hole and the small diameter hole.