HYDRAULIC CLOSED CIRCUIT SYSTEM

摘要

A hydraulic closed circuit system (100) capable of driving a hydraulic cylinder (3) is provided with the following: a hydraulic pump (1); an electric motor (2) for controlling the rotation of the hydraulic pump (1); a shuttle valve (7) in which a secondary side port (7b) communicates with a first conduit (C1) and a secondary side port (7c) communicates with a second conduit (C2); a charge pump (5) in which an ejection port communicates with a primary side port (7a) of the shuttle valve (7); and a relief valve (8) which makes the charge pressure of the charge pump (5) a set pressure. The charge pump (5) maintains the first conduit (C1) and the second conduit (C2) at a charge pressure through the shuttle valve (7). The relief valve (8) can change the set pressure.