| 摘要 |
A hydraulic system of an industrial vehicle is provided to reduce pressure loss and temperature rise of the hydraulic oil, thereby lengthening the service life. A hydraulic system of an industrial vehicle, which supplies the hydraulic oil discharged from a pump(10) to a main control valve(20), a brake master-cylinder(30) and a steering unit(40) connected to a working machine, includes a direction control valve(50) and a pressure compensation flow control valve(60). The inlet port of the direction control valve is connected to the pump and one of the inlet and outlet ports is connected to the main control valve. The inlet port of the pressure compensation flow control valve is connected to the other of the inlet and outlet ports of the direction control valve, while the outlet port is connected to the brake master-cylinder through a brake supply line(62). The pressure compensation flow control valve supplies hydraulic oil passing through the direction control valve to the brake master-cylinder at the set flow rate. The drain port of the pressure compensation flow control valve is connected to the steering unit through a steering supply line(63), in order to supply the residual hydraulic oil, not supplied to the brake master-cylinder, to the steering unit. The direction control valve is witched to supply the hydraulic oil to the pressure compensation flow control valve when the differential pressure between the pressure of the hydraulic oil supplied to the brake master-cylinder and the load sensing pressure of the steering unit from the direction control valve is smaller than the reference differential pressure, and to supply the hydraulic oil to the main control valve when the differential pressure is greater than the reference differential pressure. |
