Pressure control valve for vehicle hydrostatic drive - has three=way valve governed by pressure difference in main hydraulic lines

摘要

The hydrostatic vehicle drive unit includes a pump and a hydraulic motor, which are connected by a closed hydraulic circuit. The pressure difference that occurs between the two hydraulic lines controls a three position 3 way valve. Two pressure relief valves for the two hydraulic lines between pump and motor are connected to the three position valve. Thus with unequal pressure in the lines, one pressure relief valve is always connected to the hydraulic oil reservoir. With equal line pressure, the control valve is held closed.