| 摘要 |
PURPOSE:To prevent increase of pressure loss by providing a back pressure control valve in a return path interconnecting a control section and hydraulic pump to raise the back pressure only when steering force is strengthened to raise oil pressure and restrain the rise of the back pressure in high speed travelling. CONSTITUTION:A back pressure control valve 6 is interposed in an oil return path 4 placing a hydraulic pump 2 in ommunication with a control section 1. This valve 6 incorporates a spool valve 9 movable axially in a valve hole 8 formed in a housing 7 in the left and right directions. As oil pressure from the pump 2 is increased, this spool valve 9 is moved left through a plunger portion 11 to thereby close ports 14, 19 and return the return oil to a port 22 through paths 24, 26, 27. Thus, as the oil pressure rises in steering, back pressure in an inlet port 21 is raised. |
