| 摘要 |
PURPOSE:To simplify a steering control system for front and rear wheels by detecting the variation of the discharge quantity of a pump for rear wheels by an orifice and switching a direction selector valve in accordance with the above-described variation. CONSTITUTION:A direction selector valve Vd is equipped with pilot chambers 25 and 26 on the both sides, and the pilot chamber 25 communicates to a feeding passage 18 on the downstream side of an orifice 20, and the pilot chamber 26 communicates to a feeding passage 18 on the upstream side of the orifice 20. The direction selector valve Vd has a spool 28 in slidable ways in the body 27, and a spring is installed in the pilot chamber 25 and urged so that the spool 28 maintains the reverse phase position. When the discharge quantity of a pump P2 increases, also the differential pressure before and behind the orifice 20 increases, and also the pressure difference between the pilot chambers 25 and 26 increases, and the spool 28 shifts against the spring, and an upstream side port 23 is allowed to communicate to a downstream side port 31, and an upstream side port 24 is allowed to communicate to a downstream side port 30. |
