Fluid pressure regulating valve

摘要

975,588. Valves; clutch control. CLARK EQUIPMENT CO. Aug. 21, 1963 [Nov. 7,1962], No. 33053/63. Headings F2L and F2V. In a fluid pressure regulating valve for automatically reducing the pressure of fluid supplied to forward and reverse transmission clutches, to permit " inching" in a fork lift truck as the brakes are applied, fluid from an engine driven pump 14 is normally supplied from an inlet port 62, via an annular groove 86 in a spool member 44, to an outlet 68 leading to either clutch 20 or 22, as selected by a manuallyoperated spool selector valve 18. In the normal position (Fig. 3, not shown), the spool 44 abuts a stop member 74 upon the spindle 98 of an inner spool member 36 under the force of fluid pressure from outlet 68 acting, via a connecting passage 92, within a recess 94 against a regulating spring 40. When the brakes are fully applied fluid from the brake master cylinder acts upon piston 24, connected to rod 34, to displace the inner spool member 36 until, upon abutment of inner spool flange 96 with outer spool member 44 and the displacement thereof, the outlet 68 to the clutches is connected to exhaust port 70. Upon partial application, Fig. 2, of the brakes with the piston 24 in an intermediate position the pressure in the outlet 68 is determined by balance of the spool 44 between the tension in the spring 40 and fluid pressure in recess 94. As the brakes are applied, the spring 40 is extended and the tension thereof reduced, when the pressure in the outlet 68 is accordingly reduced. Specification 881,509 is referred to.