SUDDEN START PREVENTING UNIT FOR MOVABLE WORKING VEHICLE

摘要

PURPOSE:To have the pressure raised again from near zero point, when the speed is changed by removing the pressure oil in the back chamber of a spring tainer spool and the pressure oil in the back chamber of an accumulator without allowing the oil to pass through a throttle hole when the transmission gear is transferred from any shift position to the neutoal. CONSTITUTION:A sudden start preventing relief valve C, provided between an oil pressure pump for a hydraulic clutch unit and a hydraulic control valve, comprises a relief valve 63, a spring refainer spool 61 which gradually changes a spring pressure of a relief valve 62 through a throttle valve 58a, and an accumulator 59 which is moved back at a speed slightly faster than the spring retainer spool 61 by the pressure oil through the same throttling. A quick return valve 58 is installed so that the pressure oil which pushes the spool 61 and the accumulator 59 may flow into a drain system without passing through the throttle hole 58a through the process of pressure drop.