COMBINATION SAFETY VALVE Russian patent published in 1994 - IPC

FIELD: hydraulic machines. SUBSTANCE: arranged in housing provided with bypass passages are spring-loaded main piston and safety shut-off member. Piston forms spring and pressure chambers together with housing and is provided with throttle passage which is brought in communication with spring chamber. Bypass passage selector is made in form of piston located on side of pressure chamber for engagement with end of main piston. This piston forms together with housing an additional pressure chamber which is brought in communication with opposite bypass passage. Provided in piston body is axial passage which brings pressure chamber opposite to main piston in communication with throttle passage of main piston when pistons are engageable. Bypass passage is brought in communication which additional pressure chamber when pistons are engageable. EFFECT: enhanced efficiency. 2 dwg