| 摘要 |
1,025,753. Fluid pressure apparatus. PLESSEY CO. Ltd. Jan. 25, 1963 [Feb. 2, 1962], No. 4089/62. Heading FIP. An hydraulic or pneumatic actuator system comprises a subsidiary ram 10 connected to operate via a crank member 8 a plunger 7 for locking a main ram 2 in its extended position when pressure fluid controlled by a first valve 34, 35, 36 opened by the main ram 2 on attaining its extended position is supplied through a conduit 38 to the subsidising ram. In the unlocked position a selector valve 12 is in its left position whereby pressure fluid supplied through a conduit 19 to the valve 12 passes to the subsidiary ram cylinder 11 through a conduit 22 to maintain the subsidiary ram therein extended. In addition the pressure fluid passes through a conduit 24 and a valve 25, 26, 27 to the main ram cylinder 3 to maintain the main ram 2 retracted. The non-pressurized side of the cylinder 3 is vented to atmosphere through a conduit 31 and a port 33. To extend the main ram 2 the selector valve 12 is moved to the right whereby the subsidiary ram cylinder 11 is vented to atmosphere through the conduit 22 and an exhaust duct 29 in the valve 12 and simultaneously the main ram cylinder 3 is also vented through a port 28A leading to the duct 29. The main ram 2 therefore moves to its extended position under the action of pressure fluid supplied through the conduit 19 to the conduit 31, and on attaining its fully extended position pressure fluid is allowed to pass from a branch conduit 37 and the valve 34, 35, 36 to the cylinder 11 to thereby move the plunger 7 to its locking position. A vent 40 in the rod 9 of the subsidiary ram is arranged to maintain the main ram cylinder 3 connected to atmosphere through the port 28A when the subsidiary ram is retracted. When it is required to return the main ram to its retracted position the selector valve 12 is moved so that pressure fluid is re-supplied to the conduit 22 whereby the subsidiary ram moves to the extended position, retracting the plunger 7 and opening the valve 25, 26, 27 to supply fluid to the main cylinder through the port 28A. The cylinders and the valve 12 may be formed as a single body provided with ducts corresponding to the conduits described. A conduit B as shown in broken lines may replace the branch conduit 37. |
