GB680575A - Improvements in groundlocks for fluid pressure operated jacks provided with internal locks - Google Patents

Abstract

680,575. Hydraulic machines. ELECTROHYDRAULICS, Ltd. May 3, 1951 [March 27, 1950], No. 7659/50. Class 69 (ii). In a fluid pressure operated jack provided with internal locking means and comprising a part 6 moving within the jack cylinder 1, a latch member 9 or 10, a co-operating abutment 13 or 14 beyond which the latch member is able to pass and with which it can effect latching engagement at the end of the travel of the moving part, and a movable locking member 15 or 16 which lies in the path of the latch member so as to be pushed away by the latch member (against the pressure of a spring 17 or 18) as the latch member approaches the abutment but to return (under the action of the spring) as it drops into the latching or locking position and then to hold it firmly in engagement with the abutment, one or more groundlocks 21 are provided for preventing the movement of either the locking member (15, 16) or the latch member (9, 10) of the locking means when fluid pressure is admitted to the jack, which pressure is capable of, and intended for the purpose of, breaking the lock. In order to break the internal lock, the lock bolts 15 have to be pushed back by fluid pressure to allow the latch members 9 to slide past the abutments 13. If the movement of the lock bolts 15 is arrested by the spring-loaded groundlock bolts 21 the jack lock cannot be broken, in spite of admission of fluid pressure into the jack.