GB935847A - Locks for fluid operated jacks - Google Patents

Abstract

935,847. Fluid pressure jacks. ELECTRO-HYDRAULICS Ltd. Sept. 11, 1961 [Sept. 20, 1960], No. 32354/60. Class 78 (3). A lock for an hydraulic jack comprises circumferentially spaced locking segments arranged to move into or out of engagement with a member associated with the jack cylinder and a second member associated with the jack piston assembly. In Fig. 1 a jack is shown locked in the closed position by locking segments 8, loosely mounted on flexible rods 11, engaging a member 6 of a cylinder 1 and a member 7 of a piston assembly 3, 4. In order to extend the jack fluid pressure applied at a connection 22 moves a locking bolt 10 to the left against a spring 16. This movement carries a sleeve 9 to the left leaving an annular space and freeing segments 8 for radial movement. The fluid pressure now forces the piston assembly 3, 4 to the right, a ramp 26 on the member 7 forcing the segments 8 outwards. A sleeve 13 is then moved to the right under a spring 19 and holds the segments 8 out of engagement with the member 7, the piston assembly 3, 4 thus being freed for extension. The jack may be closed and locked by releasing the fluid pressure at the connection 23 and introducing fluid pressure at a connection 22 to act on the piston 3. Member 7 is forced to abut the sleeve 13 and to move it to the left, compressing the spring 19 and releasing segments 8. The spring 16 then acts on the locking bolt 10 to move it to the right, the sleeve 9 forces segments 8 radially inwards and slides over them to hold them in the locked position between members 5, 7. The closure of the locking bolt 10 may be assisted by pistons operated by fluid pressure (Figs. 3, 4, not shown). The Provisional Specification described an embodiment in which the locking segments 8 slide on radial pins, the flexible rods 11 being omitted and states that the lock may be fitted so as to lock a jack against closure.