GB612763A - Hydro-pneumatic lifting jack - Google Patents

Abstract

612,763. Lifting-jacks. BROOKE, H. L. June 1, 1946, No. 16709. [Class 78 (iii)] In fluid-pressure actuated jacks of the kind in which the ram is raised by liquid forced into the cylinder from a reservoir surrounding it by pressure fluid supplied from an external source, the reservoir is of low height, holds all the liquid required for lifting purposes and communicates with the cylinder only through a single valve chamber containing a spring-pressed ball valve which can be unseated by mechanical means to permit lowering. The reservoir 19, Fig. 1, comrnunicates with the cylinder 13 through ports 46 which open into a valve chamber 45 containing a spring- pressed ball valve 47, Fig. 4. This valve can be unseated by the head 50 of a pull-push control 49 which is mounted on the hollow handle 23 of the jack. In the position shown, the head restricts the flow of liquid from the reservoir to the cylinder. The pushpull device has means for locking it in either of two positions comprising a projection on the cable and two recesses in the sheath. The handle is connected to the supply of pressure fluid by quick release means 27 and contains a triggeroperated valve 28, Fig. 3, which in the position shown connects the port 36 of the handle leading to the jack to exhaust through the port 35 but when raised connects the part 36 to the supply of pressure fluid through the passage 39. In a modification, the head 50, Fig. 6, is moved by partial rotation of a rod 59 which is slidably mounted in a bracket 60 on the handle to which is secured a pin having a sharp edge 70, forced by the spring 72 into engagement with an axially-extending cam 66 secured to the rod 59. Rotation of the rod 59, limited between fixed stops by the cam 66, forces the axially-extending surface of said cam to react against the edge 70, thus sliding the rod 59 through the bracket 60 and actuating the ball valve by means of the movement imparted to the rod 64 through a bracket 63. Specification 346,684 is referred to.