ES357517A1 - A control system for hydraulic apparatus - Google Patents

Abstract

The actuating lever handles 11, 13, 15 of valves, particularly for controlling the advancing and setting of hydraulic mine roof supports, are interlocked for the programming of the operation by an apertured key-plate 16. As shown, each pair of handles a, b, c is located in a distinctive pair of slots as shown, and each handle has three positions, 1 where the associated prop is braced, 2 a neutral position, and 3 where the prop is retracted. The plate is movable in guides 17 by a lever 18 into three positions in one of which, as shown, the pair of props a are locked in the braced condition, props b can only be retracted, and props c are normally retracted but can be braced if desired. In a mid position of the plate the roles of the top and bottom pair are reversed whilst the middle pair can move between positions 1 and 3, whilst in another extreme position the top and middle pairs are locked. To avoid moving the plate quickly before the props have been fully extended and set, a spring-loaded pressurerelief valve, Fig. 4 (not shown), is located in series with at least some of the valves. The relief valve member (31) is spring-loaded through a surrounding sleeve (33) having a pressure balancing extension stem (34). The fluid has access to the sleeve interior through openings (40, 401).