GB928078A - Hydraulic reversing control - Google Patents

Abstract

928,078. Liquid-pressure engines. T. H. PARIS Inc. Nov. 21, 1960 [Nov. 23, 1959], No. 39894/60. Class 69 (2). A distributing valve for an hydraulic engine comprises a pilot spool 10 which, in the position shown, directs liquid 45 through a port 47, an annulus 21 and passages 49, 50 to the end face 32 of a movable piston 30, located between plungers 33, 34, such that when the plunger 33 enters a cavity 36 it generates a higher pressure than the primary pressure on the spool 10 and, through passages 38, 53 and pilot end chamber 39, causes the spool 10 to move to the right-hand position, so that the primary pressure is applied through passages 54, 55, 59, 58 to the opposite face 31 of the piston, and also through open check valve 64 and passage 53 to maintain the spool in the right-hand position. Initially, primary pressure is also exerted against the right end of the spool 10 by liquid which flows past a check valve 51 and through passage 52, and against the left end of a main spool 22 by the liquid in passages 54, 55, 56 and end chamber 57 so that the spool 22 is urged to the right. As the pilot spool 10 is moved to the right, annuli 21 and 20 are interconnected, and primary pressure is applied through passage 65 to the right-hand end of the main spool 22 urging it to the left. Plungers 70, 71 are manually operated to assist in purging air from the system by reciprocating the spool 10 during the initial start-up. In a modification, a plug 74 is removed, the passage 54 is blocked, and a different volume rate of liquid pressure is applied at a port 75 than is applied at the port 47, to operate the piston 30 at different speeds in opposite directions, or at the same speed when the piston loads in opposite directions are different.