GB575647A - Improvements in or relating to liquid pressure apparatus - Google Patents

Abstract

575,647. Hydraulic motors. AUTOMOTIVE PRODUCTS CO., Ltd., and SADLER, F.A.D. March 3,1944, No. 4037. [Class 69 (ii)] [Also in Group XXVI] A motor piston 13 is reciprocated by pressure fluid admitted alternately to working spaces 27 by a pilot valve 15, which is reversed by pressure fluid admitted to pilot working spaces 35 at the ends of the strokes ; the pilot valve is allowed to complete its reversing movement by use of a byepass 37 opened during the initial movement and closed towards the end of the stroke, remaining open after the closure of the reversing valve device constituted by the outer end of the oblique passage 36a and an exhaust port 24. The piston may be formed with rack teeth on its lower side meshing with a pinion on a spindle, which is thus oscillated. The space around this spindle constitutes the exhaust port 24, with which a port 30 in the piston communicates permanently, while inlet ports 20, 20a communicate permanently with grooves 34, 34a in the piston. The piston has' been moved to the left-hand position shown by fluid entering by port 20a and passing through groove 34a, valve groove 32a, port 28a, and groove 26a, to the end space 27a, fluid in the other working space discharging through ports 29, 30 and piston groove 31 ; a pin 17 guides the piston; in reaching this position it has first put working space 35 in communication with inlet port 20 through passage 36 and then put corresponding passage 36a in communication with exhaust port 24. The valve now starts to reverse, and with it the piston, and when the piston movement has closed passage 36a to exhaust port 24, byepass 37a has been connected by the valve motion through groove 32a with space 35a, and connects this space with discharge space 24 till later in the piston stroke. Fig. 6 shows a motor pump unit in which the pilot valve 15 moves in coaxial bores 68, and controls fluid supply to and discharge from the cylinder of a main motor piston 56 working in spaces 59, 59a and an auxiliary piston, both of which serve as pump plungers. Fluid is supplied through passages 52, 53 and 53a and discharged from spaces 51, 51a. The pistons are hollow, and slide on fixed grooved pistons 65, 65a, fluid being supplied to and discharged from spaces 27. The valve is moved by fluid supplied through passages 76, and main discharge passages 74a and byepasses 75a, 76a are provided. The fluid supply to the auxiliary motor is controlled by the main motor so that the two move oppositely.