GB619130A - Improvements in or relating to power operated hydraulic means and control therefor - Google Patents

Abstract

619,130. Fluid-pressure servomotor-control systems. GROVES, M. V. May 29, 1945, No. 13453. Convention date, March 10, 1944. [Class 135] [Also in Group XXXIV] The casing 16 of the control valve of a fluid-pressure brake system is secured at 12 to a stationary member, the rod 20 being actuated, e.g. by a pedal, to move the piston towards a larger piston 46, the exhaust valve 53 being thereby seated to shut off the passage 60, connected to the reservoir, from the hydraulic pressure spaces. The piston 43, at the same time, slides over a pin 40 against the action of a spring 42, to shut a valve 38 which controls the exhausting of the space 36, and to open a valve 35 to admit pressure-fluid from the pump connection 21 to the space 36. The main valve 27 is thus forced to the right, against the spring 28 thereby opening direct communication between the pump and the port 34. A hose 62 transmits the pressure-fluid to a perforated check-valve 66 which is forced against the spring 68 to open the port 65 leading to the brake cylinders and to isolate this port from the port 56 connected to the pressure reaction pipe connected to the brake cylinders. The true brake cylinder pressure is thus admitted to a space 52 between the pistons 43, 46, the pressure on the piston 43 giving " feel " to the operator, and the pressure on the piston 46 moving it against the spring 59 to produce a lapped condition of the valves. When the operator releases the rod 20, the piston 43 is returned by the pressure in the chamber 52 and by the spring 59 which returns the piston 46, the valve 53 remaining seated until the piston 43 moves away from the piston 46, allowing the exhaust valve 38 to open and the power valve 27 to close. The fluid is then returned from the brake cylinders through the passage 49, 50 to the reservoir R.