GB424952A - Self regulating apparatus for the operating pressure of a pneumatic fluid as a function of the position given to the manual controlling member with reaction of this pressure upon the said member - Google Patents

Abstract

424,952. Fluid - actuated valves. SERVO-FREIN DEWANDRE SOC. ANON., 68, Quai de Rome, Liege, Belgium. May 30, 1933, No. 15577. Void [Abridged as open to inspection under Sect. 91 of the Acts, Dec. 4, 1933]. [Class 135] [See also Group XXXIV] A pneumatic control device, more especially for air brakes comprises a distributer actuated by a manual control member 5 means of a floating lever 11 pivoted at 18 to a second lever 19 acted on by a spring 21, the floating lever 11 being acted on by the pressure of the controlled fluid applied to a piston 14. The pull applied by hand in stretching the spring is thus proportional to the fluid pressure. As shown, the supply of compressed air from the pipe 34 to the pipe 35 leading to the brake-cylinder is controlled by a valve 32 which, through its stem 31 and stop 31<a>, is actuated by clockwise movement of a bell-crank 28. Anticlockwise movement of the bell-crank allows the valve 32 to close and opens a relief valve 42 allowing air to exhaust to atmosphere from the passage 35 through passages 36-39. The bell-crank 28 is controlled by a rod 25 pivoted on a sleeve formed at the lower end of the floating lever 11, which has play at 16 with respect to the shaft 17 of the lever 19. If the fluid pressure rises too high while the hand-lever 5 is maintained in any fixed position, the pressure, acting on the piston 14, rocks the lever 11 about the point 10 and, owing to the play at 16, operates the rod 25, thus closing the valve 32 and opening the relief valve 42. If the pressure falls too low, the lever 11 is rotated in the opposite direction under the action of the spring 21 so as to open the valve 32 more widely.