Patent GB-919345-A (GB)
Title: Improvements relating to railway vehicle fluid pressure operated braking apparatus
Inventor: KERSHAW JOHN WILLIAM GREENWOOD
IPC: B60T13/68
Filed: 1958-07-28
Abstract: 919,345. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. July 28, 1959 [July 28, 1958], No. 24236/58. Class 103 (1). [Also in Group XXIX] A railway vehicle pressure-fluidoperated braking apparatus of the kind in which the magnitude of the pressure in a brake cylinder 11 is governed by the position of a valveadjusting member 27 comprises a brake pipe 12 which is adapted to be maintained charged with pressure fluid and from which the pressure fluid for operating the brake cylinder is derived, a plurality of members such as the pistons P1, P2 and P3 being displaceable individually by pressure fluid also derived from the brake pipe 12, electrically-operated means such as the solenoid-operated valves V1, V2 and V3 being operable to supply pressure fluid to the displaceable members P1, P2 and P3 either singly or in selected combinations under the control of the electrically-operated means, and brake controlling means by whioh the valve adjusting member is set to different positions corresponding respectively to the single and combinational displacements of the displaceable members. By means of the brake-controlling means on the locomotive (not shown), all the train wires TW1, TW2, TW3 are de-energized, to correspond witn the released condition of the brakes in the train. With all those of the valves V1, V2 end V3 consequently de-energized, compressed air is supplied to all the pressure chambers C1, C2 and C3 in the control valve 14 and all the pistons assume their displaced positions, as shown in Fig. 2, to hold the valve-adjusting member 27 in the extreme right-hand position. The exhaust valve stem 33 is therefore disengaged from the valve member so that the brake cylinder is open to atmosphere. The brake controlling means has, besides the release position, seven other positions in an electropneumatic braking range of its movement, and movement from the released position through these other positions produces a sequence of changes in the energization of the train wires. On moving the brake-controlling means through the braking range the valve adjusting member 27 is progressively moved in steps towards the left ; the position reached by each step corresponding to a single or combinational displacement of the pistons. The step taken in reaching position number one suffices for the valve closure member 31 to be engaged with the exhaust valve stem 33 and for this member to be lifted from its seat by snch engagement to produce a light braking action so that the brake cylinder pressure is limited in a well-known manner by the selflapping valve in accordance with the position of the valve adjusting member, and for the succeeding positions the degree of brake application is progressively intensified up to the maximum which is obtained in position number seven. Should the brake pipe pressure fall below a predetermined value, an emergency valve device 17 operates and to bring about the maximum degree of brake application. Auxiliary reservoir pressure in chamber 13 is supplied at all times to the end chamber 24 of the control valve member 14. A further embodiment is disclosed in the Specification in which a vacuum-operated electropneumatic braking system is disclosed and a suitably-modified control valve member is provided with a diaphragm in place of the piston 34. Specification 919,344 is referred to.