GB348578A - Improvements relating to braking apparatus for railway and other vehicles - Google Patents

Abstract

348,578. Fluid-pressure and electric brakes. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO.. Ltd., 82, York Road, King's Cross, London.-(Assignees of Thomas, T. H.; 219, Lincoln Avenue, Edgewood, Pennsylvania, U.S.A.) Feb. 13, 1930, No. 4875. Convention date, Feb. 14, 1929. [Class 103 (i).] The fluid-pressure and electro-dynamic brakes of a vehicle are inter-connected by means of a valve controlled by the electric braking current whereby as this current falls off in consequence of slowing down of the vehicle, fluid pressure is established in the brake cylinder inversely proportional to the strength of the current. The valve device comprises a winding 6 surrounding a polepiece 7, and an armature 8, which with a diaphragm 10 attached to the casing and to a part 9 of the armature forms a chamber 11 open at 12 to the atmosphere. A pair of connected valves 17, 21 control respectively communication of a chamber 13 connected with the brake cylinder 15, to the chamber 11 and to a chamber 26 connected to the drivers valve 28 of the fluid-pressure brake. A spring 30 acting through a rod 29 on the armature 8 tends to close and open respectively the valves 17, 21 so that when the winding is deenergized the driver may by the valve 28 supply and exhaust the brake cylinder 15 by way of the valve 21. For electrodynamic braking the motor 1 runs as a generator and the switch 4 then connects the valve winding 6 in the circuit and the drivers valve 28 is put into application position. The regenerative current is at first generally sufficient to hold the armature raised against the action of the spring 30 so that the valves 17, 21 are respectively open and closed and the brake cylinder is thus connected to the exhaust port 12. As the current falls with the slowing of the vehicle, the armature moves downwards to close the valve 17 and open the valve 21 to supply the brake cylinder until the pressure therein acting on the diaphragm 10 lifts the armature sufficiently to re-close the valve 21. The pressure established in the cylinder is thus inversely proportional to and compensates for the falling off of the electrodynamic braking effect.