GB1271078A - Brake control apparatus - Google Patents

Abstract

1,271,078. Brake control apparatus. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. 4 July, 1969 [10 July, 1968], No. 32815/68. Heading F2F. Brake control apparatus for a rail vehicle includes means responsive to an output fluid pressure of a fluid pressure control means, itself responsive to a variable fluid pressure input representing a desired brake application to produce said output pressure in accordance with said desired application, to exert a first force in dependence upon said desired application, means responsive to the first force and to a second, electrically exerted, force proportional to an operating/braking parameter of the rail vehicle to be braked to combine the said forces, and means responsive to the combined force to control the fluid pressure in a brake apparatus to produce that brake application represented by the combined force. As shown, a brake pipe 1, in which the air pressure is controlled from a driver's cab, is connected to a distributer 2 on each vehicle to be braked and which responds to variations in pressure in the pipe 1, the output of the distributer being connected to brake apparatus via a lock-out valve 4, and to a pressure-to-electric transducer 10 from which an electric current is passed to a coil 11 of an electro-pneumatic converter 8, the latter being connected also to an auxiliary reservoir 6. Electric currents representing speed and/or load on a vehicle are fed to coils 12, 13 of the converter and these are combined with the current from the transducer; the converter has an air inlet 26 from which pressure air passes through a pressure limiting valve 28 comprising a ball valve 29 on a stem 30 connected to a diaphragm 31, the valve being held in open position by a spring 32 but being closed when pressure on the diaphragm reaches a predetermined value when air passes through an orifice 33 to a passage 34 and an outlet 27, a valve 36 controlling a discharge port 35 being operated on by a spring 38 connected via a cup member 37. to an armature 40 carrying a moving coil 41; air pressure at the output 27 is controlled by electrical signals fed to the coil and so as to control leakage through the port 35. Air pressure can be fed directly from the distributer to the brake cylinders via the valve 4. In modifications (a) the vehicle load controls a valve in the distributer output; (b) the electrical control signals are combined in a magnetic amplifier, the transducer, if D.C. supply only is available, being supplied through an inverter, and the output of the amplifier being rectified by a rectifier bridge; (c) the output of the converter is fed to a relay valve, the output of which controls the brake cylinders; and (d) the speed signal is applied as an electrical signal to a moving coil of the converter and the load modifies the output pressure of the distributer 2 in a load modifier device.