Patent GB-523516-A (GB)
Title: Improvements relating to electro-pneumatic braking apparatus
IPC: B60T13/68
Filed: 1939-01-10
Abstract: 523,516. Fluid-pressure brakes. WESTING- HOUSE BRAKE & SIGNAL CO., Ltd., KERSHAW, A. G.. and SIMMONS, A. W. Jan. 10. 1939, No. 848. [Class 103 (i)] Relates to fluid-pressure brake systems comprising the usual auxiliary reservoir and triple valve for effecting application and release of the brakes by variation of brake pipe pressure and also an electric application valve for effecting an application by supply from the main reservoir or other independent source and an electric holding valve for controlling release through the exhaust port of the triple valve. To ensure that the triple valve is in its release position to enable electric release of the brake to be effected by the holding valve a valve is provided adapted automatically to reduce the auxiliary reservoir pressure slightly by venting it to a chamber subsequent to an electric application or prior to an electric release being effected. In the system shown, the electric application valve 6 is connected to the main reservoir and brake cylinder by pipes 7 and 16. The additional valve 11 is connected to the valve 6, the auxiliary reservoir and to the pipe connecting the electric holding valve to the triple valve exhaust port by pipes 14, 12 and 13 respectively. The valve 11 comprises a slide valve 19 operated by pistons 21, 29, the rod 30 of piston 29 being freely slidable in piston 21. Normally, the electric valves being de-energized Chambers 31, 32 are open to atmosphere through pipes 13, 14, the holding valve and a valve 34 of the valve 6. The slide valve 19 is thus held in the position shown by a spring 20 to connect a bulb 24 to the auxiliary reservoir through port 23. When the electric valves are energized to apply the brakes the brake cylinder is supplied through pipes 7, 16 and valve 36. Valve 35 being also raised and the pipe 13 being connected to the brake cylinder through the triple valve exhaust port, both chambers 31, 32 are at brake cylinder pressure an the slide valve 19 is moved to vent the bulb 24 to atmosphere through the valve cavity 25. When the desired cylinder pressure has been established the valve 6 is deenergized closing the valves 36, 35 and opening valve 34. Chamber 32 is thus vented to atmosphere but if the triple valve is in release position the slide valve remains in its operated position due to the pressure in chamber 31, If, however, the triple valve should be in lap position when the valve 6 is energized, cylinder pressure will not have been established in chamber 31 and / upon de-energizing the valve 6 the slide valve will move back to connect the bulb 24 to the auxiliary reservoir thus reducing the pressure in that reservoir. A similar action will occur if the triple valve becomes displaced to its lap position during an electric application since when the holding valve is de-energized to effect release the chamber 31 will be vented and the slide valve will be returned to vent the auxiliary reservoir. In a modification the valve 11 has a single piston the pressure in the piston chamber being controlled by an electrically operated double - beat valve which is energized and deenergized simultaneously with the application valve so that the bulb is connected to the auxiliary reservoir when these valves are deenergized and is connected to atmosphere when the valves are energized.