Automatic air-escape valve for railway-brakes.



Patented Apr. 27, 1915. S. CHENEY. AUTOMATIC AIR ESCAPE VALVE FOR RAILWAY BRAKES. APPLICATION FILED NOV-23, I9I4. W gwam "THE NORRIS PETERS c0. PHTJTDZLITHOHVWASHINGIOVN. n. c. SAMUEL CHENEY, 0F VIICKEPIN, VJ ESTEB-N AUSTRALIA, AUSTRALIA. AUTOMATIC AIR-ESCAPE VALVE FOR BAILXVAY-BEAKES. Specification of Letters Patent. "Patented Apr. 237, 11.915. Application filed November 23, 1914. Serial No. 873,576. To all whom it may concern: Be it known that I, SAMUEL CHENEY, a subject of the King of Great Britain, and residing at Wickepin, Western Australia, Commonwealth of Australia, have invented certain new and useful Improvements in Automatic Air-Escape Valves IEOI' Railway- Brakes, of which the following is a specification. The present invention relates to railway air brakes and particularly to those of the type which are applied by the reduction of air pressure on one side of the brake piston, 1 and it provides simple and improved means for effecting a rapid discharge and consequent reduction of such air for emergency application of the brakes. In order that my invention may be clearly understood the same will be explained with the aid of the attached drawing wherein the figure represents the device in sectional elevation. In said drawing a is the tubular piston rod having formed therein the small bore b. On each end of this rod a is carried the large and small piston respectively as c and d of difierent diameters and working in their own cylinders as e and f. The small piston acts as the valve controlling the air exit ports. These pistons are provided with approved packing rings as g and j. The larger cylinder 0 is adapted to interscrew with the small cylinder 7 as shown and cylinder 6 at its end 70 is screw threaded so as to suitably connect with the train pipe by usual union or joint while the cylinder f by its end m is likewise screw threaded so as to connect with the brake cylinder in suitable manner. The small cylinder f is formed with the radial air exit ports n whereby air from the brake cylinder is exhausted when the small piston (Z as shown in broken lines moves sufliciently to uncover said air exit ports. The object of the larger piston 0 is to control the small piston d while the train pipe is charged with air for releasing brakes or while the train pipe is in running condition, thus holding the small piston d in non-application position, that is, to keep the discharge ports 12, closed. The pistons and their rods are tubular in order to pass air therethrough to normally keep a uniform pressure per square inch on both pistons c and cl and also to feed the brake cylinders with air. ' ered and allow a total discharge of air same rod work in two cylinders as c and The bore Z) of the piston rod is sufficiently small to permit air to feed slowly therethrough. Then the pressure in the train pipe is reduced for the usual service application of the brakes, the small piston 03 will be subject to a greater pressure than the opposing pressure acting on the larger piston c, the pistons c and d being shifted owing to this lack of balance to bring the piston d into a position to uncover more or less the air exit ports a, thus permitting the air at one side of the brake piston to escape to the atmosphere and thus cause movement of the brake piston to apply the brakes. Should the train pipe pressure be completely reduced, as in emergency application of the brakes, these ports n are completely uncovfrom the brake cylinder, bringing the full braking force into action; but should, on the other hand, said train pipe pressure be only partially reduced momentarily, then the air after actuating the smaller piston d discharges through the ports a until the opposing pressures acting on both pistons are equalized, the pressure acting on the larger piston c then operating to return the small piston d to a position where it will cover and close the air escape ports a, and further reduction in the pressure of air in the brake cylinder is thereby prevented. In order to release the brakes more air is charged into the train pipe, such air being fed through the tubular piston rod into the brake cylinder, and any desired reduction of brake power can be made by suitable variation of the air pressure charged into train pipe. The respective pistons although on ftl'll difierent diameters and are connected up in tandem manner as shown. It may also be stated that the device forms or acts as a governor and is interposed in the branch pipe between the brake cylinder and train pipe. What I claim as my invention and desire to secure by Letters Patent is- In an air brake apparatus, a brake controlling air escape valve comprising a casing having cylinders of larger and smaller diameters adapted to be connected respectively to the train pipe and the brake cylinder, the cylinder of smaller diameter having a plurality of circumferentially spaced air escape ports in the lateral wall thereof, and pistons, the larger. piston having its active 7 face subject to the pressure of air'in the train pipe and the smaller piston operating 7 to simultaneously open or close all of said air escape ports in its movements and being I forming a conduit for V feeding air between opposite endsof the" subject to the pressure of air in the, brake 1o cylinder. s o 7 In testimony whereof I have hereunto set my hand inpresen'ceof two subscribing Witnesses. 7 V SAMUEL CHENEY. Witnesses: V, RICHARD SPARROW, SAMUEL RINTELL Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, ' r Washington,D.C. r



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