258 A 7 0. 6 E T LOCOMOTIVE BRAKE 



from the reducing-valve pipe direct into the application cylinder 

 or to discharge air from the application cylinder to the atmos- 

 phere. This operates the application piston independently of 

 the variation in brake-pipe pressure and applies or releases 

 the locomotive brakes. Inasmuch as the supply of air for the 

 brake cylinders is taken from the main reservoir direct and the 

 operation of the application piston depends on the pressure 

 in the application cylinder, as long as the pressure in the appli- 

 cation cylinder is maintained, the same pressure will be main- 

 tained in the brake cylinders, regardless of brake-cylinder 

 leakage or variations in brake-piston travel. 



AUTOMATIC OPERATION OF DISTRIBUTING 

 VALVE 



A conventional view of the distributing valve and its double- 

 chamber reservoir is shown in the accompanying illustration. 

 As the parts, ports, and cavities in the distributing valve are 

 located so that they cannot be shown in a true sectional view, 

 this conventional view has been prepared to help in the study 

 of the operation of the valve. It shows the pressure and 

 application chambers of the double-chamber reservoir as a 

 part of the distributing valve and of a different shape from the 

 original, being smaller in proportion to the size of the valve, 

 but with the same relative proportion to each other. However, 

 it must be borne in mind that conventional views are given 

 in order to simplify the tracing of the air through the various 

 ports, as well as to help explain the operation of the valve, 

 rather than to show its actual construction and the proper 

 location of the various ports. 



Automatic Charging Position. When the distributing valve 

 is charging, air from the main reservoir enters at MR, and passes 

 into the application-valve chamber a. This supply of main- 

 reservoir air is always present around the application valve 5, 

 unless the main-reservoir cut-out cock or the distributing- 

 valve cut-out cock is closed. 



When air is first admitted to the brake pipe, it enters the 

 distributing valve at the brake-pipe connection and passes into 

 chamber p. If the equalizing piston is not already in release 

 position, the air entering chamber p will force it to release 



