NO. 6 E T LOCOMOTIVE BRAKE 257 



The function of the application- valve pin 18 is to move 

 the application valve 5 when piston 10 moves. The pin fits 

 snugly in the stem of piston 10 and in valve 5; thus, piston 10 

 cannot move without moving valve 5. Whenever it becomes 

 necessary to remove piston 10 from its cylinder, the applica- 

 tion valve 5 and pin 18 must first be taken out. 



The upper, or application, piston of the distributing valve 

 controls the movement of the supply and exhaust valves that 

 control the brake-cylinder air supply during an application 

 of the locomotive brakes and exhaust brake-cylinder air to 

 the atmosphere during a release of the brakes. The lower, or 

 equalizing, piston controls the movement of the equalizing and 

 graduating valves. The equalizing piston, equalizing valve, 

 and graduating valve operate the same as the triple piston, 

 slide valve, and graduating valve of a triple valve. They con- 

 trol the flow of air from the pressure chamber into the applica- 

 tion cylinder and the application chamber during an automatic 

 application of the brakes, and from the application cylinder 

 and the application chamber to the distributing-valve exhaust 

 when the brake is to be released by the automatic brake 

 valve. The equalizing piston is operated by variations in 

 brake-pipe pressure, and the application piston is operated 

 by changes of pressure in the application cylinder or in the 

 exhaust-valve chamber. With the ordinary automatic brake, 

 the pressure in the brake cylinder depends on the amount of 

 air the triple valve passes from the auxiliary reservoir into the 

 brake cylinder; but with the ET equipment, the supply of air 

 for the locomotive brake cylinders comes from the main reser- 

 voir, and the pressure in the brake cylinders is determined 

 by the pressure in the application cylinder of the distributing 

 valve. With an automatic application, the pressure in the 

 application cylinder depends on how much air the equalizing 

 piston and its slide valves pass from the pressure chamber 

 into the application cylinder. 



In another method of varying the pressure in the appli- 

 cation cylinder to apply and release the locomotive brakes, 

 no movement of the equalizing piston and its valves is required. 

 This operation is performed by means of the independent 

 brake valve. This brake valve can be operated to pass air 

 18 -*- 



