NO. 6 ET LOCOMOTIVE BRAKE 263 



To graduate the release of the locomotive brakes, through 

 the automatic brake valve, the handle should be left in running 

 position just long enough to reduce the application-cylinder 

 pressure the desired amount, after which it should be moved to 

 lap, holding, or release position. As the pressure in the applica- 

 tion cylinder g reduces, the greater pressure in the exhaust- 

 valve chamber will move piston 10 and valves 5 and 16 to the 

 left and the exhaust valve 16 will allow brake-cylinder air to 

 escape through ports d and e until the pressure in the exhaust- 

 valve chamber is slightly less than that remaining in the appli- 

 cation cylinder, when the greater pressure in the application 

 cylinder will move piston 10 and valve 16 to the right and stop 

 the flow of brake-cylinder air to the atmosphere. The equal- 

 izing valve being in release position, the application chamber 

 and the application cylinder are connected to the safety valve 

 through ports h, s, and I. 



Automatic Emergency Position. When a sudden and heavy 

 reduction in brake-pipe pressure is made, it causes the distrib- 

 uting valve to operate quick-action, and the movable parts 

 will assume automatic emergency position. The pressure in 

 chamber p of the distributing valve being suddenly reduced, 

 the greater pressure in the equalizing- valve chamber quickly 

 moves the equalizing piston 26 to the right with sufficient force 

 to compress the graduating spring 46, thus allowing the equal- 

 izing piston 26 to move its full stroke an d rest against the gasket 

 25. This movement carries the equalizing valve 31 with it 

 to emergency position, port h in the equalizing-valve seat is 

 uncovered, and air from the equalizing valve chamber passes 

 through port h to passage h and the application cylinder. 

 Cavity in the equalizing valve is also moved away from port 

 h, thus closing communication between the application cylin- 

 der and the application chamber. Under these conditions, the 

 pressure chamber has only the small volume of the application 

 cylinder to fill, consequently the pressure chamber and the 

 application cylinder will equalize quicker and at a much higher 

 pressure than during a service application. The operation of 

 the application piston 10, the application valve 5, and the 

 exhaust valve 16 in emergency applications is the same as in 

 service applications, except that they are moved to application 



