NO. 6 E T LOCOMOTIVE BRAKE 271 



When a heavy and sudden brake-pipe reduction is made, 

 piston 26 moves out quickly the full length of its cylinder. . The 

 knob on the piston strikes the valve stem 50 and moves it over 

 against the tension of the spring 55. As the emergency valve 

 48 fits snugly between the shoulders on the valve stem 50, it 

 also moves to the right and uncovers port j in the valve seat. 

 This allows brake-pipe air from chamber P to pass through 

 port j to chamber X, which forces the check-valve 53 down 

 against the resistance of spring 54- This allows brake-pipe air 

 to flow to passage m in a large volume; it then passes through 

 passage M to the chamber back of the application piston 10, 

 and through port c into the brake cylinders. This makes a 

 local reduction in brake-pipe pressure, which insures that the 

 next distributing valve, or quick-action triple valve, will go into 

 quick action. 



When the brake-cylinder and brake-pipe pressures have 

 nearly equalized, spring 54 forces valve 53 back to its seat, so 

 that no air can pass from the locomotive-brake cylinders into 

 the brake pipe. When the brake-pipe pressure is increased 

 sufficiently to force piston 26 back to release position, the grad- 

 uating spring 55 forces the stem 50 and emergency valve 48 

 back to their normal positions. During this movement, valve 

 48 closes port j. 



CARE OF DISTRIBUTING VALVE 



In order that the distributing valve may work properly, the 

 valves and pistons must be kept well lubricated and free 

 from dirt. The distributing valve and its reservoir should 

 be regularly drained and the pipe connections should be kept 

 tight. If the distributing valve is to be repaired or cleaned and 

 tested, it should be removed from the double-chamber reservoir; 

 this is done by removing the nuts from the reservoir studs. 

 As all the pipe connections are made to the double-chamber 

 reservoir, removing the valve in this manner will not interfere 

 with the pipe joints. If the gasket between the distributing 

 valve and the reservoir becomes torn or injured while removing 

 the valve, a new one must be supplied, as a very slight leak 

 across this gasket, from one port to another, will interfere 

 seriously with the operation of the valve. When the pipes are 



