264 NO. 6 ET LOCOMOTIVE BRAKE 



position much quicker, and port b is opened wider than in ser- 

 vice applications. 



When the pressure in the exhaust-valve chamber becomes 

 equal to that in the application cylinder, the application piston 

 will be moved to automatic emergency lap position. When 

 the pressure chamber is charged to 70 lb., an emergency applica- 

 tion will equalize the pressures in the pressure chamber and the 

 application cylinder at about 65 lb., but when the automatic 

 brake valve is in emergency position, air from the main reservoir 

 will pass through a small port in the rotary valve and a port in 

 its seat, into the application-cylinder pipe, thence to the appli- 

 cation cylinder of the distributing valve, which raises the pres- 

 sure therein above 65 lb. The amount of pressure that will be 

 allowed to accumulate in the application cylinder will be deter- 

 mined by the adjustment of the safety valve, to which it is 

 connected. Main-reservoir air can pass through port n in the 

 rotary valve of the automatic brake valve in about the same 

 volume that it can pass to the safety valve through port x in 

 the equalizing valve, so that a pressure of 68 lb. will be held in 

 the application cylinder, as this is the pressure for which the 

 safety valve is set. As the pressure in the brake cylinders is 

 determined by the pressure in the application cylinder, also, 

 68 lb. will be obtained in them. This high brake-cylinder pres- 

 sure will cause a shorter stop to be made than with a service 

 application. 



In high-speed brake service, the operation of the distributing 

 valve is exactly the same as in ordinary service, but with the 

 high-speed brake service, the brake pipe being charged to a 

 pressure of 110 lb. and the main-reservoir pressure being 

 about 130 lb., an emergency application will raise the pressure 

 in the application cylinder, and consequently in the brake 

 cylinders to about 93 lb. In this case, however, the small 

 port x in the equalizing valve will allow air to pass from the 

 application cylinder to the safety valve a little faster than it 

 can enter the application cylinder through the small port in the 

 automatic brake valve, so that the safety valve will reduce 

 the pressure in the application cylinder from 93 to 75 lb. in 

 about the same time as the high-speed reducing valve will 

 reduce the brake-cylinder pressure to 60 lb. 



