ENGINEER'S BRAKE VALVES 131 



distributing valve and causes it to admit air to the locomotive 

 brake cylinders and exhaust air from them. Also, the inde- 

 pendent brake valve controls the passage of air from the 

 exhaust port of the distributing valve through the release 

 pipe. 



Release Position. The release position is to be used to 

 release the locomotive brakes without regard to the position 

 of the automatic brake valve and equalizing valve in the dis- 

 tributing valve; also, to release the locomotive brakes while 

 the train brakes are being held on by the automatic brake 

 valve, as well as to release the brakes, when desired, on the 

 following engine of a double-header. When the valve is held 

 in this position, air from the application cylinder of the 

 distributing valve passes through the application-cylinder 

 pipe, a port in the rotary-valve seat, a groove in the rotary 

 valve, and the exhaust port in the rotary-valve seat to the 

 atmosphere and releases the locomotive brakes. Also, in 

 release position, a port in the rotary valve, which acts as a 

 warning port to the engineer, registers with a port in the 

 rotary-valve seat and allows air to pass out to the atmosphere 

 through the warning port. The handle of the independent 

 brake valve must be held in release position against the ten- 

 sion of the return spring 6; otherwise, the spring will automat- 

 ically return the handle to running position. 



Running Position. The independent brake valve should 

 be carried at all times in running position except when it 

 is being used to operate the distributing valve to apply or 

 release the locomotive brakes or to keep the locomotive brakes 

 applied. If it is carried in any other than running position, 

 it will be impossible to control the release of the locomotive 

 brakes by the use 'of the automatic brake valve. In this 

 position, a groove in the face of the rotary valve is moved 

 away from a port in the rotary- valve seat, so that air from 

 the application cylinder of the distributing valve cannot exhaust 

 to the atmosphere. The port leading to the distributing-valve 

 release pipe is connected by means of a groove in the rotary 

 valve with a port in the valve seat, which leads to the release 

 pipe and to the automatic brake valve; consequently, the air 

 in the application cylinder and the chamber of the distributing 



