354 PRESSURE-RETAINING VALVES 



PC. No. Ref. No. Name of Part 



30,093 23 Cylinder, bushed. 



30,092 24 Valve cap. 



2,421 25 Vent valve, complete. 



2.424 26 Spring. 



2.425 27 Handle. 

 2,423 28 Rubber seat. 



Operation of Release Valve. The release valve is located 

 on the auxiliary reservoir, and is used to reduce auxiliary- 

 reservoir pressure in the event of a brake sticking, due to the 

 triple valve not moving to release position. Also, the valve 

 is used to relieve the auxiliary reservoir of pressure when a 

 brake is cut out. In using the release valve to release a brake, 

 the valve must be quickly opened its full amount and then 

 closed the instant a blow is heard at the triple-valve exhaust 

 port. 



PRESSURE-RETAINING VALVES 



PURPOSE OF RETAINING VALVES 



The pressure-retaining valve is included in all freight-brake 

 equipments, whether specified or not. It is furnished with 

 passenger equipments, without extra charge, if specified on 

 the order; it is not a part of the regular passenger schedule, 

 however, and must be specified if desired. Care should be 

 exercised to indicate the proper type of valve, depending on 

 whether or not the car is of the vestibule type. It is located 

 at the end of the car, within easy reach of the trainmen 

 when the train is in motion, and is connected by a pipe 

 with the exhaust port of the triple valve. Its purpose 

 is to retard the discharge of air from, and retain a pres- 

 sure of 15 Ib. in, the brake cylinder while the triple 

 valve is in release position and the engineer is recharging 

 the auxiliaries after a release on a grade, to be ready for 

 another application of the brakes. 



