298 P C PASSENGER-BRAKE EQUIPMENT 



Emergency Portion. The emergency portion of the control 

 valve is shown in section in Fig. 14. The emergency slide valve 

 and seat are shown in Fig. 15, in which view (a) shows the valve 

 seat and (b) the slide valve. In view (a), port n leads to the 

 service brake cylinder; port en, to chamber M, back of the 

 application piston; port o', to the emergency-cylinder exhaust; 

 and port o, to the emergency cylinder. In view (6), port n 

 passes through the valve. Both em and o are cavities in the 

 face of the valve. 



Quick-Action Portion. The quick-action portion is shown 

 in section in Fig. 16. 



OPERATION OF CONTROL VALVE 



Diagrammatic View. The control valve contains so many 

 parts, ports, and passages that it would be impossible to describe 

 its operation clearly without the use of a diagrammatic view, 

 which is here given. 



It will be noted that port a leads from the brake-pipe con- 

 nection to chamber Y, below the quick-action valve 133; also, 

 that it leads into chamber B, ahead of the release piston 3, 

 and into chamber A, ahead of the equalizing piston 20. Port 

 b leads from chamber B, through the equalizing check- valve 

 16, to port b in the equalizing slide-valve seat. Port c leads 

 from the face of the equalizing slide-valve seat to the top side 

 of the emergency check- valve 16a; continuing, it divides and 

 one branch leads to port c in the release slide-valve seat, and the 

 other branch leads to chamber R, between the two emergency 

 pistons and to the emergency reservoir. Port c' leads from 

 port c' in the equalizing slide-valve seat to the under side of the 

 emergency check-valve 16a. Port e leads from the equalizing 

 slide-valve seat to the direct and graduated release cap 18, 

 thence to port e in the release slide-valve seat. Port / leads 

 from the port / in the equalizing slide-valve seat to pressure 

 chamber Z; it also leads to the under side of the pressure- 

 chamber check- valve 16b. Port g leads from the service reser- 

 voir into the application chamber N; also, a branch leads to 

 chamber H between the two pistons of the service-reservoir 

 charging valve. Port h leads from chamber E, surrounding 



