PC PASSENGER-BRAKE EQUIPMENT 311 



graduate the release. If the rise in brake-pipe pressure is not 

 slow enough to produce this action, the movement of piston 3 

 toward graduated-release lap position will be sufficient to restrict 

 the flow of air from the emergency reservoir into chamber E to an 

 extent sufficient to adjust the rate of rise of pressure in chamber 

 E equal to the rate of rise of brake-pipe pressure in chamber B. 

 In this case, the release of air from the application chamber and 

 chamber C will be correspondingly prolonged. 



Whether the brake will be released completely or be gradu- 

 ated off depends on whether chamber-C pressure is exhausted 

 completely at one time or is exhausted by degrees, the pressure 

 being partly exhausted and then held stationary for a time, 

 this operation being repeated several times. The pressure in 

 the reduction-limiting chamber and in chamber 5 below the 

 emergency slide valve is completely exhausted when a release is 

 made, regardless of whether the release is graduated or direct. 

 Chamber E (and the pressure chamber) is connected to cham- 

 ber K through the port y, ports y and x of slide valve 22, and 

 port * in the valve seat, and emergency-reservoir air can pass 

 to chamber G through port c, ports c and v of slide valve &&, 

 and port v when slide valve 22 is moved to release position. 

 Whether the service-reservoir charging valve will be operated 

 and thus permit the service reservoir to be recharged will 

 depend on the relative pressures in chambers G and K and 

 the service reservoir. With the ordinary manipulation of the 

 brake, the service-reservoir charging valve will not be operated, 

 so that no air will pass from the emergency reservoir into the 

 service reservoir; the pressure chamber, however, will be 

 recharged with emergency-reservoir air to within 5 Ib. of the 

 pressure in the emergency reservoir. The service-reservoir 

 charging valve then opens and forms connection between the 

 emergency reservoir and the service reservoir through chamber 

 H, and the service and emergency reservoirs and the pressure 

 chamber Z are all recharged to normal pressure by air from the 

 brake pipe. 



In other words, in recharging the brake, first, the pressure 

 chamber alone is recharged to within 5 Ib. of emergency-res- 

 ervoir pressure by air from the emergency reservoir, during 

 which time the brake pipe alone is being recharged from the 



