216 TRIPLE VALVES 



valves are moved with the main piston to release position. 

 The pressure in passage c raises the check- valve 15 and as 

 port y in the slide-valve seat and port j in the slide valve 

 register, brake-pipe air can also pass through port y into 

 chamber R and the auxiliary reservoir. Port k in the slide 

 valve registers with port x in the slide-valve seat, so that air 

 can pass to the supplementary reservoir, which is charged at 

 the same time and to the same pressure as the auxiliary reser- 

 voir. In this position of the slide valve, port c in the seat is 

 not covered; hence, the chamber back of the by-pass piston 

 into which port c opens, is charged to auxiliary -reservoir pres- 

 sure. The chamber in front of the by -pass piston into which 

 port h opens, is at all times connected to chamber R and the 

 auxiliary reservoir through the ports g and h; thus, the pres- 

 sures on both sides of the by-pass piston 25 are always equal 

 except during emergency applications, when port c is connected 

 to the brake cylinder through ports d , n, and r, and the by -pass- 

 valve spring holds the by -pass valve 27 to its seat. Also, port / 

 leads from port g to the chamber in front of the by-pass valve 27, 

 and this chamber is likewise charged to auxiliary-reservoir 

 pressure. In the charging position, port n in the slide-valve 

 registers with port r in the seat, cavity w in the graduating 

 valve connects the upper ends of the ports with another port 

 in the slide-valve face that registers with the exhaust port p, 

 so that any air in the brake cylinder can pass to the atmosphere 

 through this passage. 



Release and Recharge. When releasing the brakes, the 

 brake-pipe pressure and the pressure in chamber H is increased 

 above the auxiliary-reservoir pressure. This causes the main 

 piston 4, with the slide valve and the graduating valve, to be 

 moved to full-release and charging position. Port n registers 

 with port r, port m registers with port p, and cavity w in the 

 graduating valve connects ports m and n on the back of the 

 slide valve, thus allowing brake-cylinder air to escape to the 

 atmosphere. The main piston 4 uncovers the feed-groove t, 

 which allows brake-pipe air to pass to the auxiliary reservoir. 

 Port j registers with port y, which also allows brake-pipe air 

 from chamber F to pass to chamber R and the auxiliary 

 reservoir; also, port x registers with port k and, as standard 



