

TRIPLE VALVES 181 



In releasing the brakes, the pressure in the head end of 

 t>he train rises much more rapidly and to a higher pressure 

 than in the rear end. This is due to the head end being nearer 

 the supply of air, to the frictional resistance offered to the 

 flow of the air by the brake pipe, and to the fact that each 

 triple valve starts to recharge its auxiliary the moment it 

 moves to release position. The primary object of the uni- 

 form-recharge feature, therefore, is to increase the rate of 

 rise of brake-pipe pressure toward the rear end, thereby obtain- 

 ing a quicker release and recharge of the rear brakes; this 

 results in shortening the time necessary to release all brakes, 

 in a more uniform release of all brakes, and in a more uniform 

 and quicker recharge of all auxiliaries. 



OPERATION OF TYPE K TRIPLE VALVES 

 Full-Release and Charging Position. When the engineer's 

 brake valve is placed in full-release or running position, the 

 air entering the brake pipe raises the pressure in chamber B 

 above that in the slide-valve chamber C and the auxiliary 

 reservoir, and moves the triple piston, slide valve, and gradu- 

 ating valve to the right. If brake-pipe pressure in chamber B 

 does not exceed the auxiliary -reservoir pressure in chamber C 

 by 3 lb., as is usually the case on all cars back of the thirtieth 

 car of a long train, the retarded -release stem and spring will 

 stop the triple piston and slide valve in full-release position. 

 When in this position, the feed -groove in the triple-piston 

 bushing is uncovered and brake -pipe air passes through it 

 past the triple piston and charges the auxiliary reservoir; also, 

 a port in the slide valve registers with a port in the slide- 

 valve seat and conveys air to the slide-valve chamber and the 

 ^auxiliary, thus assisting in charging the auxiliary reservoir, 

 the check- valve 15 being unseated by brake-pipe pressure 

 while air is passing to the auxiliary reservoir. 



The cavity in the slide valve fully connects the brake cylinder 

 with the exhaust so that brake-cylinder air can escape freely 

 to the atmosphere. 



Air flows from the brake pipe through the feed-groove into 

 the auxiliary until the pressures equalize and the auxiliary 

 reservoir is fully charged. Air flows through the feed-port 



