212 TRIPLE VALVES 



release, to nearly standard pressure. The supplementary 

 reservoir is charged through the triple valve from the brake 

 pipe at the same time and to the same pressure as the aux- 

 iliary reservoir. It is connected to the triple valve by means 

 of a pipe leading from the reservoir to the supplementary- 

 reservoir connection on the brake-cylinder head. There is 

 no direct connection between the auxiliary and the supple- 

 mentary reservoir. The triple slide yalve controls the flow of 

 air from the auxiliary reservoir to the supplementary reservoir 

 and from the supplementary reservoir to the auxiliary reservoir. 

 The cut-out cock in the supplementary-reservoir pipe is for 

 the purpose of cutting out the reservoir when desired, as in the 

 case of the car being in a train in which most of the cars are 

 equipped with the type PM brake. At such times, the cut-out 

 cock between the triple valve and supplementary reservoir 

 should be closed in order to have the L triple valve work in 

 harmony with the older forms of triple valves. Closing this 

 cut-out cock renders the graduated-release and the high emer- 

 gency-pressure features inoperative. 



In trains of mixed LN and PM equipments, the LN equip- 

 ment may be left cut in if desired and the brakes operated 

 accordingly, provided that more than half the cars have the 

 LN equipment. However, it must be remembered that, in 

 using the graduated-release feature, the PM equipments will 

 release entirely at the first graduated release. The cars 

 having the LN equipment, therefore, will have to do the 

 braking for the entire train during the remainder of the stop, 

 and there will be danger of wheel sliding on those cars. To 

 avoid wheel sliding, the brake-cylinder pressure should be 

 graduated down to a safe pressure before the speed is low. 



DIAGRAMMATIC VIEWS OF TRIPLE 



Fig. 2 gives a diagrammatic view of a type L triple valve with 

 the check-valve case 13, and the cylinder cap 18 removed. 

 The triple valve is represented as having the auxiliary-reser- 

 voir end, the cylinder-cap end, the check-valve-case end, the 

 slide-valve seat, and the by -pass mechanism in the same plane 

 so as to show more readily the relations of the ports to each 

 other. 



