TRIPLE VALVES 



191 



brake had set nearly in full. With the K triple valves, when 

 the brake-pipe pressure at the first car had fallen to 55 lb., 

 the reduction at the last car was 62 lb. so the rear brakes 

 were applied with a good effective deduction. It required the 

 same interval, 25 sec., with both types of triples to reduce 

 the pressure at the first car to 55 lb.; consequently, the curves 

 show clearly that the quick-service feature of the K triple 

 valves causes a more uniform reduction throughout the train. 

 The fourth test was a comparison of rate of propagation of 

 brake-pipe reduction throughout a train of one hundred cars, 

 4,000 ft. long, equipped with types H and K triple valves, when 



w 



3^5'' 





40 so fo so 00 yo /0' 

 FIG. 4 



a 17-lb. service reduction was made. The results of the test 

 are shown in Fig. 4. These curves contrast the rates at which 

 the two types of triple valves cause a reduction to travel back 

 through the brake pipe. The time is from the movement of 

 the brake-valve handle to the beginning of the fall in brake- 

 pipe pressures. 



In Fig. 5 are given brake-cylinder cards showing the appli- 

 cation curves of H and K triple valves on a train of one hundred 

 cars, when a 15-lb. brake-pipe reduction was made from a 70-lb. 

 brake-pipe pressure. These curves show the effect of the dif- 

 ferent rates of reduction on the application of the brakes for 

 the two types of triple valves. The H triples required 15 sec. 



