190 



TRIPLE VALVES 



reduction at each triple valve, due to the quick-service feature 

 of the triple valve, gives the necessary rate of reduction toward 

 the rear of the train. For example, after 25 sec. the pressure 

 on the first car had fallen 15 lb.; on the fifteenth car, 12 lb.; 

 on the thirtieth, 10 lb.; the fiftieth and seventy-fifth, 8 lb.; 

 and on the one-hundredth, 7 lb. This shows only 8 lb. dif- 

 ference between the first and last cars. 



The third test was a comparison of fall in brake -pipe pressure 

 throughout a one-hundred-car train, 4,000 ft. long, equipped 



FIG. 3 



with types K and H triple valves, when service reduction 

 was made. The results of this test are shown in Fig. 3. 

 These curves show how the brake-pipe pressure throughout the 

 train actually falls during a continuous full-service reduction 

 of the brakes. It will be noted with the H triple valves that 

 25 sec. elapsed before sufficient brake-pipe reduction had 

 taken place at the last car to cause any movement of the 

 triple valve; the head end had reduced to 55 lb. so the first 



