188 



TRIPLE VALVES 



FREIGHT-BRAKE TESTS 



Rack Tests. In the first test, it was desired to find the fall 

 in brake-pipe pressure of a one-hundred-car train 4,000 ft. 

 long. Indicators were, therefore, placed on the first, fifteenth, 

 thirtieth, fiftieth, seventy-fifth, and one-hundredth cars. ~ To 

 test the brake pipe alone, the triple valves were cut out and 

 the brake-valve handle placed in emergency position. The 

 results of this test are shown in Fig. 1. The curves show the 



/O /f 20 



Tlme/aJeconcto from 



PIG. 1 



characteristics in the fall of brake-pipe pressure in various parts 

 of the train and the relative pressures on the different cars 

 indicated at any time during the reduction. For instance, 

 at 25 sec. the pressure on the first car had fallen 48 lb.; on the 

 fifteenth car, 26 lb.; on the thirtieth car, 15 lb.; on the fiftieth 

 car, 7 lb.; on the seventy-fifth car, 6 lb.; on the one-hundredth 

 car, 5 lb. This shows a difference of 43 lb. in the brake-pipe 



