TRIPLE VALVES 209 



LN equipment makes a graduated-release feature possible for 

 the type L triple valve. With type L triples, therefore, the 

 brakes can be graduated either on or off, thus adding much 

 to the flexibility of the brake. This results in reducing shock 

 effects on long, heavy trains, and eliminates the loss of time 

 and the risk incident to two-application stops. Also, graduat- 

 ing the brake off greatly reduces the risk of wheel sliding, and, 

 in connection with the quick-recharge feature, makes it possible 

 for a large number of applications to be made without exhaust- 

 ing the air supply. 



Quick-Recharge Feature. Increased weight of coaches neces- 

 sitated an increase in the size of the brake cylinders used, 

 until on the heavy coaches of today 16-in. and 18-in. cylinders 

 are used instead of 10-in. and 12-in. cylinders. With an 8-in. 

 piston travel, the 18-in. cylinder has a capacity of 2,036 cu. in. 

 against a capacity of 675 cu. in. for the 10-in. cylinder. The 

 18-in. cylinder, therefore, will take three times as much air 

 from its auxiliary at each application as the 10-in. cylinder. 

 In recharging, therefore, the feed-groove of the triple of the 

 18-in. cylinder must be much larger than that of the triple 

 of the 10-in. cylinder, in order to have the two recharge in the 

 same time. Large feed-grooves, however, have a tendency to 

 make a brake sluggish in applying on moderate reductions, 

 on account of the back flow from the auxiliary- reservoir; 

 consequently, they are undesirable. 



The L triple valve uses the regular size of feed-groove; 

 besides, it employs in the slide-valve seat a quick-recharge 

 port that is controlled by the slide valve, the check- valve pre- 

 venting any back flow from the auxiliary reservoir during 

 applications. This results in a rapid recharging of the auxiliary 

 reservoirs, to nearly standard pressure, so that nearly full 

 braking power is obtained immediately after a release has 

 been made; consequently, a number of applications can be 

 made in quick succession without materially reducing the 

 pressure in the brake system. 



Service-Application Safery-Valve Feature. The auxiliary 



reservoir used with the LN equipment is smaller for the same 



size of brake cylinder than the auxiliary reservoir used with 



the other equipments. This limits the brake-cylinder pressure 



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