NO. 6 ET LOCOMOTIVE BRAKE 245 



ordinary passenger service, double-pressure-control service, 

 freight service, or any kind of switching service. It has all 

 the advantages of the older types of brake equipment and 

 many other important advantages found by practical experi- 

 ence to be necessary in modern locomotive brake service. 



The locomotive brakes can be applied with a graduated, 

 a full-service, or an emergency application. They can be 

 applied and released in conjunction with the brakes on the 

 cars or independently of them, and they can be released either 

 wholly or partly at the will of the engineer. Also, it is 

 possible to release the train brakes and hold the locomotive 

 brakes applied full force. When double-heading, the brake on 

 either locomotive can be applied or released by the engineer 

 on that engine without affecting any other brake. This is a 

 valuable feature, because it permits the engine brake to be 

 released in case the drivers slide and applied again as soon 

 as the wheels begin to turn. 



The supply of air for the locomotive brake cylinders is 

 taken direct from the main reservoir, and the distributing 

 valve is designed so as to supply automatically brake-cylinder 

 leakage, from the main reservoir, thus preventing the loco- 

 motive brakes from leaking off as they do when the brake- 

 cylinder supply is taken from the auxiliary reservoir. 



Neither the length of the brake-piston travel nor the brake- 

 cylinder leakage affects the brake-cylinder pressure, and so 

 long as the brake piston does not strike the non-pressure head 

 of the cylinder or the brake rigging does not catch something 

 that will prevent the power exerted on the piston from being 

 transmitted to the brake shoes, the engine and tender brakes 

 will be applied with the same pressure. If the brake is 

 applied with the independent brake valve in order to prevent 

 the engine from moving after being stopped, it will not leak 

 off; and when standing on a down grade the locomotive brake 

 can be applied independently to hold the train while the 

 auxiliaries on the cars are being recharged. 



