NO. 6 E T LOCOMOTIVE BRAKE 243 



NO. 6 ET LOCOMOTIVE BRAKE 



DEVELOPMENT OF ET BRAKE 



When the straight-air brake was first put into service, 

 the locomotive was not fitted with brakes lest the drivers 

 might slide and flatten. However, the desire for maximum 

 braking power for the train soon led to the use of a tender 

 brake and, later, to a brake on the drivers. After the auto- 

 matic brake superseded the straight-air brake, a truck brake 

 was added, thus completing the locomotive equipment. The 

 next step was to equip the locomotive with a straight-air brake 

 in combination with the regular automatic air brake, thus pro- 

 viding the engineer with independent control of the locomotive 

 brake, which greatly increased the flexibility and efficiency of 

 the brake system as a whole. 



Although the combined straight-air and automatic brake 

 greatly increased the flexibility of control of the engine brake, 

 especially in switching and in handling slack in freight service, 

 it increased considerably the number of pieces that went to 

 make up a complete locomotive brake equipment. Then the 

 duplex main-reservoir regulation, the double-pressure control, 

 and the high-speed brake equipment added more apparatus 

 to the equipment, making it still more cumbersome. In fact, 

 from the very adoption of the automatic brake, all improve- 

 ments were made by adding apparatus to the equipment 

 existing at the time; consequently, as the improvements pro- 

 gressed, the equipment became more and more complicated. 



With the increase in speed and weight of trains, the con- 

 ditions of train service necessitated still further improve- 

 ments in the brake system. It was apparent that to meet 

 the requirements by the addition of the necessary apparatus 

 to the brake system then in general use would make the 

 system too cumbersome. This naturally led to the design 

 of a locomotive brake equipment that would include in one 

 apparatus all the desirable features of the existing brake 

 system and eliminate many of the undesirable features, 



