ENGINEER'S BRAKE VALVES 103 



ENGINEER'S BRAKE VALVES 



HISTORY OF VALVE 



The engineer's brake valve is that part of the air-brake 

 equipment by means of which the engineer can control the 

 action of the brakes. It is located in the cab of the engine 

 in a position convenient to the engineer. Its function is to 

 regulate the flow of air from the main reservoir to the brake 

 pipe, and through the chamber in the brake valve to the small 

 equalizing reservoir under the right running board; from the 

 brake pipe through the engineer's valve to the atmosphere; 

 and from the chamber, the equalizing reservoir, and brake pipe 

 to the atmosphere; also, if desired, it prevents any flow, of 

 air whatsoever. The equalizing reservoir is connected to the 

 chamber of the brake valve, with the object of increasing the 

 volume of that chamber. Air passes through the chamber 

 when going either into or out of the brake-valve reservoir. 



Three- Way Cock. The first style of valve (used with the 

 non-automatic or straight-air brake as early as 1868) con- 

 trolled the passage of the air from the main reservoir to the train 

 pipe and brake cylinders to 

 apply the brake, and held the 

 air in the brake cylinders and 

 train pipe to keep the brake 

 applied; also, it allowed the air 

 to pass out to the atmosphere 

 to release the brake. It was a 

 three-way cock, as shown in 

 Fig. 1, having three ports in the 

 plug that could connect with p IG 



the passages in the body of the 

 cock and control the passage of the air. The pipe on the right 

 was connected to the main reservoir, that on the left to the train 

 pipe, while the middle one was the exhaust, leading to the 

 atmosphere. Some three-way cocks are still in service, but 



