138 



ENGINEER'S BRAKE VALVES 



To make a partial application of the brake, the handle 4 

 is moved to application position until the desired brake- 

 cylinder pressure is obtained, when it is moved to lap. To 

 increase the application, move 'the handle to application posi- 

 tion for the proper increase, and then back to lap. 



In lap position, both valves are closed, so no air can pass into 

 the brake cylinder, or from the brake cylinder to the atmos- 



FIG. 2 



phere. Valve 12 is held up against its seat by the combined 

 efforts of spring 15 and the pressure beneath the valve; the 

 other valve is held up against its seat by spring 27 and the 

 pressure beneath it. 



To release the brake, move the handle to release position. 

 This allows valve 12 to close and cut off the supply of air to 



