120 ENGINEER'S BRAKE VALVES 



the valve seat, making a large and direct communication 

 between the brake pipe and atmosphere through cavity o 

 in the rotary valve and the exhaust cavity in the valve seat. 

 This direct passage causes a sudden and heavy discharge of 

 brake-pipe pressure, causing the triple valves and distributing 

 valve to go to the emergency position and apply the brake in 

 the shortest possible time. In this position the groove n in 

 the rotary valve connects ports g and I in the valve seat, thereby 

 allowing equalizing reservoir air to flow into the application 

 chamber. 



The oil plug 29 is placed in the top case 4 at a point to 

 fix the level of the oil surrounding the rotary valve. A leather 

 washer 8 prevents air in the rotary -valve chamber from leaking 

 past the rotary-valve key to the atmosphere. A spring 30 

 keeps the rotary- valve key firmly pressed against the washer 8 

 when no main-reservoir pressure is present. The handle 9 

 contains a latch 11 that fits into notches in the top case; 

 these notches are so located as to indicate the different posi- 

 tions of the brake-valve handle. The spring 10 back of the 

 latch forces the latter against the body with sufficient pres- 

 sure to distinctly indicate when the handle arrives at each 

 position. 



To remove the brake valve, take off nuts 27, thus allowing 

 it to come away without disturbing the pipe bracket or breaking 

 any pipe joints. To take the valve proper apart, remove cap- 

 screws 28. 



The brake valve should be located so that the engineer 

 can operate it from his usual position, while looking forwards 

 or backwards out of the side cab window, and in such a manner 

 that the handle will not meet with any obstruction through- 

 out its entire movement. 



H-6 AUTOMATIC BRAKE VALVE 



PIECE AND REFERENCE NUMBERS 



The H-6 automatic brake valve, shown in Fig. 1, is a part 

 of, and is regularly supplied with, the No. 6 ET locomotive 

 brake equipment; its weight is 50 Ib. The piece 'number of 

 H-6 brake valve, with brass handle and pipe bracket, complete, 



