262 NO. 6 ET LOCOMOTIVE BRAKE 



Automatic Release Position. To release the locomotive 

 brakes through the automatic brake valve, both the H-6 and 

 S-6 brake valves must be in running position. When the auto- 

 matic brake valve is placed in release position, air from the 

 main reservoir passing into the brake pipe increases the brake- 

 pipe pressure, which causes the triple valves on the cars to 

 move to release position and release the train brakes. At the 

 same time, the increase of brake-pipe pressure also increases the 

 pressure in chamber p of the distributing valve above that 

 in the equalizing- valve chamber, which forces the equalizing 

 piston 26 to the left, carrying with it to release position the 

 equalizing valve 31 and the graduating valve 28. When in 

 this position, the equalizing piston 26 opens the feed-groove v, 

 which allows air from chamber p to flow past piston 26 to the 

 equalizing- valve chamber, and out through port and passage 

 o into the pressure chamber, until the pressure equalizes on both 

 sides of the equalizing piston 26. The graduating valve 28 has 

 the top end of port z blanked, and communication between 

 ports r and 5 is cut off. Cavity k in the equalizing valve con- 

 nects ports h and w with the exhaust port i that leads to 

 the distributing-valve release pipe, but as the automatic brake 

 valve is in release position, its rotary valve closes the opening 

 from the release pipe to the atmosphere and prevents the 

 distributing valve from releasing the locomotive brakes. In 

 order to connect the distributing-valve release pipe with the 

 atmosphere and thus release the locomotive brakes with the 

 automatic brake valve, the automatic brake valve must be 

 moved to running position. This allows the air from the 

 application cylinder and chamber to escape to the atmosphere 

 through ports h and w, cavity k, and port i into the distributing- 

 valve release pipe, thence through the S-6 brake valve into the 

 release pipe and out to the atmosphere through the automatic 

 brake valve. As the air in the application cylinder reduces, 

 the greater pressure in the exhaust-valve chamber moves piston 

 10 to the left, carrying with it the application valve 5 and the 

 exhaust valve 16. This movement of the application valve 

 does not affect port b, but the exhaust valve 16 connects the 

 brake cylinders with the atmosphere and brake-cylinder pres- 

 sure exhausts through ports d and e, thus releasing the brake. 



