NO. 6 E T LOCOMOTIVE BRAKE 255 



a difference of pressure on its two faces. In this view the 

 stem is broken away so as to show the rivets a that secure 

 the exhaust-valve yoke- / to the stem and the pin ab that fits 

 in the groove in the -application- valve pin 18. The guide, or 

 solid piston, ^7 around the stern just back of piston 10 fills 

 the cylinder between the application-piston cylinder and the 

 exhaust-valve bushing, so that it is nearly air-tight. This 

 acts as a dashpot to make piston 10 move back and forth 

 gradually and thus steadies the movement of the valves 5 

 and 16. The other figures show the application graduating 

 stem 19 and spring 20, and the application graduating-stem 

 nut 21. 



DUTY OF PARTS 



The duty of the equalizing piston 26 is to control the move- 

 ment of the equalizing valve SI and the graduating valve 28, 

 as well as to open and close the feed-groove r. It is caused 

 to move by creating a difference of pressure on its two faces, 

 the greater pressure moving it toward the lesser pressure. 

 The equalizing valve 31 opens and closes communication 

 between the pressure chamber, the application cylinder, and 

 the application chamber, and between the application cylinder, 

 the application chamber, and the distributing- valve exhaust. 

 The equalizing valve is made shorter than the distance between 

 the shoulders on the equalizing-piston stem, so that, when it 

 is in service position, the piston can move the graduating valve 

 far enough to open and close port z without moving the equali- 

 zing valve. The graduating valve 28 opens and closes port z 

 in the equalizing valve 31, and thus graduates the flow of air 

 from the pressure chamber into the application cylinder when 

 a graduated-service application is made with the automatic 

 brake valve. The graduating valve also opens communica- 

 tion between the application cylinder and the safety valve 

 through ports r and s in the equalizing valve when in service 

 position, and closes this communication when in service-lap 

 position. 



The application piston 10 controls the movement of the 

 application valve 5 and the exhaust valve 16. It is caused to 

 move by increasing or decreasing the pressure in the application 



