ENGINEER'S BRAKE VALVES 127 



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 makes a sudden and heavy discharge of brake-pipe 

 pressure, causing the triple valves and distributing valve to 

 go to the emergency position and give maximum braking power 

 in the shortest possible time. 



SF-1 INDEPENDENT BRAKE VALVE 



PIECE AND REFERENCE NUMBERS 



The SF-1 independent brake valve, here shown, is a part 

 of, and regularly supplied with, the No. 5 ET locomotive 

 brake equipment; its weight is 14 Ib. The SF independent 

 brake valve, formerly supplied with the No. 5 ET equipment, 

 differs from the SF-1 valve in the items, Ref. Nos. 9, 10, 12, 

 27, and 28, in the accompanying list. The SF valves now in 

 service may be readily changed to incorporate the new type 

 of spring and housing by drilling a A-in. hole for the stop-pin 

 and substituting Ref. Nos. 9, 10, 12, 27, and 28 in place of 

 similar details removed. It is impossible to apply either the 

 spring or any detail of the new construction to old SF valves 

 unless the complete set of details comprised in the improved 

 arrangement is first changed and the A-in. hole is drilled 

 according to directions, which will be furnished by the West- 

 inghouse Air-Brake Company on request. In ordering repair 

 parts for this valve, it should therefore be carefully noted 

 whether they are desired for the SF or SF-1 valve. The piece 

 number of SF-1 independent brake valve with brass handle 

 and pipe bracket, complete, is 21,736; with malleable-iron 

 handle and pipe bracket, complete, 21,737. The piece and 

 reference numbers of the various parts are given in the 

 accompanying list. 



PC. No. Ref. No. Name of Part 



10,214 2 Rotary -valve seat. 

 21,738 3 Body, includes 11, 20, and 27. 

 12,306 4 Pipe bracket, includes 23 and 24. 

 11 934 5 Rotary valve. 



