TRAIN AIR-SIGNALING SYSTEM 407 



PC. No. Ref. No. Name of Part 



2.156 Car discharge valve, complete. 



2.157 2 Body. 



2.158 3 Stem, complete, includes 11. 



2.161 4 Spring. 



2.162 5 Handle. 



2.163 6 Stop-pin. 



2.164 7 Cap. 



2.165 8 i-in. union nut. 



2.166 9 i-in. union swivel. 

 2,204 10 i-in. union gasket. 

 2,160 11 Rubber seat. 



The signal cord is attached to the handle 5. When the signal 

 cord on either side of the discharge valve is pulled, the handle 

 5 strikes the stem 3 of the discharge valve and forces the valve 

 from its seat. Air from the signal pipe then passes through 

 the branch pipes into the discharge valve, past the discharge 

 valve, and out to the atmosphere, causing a reduction in signal- 

 pipe pressure. As soon as the signal cord is released, the spring 

 4 forces the discharge valve to its seat again and stops the dis- 

 charge of air from the signal pipe. 



The branch pipe to the discharge valve is supplied with a 

 strainer (where it connects with the main signal pipe) and a 

 cut-out cock, the former to prevent dirt from reaching the dis- 

 charge valve, and the latter to enable the discharge valve to be 

 cut out in case it is disabled. The handle of the cut-out cock 

 stands parallel with the pipe when the discharge valve is cut 

 out, and at right angles to it when cut in. Also, the cut-out 

 cocks in the signal pipe on either side of the signal hose are 

 closed when the handles stand parallel with the pipe, and open 

 when at right angles to it . The couplings in the signal hose are 

 of a different size than those in the air-brake hose, so that signal 

 hose and brake hose cannot be coupled by mistake. 



