88 Book of Locomotives 



The low-pressure boiler occupies the 

 same position as the barrel of the normal 

 locomotive boiler, and the water is evapo- 

 rated by the gases passing through the 

 boiler tubes. The barrel on this low-pres- 

 sure boiler is also of nickel steel, but both 

 tube plates are of mild steel. 



An ordinary live steam injector is pro- 

 vided on the driver's side and an exhaust 

 steam injector on the fireman's side of the 

 engine to feed the low-pressure boiler. 



As steam is raised much more quickly 

 in the high-pressure drum than in the low- 

 pressure boiler, arrangements are made to 

 deflect, by means of an intercepting valve, 

 any excess steam from the high-pressure 

 drum into the low-pressure boiler, thus 

 avoiding waste through blowing-off. 



The method of working this locomotive 

 is more or less normal. The regulator 

 handle works both the high-pressure and 

 the low-pressure regulator simultaneously. 

 On opening the regulator, steam is admitted 

 into the high-pressure cylinder after passing 

 through the high-pressure superheater, 



