378 



AGRICULTURAL ENGINEERING 



These boilers are not regarded as very durable and are quite 



difficult to clean properly. 



The Locomotive Type of Boiler. The locomotive type of 

 boiler is the one most generally used for trac- 

 tion engine service. It consists of a fire box 

 made of steel plates, in which the furnace is 

 placed; a cylindrical shell extending forward, 

 containing a comparatively large number of 

 tubes; a smoke box at the front end; and a 

 stack to carry the smoke away. 



The fire box is almost entirely surround- 

 ed with water. The plate directly above the 



Fig. 240. A r J 



vertical boiler, fire is called the crown sheet and the plates 

 vaive; 'b, try forming the sides of the box are called side 



cocks; C, injec- . 



tor; d, hand sheets. In some instances lire boxes are so 



hole; E, pressure , , , , , 



gauge; f, gauge made as to nave water beneath the grates; 

 doorf'if, 'as F h such a boiler is said to have a water bottom. 

 The boiler has a cylindrical chamber riveted 

 to the top of the shell, in which the steam collects and from 

 which it is drawn to the engine. This part is called the 

 steam dome, and is a device for drying the steam. 



All parts of the boiler are made of the best steel plates, and 

 the seams are carefully riveted together. The joints are made 



Fig. 241. A boiler of the locomotive type in section: A, steam dome; 

 B, smoke box; C, fire box; D, grates; E, tubes; F, crown sheet. 



