CHAPTER XXI 



TRACTION ENGINES 



580. Traction engines. The steam boiler and the 

 steam engine have been considered separately. If the 

 two should now be combined by means of a steam pipe 

 and placed on skids or trucks they would be termed a 

 portable steam engine. A gasoline engine placed on skids 

 or trucks is known as a portable gasoline engine. Such 

 engines are not self-propelling, but have to be moved by 

 means of animals or some mechanical device. The trac- 

 tion steam engine is the boiler, engine, and propelling 

 device all in one. The traction gasoline engine is the en- 

 gine and propelling device combined. In other words, 

 the traction engine develops the power by which it moves 

 itself over roads, fields, etc. The action of the traction 

 engine is to convert energy into horizontal motion which 

 has no direct path ; that is, the heat from the fuel is trans- 

 ferred from the boiler to the water, then from the water 

 to the steam pipe, and from the steam pipe to the engine, 

 where it is changed from heat energy to mechanical 

 energy. The mechanical energy is then transferred from 

 the engine to the clutch, thence to the drive wheels, which 

 propel the combined unit over its path. The gasoline 

 traction engine is similar to the steam engine in part only 

 and is considered by itself. 



ENGINE MOUNTING 



In nearly all types of traction engines the engine is 

 mounted upon the boiler, and the boiler is mounted upon 

 the truck. There are now being made some engines 



