CHAPTER LIV 



THE PRINCIPLES OF THE GASOLINE OR OIL 



ENGINE 



Relative Importance. The general introduction of the 

 gasoline or oil engine to do certain classes of work on the farm 

 places it next to the horse in importance among the various 

 farm motors now in use. So general has become its intro- 

 duction and so varied its uses that it is now imperative that 

 every farmer be familiar with the principles of its operation 

 and the essentials of its successful management. 



Classification of Motors. The gasoline or oil engine is a 

 heat engine, since its function is to convert heat or heat 

 energy, liberated by the combustion of gasoline or oil, into 

 mechanical energy. With this respect it is to be classed 

 with any motor using fuel of any sort. 



The gasoline or oil engine is an internal-combustion engine 

 or motor, in which the fuel, along with a sufficient amount of 

 air to support combustion, is ignited inside of a closed cylin- 

 der. The steam engine might be styled an external-combus- 

 tion engine, in that the combustion takes place outside of the 

 boiler or vessel withholding the pressure produced. In the 

 internal-combustion engine the heat released causes an 

 increased pressure of the gases in the cylinder, including the 

 products of combustion, which push upon the piston and 

 cause it to move forward, allowing the gases to expand and 

 do work. 



Fuels. The gasoline or oil engine does not differ essen- 

 tially from the gas engine, the difference consisting primarily 

 in a device called the carburetor, provided to convert the 



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