GAS, OIL AND ALCOHOL ENGINES 



407 



port openings the burnt gas rushes out through the ex- 

 haust port and the new charge comes in through the in- 

 let port. Thus we see that when the piston is compress- 

 ing a charge in the cylinder a new charge is being taken 

 into the crank case, and when the charge in the cylinder 

 is expanding the gas in the crank case is being com- 

 pressed. 



FIG. 287 SUCTION, COMPRESSION 

 AND IGNITION STROKE OF TWO- 

 CYCLE ENGINE 



FIG. 288 EXPANSION, EXHAUST 

 AND INLET STROKE OF TWO- 

 CYCLE ENGINE 



558. Construction. (Only the four-cycle engine will 

 be considered hereafter.) The parts of a gasoline engine 

 necessary to be examined for proper construction are: 

 cylinder head, cylinder, base, piston, and piston rings, 

 connecting rod, crank shaft, flywheels, valves, governor, 

 carburetor, ignitor, and cooling device. 



