GAS ENGINES 367 



movable plate rotates and presses against the disk. When 



this contact takes place a cur- 

 rent flows from the accumulator 

 through the different parts, in- 

 cluding the induction coil, and 

 back to the accumulator. In 

 this circuit is a spark plug so 

 arranged that there is a small gap 

 FIG. 183.-cl^bureterin through which the current passes 

 Section. and produces a spark. 



Questions 



1. How does a gas engine work? 



2. What is the combustible or inflammable material used? 



3. What is the supporter of combustion? 



4. What are the gases exploded? 



5. How is gasoline made into a gas? 



6. What is the source of energy of the gas engine? 



7. What are the two types of gas engines commonly used? 



8. Explain the operation of each type. 



9. How does the two-cycle engine differ from the four-cycle 

 engine? 



10. What is the object of compressing the charge in a gas engine? 



11. Does the nitrogen of the air take part in the explosion? 



12. What are the products of combustion in the explosion if we 

 assume the gas is composed of hydrocarbons? 



13. At what point should ignition take place to get best results? 



14. Upon what does a successful and reliable ignition depend? 



15. How is ignition accomplished in a gas engine? 



16. Name two systems of ignition. 



17. Give advantages and disadvantages of each system. 



18. What is the great source of loss of power in a gas engine? 



Problems 



1. The horse-power of a four-cycle engine is estimated approxi- 

 mately by multiplying the area of the piston by the length of stroke, 



