GAS ENGINES 



507 



Ground gamma Pr/mory /ermina/, 

 fermina/, 



engine a distributor is used. The jump-spark system requires 

 a high-tension or inductor type of magneto, or a low-tension 

 current with an induction coil. 

 Make-and-break system. 

 The make-and-break ignition 

 is used on most small station- 

 ary engines and on those using 

 a very high compression. 

 Until recently it was regularly 

 used on multiple-cylinder en- 

 gines in racing automobiles. 

 It is simple in construction, 

 very reliable in operation at 

 slow speeds, and comparatively 

 inexpensive when it is neces- 

 sary to replace parts. The 

 essentials of a make-and-break 

 equipment are: source of cur- 

 rent (battery or magneto), 

 switch, coil, and make-and-break mechanism (Fig. 398) . The 

 make-and-break mechanism must be so constructed that the 



-Jecorx/ary 

 ?erm/na/ 



Fig. 400. An induction or jump- 

 spark coil, showing the connections 



-Jpark plug 



Jecondary or high-tension circuity 



Y/brator- 



Co/7 



screw, 



@ Timer 



TOOT 



- -3a fiery 



Fig. 401. Wiring diagram for a jump-spark ignition system 



Primary or fo in- 

 tension circuity 



