GAS ENGINES 513 



cranks. The fourth throw is 180 from two and three, and 

 360 from the first. It is to be noted that the four-cylinder 

 crank shaft is very naturally balanced. 



In a six-cylinder engine (Fig. 409) an impulse is delivered 

 each sixth of 720 , or each one-third revolution. The six- 

 cylinder crank shaft must have six throws 120 apart. As 

 regularly made the distances are: 



No. 1 to No. 2 120 



No. 1 to No. 3 240 



No. 1 to No. 4 240 



No. 3 to No. 4 360 



No. 2 to No. 5 360 



No. 1 to No. 6 360 



Nos. 1 and 6 lie in the same plane, Nos. 2 and 5 in the same 

 plane, and Nos. 3 and 4 in the same plane. There are two 

 types of six-cylinder crank shafts, left-hand and right-hand. 

 In the right-hand crank shaft No. 2 is 120 from No. 1 

 in the direction the shaft turns. In the left-hand it is 240 

 in the direction of turning. 



In an eight-cylinder engine (Fig. 410) an impulse is 

 delivered for each 

 eighth of 720° or 

 each quarter-revo- 

 lution. The eight- 

 cylinder crank 

 shaft is exactly the 

 same as the four- 

 cylinder shaft. The 

 additional cylinders 

 are connected to 

 the cranks along- 

 side or on top of the Fig. 410. Showing relation of cylinder blocks as 

 ,1 r , used hi the " V"-type eight-cylinder engine 



other four connect- 



ing rods. The interpolation of the additional four cylinders 

 is obtained by means of setting the second four 

 cylinders at an angle of 90 to the first four. 



