196 FARM MACHINERY 



spreaders have an advantage over others in the arrange- 

 ment of rollers and the track on which they roll. The 

 rollers may be either attached to the bed or to the slats. 

 270. Main drive. The main drive to the beater varies 

 with different machines. The power may be taken from 

 the main axle with a large gear wheel or by means of a 

 large sprocket and a heavy chain or link belt. It is 



FIG. 148 A CHAIN DRIVE TO THE BEATER. NOTE THE METHOD OF 

 REVERSING THE MOTION 



almost universal practice to use a combination of a chain 

 and a gear in the drive. The speed of the beater must 

 be such that the speed of the traction wheels must be in- 

 creased twice, while the direction of rotation must be re- 

 versed. To reverse the direction of the motion, the gear 

 is used. The heavy chain or link belt offers some advan- 

 tage in case of breakage. A single link may be replaced 

 at a small cost, while if a tooth is broken from a large 

 gear the entire wheel must be replaced. 



