212 SCIENCE OF SUCCESSFUL THRESHING 



(which is near the center, and covered with a narrow strip 

 of rubber) on the outside, and not next to the pulley. The 

 cleaner a rubber belt is kept, the better. No dressing of 

 any kind should be used. Anything of a sticky nature 

 adhering to it, will have a tendency to pull off the outer 

 coating of rubber and greatly injure the belt. Oils of all 

 kinds should be carefully avoided, and should a rubber belt 

 accidentally become covered with oil, it is best to wash it 

 off with soap and water. The best place to store rubber 

 belts is in the cellar, because darkness and slightly damp 

 air tend to preserve rubber, whereas light, especially direct 

 sunlight, and extreme dryness tend to rot it. 



The Main Belt is usually of rubber or stitched canvas 

 in widths of six, seven or eight inches, and made endless 

 in lengths of 120, 150 or 160 feet. The object in having 

 it so long is to place the engine far enough from the grain 

 to be safe from fire. Accordingly, the 120 foot length 

 may be used when the fuel is coal, but when burning wood 

 or straw, the longer lengths should be used. The amount 

 of barn and stack threshing and the usual arrangement of 

 the stacks in the locality in which the rig is to operate 

 must also be taken into consideration in choosing the length 

 of belt. With the engine having a forty-inch fly-wheel 

 and running at 250 revolutions per minute, the main belt 

 will travel 2625 feet, or almost exactly one-half mile in 

 a minute. A belt has a greater tendency to slip on the 

 smaller of the two pulleys over which it runs and for this 

 reason, the cylinder pulley is covered with leather or 



