Flat Belt Basics: Subtle Adjustments Contribute to Efficient Belt Operation

Enlarge Image Image Gallery A correctly aligned tractor and separator. courtesy Sam Moore

First, a belt can be defined as being a continuous strip of flexible material placed around two pulleys under a certain amount of tension to transmit power from one pulley to the other. This definition also describes chain, rope and V-belts, but we’ll stick to the flat belts used to power many farm machines, such as threshers, balers, hammer mills, husker-shredders and silo fillers.

Belts were made of leather, canvas and rubber. Leather was considered the best, but was the most expensive and required more care. Double thickness leather belts were made for heavy-duty use on large diameter pulleys but weren’t flexible enough for smaller pulleys. Few leather belts are seen today.

Canvas belting is made of several layers of canvas stitched along both edges as well as several times down the center. Canvas is the cheapest belt material, and usually is treated with oil or painted to make it waterproof. A 4-ply canvas belt is considered as strong as single-ply leather.

Probably the most common belt found today is the rubber belt. Made with a foundation of several layers of cotton duck to which a rubber compound is applied and vulcanized, a rubber belt is impervious to steam and water, and will not slip as readily as a leather belt. Three-ply rubber and single-ply leather belts have equivalent strengths.

The metal lacings consist of a series of loops applied to each end of the belt by hammering them into the belt material or using a special machine to press them into place. The belt ends are brought together so the loops interlace and a rawhide or steel hinge pin is inserted through the loops to hold them together. This method of connecting has the advantage of being easy to disconnect and is quite flexible.