Pulley crown keeps flat belts on track

Thank you for the many nice articles on forgotten tools from an earlier era. I appreciated the “Belt Basics” article in the January 2010 issue as to the makeup of various belts. I would like to add the following information:

The question has often been asked, particularly by the younger generation, “What keeps a belt from running off a pulley, especially when the pulleys are a long way apart?” Every pulley is built with a crown over the center of the pulley, about 1/16 to 1/8 inch, depending on the width of the pulley. It is the natural tendency of a turning belt to climb to the highest point on the pulley, even though they are not perfectly aligned.

I first learned this 72 years ago when I was 10 years old. Two men were trying to line up a 3 hp engine for pumping water, but the belt kept leaving the engine pulley. Then one man took a roll of Bulldog tape (forerunner of duct tape) from his pocket and wrapped several passes over the center of the pulley and their lineup problems were solved.

In 1944, we had to buy a large pulley for a grain paddle elevator. We were sold a 16-inch wooden pulley, 4 inches wide. It was several layers of wood bonded together with a large center hole, where two half-sleeves were slipped into with a center hole to match the size of the shaft. We slipped the pulley over the shaft and tightened four bolts to clamp it to the shaft. It was still in good shape 15 years later when we retired the elevator, even though the pulley was outdoors and exposed to the elements all that time.

Herman Vander Vos
Bozeman, Mont.

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