Goodyear Engineered Products (Akron, Ohio) has developed the Gatorback Sport drive belt for all-terrain vehicles (ATVs), the first continuously variable transmission (CVT) belt with carbon fiber reinforcement in its body construction, according to Loren Danhauer, Goodyear’s chief belt engineer.

A CVT system varies the working ratio of two V-shaped pulleys linked by the belt, says Jonathan Cocco, marketing manager for Goodyear aftermarket products. The distance between pulley flanges can fluctuate, allowing the belt to ride smoothly up or down the pulley, continuously changing the gear ratio and, consequently, the vehicle’s speed. The pulleys are part of a power-sensing drive that increases tension during acceleration and reduces tension when power is reduced. Danhauer says conventional CVT belt sidewalls can glaze and char from heat buildup when engaged with pulleys under extreme loads. Material from the top width of the belt then turns down and inward, creating vibrations that can quickly destroy the belt. In contrast, the chopped carbon fiber in the Gatorback’s rubber compound allows desired edge slippage without losing top width: “We’re able to align the carbon fiber in the rubber compound to provide added stiffness across the width of the belt,� says Cocco.

While the belt’s lateral strength comes from carbon fiber, its longitudinal strength comes from Goodyear Flexten aramid cords run along the belt’s circumference. The aramid fiber reportedly minimizes stretch, stabilizes overall length and maximizes horsepower transmission.

The concept was developed in 2006, when noted NASCAR auto racing team Hendrick Motor-sports needed a more robust engine timing belt, and Goodyear responded by mixing carbon reinforcement in rubber compounds. The result was an advanced composite that could withstand the increased loads and higher temperatures and, therefore, retain precise timing, allowing engines to run more efficiently.

For product info, visit www.compositesworld.com/ct/apr/2007