Rainbow Precision Products provides a complete range of power transmission & material handling equipment. We are an authorized Goodyear Engineered Products distributor. Single Groove Adjustable Pitch Sheaves (Pulley) Increase efficiency, vary speed, and extend the life of your drive by changing the pitch on these cast iron pulleys. Turn the sides of the pulley on the threaded hub to increase or decrease the pitch. These pulleys are for use with 3L, 4L, 5L, section V-belts, also A-section and B-section V-belts, unless otherwise stated.