Belt drives transfer power using friction created between the belt and pulleys. Which components are involved in this friction?

• A. Belt and pulleys
• B. Shafts and bearings
• C. Belts and rollers
• D. Pulleys and shafts

Answer: (A)

Power in a belt drive is transmitted through the contact surface where the belt presses against the rotating pulley. The belt wraps around the pulley, and the friction between the belt material and the pulley surface provides the grip that drags the belt and turns the driven pulley. This friction occurs specifically at the belt-pulley interface, not at the shafts or bearings, which merely support rotation, or at rollers or other components that aren’t the friction interface for driving motion. So the components involved in this friction are the belt and the pulleys.