Belt and Chain Drives Flashcards

A driving pulley has a diameter of 10 inches and the driven pulley has a diameter of 5 inches. What is the speed of the driven pulley relative to the driving pulley?

Answer: Twice the speed

The driven pulley is smaller, so it must rotate twice as fast to keep belt speed constant — speed ratio is inversely proportional to pulley diameters.

In an open belt drive connecting two pulleys, both pulleys rotate in:

Answer: The same direction

In an open belt drive, the belt wraps around both pulleys in the same orientation, so both rotate in the same direction.

What is the primary advantage of a V-belt over a flat belt for power transmission?

Answer: Higher friction grip and reduced slipping

The wedging action of a V-belt seated in its groove creates more friction contact than a flat belt, significantly reducing slippage under load.

To reverse the direction of rotation of a driven pulley in a belt drive, you would use a:

Answer: Crossed belt drive

A crossed belt drive reverses the direction of the driven pulley by crossing the belt between the two pulleys before it wraps around the driven side.

A chain drive is preferred over a belt drive when the application requires:

Answer: Exact speed ratio with no slip

Chains engage sprocket teeth positively with no slippage, ensuring a constant and precise velocity ratio that friction-based belt drives cannot guarantee.

In a belt drive system, which side of the belt carries the greatest tension?

Answer: The tight side

The tight side (pulled by the driving pulley) carries more tension than the slack side, and this tension difference is what transmits power between the pulleys.

A driving pulley rotates at 600 RPM with an 8-inch diameter and drives a pulley with a 24-inch diameter. What is the speed of the driven pulley?

Answer: 200 RPM

Driven speed = Driver speed × (Driver diameter / Driven diameter) = 600 × (8/24) = 200 RPM.