WTMA Belt and Chain Drives 1 — Questions and Answers
Question 1: 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?
- Half the speed
- Twice the speed (Correct answer)
- The same speed
- Four times the speed
Correct 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.
Question 2: In an open belt drive connecting two pulleys, both pulleys rotate in:
- Opposite directions
- The same direction (Correct answer)
- Alternating directions
- Perpendicular directions
Correct 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.
Question 3: What is the primary advantage of a V-belt over a flat belt for power transmission?
- Greater speed capability
- Lower cost and easier installation
- Higher friction grip and reduced slipping (Correct answer)
- Longer service life in wet conditions
Correct 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.
Question 4: To reverse the direction of rotation of a driven pulley in a belt drive, you would use a:
- Compound belt drive
- Crossed belt drive (Correct answer)
- Multi-groove belt drive
- Step pulley arrangement
Correct 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.
Question 5: A chain drive is preferred over a belt drive when the application requires:
- Quiet operation at high speeds
- Exact speed ratio with no slip (Correct answer)
- Flexible shaft alignment tolerance
- Low maintenance in dusty environments
Correct 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.
Question 6: In a belt drive system, which side of the belt carries the greatest tension?
- The slack side
- Both sides equally
- The tight side (Correct answer)
- Tension is the same throughout the belt
Correct 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.
Question 7: 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?
- 100 RPM
- 200 RPM (Correct answer)
- 400 RPM
- 1,800 RPM
Correct answer: 200 RPM
Driven speed = Driver speed × (Driver diameter / Driven diameter) = 600 × (8/24) = 200 RPM.
WTMA Belt and Chain Drives 1
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?