CDL Air Brakes TestInspecting Air Brake SystemsEasy
A driver is performing a pre-trip inspection on a vehicle equipped with air brakes. When checking the air compressor, what is the minimum tension requirement for its drive belt?
- ANo more than 1 inch of play at the center of the longest span.
- BNo more than 3/4 inch of play at the center of the longest span.
- CNo less than 1/2 inch of play at the center of the longest span.
- DNo less than 1 1/4 inches of play at the center of the longest span.
Show answer & explanationAnswer & explanation
Correct answer: B. No more than 3/4 inch of play at the center of the longest span.
The general rule for air compressor drive belt tension, similar to other drive belts, is that it should not have more than 3/4 inch of play (deflection) at the center of its longest span when pressed firmly.
Why the other options are wrong
- A. 1 inch of play is generally too much, indicating a loose belt.
- C. This specifies a minimum, not a maximum, and 1/2 inch could be too tight or too loose depending on context.
- D. 1 1/4 inches of play is excessive and indicates a very loose belt.
Air Compressor Drive Belt Tension
The correct tension ensures the air compressor operates efficiently without slipping or putting undue stress on components.
- Checked by pressing on the longest span of the belt.
- Should not exceed 3/4 inch of play.
- Too loose can cause slipping; too tight can damage bearings.
Memory trick: Belt's tight, not too much give, 3/4 inch to live!