CDL General Knowledge TestCombination Vehicles (if applicable)Medium
A driver is performing a pre-trip inspection. When checking the slack adjusters on a combination vehicle, what is the maximum allowable movement (play) when pulled by hand?
- A1 inch
- B1/2 inch
- C2 inches
- D3 inches
Show answer & explanationAnswer & explanation
Correct answer: A. 1 inch
When checking manual slack adjusters, there should be no more than 1 inch of movement (play) when pulled by hand. Any more indicates that they are out of adjustment and the brakes will not work effectively.
Why the other options are wrong
- B. 1/2 inch is generally considered ideal, but 1 inch is the maximum allowable limit.
- C. 2 inches is excessive movement and indicates the brakes are dangerously out of adjustment.
- D. 3 inches is severely out of adjustment and would result in very poor braking performance.
Slack Adjuster Play
The allowable movement of a slack adjuster when pulled by hand, indicating proper brake adjustment.
- Crucial for effective braking.
- More than 1 inch means maladjustment.
- Affects all air-braked vehicles.
Memory trick: One inch of play is the most for the day.