CDL General Knowledge TestDriving SafelyHard
When performing a pre-trip inspection, a commercial driver notices that the slack adjusters on a pushrod-type brake are not properly adjusted. What is the maximum allowable play (free travel) for a manual slack adjuster when the brakes are disengaged?
- A2 inches
- B1 inch
- C3/4 inch
- D1/2 inch
Show answer & explanationAnswer & explanation
Correct answer: B. 1 inch
For manual slack adjusters on pushrod-type brakes, the pushrod should not move more than 1 inch when the brakes are disengaged. More than 1 inch indicates excessive slack and improper adjustment, which can lead to reduced braking efficiency and potential brake failure.
Why the other options are wrong
- A. 2 inches is severely out of adjustment and highly dangerous.
- C. 3/4 inch is within an acceptable range, but 1 inch is the specified maximum limit.
- D. 1/2 inch is too little; some play is normal and necessary.
Slack Adjuster Play Limit
The maximum permissible free travel (play) for a manual slack adjuster's pushrod on an air brake system, indicating proper adjustment.
- Ensures effective braking
- Checked during pre-trip
- Excessive play reduces braking force
Memory trick: One Inch is the limit, don't ignore it.