CDL General Knowledge TestCombination Vehicles (if applicable)Medium
A driver needs to adjust the slack adjusters on a combination vehicle. Which of the following statements about adjusting automatic slack adjusters is correct?
- AAutomatic slack adjusters only need manual adjustment if they are obviously out of adjustment.
- BIf an automatic slack adjuster requires frequent manual adjustment, it indicates a problem that needs repair.
- CAutomatic slack adjusters should be manually adjusted regularly as part of a pre-trip inspection.
- DManual adjustment of automatic slack adjusters is a routine maintenance procedure to ensure proper brake function.
Show answer & explanationAnswer & explanation
Correct answer: B. If an automatic slack adjuster requires frequent manual adjustment, it indicates a problem that needs repair.
Automatic slack adjusters are designed to maintain proper brake adjustment automatically. If they require frequent manual adjustment, it indicates a malfunction within the brake system (e.g., worn linings, faulty adjuster) that needs professional repair, not routine manual intervention.
Why the other options are wrong
- A. While true that they should be checked, needing manual adjustment at all (unless new) points to a problem.
- C. This is incorrect; automatic slack adjusters should not be regularly adjusted manually.
- D. This is incorrect; manual adjustment is not routine for automatic slack adjusters.
Automatic Slack Adjusters
Automatic slack adjusters maintain brake adjustment automatically. Frequent manual adjustment signals a system defect, not routine maintenance.
- Self-adjusting mechanism.
- Manual adjustment is rare.
- Frequent adjustment = problem.
Memory trick: Auto-adjusters keep brakes tight; if not, something's not right.