CDL Air Brakes TestInspecting Air Brake SystemsMedium
A driver is inspecting the brake drums on a vehicle equipped with air brakes. Which of the following conditions would NOT require the brake drum to be replaced?
- AHeat checks that are deep and numerous.
- BA smooth, polished surface with no scoring or discoloration.
- CCracks on the friction surface extending to the edge.
- DMissing or loose bolts holding the drum to the wheel hub.
Show answer & explanationAnswer & explanation
Correct answer: B. A smooth, polished surface with no scoring or discoloration.
A smooth, polished surface with no scoring or discoloration indicates normal wear and a properly functioning brake system, which would not require drum replacement. Cracks, deep heat checks, or loose mounting bolts are all reasons for replacement.
Why the other options are wrong
- A. Deep and numerous heat checks compromise the drum's integrity and braking performance, requiring replacement.
- C. Cracks extending to the edge indicate structural failure and require immediate replacement for safety.
- D. Missing or loose bolts are a severe safety hazard and necessitate immediate repair or replacement of the drum/hub assembly.
Brake Drum Inspection Criteria
Key conditions to evaluate when inspecting brake drums to ensure safe and effective braking.
- Replace if cracked, severely scored, or heat-checked.
- Check for loose or missing mounting hardware.
- Normal wear (smooth, polished surface) is acceptable.
- Measure for exceeding maximum diameter.
Memory trick: Drum's good: smooth and clean, not cracked or mean!