CDL Combination Vehicles TestCoupling and UncouplingMedium
A driver is inspecting the kingpin for wear. According to safety regulations, what type of damage or wear on the kingpin would immediately render the trailer unsafe to operate?
- AA bent or cracked kingpin.
- BSlight discoloration from heat exposure.
- CMinor surface rust on the kingpin.
- DScratches or light scoring on the kingpin shank.
Show answer & explanationAnswer & explanation
Correct answer: A. A bent or cracked kingpin.
A bent or cracked kingpin is a critical structural defect that would immediately compromise the safety of the coupling and render the trailer unsafe to operate, risking separation.
Why the other options are wrong
- B. Slight discoloration usually indicates past heat exposure but not necessarily current structural damage unless accompanied by other signs.
- C. Minor surface rust is typically cosmetic and not a structural defect.
- D. Scratches or light scoring, if not deep, may not be an immediate safety concern, though they should be monitored.
Kingpin Critical Defects
A bent or cracked kingpin is a critical structural defect that makes a trailer immediately unsafe to operate due to the high risk of catastrophic failure and separation.
- Compromises coupling integrity.
- Leads to immediate 'out-of-service' condition.
- Must be repaired or replaced before use.
Memory trick: Bent or cracked? Trailer's been attacked!