CDL General Knowledge TestCombination Vehicles (if applicable)Medium
A driver notices a distinct 'chucking' or 'surging' motion in the combination vehicle, especially during acceleration or deceleration. What is the most likely cause?
- AExcessive play in the steering linkage of the tractor.
- BMalfunctioning trailer brake chamber.
- CA worn or damaged kingpin or fifth wheel assembly.
- DImproper tire pressure on the trailer axles.
Show answer & explanationAnswer & explanation
Correct answer: C. A worn or damaged kingpin or fifth wheel assembly.
Chucking or surging (a rhythmic forward and backward jerking) is often caused by excessive play or wear in the coupling components, specifically the kingpin or the fifth wheel assembly. This allows for too much movement between the tractor and trailer.
Why the other options are wrong
- A. Steering linkage play affects directional control, not the fore-aft surging of the entire combination.
- B. A malfunctioning brake chamber would affect braking performance, not cause a general surging motion during acceleration/deceleration.
- D. Improper tire pressure primarily affects handling, fuel economy, and tire wear, not a surging motion.
Chucking/Surging (Combination Vehicle)
A rhythmic forward and backward jerking motion felt in a combination vehicle, typically during changes in speed, caused by excessive play in the coupling components.
- Caused by worn kingpin or fifth wheel.
- Indicates excessive movement between tractor and trailer.
- Requires immediate inspection and repair.
Memory trick: Chucking means your connection's sucking.