Home › CDL Practice Tests › Combination Vehicles Questions › Question 79
What is a jackknife most closely associated with?
- A.A type of fifth wheel grease
- B.A method of parking doubles
- C.A tool used to change tires only
- D.Drive or trailer wheels locking and the trailer swinging around, folding the combination at the coupling
Correct answer
D. Drive or trailer wheels locking and the trailer swinging around, folding the combination at the coupling
Why
When locked wheels lose side grip, the trailer can pivot around the kingpin and fold against the tractor. Preventing wheel lockup with smooth, controlled braking is the main protection.
Manual topic: Combination Vehicles - Rollover and Rearward Amplification · From the Combination Vehicles practice bank (CV-079).