CDL General Knowledge TestCombination Vehicles (if applicable)Medium
When backing a combination vehicle, what is the most effective way to correct a 'jackknife' situation once it has started?
- AIncrease engine RPM and turn the steering wheel into the direction of the trailer swing.
- BPull forward to straighten out the combination, then resume backing.
- CApply the trailer hand brake firmly and continuously.
- DTurn the steering wheel sharply in the opposite direction of the trailer swing.
Show answer & explanationAnswer & explanation
Correct answer: B. Pull forward to straighten out the combination, then resume backing.
Once a jackknife begins, the quickest and safest way to recover is to stop immediately and pull forward gently. This straightens the vehicle out and allows the driver to restart the backing maneuver correctly.
Why the other options are wrong
- A. Increasing RPM and turning into the swing can exacerbate the jackknife, especially if the wheels are already turning too sharply.
- C. Applying the trailer hand brake during a jackknife can lock the trailer wheels, making the situation worse.
- D. Sharply turning against the swing can worsen the jackknife or cause loss of control.
Jackknife Recovery (Backing)
To recover from a jackknife while backing, stop immediately and pull forward to straighten the vehicle before attempting to back again.
- Occurs when tractor and trailer form a sharp angle.
- Immediate stop is crucial.
- Pulling forward corrects the angle.
- Avoid sharp steering or trailer brakes.
Memory trick: When things go wrong, go straight and try again.