In a combination vehicle, what typically happens first in a jackknife skid caused by hard braking?
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Correct!
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Correct answer to question 105 (Combination Vehicles): The tractor's drive wheels lose traction and the trailer's momentum pushes the tractor sideways
Why
A jackknife often begins when the tractor's drive wheels lock or spin under hard braking, and the trailer's continued momentum then pushes the tractor sideways, folding the combination at the coupling.
Updated: November 2026
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