Ontario Class A Practice Test · Question
What is a primary cause of a jackknife during braking in a tractor-trailer?
A jackknife often occurs when the tractor's drive wheels lose traction and skid, while the momentum of the trailer continues to push the tractor, causing it to
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Question: What is a primary cause of a jackknife during braking in a tractor-trailer?
Answer options:
- Applying sufficient brake pressure to the trailer only. ✅ Skidding of the tractor's drive wheels while the trailer continues to push.
- Over-steering at high speeds on dry pavement.
- Excessive use of the engine brake on a downgrade.
Correct answer: Skidding of the tractor's drive wheels while the trailer continues to push.
Explanation: A jackknife often occurs when the tractor's drive wheels lose traction and skid, while the momentum of the trailer continues to push the tractor, causing it to pivot sharply. This instability can be triggered by aggressive braking, especially on slippery surfaces.
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