What is the most common cause of a tractor-trailer jackknife?
Answer: B
Rear drive-wheel skid on the tractor
The most common cause of jackknifing is a rear drive-wheel skid on the tractor. The back of the tractor begins to move sideways during the skid and the weight of the trailer then pushes forward compounding the issue.
All choices
- AA skid on the front steering wheels
- BRear drive-wheel skid on the tractor
- CA trailer wheel skid
Why the other answers are wrong
A. A skid on the front steering wheels
Jackknifing is most commonly caused by rear drive-wheel skids, not front steering wheel skids.
C. A trailer wheel skid
Trailer wheel skids are less likely to cause jackknifing than rear drive-wheel skids on the tractor.
CDL Combination Vehicles Test Info
Questions on Exam
20
Passing Score
80%
Time Limit
Typically 30 minutes; varies by testing location
The Combination Vehicles test content is federally standardized, so this question applies in every state. Age limits, fees, and testing procedures do vary — check your state's CDL requirements.
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More CDL Combination Vehicles Practice Questions
- Off-tracking or cheating causes which of these to follow the wider path while making a turn?
- When driving behind another vehicle, under good conditions, you should allow at least one second between your vehicle and the vehicle ahead for each ____ feet of your vehicle length.
- Which part of the kingpin should the locking jaw close around?
- Where should the tractor be when you inspect the landing gear after uncoupling the trailer?
- After you have coupled the trailer you should raise the landing gear by first using: