01
Jackknife definition
A dangerous loss of alignment in which a tractor and trailer fold toward one another.
In commercial driving, the exact legal or technical application can depend on vehicle configuration, cargo, operating authority, and state rules. Drivers should confirm requirements in the current official CDL manual and applicable federal regulations.
02
Practical example
A CDL examiner may ask the applicant to demonstrate or explain jackknife while maintaining control and checking the surrounding area.
03
Why Jackknife matters
Mastering jackknife supports safer vehicle control and may be evaluated during CDL training or the state skills test.
04
Frequently asked questions
What does Jackknife mean in trucking?
A dangerous loss of alignment in which a tractor and trailer fold toward one another.
Why should CDL drivers understand Jackknife?
Mastering jackknife supports safer vehicle control and may be evaluated during CDL training or the state skills test.
Where can I learn more about Jackknife?
Review your state’s official CDL manual, use ELDT Info study resources, and ask a qualified instructor how the term applies to the vehicle or operation you plan to drive.