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Difficulty: MediumSkid Control and Recovery

Applying the trailer hand brake (trolley valve) is an effective and recommended method to straighten out a commercial combination vehicle when the trailer begins to slide sideways in a jackknife.

Answer: Answer

Answer

False. Drivers must never use the trailer hand brake to straighten a jackknifing trailer.
The statement is false. Commercial driver safety standards strictly forbid using the trailer hand brake to fix a trailer skid. The trailer begins sliding when its wheels lose traction; activating the hand brake causes immediate wheel lockup, eliminating any chance of the tires regaining rolling traction and causing the trailer to swing around more violently.

Step-by-Step Solution

1
Analyze the mechanical cause of a trailer skid and jackknife.
Recognize that a trailer skids because the trailer tires have lost rolling traction on the road surface.
Tires require rolling contact to maintain directional control and resist lateral forces.
2
Evaluate the effect of applying the trailer hand brake during a trailer slide.
Applying the trailer brakes applies friction to already slipping wheels, locking them completely.
Locked wheels cannot generate cornering or stabilizing forces, making the trailer slide faster and worsening the jackknife.
3
Identify the standard recovery procedure for a trailer skid.
Release the service brakes immediately to allow trailer wheels to regain rolling grip.
Regaining rolling traction is the only way the trailer can follow the tractor's path and recover alignment.

Key Concept

Trailer Skid Recovery and Jackknife Prevention
Estimated Time:1m 0s
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Topics

Skid Control and Recovery

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