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Difficulty: HardSkid Control and Recovery

A commercial motor vehicle is traveling across a highway section covered with packed snow. As the vehicle exits a gentle curve, the drive wheels break traction and the rear of the vehicle steps out toward the right shoulder. What sequence of control inputs must the driver execute to successfully regain directional control and prevent a secondary counter-skid?

  1. A
    Engage the engine retarder to maximum capacity to pull the drive axle back into alignment while keeping the steering wheel centered.
  2. B
    Apply firm service brake pressure to lock all wheels while steering sharply to the left toward the center lane.
  3. Ease off the accelerator, steer to the right in the direction of the rear slide, and quickly counter-steer back as the vehicle aligns with the path of travel.Answer
  4. D
    Maintain aggressive brake application through the turn while holding the steering wheel locked in the direction of the original curve.

Answer

Ease off the accelerator, steer to the right in the direction of the rear slide, and quickly counter-steer back as the vehicle aligns with the path of travel.
Proper drive-wheel skid recovery requires three sequential actions: releasing the throttle or braking force to restore rolling traction, steering in the direction of the rear slide to arrest the rotational motion, and rapidly counter-steering back the other way as the vehicle straightens to prevent a secondary skid (fishtailing).

Step-by-Step Solution

1
Stop acceleration and avoid applying the service brakes.
The drive wheels stop spinning and can begin regaining rolling traction with the road surface.
Braking or applying throttle during a drive-wheel skid consumes available tire adhesion that is needed for directional control.
2
Turn the steering wheel to the right (in the direction the rear of the vehicle is sliding).
The front steer tires align with the vehicle's actual direction of momentum, arresting the lateral spin.
Turning in the direction of the rear slide brings the front and rear axles back into trailing alignment.
3
Counter-steer back to the left as soon as the vehicle starts straightening.
The vehicle stabilizes along its intended path without whipping into a reverse skid.
Without immediate counter-steering, the rotational inertia will swing the vehicle into a violent secondary skid in the opposite direction.

Key Concept

Drive-wheel skid recovery and secondary counter-steering technique
Estimated Time:1m 30s
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Topics

Skid Control and Recovery

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