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Question

Difficulty: EasyWinter Driving

When driving on a roadway made slippery by snow or ice, which action is recommended to maintain vehicle stability and control?

  1. A
    Keep the engine retarder engaged at maximum power to reduce reliance on service brakes
  2. Turn off the engine retarder to prevent the drive wheels from losing traction and skiddingAnswer
  3. C
    Maintain the standard dry-road following distance of one second per 10 feet of vehicle length without adjustment
  4. D
    Drive with front steer tire tread depth worn down to 2/32 inch to provide a wider contact patch on snow

Answer

Turn off the engine retarder to prevent the drive wheels from losing traction and skidding.
Turning off the engine retarder is essential on slippery, snow-covered, or icy roads because retarders apply retarding force directly to the drive wheels. On slick pavement, this auxiliary drag can overcome limited tire friction, locking the drive wheels and sending the vehicle into an immediate drive-wheel skid or jackknife.

Step-by-Step Solution

1
Assess the roadway surface condition and identify reduced traction caused by winter weather.
Recognize that snow and ice significantly lower the friction threshold between the tires and the road surface.
Slippery road conditions require disabling auxiliary systems that can induce wheel lockup.
2
Adjust auxiliary vehicle braking systems by turning off the engine retarder.
Auxiliary braking force is removed from the drive axle, keeping wheels free to rotate and track smoothly.
Retarders apply mechanical drag exclusively to drive wheels, which readily induces drive-wheel skids when traction is poor.

Key Concept

Disengaging engine retarders on slippery surfaces during winter driving
Estimated Time:45s
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Topics

Winter Driving

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