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Question

Difficulty: EasyWinter Driving

You are operating a commercial motor vehicle on a highway where packed snow and patches of ice have accumulated. To maintain vehicle control and avoid initiating a drive-wheel skid, which action should you take regarding your vehicle's engine retarder?

  1. A
    Keep the retarder set to its maximum setting to prevent brake fade on icy grades.
  2. Turn off the engine retarder completely when driving on slippery, snow-covered, or icy roads.Answer
  3. C
    Keep the retarder engaged while decreasing your following distance to three seconds behind the traffic ahead.
  4. D
    Leave the retarder active and counter-steer away from the skid direction if the drive wheels break traction.

Answer

Turn off the engine retarder completely when driving on slippery, snow-covered, or icy roads.
Turning off the engine retarder is essential on snow and ice because retarders apply retarding force exclusively to the drive wheels. On slick surfaces with low friction coefficients, this braking torque can cause the drive wheels to lock up and lose directional grip, resulting in a sudden drive-wheel skid or jackknife.

Step-by-Step Solution

1
Assess the roadway traction condition
Identify that packed snow and ice create a low-traction, slippery driving surface.
Road surfaces with reduced traction require specific vehicle handling adjustments to maintain stability.
2
Determine the safety requirement for auxiliary braking systems (engine retarders)
Recognize that retarders exert braking torque only on drive axles, which can overcome available traction and cause drive wheels to skid.
According to standard commercial driving guidelines, retarders must always be switched off on wet, snow-covered, or icy roadways.

Key Concept

Engine retarder deactivation on low-traction winter road surfaces
Estimated Time:45s
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Topics

Winter Driving

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