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Question

Difficulty: MediumSpeed on Curves and Downgrades

A commercial motor vehicle is traveling on a two-lane highway and approaching a sharp curve. What is the correct procedure for safely negotiating this curve?

  1. A
    Maintain cruising speed until entering the curve, then apply steady service brake pressure to scrub off excess speed.
  2. Reduce speed to a safe pace before entering the curve, then maintain a slight, steady throttle through the turn.Answer
  3. C
    Shift the transmission into neutral before entering the turn to allow the wheels to roll freely and minimize lateral tire friction.
  4. D
    Rely on continuous light foundation brake application while downshifting mid-turn to maintain maximum engine drag.

Answer

Reduce speed to a safe pace before entering the curve, then maintain a slight, steady throttle through the turn.
Reducing speed to a safe rate before entering the curve preserves tire traction for steering and lateral stability. Once established in the curve, applying light, steady power keeps the vehicle balanced and prevents sudden weight transfers that could cause a skid or rollover.

Step-by-Step Solution

1
Assess the approach and recognize the upcoming curve.
Identified the need for proactive speed reduction before entering the turn.
Tires have a limited amount of traction that must be shared between steering, braking, and driving forces.
2
Decelerate and shift to the appropriate gear prior to entering the curve.
The vehicle enters the curved roadway segment at or below safe advisory speed.
Braking while turning easily exceeds tire traction limits and can cause drive-wheel or steer-wheel skids.
3
Maintain smooth steering and light, steady power through the arc of the turn.
Vehicle stability and suspension balance are maintained throughout the maneuver.
Gentle throttle stabilizes the combination unit and maintains forward momentum without overloading tire grip.

Key Concept

Speed Management and Traction on Curves
Estimated Time:1m 0s
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Topics

Speed on Curves and Downgrades

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