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Question

Difficulty: EasySpeed on Curves and Downgrades

A commercial motor vehicle driver is approaching a sharp curve on an unfamiliar roadway. What is the safest procedure for managing vehicle speed through the curve?

  1. A
    Maintain normal highway speed until entering the curve, then apply firm brake pressure while steering through the turn.
  2. Reduce speed to a safe level before entering the curve, then maintain steady speed or accelerate slightly through the turn.Answer
  3. C
    Ride the service brake pedal continuously with light pressure throughout the entire length of the curve to regulate speed.
  4. D
    Activate maximum retarder braking while steering through the turn rather than reducing speed beforehand.

Answer

Reduce speed to a safe level before entering the curve, then maintain steady speed or accelerate slightly through the turn.
The safest method for navigating any curve in a commercial vehicle is to slow down to a safe speed before entering the curve. This ensures all braking is completed while traveling straight, allowing tire traction to be dedicated fully to steering during the turn.

Step-by-Step Solution

1
Assess the curve and identify an appropriate safe speed before entry.
Driver establishes a target speed below the posted advisory speed if carrying cargo or facing adverse conditions.
Heavy commercial vehicles have a higher center of gravity and require earlier speed reduction than passenger cars.
2
Apply the brakes and downshift if necessary while still traveling in a straight line before the curve.
Vehicle enters the curve at a stable, controlled speed with tires maintaining maximum lateral traction.
Braking in a straight line prevents lateral weight transfer and eliminates the risk of wheel lockup during steering.
3
Guide the vehicle smoothly through the curve while maintaining slight engine power.
The vehicle pulls steadily through the turn with optimal stability and tracking.
Light throttle provides positive driveline traction and stabilizes vehicle balance throughout the maneuver.

Key Concept

Speed adjustment before entering curves
Estimated Time:45s
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Topics

Speed on Curves and Downgrades

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