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Question

Difficulty: EasySpeed on Curves and Downgrades

Before entering a sharp curve on a roadway, what action should a commercial driver take to maintain vehicle control and prevent skidding?

  1. A
    Maintain normal cruising speed until the apex of the curve, then apply firm service brakes.
  2. Slow down to a safe speed before entering the curve, then accelerate slightly or maintain steady speed through it.Answer
  3. C
    Ride the service brakes lightly throughout the entire curve to prevent brake fade.
  4. D
    Apply the engine retarder at maximum setting halfway through the curve to counteract centrifugal force.

Answer

Slow down to a safe speed before entering the curve, then accelerate slightly or maintain steady speed through it.
The correct answer emphasizes slowing down before entering the curve. Commercial vehicles require tire grip for steering; decelerating ahead of the turn ensures that tires are not overburdened by simultaneous heavy braking and lateral cornering forces, keeping the combination stable.

Step-by-Step Solution

1
Identify the upcoming road curvature and evaluate safe approach speed.
Recognize that commercial vehicles have a high center of gravity and limited tire traction budget during cornering.
Tires provide a finite amount of grip that must be shared between directional steering and deceleration forces.
2
Complete all necessary deceleration and downshifting prior to reaching the curve entrance.
The vehicle enters the curve at a controlled speed without requiring heavy braking while turning.
Braking while steering increases the risk of wheel lockup, loss of steering control, and vehicle rollover.
3
Maintain stable throttle or accelerate very gently through the turn.
The vehicle remains balanced with optimal weight distribution and directional stability.
Steady power keeps drive wheels tracking properly and stabilizes the chassis throughout the curve.

Key Concept

Speed management prior to curve entry to preserve steering traction and prevent skids or rollovers
Estimated Time:45s
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Topics

Speed on Curves and Downgrades

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