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Difficulty: HardSpeed on Curves and Downgrades

Applying foundation service brakes while actively steering through a roadway curve enhances commercial vehicle stability by increasing dynamic tire grip on the outer wheels.

Answer: Answer

Answer

False
The statement is false because commercial vehicle tires have a finite traction budget. When navigating a curve, tire grip is primarily used to counter lateral centrifugal forces. Applying service brakes inside the curve forces tires to divide grip between braking and steering. This significantly elevates the risk of locking the drive or trailer wheels, causing a severe jackknife or skid. CDL safety protocols require all deceleration to be completed in a straight line before entering the curve.

Step-by-Step Solution

1
Examine the distribution of tire traction forces during cornering.
Tire friction is finite and must handle lateral forces required to keep the commercial vehicle following the curve.
Tire adhesion cannot exceed 100% of available road grip.
2
Analyze the mechanical consequence of introducing service braking during an active turn.
Braking introduces longitudinal demand, which reduces available lateral grip and overloads tire friction capacity.
Simultaneous braking and steering easily leads to loss of directional control and wheel lockup.
3
Identify the standard CDL operating procedure for curve speed control.
The commercial vehicle must slow down to a safe speed prior to curve entry, maintaining a steady speed or light pull through the turn.
Pre-curve speed reduction reserves all available tire traction for steering stability.

Key Concept

Traction allocation and pre-entry speed management on curves
Estimated Time:1m 30s
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Topics

Speed on Curves and Downgrades

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