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Question

Difficulty: MediumStopping and Braking Procedures

Resting a foot lightly on the service brake pedal while driving generates continuous friction, causing excessive heat buildup that leads to brake drum expansion and lining glazing, resulting in brake fade.

Answer: Answer

Answer

True
The statement is true because riding the service brakes creates continuous mechanical friction. The accumulated heat causes thermal expansion of the brake drums away from the shoes and glazes the linings, resulting in dangerous brake fade.

Step-by-Step Solution

1
Analyze the operational impact of resting a foot on the brake pedal while operating a commercial vehicle.
Identified that even slight pedal pressure causes the brake shoes or pads to drag continuously against the drums or rotors.
Brake components require full release between applications to dissipate heat generated during stops.
2
Examine the thermodynamic effects of continuous friction on the brake assembly.
Identified that continuous friction generates extreme thermal buildup, causing metal drums to expand radially and friction materials to glaze.
Thermal expansion increases the clearance between friction surfaces, while glazing hardens the lining surface and lowers the coefficient of friction.
3
Determine the resulting safety condition known in commercial driving.
Confirmed that this phenomenon is brake fade, which severely lengthens stopping distances or causes total braking failure.
The statement accurately links riding the brakes to excessive heat generation, drum expansion, lining glazing, and brake fade.

Key Concept

Thermal Brake Fade and the Hazards of Riding the Service Brakes
Estimated Time:45s
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Topics

Stopping and Braking Procedures

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