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Difficulty: MediumStopping Distance Components

Brake lag distance in an air brake-equipped commercial vehicle is caused by the physical delay of compressed air traveling through the brake lines to activate the brake chambers, rather than driver reaction time.

Answer: Answer

Answer

True
Brake lag is an inherent pneumatic delay in air brake systems, taking approximately 0.5 seconds for compressed air to flow through the lines and push the pushrods in the brake chambers. This occurs after the brake pedal is depressed and is completely independent of the driver's perception and reaction times.

Step-by-Step Solution

1
Identify the distinct components that comprise total stopping distance in an air brake system.
Total stopping distance consists of four sequential segments: perception distance, reaction distance, brake lag distance, and braking distance.
Air brake systems have a unique physical delay not present in hydraulic systems.
2
Distinguish human response factors from mechanical system delays.
Driver perception and driver reaction account for human recognition and physical foot movement, whereas brake lag accounts for compressed air transit time (approximately 0.5 seconds).
Brake lag is purely a pneumatic property of air brake mechanics, not human response time.
3
Evaluate the statement against commercial vehicle braking definitions.
The statement correctly attributes brake lag to the transit time of compressed air through lines and chambers rather than driver reaction.
The definition accurately reflects CDL stopping distance principles.

Key Concept

Air Brake Lag Distance versus Human Reaction Distance
Estimated Time:45s
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Topics

Stopping Distance Components

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