Which trailer air line keeps the trailer air tanks charged and also triggers trailer emergency braking if it loses pressure?

• A.The service (control) line only
• B.The backup light wire
• C.The slack adjuster grease line
• D.The supply (emergency) line

Why

The supply line continuously charges the trailer reservoirs under normal operation. If that line breaks or disconnects, the sudden loss of supply pressure applies the trailer emergency (spring) brakes.

Manual topic: Air Brakes - Air Brake System Components · From the Air Brakes practice bank (AB-015).

Practice this subject as a full test

More Dual Air Brake System & Components questions

• What is the main purpose of a dual air brake system on a modern truck?
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• In a dual air brake system, what does the secondary system typically control?
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• If one circuit of a dual air brake system fails completely, what should the driver expect?