Question 37 of 120

As part of the air brake check on a triples combination, why should you test the parking brakes on each trailer separately if possible?

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Testing them separately is required only for hazmat loads
It has no safety purpose, only a maintenance record purpose kept for the logbook that nobody actually reads afterward
Parking brakes only need to be tested on the tractor
To confirm each unit's parking brake actually holds rather than assuming the whole combination is secure

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Correct answer to question 37 (Doubles/Triples): To confirm each unit's parking brake actually holds rather than assuming the whole combination is secure

Why

A parking brake that fails to hold on one trailer wouldn't be caught by checking the tractor alone, so each unit's parking brake needs to be confirmed individually when possible.

Updated: November 2026

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As part of the air brake check on a triples combination, why should you test the parking brakes on each trailer separately if possible?

Why

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