Maintenance & inspection
What is brakes and air lines?
Brakes and air lines cover the braking system a driver can check before use — warning lights, air build, audible leaks, and the condition of the lines between unit and trailer.
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<img src="https://fleetoptix.co.uk/glossary/brakes/diagram.svg" alt="brakes and air lines — diagram from FleetOptix" width="880" height="620" loading="lazy">
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<a href="https://fleetoptix.co.uk/glossary/brakes">What is brakes and air lines?</a> — diagram by
<a href="https://fleetoptix.co.uk">FleetOptix</a>
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</figure>The driver's check is about the system's readiness rather than its performance. Warning devices, air pressure build and obvious leaks are all checkable in the cab and the yard; efficiency is a workshop matter.
Air leaks are audible, which makes them one of the few defects a driver can find without looking. Standing still and listening is a real part of the check.
Trailer parking brake and coupling-related brake checks are specific to combinations and are the ones most often abbreviated when a driver is under time pressure.
What goes wrong in practice
- Warning lights noted as normal without knowing what normal is for that vehicle.
- Audible leaks dismissed as usual for that trailer.
- Trailer brake checks skipped on a quick changeover.