How should air levels be checked in air brakes during inspection?

Air levels in air brakes should be checked by referring to gauge readings to confirm proper air pressure. This method is essential because air brake systems rely on maintaining adequate pressure for effective braking. The gauges provide a direct and accurate reading of the air pressure levels in the system, allowing the driver to ensure that they are within the manufacturer's recommended range. Maintaining proper air pressure is crucial for safety, as insufficient pressure can lead to brake failure or reduced braking efficiency.

Using gauge readings makes it easy to assess the entire system's condition quickly, ensuring that any issues can be identified before operating the vehicle. This method is a standard practice in pre-trip inspections because it is both efficient and reliable compared to other methods that could miss critical aspects of the air brake system's health.