What is the role of a low air warning device in a dual air brake system?

The role of a low air warning device in a dual air brake system is to indicate when the air pressure in the system drops to a level that could compromise braking performance. It serves as a safety mechanism, alerting the driver that the air pressure is approaching a critical level that may prevent the brakes from functioning properly.

When the air pressure drops below a certain threshold, the device activates, typically emitting a visual or audible signal. This warning is crucial because air brakes rely on a sufficient level of air pressure to function reliably. If the pressure is insufficient, the brakes may fail, which poses a significant safety risk. By providing this early warning, the driver can take appropriate action, such as pulling over and inspecting the system, before a potential braking failure occurs.

Therefore, the correct choice highlights the importance of monitoring air pressure within the air brake system, ensuring both the driver’s awareness and the safety of the bus’s operation.