What activates the low air warning device in a brake system?

The low air warning device in a brake system is activated when the air pressure in the system drops to approximately 55 psi. This device is crucial for ensuring the safety of the vehicle and its ability to stop effectively. When the pressure reaches this threshold, the warning device alerts the driver, signaling that the air brake system pressure is insufficient for safe operation.

Maintaining adequate air pressure is essential for the brakes to function properly, and this warning device serves to prevent potential brake failure due to low air pressure. The specific setting of 55 psi is established as a standard in many commercial vehicles to allow drivers time to address the situation before reaching critically low pressure levels.