What activates the emergency brakes in response to a loss of air pressure?

The emergency brakes are designed to activate automatically in response to a loss of air pressure as a critical safety feature in many commercial vehicles, including school buses. This system is essential because a sudden drop in air pressure could compromise the vehicle's ability to stop safely through normal braking systems.

When the air pressure reaches a certain low threshold, an automatic release mechanism engages the emergency brakes, bringing the vehicle to a safe halt without requiring the driver's direct input. This function ensures that even in a situation where the driver may not be able to react quickly enough, the vehicle has an inherent safety measure that engages to prevent potential accidents.

Other methods for brake activation, such as manual knobs or hydraulic engagement, do not serve the same purpose as they rely on the driver's actions or specific conditions that may not be immediately available during a pressure loss scenario.