The governor should supply more air to the tanks when the system pressure drops by approximately how much?

The governor in an air brake system is designed to monitor the air pressure in the system and maintain it at optimal levels for safe and effective braking. When the system pressure drops by a certain threshold, the governor engages to supply more air to the tanks, ensuring that the pressure remains sufficient for braking.

The correct drop, which is approximately 25 psi, is crucial because it reflects the system's need to react actively and responsibly to prevent pressure from falling too low, which could jeopardize the effectiveness of the air braking system. When the system pressure declines significantly, it can lead to delayed braking response or complete failure in extreme cases. By initiating a refill of air when the pressure is reduced by this specific margin, the governor ensures that the brake valves function properly, maintaining overall system reliability and safety.

Understanding this threshold helps operators be aware of how their air brake systems are designed to function effectively under pressure changes, highlighting the importance of routine checks and maintenance for the air supply system.