NC CDL General Knowledge Practice Test 2025 - Free CDL Practice Questions and Study Guide

The primary function of the Governor in the air brake system is to control the air pressure in the brake system. This component plays a crucial role in maintaining the appropriate air pressure necessary for the brakes to function effectively. The Governor automatically regulates the pressure in the air tanks, ensuring that there is enough air for braking but also preventing the system from over-pressurizing, which could lead to brake failure or damage.

When the air pressure drops below a certain level due to use or leaks, the Governor activates the compressor to replenish the air supply. On the other hand, when the pressure reaches the upper limit, the Governor will stop the compressor from pumping in more air. This balance is essential to ensure reliable braking performance and safety while driving. Other options listed do not have the same relevance to the air brake system's functioning as the Governor’s role in air pressure control does.