What happens at a pressure of 90 psi in an air brake system?

In an air brake system, a pressure of 90 psi indicates the cut-in pressure. This is the threshold at which the compressor is designed to start pumping air into the system to maintain the necessary pressure for proper brake function. Understanding cut-in pressure is essential for bus drivers, as it ensures that the air brake system can recharge and maintain adequate pressure to operate the brakes effectively.

The cut-in pressure is key for the safety and reliability of the braking system. If the pressure drops below this level, drivers should be aware that the compressor will engage to prevent a situation where the brakes might become ineffective due to insufficient air pressure. Maintaining proper air pressure is critical for ensuring that the brakes can operate as expected, thereby enhancing safety on the road. This is especially pertinent in North Carolina, where stringent regulations govern school bus operation to ensure the safety of children and other road users.