Illinois CDL Practice Exam.

The safety valve in an air brake system plays a critical role in maintaining the integrity and safety of the braking system. Its primary function is to prevent excessive pressure buildup in the air tanks. When the pressure reaches a threshold of approximately 150 psi, the safety valve activates and opens to release excess air. This function is essential as it protects both the air tanks and the entire air brake system from potential damage or failure due to overpressure. This mechanism is crucial for ensuring that the air brake system operates within safe limits, thereby enhancing safety for the driver and the vehicle. The effective functioning of the safety valve is vital as it acts as a safeguard against catastrophic failures that could result from pressures exceeding recommended levels.