Georgia Commercial Driver License Practice Test

A dual air system functions under what condition?

1. Only when both systems have high pressure

2. When both brakes can be controlled separately

3. If one system has low pressure, both brakes will fail

4. Only if both systems are engaged

The correct answer is: If one system has low pressure, both brakes will fail

A dual air system is designed for safety and redundancy in heavy vehicles, ensuring that if one air brake system fails, the other can still function effectively to stop the vehicle. The importance of having two separate air systems is highlighted by the fact that if one of the systems experiences low pressure, the overall braking performance can be compromised, potentially leading to both brakes failing if the conditions aren’t favorable. In scenarios where one of the dual air systems drops to low pressure, it indicates a significant issue that could render that system inoperative. Therefore, the vehicle's safety relies on both systems maintaining adequate pressure. If the operational capacity of one system diminishes, it can significantly affect the brake function of the other system, underscoring why maintaining pressure in both systems is crucial for safety. While the other choices may describe various aspects of brake function or system engagement, they do not encompass the critical safety component that the dual air system is designed to address regarding low pressure vulnerabilities.