Michigan Commercial Driver's License (CDL) Practice Exam

What should you do if your truck’s air pressure gauge shows low pressure?

1. Conserve momentum

2. Pull over and inspect the air tank

3. Increase your speed to build pressure

4. Ignore it if the brakes still work

The correct answer is: Pull over and inspect the air tank

When the truck’s air pressure gauge shows low pressure, pulling over and inspecting the air tank is essential for safety. Low air pressure in a vehicle equipped with air brakes can lead to brake failure, which poses a significant risk to the driver, other road users, and the cargo. By stopping to inspect the air tank, the driver can determine the cause of the low pressure, such as a leak or malfunction, and take necessary actions to address the issue before continuing to drive. In situations where air pressure is low, conserving momentum or increasing speed may seem like practical approaches, but they do not address the underlying problem of insufficient brake pressure. Ignoring low air pressure can lead to an emergency stop situation where the brakes might not respond adequately. Ensuring the air pressure is within the safe operational range is crucial for maintaining control of the vehicle and ensuring the safety of all road users.