Before driving a vehicle with air brakes, you should ensure that the spring brakes come on automatically when:
Answers
Air pressure falls below 45 psi.
Air pressure falls below 20 psi.
Driving downhill.
Driving uphill.
The Correct Answer and Explanation is :
The correct answer is: Air pressure falls below 45 psi.
Explanation:
Air brakes are an essential safety feature in vehicles like trucks, buses, and some heavy equipment. These systems operate by using compressed air to control the brakes, and they are designed to prevent accidents by ensuring that the brakes are applied when air pressure drops to a certain level.
The spring brakes, which are a part of the air brake system, are designed to engage automatically if the air pressure falls below a critical threshold. This is a safety mechanism to ensure that the vehicle will stop or at least slow down in the event of a failure in the air brake system. The spring brakes are typically mechanical and use a spring tension to apply the brakes when air pressure is lost.
The specific threshold where the spring brakes engage is typically 45 psi (pounds per square inch). At this level, the air pressure is low enough to trigger the spring brakes, which are designed to activate as a backup safety measure. If air pressure falls below 45 psi, it means the system is not functioning properly, and the spring brakes will automatically engage to slow the vehicle.
On the other hand, air pressure below 20 psi is typically too low for the system to operate safely. At this point, the vehicle would be at a significant risk of brake failure, and the driver should immediately address the problem.
In terms of driving uphill or downhill, the air pressure level does not directly change in response to the vehicle’s incline. The system is designed to function independently of terrain, as long as the air pressure remains above the critical threshold. Therefore, the key consideration is air pressure, not the vehicle’s incline.