SGI Air Brakes Endorsement Flashcards

What is the minimum air pressure required before a driver can move an air brake-equipped vehicle?

Answer: 100 psi

The air pressure must build to at least 100 psi before the vehicle is safe to move, ensuring adequate braking pressure is available.

What does the low air pressure warning device activate at?

Answer: 60 psi or below

The low air pressure warning (buzzer or light) activates when reservoir pressure drops to 60 psi or below, alerting the driver.

What happens if air pressure drops below approximately 20–45 psi in a spring brake system?

Answer: The spring brakes apply automatically

Spring brakes apply automatically when reservoir air pressure drops too low, preventing the vehicle from moving without adequate brake pressure.

What is the purpose of the air dryer in an air brake system?

Answer: To remove moisture and contaminants from compressed air

The air dryer removes moisture and oil from the compressed air before it enters the reservoirs, preventing corrosion and freeze-ups.

During a pre-trip inspection, what should the static air leakage test measure?

Answer: Air pressure drop over one minute with engine off and brakes applied

The static leakage test checks that pressure does not drop more than 4 psi per minute (single vehicle) with brakes applied and engine off.

What is brake fade, and when does it occur?

Answer: Reduction in braking effectiveness due to heat build-up from overuse

Brake fade occurs when repeated or prolonged braking generates excessive heat, reducing the friction material's ability to slow the vehicle.