SGI Air Brakes Endorsement Flashcards

What is the correct method for descending a long steep grade with air brakes?

Answer: Select a low gear before descending and use steady light brake applications

Selecting a low gear before the grade and using light, intermittent brake applications prevents heat build-up and brake fade.

What does the governor in an air brake system do?

Answer: Maintains air pressure between the cut-in and cut-out range

The governor controls the air compressor, turning it on at the cut-in pressure (around 100 psi) and off at the cut-out pressure (around 120–130 psi).

What is the purpose of the tractor protection valve?

Answer: To protect the tractor air supply if the trailer develops a severe leak

The tractor protection valve closes automatically if the trailer's air line ruptures, preserving enough air in the tractor for safe braking.

In a combination vehicle, what do the red and blue glad hand couplings connect?

Answer: Red is the emergency (supply) line; blue is the service (control) line

The red glad hand connects the emergency (supply) line and the blue connects the service (control) line between the tractor and trailer.

What does a driver do first when testing parking brakes before a trip?

Answer: Apply the parking brake and attempt to move the vehicle forward slowly

Testing the parking brake by applying it and gently moving the vehicle confirms that it holds the vehicle securely.

What is the maximum air pressure drop allowed in one minute during a static leakage test for a combination vehicle?

Answer: 8 psi

For a combination vehicle (tractor-trailer), the static leakage test allows a maximum drop of 8 psi per minute with brakes applied.