Adjustment & Testing Flashcards

What is the purpose of the automatic slack adjuster on air brake systems?

Answer: To maintain proper brake lining-to-drum clearance automatically

Automatic slack adjusters maintain the correct clearance between the brake lining and drum as linings wear, eliminating the need for manual adjustment during normal operation.

When manually adjusting brake slack, which direction do you turn the adjusting bolt to tighten (reduce slack)?

Answer: Clockwise

Turning the adjusting bolt clockwise tightens the brake by moving the brake shoe closer to the drum, reducing the pushrod stroke needed to apply the brake.

What is the maximum allowable brake chamber pushrod stroke for a standard type-30 chamber?

Answer: 3 inches

A type-30 brake chamber has a maximum allowable stroke of 3 inches before the brakes are considered out of adjustment and the vehicle must be placed out of service.

During a brake adjustment check, you measure the pushrod stroke with the brakes applied at approximately what air pressure?

Answer: 90 psi

Pushrod stroke is measured with full service brake application at approximately 90 psi to get a consistent and accurate reading of the slack condition.

What does it mean if the low air pressure warning activates while checking brake adjustment during a pre-trip?

Answer: The air compressor or governor may not be functioning properly

If the low air pressure warning activates during testing, it signals that the compressor is not maintaining adequate system pressure, pointing to a problem with the compressor or governor.

Which of the following correctly describes the 'applied stroke' measurement used in brake adjustment checks?

Answer: The distance the pushrod travels from rest when brakes are fully applied

Applied stroke is the distance the brake chamber pushrod moves from its rest (released) position to its applied position when the service brakes are fully applied.