Air Brake Maintenance & Troubleshooting Flashcards

A truck's brakes are pulling to one side during a stop. When should this be addressed?

Answer: Immediately — pulling indicates unequal braking force that can cause loss of vehicle control

Brake pull means one side is applying more force than the other, creating a dangerous steering imbalance that requires immediate inspection.

What is 'brake chatter' and what typically causes it?

Answer: Rapid brake grab-and-release vibration caused by out-of-round drums or glazed linings

Brake chatter is caused by out-of-round drums or glazed lining surfaces creating an uneven, pulsating contact pattern during brake application.

How is pushrod stroke on a brake chamber properly measured?

Answer: Have an assistant apply 90 psi service brake pressure and measure how far the pushrod extends from the chamber

Pushrod stroke must be measured with service brakes applied at operating pressure — this shows the actual brake application geometry.

What is the maximum allowable pushrod stroke for a standard Type 30 brake chamber before adjustment is required?

Answer: 2.5 inches (63.5 mm)

A Type 30 brake chamber has a maximum allowable pushrod stroke of 2.5 inches; exceeding this means the brake is out of adjustment.

What does a ruptured or leaking brake chamber diaphragm cause?

Answer: Loss of braking force on that wheel as pressurized air escapes the chamber

A torn diaphragm allows compressed air to escape the service chamber rather than pushing the pushrod, eliminating braking force at that wheel.

What must be done when brake drums are found to be worn beyond the manufacturer's maximum diameter specification?

Answer: Replace the drums immediately — oversized drums overheat more easily and reduce braking effectiveness

Drums worn beyond maximum diameter have thinner walls that cannot dissipate heat effectively, causing rapid brake fade and risk of drum failure.