Air Brake System Leak Test Quiz

What is the maximum allowable air pressure loss for a straight truck during a static leak test?

• 3 psi in one minute

• 2 psi in one minute

• 4 psi in one minute

• 1 psi in one minute

Before performing a leak-down test, what should you do first?

• Turn on the headlights

• Build full air pressure (governor cut-out)

• Check oil levels

• Engage the trailer hand valve

True or False: The engine must be running during the leak down test.

• True

• False

During a static leak test, which brakes must be released?

• Only trailer brakes

• Only tractor brakes

• Both service and parking brakes

• All brakes must be released

Which tool is commonly used to monitor air pressure during the leak test?

• Air compressor

• Pressure regulator

• Air pressure gauge

• Manometer

How long should you observe the air pressure gauge during the static leak test?

• 30 seconds

• 1 minute

• 3 minutes

• Until the warning buzzer sounds

At what air pressure should the low air pressure warning activate in most vehicles?

• above 90 psi

• at 80 psi

• at 60 psi

• above 55 psi

True or False: A vehicle can still be operated legally if it loses 6 psi in a minute during the leak-down test.

• True

• False

Which system component is tested during the leak-down test?

• Engine

• Fuel system

• Air brake system

• Cooling system

What condition must the vehicle be in to begin a proper leak-down test?

• In motion at 5 mph

• Engine revving at idle

• Key on, engine off, air pressure fully built

• Brakes fully applied