ASE T4 Domain 1: Air Brakes Diagnosis and Repair

What is the typical cause of a rapid brake chamber stroke increase when a brake application is made?

When testing a tractor with a fully charged air system, the trailer brakes do not release. What should be checked first?

What is the MOST likely cause of a spring brake chamber not releasing on a tandem axle truck?

During a high-pressure test, the air pressure drops significantly after the engine is turned off. The FIRST component to suspect would be the:

A truck with air brakes has a pedal that feels spongy and goes to the floor when applied. The most likely cause is:

The air pressure gauge shows a slower build-up of air pressure than normal. What could be the cause of this condition?

If the air brake system has a significant delay in pressure drop after the engine is shut off, what is the most likely problem?

When a service brake application feels uneven or jerky, what should be suspected?

If an automatic slack adjuster must be manually adjusted often, what is the probable cause?

A continuous air leak from the tractor protection valve exhaust with the trailer connected and the system pressurized indicates:

After replacing the brake shoes on a truck with S-cam brakes, the technician notices that one wheel requires more air pressure to apply the brake than the others. What is the MOST likely cause?

During a full-function valve test, a slow return to normal cut-out pressure after the valve is released suggests:

What would likely cause a decrease in air pressure after a foot valve rebuild during the foot valve leak test?

In a dual circuit air brake system, when one circuit fails to maintain pressure, what should be checked first?

During the initial pressure build-up from 85 to 100 psi, the air pressure rises too slowly. What component should be inspected?

A truck with S-cam drum brakes has uneven brake shoe wear. The LEAST likely cause of this would be:

A technician notices that an air brake-equipped vehicle takes longer than usual to stop. The first component to inspect should be the:

When a manual slack adjuster has more than one inch of free play at the pushrod, what is the likely cause?

A driver reports that the air pressure warning buzzer activates at normal pressures. The most likely cause is:

The spring brakes release when air pressure is removed from the parking brake circuit. What is the probable cause?

An air brake system has a new compressor but still struggles to build up pressure. What should be checked first?

After an air tank drain, the low pressure warning signal activates too late as pressure falls. The most probable cause is:

During a brake application, air pressure does not build up in the secondary circuit of a dual air system. What should be the primary area of focus for diagnosis?

A technician finds that the air brake system does not release immediately after the air pressure builds to a normal range. The probable cause is:

During an inspection, a technician observes oil in the air brake system. This is most likely due to:

When a heavy-duty truck is experiencing low braking power, and there are no air leaks or mechanical faults, the next component to inspect should be the:

During a road test, a truck's air brake system activates the ABS intermittently under normal braking conditions. The most likely cause is:

An air brake system fails the applied leakage test with higher than normal air loss. The primary component to be checked is the:

A technician notes that the air brake compressor cycles more frequently than normal. The FIRST thing to inspect would be:

A heavy-duty truck experiences uneven braking action. The most likely cause could be: