T4 ASE Brakes Exam Questions With Correct
Answers 2025\2026 A+ Grade
Psi loss rate for Straight Truck
- accurate answers-2 psi/minute
Psi loss rate for combination vehicle
- accurate answers-less than 3 psi/minute
Service Brake Pressure Drop Test
- accurate answers-Apply service brake to 90 psi. Loss rate should be less than
3 psi/minute for straight vehicles and less than 4 psi/minute for combination
vehicles.
Improperly adjusted brake shoes
- accurate answers-Cause
1) brake imbalance
2) increased stopping distance
3) excessive heat and wear
Instability and premature wear
- accurate answers-a 4 psi difference in the air delivery between axles is
enough to cause instability and premature wear.
Troubleshooting poor brake performance due to air
- accurate answers-1) inspect air compressor
2) verify pressure build up
3) look for clogged air compressor filter
4) possible slipping belt
5) possible air leaks
6) possible defective governor
Pressure Governors
- accurate answers-1) regulates air going to system
2) adjustable pressure
3) defective governor or out of adjustment can cause compressor to function
improperly.
4) designed to regulate the compressors output.
, 5) may be attached to compressor or externally mounted.
Air Compressors
- accurate answers-1) Power is transferred to the air compressor by either an
internal gear or by an external belt. Belt is most common.
2)air can be drawn directly from the atmosphere through a filter.
3) Pistons push the air through a discharge valve to the supply reservoir.
Supply Reservoir "Wet Tank"
- accurate answers-1) tank closest to the compressor.
2) "pop off valve" located on this tank to keep from over pressuring the
system.
Pop-off valve
- accurate answers-Also known as the pressure relief valve, exhaust valve,
adjustable pressure limiting (APL) valve, or overflow valve; this valve is the
point of exit of excessive pressure buildup before damaging air components.
Manual and Automatic Drain Valves
- accurate answers-1) installed in each reservoir/tank to help purge the
system from moisture.
2)Used in high humid or wet climates.
3) manual drain valves should be drained on a daily basis
Air Dryer
- accurate answers-1) used to keep condensation out of the system using a
desiccant material to remove moisture.
2
Air Compressor troubleshooting
- accurate answers-1) can develop air leaks and pass oil into the brake system
which will cause poor braking and or grabbing or dragging.
2) clogged air intake filter will cause slow pressure build up.
Answers 2025\2026 A+ Grade
Psi loss rate for Straight Truck
- accurate answers-2 psi/minute
Psi loss rate for combination vehicle
- accurate answers-less than 3 psi/minute
Service Brake Pressure Drop Test
- accurate answers-Apply service brake to 90 psi. Loss rate should be less than
3 psi/minute for straight vehicles and less than 4 psi/minute for combination
vehicles.
Improperly adjusted brake shoes
- accurate answers-Cause
1) brake imbalance
2) increased stopping distance
3) excessive heat and wear
Instability and premature wear
- accurate answers-a 4 psi difference in the air delivery between axles is
enough to cause instability and premature wear.
Troubleshooting poor brake performance due to air
- accurate answers-1) inspect air compressor
2) verify pressure build up
3) look for clogged air compressor filter
4) possible slipping belt
5) possible air leaks
6) possible defective governor
Pressure Governors
- accurate answers-1) regulates air going to system
2) adjustable pressure
3) defective governor or out of adjustment can cause compressor to function
improperly.
4) designed to regulate the compressors output.
, 5) may be attached to compressor or externally mounted.
Air Compressors
- accurate answers-1) Power is transferred to the air compressor by either an
internal gear or by an external belt. Belt is most common.
2)air can be drawn directly from the atmosphere through a filter.
3) Pistons push the air through a discharge valve to the supply reservoir.
Supply Reservoir "Wet Tank"
- accurate answers-1) tank closest to the compressor.
2) "pop off valve" located on this tank to keep from over pressuring the
system.
Pop-off valve
- accurate answers-Also known as the pressure relief valve, exhaust valve,
adjustable pressure limiting (APL) valve, or overflow valve; this valve is the
point of exit of excessive pressure buildup before damaging air components.
Manual and Automatic Drain Valves
- accurate answers-1) installed in each reservoir/tank to help purge the
system from moisture.
2)Used in high humid or wet climates.
3) manual drain valves should be drained on a daily basis
Air Dryer
- accurate answers-1) used to keep condensation out of the system using a
desiccant material to remove moisture.
2
Air Compressor troubleshooting
- accurate answers-1) can develop air leaks and pass oil into the brake system
which will cause poor braking and or grabbing or dragging.
2) clogged air intake filter will cause slow pressure build up.
