T4 BRAKES ASE EXAMINATION TEST 2026
COMPLETE QUESTIONS WITH SOLUTIONS
GRADED A+
⩥ Psi loss rate for combination vehicle. Answer: less than 3 psi/minute
⩥ Service Brake Pressure Drop Test. Answer: 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. Answer: Cause
1) brake imbalance
2) increased stopping distance
3) excessive heat and wear
⩥ Instability and premature wear. Answer: 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. Answer: 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. Answer: 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. Answer: 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". Answer: 1) tank closest to the
compressor.
, 2) "pop off valve" located on this tank to keep from over pressuring the
system.
⩥ Pop-off valve. Answer: 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. Answer: 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. Answer: 1) used to keep condensation out of the system
using a desiccant material to remove moisture.
2
⩥ Air Compressor troubleshooting. Answer: 1) can develop air leaks and
pass oil into the brake system which will cause poor braking and or
grabbing or dragging.
COMPLETE QUESTIONS WITH SOLUTIONS
GRADED A+
⩥ Psi loss rate for combination vehicle. Answer: less than 3 psi/minute
⩥ Service Brake Pressure Drop Test. Answer: 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. Answer: Cause
1) brake imbalance
2) increased stopping distance
3) excessive heat and wear
⩥ Instability and premature wear. Answer: 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. Answer: 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. Answer: 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. Answer: 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". Answer: 1) tank closest to the
compressor.
, 2) "pop off valve" located on this tank to keep from over pressuring the
system.
⩥ Pop-off valve. Answer: 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. Answer: 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. Answer: 1) used to keep condensation out of the system
using a desiccant material to remove moisture.
2
⩥ Air Compressor troubleshooting. Answer: 1) can develop air leaks and
pass oil into the brake system which will cause poor braking and or
grabbing or dragging.
