T4 Brakes ASE: Exam Questions and Verified
Answers (GRADED A+) | Latest Update 2026/2027
| 100% GUARANTEED PASS | NEWEST VERSION!!
Psi loss rate for Straight Truck -CORRECTANSWER 2 psi/minute
Psi loss rate for combination vehicle -CORRECTANSWER less than 3 psi/minute
Service Brake Pressure Drop Test -CORRECTANSWER 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 -CORRECTANSWER Cause
1) brake imbalance
2) increased stopping distance
3) excessive heat and wear
Instability and premature wear -CORRECTANSWER 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 -CORRECTANSWER 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
Air Compressors -CORRECTANSWER 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" -CORRECTANSWER 1) tank closest to the compressor.
2) "pop off valve" located on this tank to keep from over pressuring the system.
Pop-off valve -CORRECTANSWER 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 -CORRECTANSWER 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
Pressure Governors -CORRECTANSWER 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 Dryer -CORRECTANSWER 1) used to keep condensation out of the system using a
desiccant material to remove moisture.
2
Answers (GRADED A+) | Latest Update 2026/2027
| 100% GUARANTEED PASS | NEWEST VERSION!!
Psi loss rate for Straight Truck -CORRECTANSWER 2 psi/minute
Psi loss rate for combination vehicle -CORRECTANSWER less than 3 psi/minute
Service Brake Pressure Drop Test -CORRECTANSWER 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 -CORRECTANSWER Cause
1) brake imbalance
2) increased stopping distance
3) excessive heat and wear
Instability and premature wear -CORRECTANSWER 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 -CORRECTANSWER 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
Air Compressors -CORRECTANSWER 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" -CORRECTANSWER 1) tank closest to the compressor.
2) "pop off valve" located on this tank to keep from over pressuring the system.
Pop-off valve -CORRECTANSWER 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 -CORRECTANSWER 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
Pressure Governors -CORRECTANSWER 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 Dryer -CORRECTANSWER 1) used to keep condensation out of the system using a
desiccant material to remove moisture.
2
