T4 ASE Brakes
fully solved &
updated 2025-
2026(latest
version verified
for accuracy)
Psi loss rate for Straight Truck - answer 2 psi/minute
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.
fully solved &
updated 2025-
2026(latest
version verified
for accuracy)
Psi loss rate for Straight Truck - answer 2 psi/minute
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.
