T4 BRAKES ASE FINAL PAPER 2026 FULL
QUESTIONS AND CORRECT ANSWERS
GRADED A+
⩥ Crack pressure. Answer: air pressure value required at the input from
the foot valve before the relay valve will send air pressure to the brakes
controlled by that valve.
Important element of brake timing and balance and is determined by
axles. Wrong timed crack pressures will cause delay or premature
braking in rear trailers or axles.
⩥ Quick Release Valve. Answer: After a stop, when the driver lifts his
foot from the brake pedal, a quick release valve allows brake actuation
air to be quickly exhausted near the brakes it serves, rather than having
to travel back through the supply line thus speeding brake release
timing.
Minimum apply and release times are .45 sec (apply time) and .55 sec
(release time)for tractors.
.6 sec (apply time) and 1.2 sec (release time) for non pulling trailers.
, ⩥ Tractor Protection Valve. Answer: Senses pressure in one or both lines
that carry air to the trailer.
Valve closes when breakaway or disconnect from trailer.
Leak test- soapy water should not exceed 1in bubble every 5 sec.
⩥ Spring Brake Valve. Answer: Limits the air pressure used to keep the
trailer parking brakes off. By means of an internal check valve.
Per Federal Motor Truck Safety Standards, The parking brake must hold
its gross weight rating stationary, on a smooth, dry, concrete roadway
facing uphill on a 20% grade.
⩥ Reservoir Safety Valve. Answer: Protects the air brake system from
excessive air pressure build up in the primary reservoir.
Leak test- Soapy water with bubbler less than 3in in 3 sec.
⩥ Automatic Moisture Ejection Valve. Answer: designed to expel
moisture and contaminants from the reservoir without manual operation.
When the governor cut-out is reached the valve opens and releases
moisture and contaminants.
QUESTIONS AND CORRECT ANSWERS
GRADED A+
⩥ Crack pressure. Answer: air pressure value required at the input from
the foot valve before the relay valve will send air pressure to the brakes
controlled by that valve.
Important element of brake timing and balance and is determined by
axles. Wrong timed crack pressures will cause delay or premature
braking in rear trailers or axles.
⩥ Quick Release Valve. Answer: After a stop, when the driver lifts his
foot from the brake pedal, a quick release valve allows brake actuation
air to be quickly exhausted near the brakes it serves, rather than having
to travel back through the supply line thus speeding brake release
timing.
Minimum apply and release times are .45 sec (apply time) and .55 sec
(release time)for tractors.
.6 sec (apply time) and 1.2 sec (release time) for non pulling trailers.
, ⩥ Tractor Protection Valve. Answer: Senses pressure in one or both lines
that carry air to the trailer.
Valve closes when breakaway or disconnect from trailer.
Leak test- soapy water should not exceed 1in bubble every 5 sec.
⩥ Spring Brake Valve. Answer: Limits the air pressure used to keep the
trailer parking brakes off. By means of an internal check valve.
Per Federal Motor Truck Safety Standards, The parking brake must hold
its gross weight rating stationary, on a smooth, dry, concrete roadway
facing uphill on a 20% grade.
⩥ Reservoir Safety Valve. Answer: Protects the air brake system from
excessive air pressure build up in the primary reservoir.
Leak test- Soapy water with bubbler less than 3in in 3 sec.
⩥ Automatic Moisture Ejection Valve. Answer: designed to expel
moisture and contaminants from the reservoir without manual operation.
When the governor cut-out is reached the valve opens and releases
moisture and contaminants.
