T4 ASE BRAKES (MEDIUM/HEAVY DUTY
BRAKES) EXAM 2024/25!!WITH
CORRECT SOLUTIONS
2. The Driver Vehicle Inspection Report DVIR should be submitted :
A. according to the vehicle maintenance schedule
B. when a failure occurs
C. weekly
D. daily - ANSWER - The correct answer is D. Federal Motor Vehicle Safety Standards ( FMVSS ) require
the driver to submit a DVIR to their motor carrier or owner at the end of each day . The DVIR is used to
identify defects or deficiencies that would result in a mechanical breakdown or effect the safe operation
of a vehicle Once a driver submits the DVIR , a motor carrier or its agent must investigate and repair the
defect or deficiency .
3. Which of the following cannot cause a drum on an air - braked vehicle to overheat ?
A. an over - tightened brake adjuster at that wheel
B. under - adjusted brake ( s ) elsewhere on the vehicle
C. too - high governor cut - out pressure
D. driving downhill in too high a gear. - ANSWER - 3. The correct answer is C. The governor controls the
air compressor output by unloading or cycling it . It has no direct effect on the mechanical brake parts .
While the pressure setting is important to maintain air brake system pressure within acceptable limits ,
an incorrect setting will not cause the drum on an air - braked vehicle to overheat . All other choices
given , however , will cause overheating problems .
4. All the brakes drag on a truck with hydraulic brakes . Which of the following could be the cause ? A.
air in the hydraulic system
B. too high a vacuum supply to the power brake booster
C. a leaking secondary cup in the master cylinder
D. no brake pedal free travel - ANSWER - 4. The correct answer is D. Only a brake pedal with no free
travel will cause all of the brakes to drag . Answer A - air in the hydraulic system , will cause a spongy
pedal , while answer B - too high a vacuum to the power booster , won't affect brake drag at all . Answer
,C , a leaking secondary cup in the master cylinder , could increase pedal travel , but won't cause the
brakes to drag .
5. Which of the following could cause a pulsating brake pedal on a truck with hydraulic brakes ?
A. zero brake pedal free travel
B. glazed linings
C. an out - of - round brake drum
D. a frozen wheel cylinder piston. - ANSWER - 5. The correct answer is C. Of the choices given , only an
out - of - round brake drum can cause pulsation in a hydrau lic brake system . Answer A , zero brake
pedal free travel , will cause a dragging brake condition , but not pulsation . Answer B , glazed linings ,
will affect stopping performance and noise , and answer D , a frozen wheel cylinder , will de grade
stopping performance , but will not cause pulsation.
6. Air pressure gauges change an air pressure signal into an electronic voltage signal using which of the
following components ?
A. inductor
B. capacitor
C. transducer
D. regulator - ANSWER - 6. The correct answer is C. An element inside an air pressure transducer
responds to air pressure increase or decrease, and the transducer converts that pressure differentiation
into a voltage signal, which is displayed in a proportionate reading on the dash gauge.
7. Technician A says that linings worn too thin on an air - braked vehicle can cause the S - camshaft to
roll over . Technician B says this condition can cause excess brake pedal travel . Who is right ?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - 7. The correct answer is A. The brake adjuster is connected to a shaft that
runs perpendicular to the plane formed by the pushrod and slack adjuster. As the pushrod is extended,
the shaft rotates. The shaft, in turn, is connected to an S-shaped cam between the brake shoes. As the
shaft rotates, so does the cam. The brake shoes are forced apart and against the brake drum, creating
the friction needed to slow the vehicle. Thin brake linings can allow the S-cam to roll over, but will not
affect brake pedal travel.
, 8. Spring brakes on an air - braked vehicle must be able to hold the vehicle facing uphill or downhill on
what percent grade ?
A. 10 %
B. 20 %
C. 30 %
D. 40 % - ANSWER - 8. The correct answer is B. Per Federal Motor Vehicle Safety Standard (FMVSS) 121,
the parking brakes must be able to hold a vehicle, loaded to its gross weight rating, stationary on a
smooth, dry, concrete roadway, facing uphill or downhill on a 20% grade. In the emergency mode, the
parking brakes must be able to exert a retarding force equal to 28% of the gross axle rating.
9. The driver of a truck with hydraulic brakes says the pedal reserve is too low . Technician A says the
brakes could be out of adjustment Technician B says one brake system may have failed . Who is right ?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - 9. The correct answer is C, both Technicians are right.
Either condition will cause the driver to notice a low pedal reserve.
10. The parking brakes fail to apply on a truck with air brakes . Technician A says this could be caused by
low air pressure in the spring brake chamber . Techni cian B says this could be caused by a ruptured
spring brake diaphragm . Who is right ?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - 10. The correct answer is D, neither technician is right.
In addition to applying the service brakes used in everyday driving, the brake chambers on the rear
tractor axles and on the trailer axles apply the parking brakes. These brake chambers (spring brakes)
incorporate a second chamber containing a second diaphragm and a powerful spring.
When the vehicle is in use, air pressure supplied to the spring diaphragm compresses the spring and the
parking brakes are held off. When the vehicle is parked, the dash valves are pulled out. This exhausts
spring brake hold-off air, allowing the spring to apply the parking brakes. Neither low air pressure in the
spring brake chamber nor a ruptured diaphragm can prevent the parking brake from being applied.
BRAKES) EXAM 2024/25!!WITH
CORRECT SOLUTIONS
2. The Driver Vehicle Inspection Report DVIR should be submitted :
A. according to the vehicle maintenance schedule
B. when a failure occurs
C. weekly
D. daily - ANSWER - The correct answer is D. Federal Motor Vehicle Safety Standards ( FMVSS ) require
the driver to submit a DVIR to their motor carrier or owner at the end of each day . The DVIR is used to
identify defects or deficiencies that would result in a mechanical breakdown or effect the safe operation
of a vehicle Once a driver submits the DVIR , a motor carrier or its agent must investigate and repair the
defect or deficiency .
3. Which of the following cannot cause a drum on an air - braked vehicle to overheat ?
A. an over - tightened brake adjuster at that wheel
B. under - adjusted brake ( s ) elsewhere on the vehicle
C. too - high governor cut - out pressure
D. driving downhill in too high a gear. - ANSWER - 3. The correct answer is C. The governor controls the
air compressor output by unloading or cycling it . It has no direct effect on the mechanical brake parts .
While the pressure setting is important to maintain air brake system pressure within acceptable limits ,
an incorrect setting will not cause the drum on an air - braked vehicle to overheat . All other choices
given , however , will cause overheating problems .
4. All the brakes drag on a truck with hydraulic brakes . Which of the following could be the cause ? A.
air in the hydraulic system
B. too high a vacuum supply to the power brake booster
C. a leaking secondary cup in the master cylinder
D. no brake pedal free travel - ANSWER - 4. The correct answer is D. Only a brake pedal with no free
travel will cause all of the brakes to drag . Answer A - air in the hydraulic system , will cause a spongy
pedal , while answer B - too high a vacuum to the power booster , won't affect brake drag at all . Answer
,C , a leaking secondary cup in the master cylinder , could increase pedal travel , but won't cause the
brakes to drag .
5. Which of the following could cause a pulsating brake pedal on a truck with hydraulic brakes ?
A. zero brake pedal free travel
B. glazed linings
C. an out - of - round brake drum
D. a frozen wheel cylinder piston. - ANSWER - 5. The correct answer is C. Of the choices given , only an
out - of - round brake drum can cause pulsation in a hydrau lic brake system . Answer A , zero brake
pedal free travel , will cause a dragging brake condition , but not pulsation . Answer B , glazed linings ,
will affect stopping performance and noise , and answer D , a frozen wheel cylinder , will de grade
stopping performance , but will not cause pulsation.
6. Air pressure gauges change an air pressure signal into an electronic voltage signal using which of the
following components ?
A. inductor
B. capacitor
C. transducer
D. regulator - ANSWER - 6. The correct answer is C. An element inside an air pressure transducer
responds to air pressure increase or decrease, and the transducer converts that pressure differentiation
into a voltage signal, which is displayed in a proportionate reading on the dash gauge.
7. Technician A says that linings worn too thin on an air - braked vehicle can cause the S - camshaft to
roll over . Technician B says this condition can cause excess brake pedal travel . Who is right ?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - 7. The correct answer is A. The brake adjuster is connected to a shaft that
runs perpendicular to the plane formed by the pushrod and slack adjuster. As the pushrod is extended,
the shaft rotates. The shaft, in turn, is connected to an S-shaped cam between the brake shoes. As the
shaft rotates, so does the cam. The brake shoes are forced apart and against the brake drum, creating
the friction needed to slow the vehicle. Thin brake linings can allow the S-cam to roll over, but will not
affect brake pedal travel.
, 8. Spring brakes on an air - braked vehicle must be able to hold the vehicle facing uphill or downhill on
what percent grade ?
A. 10 %
B. 20 %
C. 30 %
D. 40 % - ANSWER - 8. The correct answer is B. Per Federal Motor Vehicle Safety Standard (FMVSS) 121,
the parking brakes must be able to hold a vehicle, loaded to its gross weight rating, stationary on a
smooth, dry, concrete roadway, facing uphill or downhill on a 20% grade. In the emergency mode, the
parking brakes must be able to exert a retarding force equal to 28% of the gross axle rating.
9. The driver of a truck with hydraulic brakes says the pedal reserve is too low . Technician A says the
brakes could be out of adjustment Technician B says one brake system may have failed . Who is right ?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - 9. The correct answer is C, both Technicians are right.
Either condition will cause the driver to notice a low pedal reserve.
10. The parking brakes fail to apply on a truck with air brakes . Technician A says this could be caused by
low air pressure in the spring brake chamber . Techni cian B says this could be caused by a ruptured
spring brake diaphragm . Who is right ?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - 10. The correct answer is D, neither technician is right.
In addition to applying the service brakes used in everyday driving, the brake chambers on the rear
tractor axles and on the trailer axles apply the parking brakes. These brake chambers (spring brakes)
incorporate a second chamber containing a second diaphragm and a powerful spring.
When the vehicle is in use, air pressure supplied to the spring diaphragm compresses the spring and the
parking brakes are held off. When the vehicle is parked, the dash valves are pulled out. This exhausts
spring brake hold-off air, allowing the spring to apply the parking brakes. Neither low air pressure in the
spring brake chamber nor a ruptured diaphragm can prevent the parking brake from being applied.
