Transit Bus ASE Test
Preparation - (Test H4) Brake
Test - part 2 with 100% correct
anwers
In the pictures above, Technician A says draining fluid from one side will
drain all the gear oil from both differential and both planetary gear hub
ends. Technician B says you must check and fill gear oil from just the
differential; this will fill both planetary hub ends. Who is right?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
Answer D is correct. Technician A is wrong because draining one side will
not drain all the gear oil from the differential and both planetary gear
hubs; they must be independently drained and filled. Technician B is
wrong because you must fill and check the gear oil level separately.
When adjusting wheel bearings, Technician A says torque the adjusting
nut to 200 ft.llbs, then back off one turn, re-torque to 50 ft.llbs, and
perform a specified final back off followed by an end play check.
Technician B says wheel end play should be measured with a dial indicator.
Who is right?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
Answer C is correct. Technicians A and B are accurately describing steps in
the TMC wheel end procedure, which
every truck technician should know.
When discussing excessive air pressure drops during routine stops,
Technician A says that the slack adjusters may be out of adjustment.
Technician B says that it could be caused by a build-up of moisture in the
reservoirs. Who is right?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
,Answer C is correct. Both technicians are correct. Slack adjusters that are
out of adjustment demand greater brake chamber travel, which requires a
larger volume of air. A build-up of moisture in the reservoirs decreases the
volume of reserve air so each brake application will use up more of the
volume available.
When replacing brake linings on the front axle of a bus, all statements are
true EXCEPT:
A. replace return springs.
B. lubricate all moving parts in the foundation brake system before the
bus goes back in service.
C. replace camshaft seals.
D. cam bushings should not exceed 0.030" of play.
Answer C is correct. Replace the seals only if they are damaged, leaking,
or servicing the camshaft and camshaft
bushings. Answers A, B, and D are true when doing a brake reline.
Replacing the return springs, lubricate the moving
parts in the foundation brake system when the linings have been installed,
which include the camshaft, anchor pins, and
slack adjuster, (be careful not to get grease on brake linings) and replace
the cam bushings when play exceeds 0.030", are
all correct when replacing the brake linings.
What would be a result of a technician installing a wheel speed sensor
more than specified air
gap?
A. Output voltage would increase.
B. Output voltage would decrease.
C. Input voltage would increase.
D. Input voltage would decrease.
Answer B is correct. More of gap between the sensor and the reluctor
wheel, the lower the output voltage. Answers C and
D are wrong. The sensor produces an AC output voltage. Answer A is
wrong. An increase in voltage would be a result of
a sensor closer to the tone/reluctor wheel.
Which of these is the LEAST-Likely cause of wheel bearing failure?
A. Overloading
B. Contamination
C. A damaged race
D. Improper lubricant
Answer A is correct. Overloading is the LEAST-Likely cause of a wheel
bearing failure because bearings are specified for the expected load
capabilities of a vehicle with a generous margin of error. Contamination,
damaged race, and improper lubricant are more common causes of
bearing failure.
, All of the following are common brake testers EXCEPT:
A. performance-based brake testers.
B. hydraulic tester.
C. electronic tester
D. mechanical tester
Answer B is correct. A PBBT measures brake forces at each wheel.
Electronic testers, such as Vericom and Fraser,
sense rate of speed change and then uses this data to calculate stopping
distances and a mechanical tester such as Tapley
meter is a pendulum device that measures deceleration but only saves a
value that represents the maximum deceleration
reached during the stop.
A technician is performing an air pressure balance test between the front
axle and rear axle of a bus. Where should the pressure gauges be located?
A. At the brake application valve
B. At two corresponding relay valves
C. At each of the corresponding reservoirs
D. At two corresponding brake chambers
Answer D is correct. When performing an air pressure balance test the
test gauges should be located at two corresponding brake chambers
because the pressure is important but so is the timing of the delivery. The
distance the air has to travel and the condition of the lines and fittings will
affect this, so the gauges should be as close to the brake assemblies as
possible.
When checking air pressure brake balance on a bus, what is the maximum
permitted variation
from axle to axle?
A. 4 psi (27.6 kPa)
B. 8 psi (55.2 kPa)
C. 12 psi (82.7 kPa)
D. 16psi(1l0.3kPa)
Answer A is correct. Test specification for air pressure variation from axle
to axle on the same vehicle is no more than 4 psi.
What force in spring brake chambers is being used to brake the vehicle
when an inversion valve is operating during a failure?
A. Spring brake power spring
B. Service air
C. Service chamber retraction spring
D. Hold-off air
Answer A is correct. An inversion valve is a failure back-up device that
helps control braking in the event of a catastrophic primary brake system
failure by modulating the hold-off pressure in the spring brake chambers;
Preparation - (Test H4) Brake
Test - part 2 with 100% correct
anwers
In the pictures above, Technician A says draining fluid from one side will
drain all the gear oil from both differential and both planetary gear hub
ends. Technician B says you must check and fill gear oil from just the
differential; this will fill both planetary hub ends. Who is right?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
Answer D is correct. Technician A is wrong because draining one side will
not drain all the gear oil from the differential and both planetary gear
hubs; they must be independently drained and filled. Technician B is
wrong because you must fill and check the gear oil level separately.
When adjusting wheel bearings, Technician A says torque the adjusting
nut to 200 ft.llbs, then back off one turn, re-torque to 50 ft.llbs, and
perform a specified final back off followed by an end play check.
Technician B says wheel end play should be measured with a dial indicator.
Who is right?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
Answer C is correct. Technicians A and B are accurately describing steps in
the TMC wheel end procedure, which
every truck technician should know.
When discussing excessive air pressure drops during routine stops,
Technician A says that the slack adjusters may be out of adjustment.
Technician B says that it could be caused by a build-up of moisture in the
reservoirs. Who is right?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
,Answer C is correct. Both technicians are correct. Slack adjusters that are
out of adjustment demand greater brake chamber travel, which requires a
larger volume of air. A build-up of moisture in the reservoirs decreases the
volume of reserve air so each brake application will use up more of the
volume available.
When replacing brake linings on the front axle of a bus, all statements are
true EXCEPT:
A. replace return springs.
B. lubricate all moving parts in the foundation brake system before the
bus goes back in service.
C. replace camshaft seals.
D. cam bushings should not exceed 0.030" of play.
Answer C is correct. Replace the seals only if they are damaged, leaking,
or servicing the camshaft and camshaft
bushings. Answers A, B, and D are true when doing a brake reline.
Replacing the return springs, lubricate the moving
parts in the foundation brake system when the linings have been installed,
which include the camshaft, anchor pins, and
slack adjuster, (be careful not to get grease on brake linings) and replace
the cam bushings when play exceeds 0.030", are
all correct when replacing the brake linings.
What would be a result of a technician installing a wheel speed sensor
more than specified air
gap?
A. Output voltage would increase.
B. Output voltage would decrease.
C. Input voltage would increase.
D. Input voltage would decrease.
Answer B is correct. More of gap between the sensor and the reluctor
wheel, the lower the output voltage. Answers C and
D are wrong. The sensor produces an AC output voltage. Answer A is
wrong. An increase in voltage would be a result of
a sensor closer to the tone/reluctor wheel.
Which of these is the LEAST-Likely cause of wheel bearing failure?
A. Overloading
B. Contamination
C. A damaged race
D. Improper lubricant
Answer A is correct. Overloading is the LEAST-Likely cause of a wheel
bearing failure because bearings are specified for the expected load
capabilities of a vehicle with a generous margin of error. Contamination,
damaged race, and improper lubricant are more common causes of
bearing failure.
, All of the following are common brake testers EXCEPT:
A. performance-based brake testers.
B. hydraulic tester.
C. electronic tester
D. mechanical tester
Answer B is correct. A PBBT measures brake forces at each wheel.
Electronic testers, such as Vericom and Fraser,
sense rate of speed change and then uses this data to calculate stopping
distances and a mechanical tester such as Tapley
meter is a pendulum device that measures deceleration but only saves a
value that represents the maximum deceleration
reached during the stop.
A technician is performing an air pressure balance test between the front
axle and rear axle of a bus. Where should the pressure gauges be located?
A. At the brake application valve
B. At two corresponding relay valves
C. At each of the corresponding reservoirs
D. At two corresponding brake chambers
Answer D is correct. When performing an air pressure balance test the
test gauges should be located at two corresponding brake chambers
because the pressure is important but so is the timing of the delivery. The
distance the air has to travel and the condition of the lines and fittings will
affect this, so the gauges should be as close to the brake assemblies as
possible.
When checking air pressure brake balance on a bus, what is the maximum
permitted variation
from axle to axle?
A. 4 psi (27.6 kPa)
B. 8 psi (55.2 kPa)
C. 12 psi (82.7 kPa)
D. 16psi(1l0.3kPa)
Answer A is correct. Test specification for air pressure variation from axle
to axle on the same vehicle is no more than 4 psi.
What force in spring brake chambers is being used to brake the vehicle
when an inversion valve is operating during a failure?
A. Spring brake power spring
B. Service air
C. Service chamber retraction spring
D. Hold-off air
Answer A is correct. An inversion valve is a failure back-up device that
helps control braking in the event of a catastrophic primary brake system
failure by modulating the hold-off pressure in the spring brake chambers;
