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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 .
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 Scam 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.
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.
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.