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1. Which of the following features of a hydraulic brake system are mandatory by FMVSS 105 compliant vehicle?
a.
dual hydraulic circuits
b.
mechanical parking brakes
c.
mechanical emergency brake
d.
all of the above
2. Technician A says that a dual circuit hydraulic brake system master cylinder can be known as a tandem master
cylinder. Technician B says that a tandem master cylinder has a single bore and two separate pistons. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
3. What does the term hygroscopic mean?
a.
designed to absorb moisture
b.
designed to resist moisture absorption
c.
designed to act as a hydraulic medium
d.
designed to resist expansion when subjected to temperature rise
4. Which of the following statements about a typical hydraulic brake system are true?
a.
a hydraulic brake pedal acts as a lever to multiply force
b.
application force is multiplied hydraulically by the wheel cylinders
c.
actual braking force at the wheels correlates with the mechanical force input at the pedal
d.
all of the above
5. Which of the following statements regarding the function of a tandem master cylinder during normal operation is true?
a.
primary piston is actuated mechanically
b.
secondary piston is actuated hydraulically
c.
there is a single bore
d.
all of the above
6. Technician A says that DOT 4 hydraulic brake fluid can be destroyed in as little as one hour exposure to atmospheric
air. Technician B says that DOT 5 hydraulic brake fluid is hygroscopic. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
7. What could the source(s) of hydraulic fluid pressure that operates typical brake boosters?
a.
power steering pump
b.
dedicated hydraulic pump
c.
reserve electric motor and pump
d.
all of the above
8. What is the primary function of a pressure differential valve used in a hydraulic brake circuit?
a.
alerts the driver to a partial system hydraulic failure
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b.
ensures brakes are prioritized over the power steering requirement for brake fluid
c.
alerts the driver to a partial system mechanical failure
d.
all of the above
9. Which of the following valves delays application force to front disc brakes to balance a typical disc/drum hydraulic
brake system?
a.
pressure differential valve
b.
metering valve
c.
proportioning valve
d.
load proportioning valve
10. Which of the following valve(s) is designed to reduce rear wheel lock-up to balance a disc/drum system?
a.
pressure differential valve
b.
proportioning valve
c.
metering valve
d.
all of the above
11. Which of the following are functions of a typical hydraulic brake system combination valve?
a.
delays application of front disc brakes
b.
reduces rear wheel lock-up
c.
alerts the driver to a partial circuit hydraulic failure
d.
all of the above
12. Which brake shoe in a non-servo drum brake assembly is energized during braking when a vehicle is traveling in a
forward direction?
a.
leading shoe
b.
trailing shoe
c.
both shoes
d.
neither shoe
13. What is the most common type of parking brake used on trucks equipped with an air-over-hydraulic system?
a.
canister-spring brake
b.
driveline mounted drum brake
c.
cable and lever actuated secondary shoe
d.
driveline-mounted, lever-actuated disc brake
14. When the driver depresses the brake pedal of the typical truck with air-over-hydraulic brakes, which of the following
occurs?
a.
hydraulic pressure actuates the hydraulic booster assemblies
b.
hydraulic fluid flows through the quick release valves
c.
modulated air pressure actuates pneumatic booster assemblies
d.
modulated hydraulic pressure actuates the pneumatic booster assemblies
15. Which of the following guidelines is best practice for reusing brake fluid drained during bleeding operations?
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a.
allow it to settle first in a clear container to check for contaminants
b.
filter through a strainer to remove particles
c.
boil it to remove all moisture
d.
never attempt to reuse any used brake fluid
16. A truck equipped with air-over-hydraulic brakes has illuminated a dash-warning light indicating excess brake lining
wear. What would generate this signal?
a.
the brake system ECU
b.
the rear drums
c.
ABS sensor
d.
brake pedal
17. What should be used to remove pitting and corrosion from an aluminum master cylinder bore?
a.
crocus cloth
b.
cylinder hone
c.
emery paper and a wooden dowel
d.
none of the above
d
18. What should be done before forcing a caliper piston back into its bore while servicing hydraulic disc brakes?
a.
open the bleed nut and drain the displaced fluid
b.
open the master cylinder lid to allow the fluid to return to the reservoir
c.
either A or B
d.
neither A nor B
19. Which of the following measuring tools should be used to check lateral rotor runout?
a.
micrometer
b.
dial indicator
c.
digital calipers
d.
micrometer with a Vernier scale
20. Which of the following methods would be preferred when bleeding a typical air-over-hydraulic brake system?
a.
pressure bleeder
b.
maximum air system pressure
c.
allow the system to self-bleed
d.
any of the above
21. Which of the following types of power boosters are used in light and medium-duty truck brake systems?
a.
vacuum boosters
b.
hydraulic boosters
c.
pneumatic boosters
d.
all of the above
22. Technician A says that most current truck hydraulic brake systems use single-acting wheel cylinders. Technician B
says that in a double-acting wheel cylinder, a pair of pistons are actuated from a single bore, and act on both brake shoes.
Who is correct?
a.
Technician A only
b.
Technician B only
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c.
Both A and B
d.
Neither A nor B
b
23. Technician A says that in a servo-type hydraulic drum brake, each shoe is separately anchored at its heel. Technician
B says that in a non-servo type brake system, the trailing shoe is only energized when the vehicle is travelling in reverse.
Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
d
24. Technician A says that drum servo brakes are self-energizing. Technician B says that servo brakes both primary and
secondary shoes play a role in braking the drum whether the vehicle is moving forward or in reverse. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
25. Technician A says that ABS hydraulic brake systems should be bled using a bleeder ball. Technician B says that a
bleeder ball regulates output air pressure at approximately 15 psi. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
26. When honing a cast iron master cylinder, what should be used to lubricate the hone?
a.
diesel fuel
b.
engine oil
c.
solvent
d.
brake fluid
d
27. Technician A says that contaminants tend to collect in the caliper bore of a hydraulic disc brake system so the piston
should never be forced back into its bore without cracking the bleed screw. Technician B says that ABS hydraulic brake
systems are more vulnerable to problems caused by contaminants in brake fluid. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
28. You are measuring the axial TIR of a hydraulic brake rotor and through one revolution you measure +0.003-inch and –
0.006-inch. What is the TIR?
a.
0.003-inch
b.
0.006-inch
c.
0.009-inch
d.
0.018-inch
29. Technician A says that excessive rotor runout on hydraulic brake systems can result in brake pedal pulsation.
Technician B says that excessive rotor runout can cause decreased pedal travel. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
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30. What is the primary cause of disc brake rotor warpage?
a.
excessive brake pressure
b.
over-heating
c.
operation in wet conditions
d.
panic brake stops
b