Name:
Class:
Date:
1. Which of the following would represent atmospheric pressure at sea level?
a.
14.7 psi
b.
29.8 inches Hg
c.
101.3 kPa
d.
all of the above
d
2. Hydraulic pressure is used in ?
a.
Brakes systems
b.
Steering systems
c.
Automatic transmissions
d.
All of the above
d
3. Which of the following hydraulic principles would best apply to the operation of a truck wet line kit?
a.
hydromechanics
b.
hydrostatics
c.
hydroponics
d.
hydrodynamics
b
4. Which of the following hydraulics principles would describe how torque is transmitted through a torque converter?
a.
hydromechanics
b.
hydrostatics
c.
hydrodynamics
d.
hydroplaning
5. Who’s law states that when pressure is applied to a confined liquid, the force is applied to the area of containment will
be uniform throughout?
a.
Bernoulli
b.
Pascal
c.
Charles
d.
Boyle
b
6. If you had a tubular column of one square inch diameter that extended from sea level to 50 miles into the stratosphere,
how much would the air in the tube weigh?
a.
101.3 kilograms
b.
14.7 kilograms
c.
101.3 pounds
d.
14.7 pounds
d
7. If you had a pressure gauge calibrated in psia that was subject only to atmospheric pressure, what would be displayed
on its scale at sea level?
a.
zero
b.
14.7
c.
29.8
d.
101.3
b
8. If you had a pressure gauge calibrated in psi that was subject only to atmospheric pressure, what would be displayed on
its scale at sea level?
a.
zero
b.
14.7
c.
29.8
d.
101.3
9. Technician A says that an example of force is any kind of pushing effort. Technician B says that an example of force is
Name:
Class:
Date:
any kind of pulling effort. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
10. How is the formula for force calculated?
a.
work multiplied by area
b.
power divided by area
c.
pressure divided by area
d.
pressure multiplied by area
11. Which of the following best describes what is meant by a perfect vacuum?
a.
any pressure below atmospheric
b.
a volume in which all matter is evacuated
c.
suction side of a hydraulic circuit
d.
a psia gauge reading of less than 14.7
b
12. Which of the following would be found in a sealed vessel that was subject to a perfect vacuum?
a.
air only
b.
oxygen only
c.
nitrogen only
d.
nothing
13. On a hydraulic circuit with a reservoir vented to atmospheric pressure, which of the following best explains what
moves the fluid from the reservoir to the pump inlet?
a.
static head pressure from the atmosphere
b.
suction at the pump inlet
c.
inertia of fluid established at pump outlet
d.
vortex of fluid flow through pump
14. Which of the following fit the description of a fluid?
a.
gases
b.
liquids
c.
vapors
d.
all of the above
15. Technician A says that all gases can be classified as fluids. Technician B says that all liquids can be classified as
fluids. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
16. Technician A says that a reading of one psi on a pressure gauge is equal to approximately 2-inches of Hg (mercury)
measured on a manometer. Technician B says that one inch of Hg is equivalent to approximately 2-inches of H20 on a
manometer. Who is correct?
a.
Technician A only
b.
Technician B only
Name:
Class:
Date:
c.
Both A and B
d.
Neither A nor B
ANSWER:
a
17. Which of the following expresses flow rate in a hydraulic circuit?
a.
feet per second (fps)
b.
gallons per minute (gpm)
c.
feet head
d.
all of the above
b
18. In a confined hydraulic circuit, what must happen when there is flow through the circuit?
a.
pressure rise
b.
pressure drop
c.
fluid leakage
d.
fluid pressure spikes
ANSWER:
b
19. Which of the following is the equation used to calculate work in hydraulic circuits?
a.
force multiplied by distance
b.
force divided by distance
c.
area multiplied by pressure
d.
area divided by pressure
20. In hydraulics, what is the machine that creates the mechanical force required to rotate a pump known as?
a.
lever
b.
engine
c.
bell crank
d.
prime mover
ANSWER:
d
21. What is the term used to describe the streamlining of flow through a hydraulic circuit?
a.
boundary lubrication
b.
hydrodynamics
c.
laminar flow
d.
pressure wave reflection
ANSWER:
c
22. Which of the following truck hydraulic systems would use an open circuit principle?
a.
garbage packer cylinders
b.
tail lift gate
c.
dump ram
d.
power-assisted steering
d
23. Technician A says that in an open center circuit the hydraulic pump is rested (unloaded)when flow is not required by
the actuator. Technician B says that in a closed-center circuit, the hydraulic pump runs continuously. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
ANSWER:
d
24. Technician A says that accumulators are used to store potential energy in a hydraulic circuit. Technician B says that
accumulators can be used to dampen shock and buffer sudden pressure rises. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
ANSWER:
c
Name:
Class:
Date:
25. What is used to apply force to an accumulator in a hydraulic circuit?
a.
spring force
b.
weight force
c.
gas pressure
d.
all of the above
d
26. Which of the following pumps would usually be classified as non-positive displacement?
a.
plunger
b.
wobble plate
c.
gear
d.
engine coolant pump
ANSWER:
d
27. Technician A says that most hydraulic circuits use positive displacement pumps. Technician B says that pressure only
results in a hydraulic circuit when some resistance to flow is provided. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
ANSWER:
28. Which of the following will have most influence in determining the volume of oil moved through a pump described as
fixed displacement?
a.
inlet flow area
b.
outlet flow area
c.
restriction downstream from outlet
d.
rotational speed of pump
ANSWER:
d
29. Technician A says that a vane pump is classified as non-positive. Technician B says that a gear pump uses a positive
displacement pumping principle. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
b
30. Where would you most likely find a hydraulic vane pump in a heavy-duty truck?
a.
cab lift hydraulics
b.
power-assisted steering circuit
c.
engine coolant pump
d.
fuel transfer pump
b
31. In a typical vane type pump, what does the rotor turn within?
a.
barrel
b.
swash cylinder
c.
cam ring
d.
bushing
ANSWER:
32. Technician A says that in an unbalanced vane pump, there is usually just a single outlet port. Technician B says that a
balanced vane pump will usually have a pair of inlet and a pair of outlet ports. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
ANSWER:
33. Technician A says that changing the swash angle in a swashplate pump varies the displacement of the pump.
Name:
Class:
Date:
Technician B says that some swashplate pumps are fixed displacement. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
34. Technician A says that a swashplate pump is sometimes described as a wobble plate. Technician B says that pumping
action in a swashplate pump is created when the swashplate rotates. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
b
35. Where might you find a cam-actuated, radial piston pump on a highway truck?
a.
fuel transfer pump
b.
common-rail, diesel fuel injection system
c.
PTO wet line kit
d.
cab-lift hydraulics
b
36. Technician A says that as pump discharge pressure increases, internal leakage decreases. Technician B says that
internal leakage is caused by back pressure. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
b
37. What do car carrier trailers usually use to actuate several separate hydraulic circuits?
a.
a battery-driven electric motor
b.
several battery-driven electric motors
c.
engine-driven PTO pump
d.
transmission-driven PTO pump
b
38. What is an application of a counterbalance valve?
a.
maintaining back pressure
b.
acts as a relief valve
c.
pressure reduction
d.
safety pop-off
39. What type of valve is often used to control the speed of an actuator?
a.
pilot operated relief
b.
flow control
c.
pressure control
d.
counter balance
b
40. Which of the following can be used as directional control valves?
a.
check
b.
pilot
c.
spool
d.
all of the above
d
41. What type of valve is used as the primary directional control valve in most hydraulic circuits?
Name:
Class:
Date:
a.
ball and poppet
b.
gate valve
c.
spool valve
d.
pressure relief valve
42. Technician A says that spool valves may be controlled hydraulically or electrically. Technician B says that spool
valves can be controlled manually or pneumatically. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
43. Which of the following terms would properly define a hydraulic cylinder?
a.
rotary actuator
b.
linear actuator
c.
linear motor
d.
linear pump
44. Technician A says that a single acting cylinder can have a wet side and a dry side. Technician B says that an example
of a double-acting cylinder would be the ram used to raise a dump truck box. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
45. Which of the following will have most influence over the rpm of a hydraulic pump?
a.
output flow of oil
b.
pressure of oil
c.
input flow of oil
d.
load applied to pump output
46. What is the nominal diameter of hydraulic hose rated at #6 dash?
a.
1/4 inch
b.
3/8 inch
c.
1/2 inch
d.
5/8 inch
47. Which of the following types of hydraulic hose should be used to sustain the highest pressures and surge spikes?
a.
fabric braid
b.
single wire braid
c.
multiple wire braid
d.
spiral wire braid
48. Technician A says that when coupling hydraulic fittings, pipe seal compound should usually be applied to female ends
only. Technician A says that when final torquing hydraulic fittings, two wrenches should always be used. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
49. Technician A says that ISO 32 is the most commonly used viscosity grade for hydraulic fluids. Technician B says that
ISO 32 is equivalent to SAE 20 grade. Who is correct?
a.
Technician A only
b.
Technician B only
Name:
Class:
Date:
c.
Both A and B
d.
Neither A nor B
50. What is the usual cause of a hydraulic oil that has a milky appearance?
a.
aeration
b.
contamination with engine oil
c.
contamination with water
d.
chemical breakdown
51. What does a hydraulic analyzer test?
a.
circuit flow
b.
peak pressure
c.
circuit leakage
d.
all of the above
d
52. Technician A says that pump flow at maximum pressure should be at least 75% of the flow measured at 0 pressure in
simple hydraulic cylinder circuit. Technician B says that one way of checking internal leakage in a simple hydraulic
cylinder circuit is to disconnect the return hose when the cylinder is actuated, and watch for leakage. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B