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License Seminar > Hydraulics > Flashcards

Hydraulics Flashcards

1
Q

The difference between the pressure at a point being measured and that of a perfect vacuum is known as __________

A

absolute pressure

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2
Q

A pressure reading of 00.0 psig is theoretically equal to __________.

A

14.7 psia

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3
Q

Which unit of measurement is used to measure mechanical potential energy?

A

Foot-pounds

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4
Q

Mechanical energy in transition is referred to as __________.

A

work

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5
Q

Power is defined as the __________ .

A

rate of doing work

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6
Q 
Which of the following terms could be applied to the simple definition 'the energy of motion'?
A	Electrical energy
B	Thermal energy
C	Potential energy
D	Kinetic energy
A

D Kinetic energy

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7
Q

A compound bourdon tube gauge is capable of measuring pressure and __________ .

A

vacuum

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8
Q

A compound gauge is used to measure __________ .

A

pressure and vacuum

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9
Q

A reservoir, as used in hydraulic systems aboard ship, is used to store hydraulic oil. Another function is to __________.

A

act as a base or foundation for the power unit

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10
Q

In order for the hydraulic pump installed in a constant flow system to maintain adequate flow, the pump suction should __________.

A

be arranged to develop a maximum vacuum of approximately 10” of mercury

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11
Q

Return lines in a non-pressurized hydraulic system reservoir should enter the tank well below the fluid surface level to __________.

A

prevent foaming

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12
Q

The component used in a hydraulic system to store potential energy in the form of hydraulic fluid under pressure, is the __________.

A

accumulator

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13
Q

A valve installed in a hydraulic system to control the reversal of fluid flow is called a __________ .

A

directional control valve

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14
Q

A device incorporating a variable orifice placed in series with a check valve in a hydraulic system, is used to __________.

A

allow throttled fluid flow in one direction only

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15
Q

A hydraulic system directional control valve fitted with ‘detent’ will __________ .

A

usually be shifted into three specific positions

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16
Q

Return lines to hydraulic systems reservoirs should__________ .

A

end the return line as far as practicable from the pump suction

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17
Q

The purpose of a restrictor valve, as it is used in a hydraulic hatch cover system, is to __________ .

A

control the speed of the hatch cover movement while closing

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18
Q 
In which of the listed hydraulic system components could an O-ring seal be satisfactorily used in providing a seal?
A	High pressure pump shaft casing
B	Low pressure pump shaft casing
C	Linear actuator without nylon insert
D	relief valve spool
A

D relief valve spool

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19
Q 
Hydraulic system reservoirs should be maintained at recommended normal levels to reduce \_\_\_\_\_\_\_\_\_\_ .
A	condensation on inside walls
B	heat retention of working fluid
C	frequency of fluid changeover
D	all of the above
A

D all of the above

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20
Q 
Which of the valves listed is NOT considered to be a hydraulic system directional control valve?
A	counterbalance valve
B	Two-position valve
C	Three-position valve
D	Detented-position valve
A

A counterbalance valve

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21
Q 
Which of the devices listed would be considered a hydraulic system directional control valve?
A	three-position valve
B	sequencing valve
C	unloading valve
D	counterbalance valve
A

A three-position valve

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22
Q

The rubber bladder or separator bag installed in a hydraulic accumulator should only be filled with __________ .

A

dry nitrogen

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23
Q 
Which of the devices listed is considered to be a hydraulic system directional control valve?
A	Unloading valve
B	Counterbalance valve
C	detented position valve
D	Sequencing valve
A

C detented position valve

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24
Q

blank

A

blank

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25
Q

One function provided by a hydraulic accumulator is to __________.
A provide an area where air can separate from the oil
B provide an area to separate solid contaminants from the oil
C act as an oil and water separator
D absorb sudden changes in hydraulic fluid flow occurring in the system

A

D absorb sudden changes in hydraulic fluid flow occurring in the system

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26
Q

A hydraulic fluid flow control circuit, controlling linear actuator speed, with the pump operating below maximum operating pressure is known as the __________.

A

bleed-off circuit

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27
Q

As a general rule of thumb, the reservoir used in a hydraulic system should have a capacity, when at the normal level, approximately equal to __________ .

A

two to three times the normal flow rate through the system

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28
Q

The purpose of an accumulator in a hydraulic system is to __________.

A

store potential energy in the form of hydraulic fluid under pressure in the system

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29
Q

Dry seal threads, typically used for tubing to pipe connectors, and threaded piping in hydraulic systems are __________.

A

different than NPT as the crest of a matching thread is in contact with the trough of the opposing threads

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30
Q

Most solenoid valves are actuated by __________ .

A

an electromagnet

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31
Q 
Which of the listed pressure-control valves would be used in a hydraulic system to temporarily divert some, or all of the pump discharge until the additional flow was required?
A	compound, pressure-relief valve
B	unloading valve
C	counterbalance valve
D	sequence valve
A

B unloading valve

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32
Q

Copper is sometimes used for fluid power lines because it __________.

A

has high resistance to corrosion

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33
Q

Hydraulic system tubing should be anchored every three or four feet to prevent __________ .

A

tube fitting leaks from vibration and pressure surges

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34
Q

Plug valves installed in hydraulic systems are most suitable for use as __________.

A

two position flow control valves

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35
Q

Which of the listed pressure control valves would be used to establish the maximum operating pressure of a hydraulic system?

A

Pressure-relief valve

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36
Q

The portion of a hydraulic hose that determines its overall strength is the __________.

A

braided inner layer(s)

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37
Q

When installing a hydraulic hose, which of the following precautions should be taken?
A The hose should not be twisted.
B The hose should be protected with a sleeve if it is subjected to rubbing.
C There should be some slack in the hose.
D All of the above.

A

D All of the above.

38
Q

To charge a bladder type hydraulic accumulator __________.

A

remove all hydraulic system pressure and bring the pneumatic pressure to the accumulator preload pressure

39
Q 
Directional control valves used in hydraulic systems may be positioned \_\_\_\_\_\_\_\_\_\_ .
A	manually
B	mechanically
C	electrically
D	all of the above
A

D all of the above

40
Q

A hydraulic fluid flow control circuit, used to control linear actuator speed during retraction, with the pump operating at above maximum pressure, is known as a __________.

A

metered-out circuit

41
Q

The size of flexible hose used in a hydraulic system is indicated by __________ .

A

the numerical designation found on the ‘skin’ of the hose

42
Q 
In application, which of the listed sealing devices is most similar to an O-ring?
A	V-ring
B	U-ring
C	quad ring
D	Cup seal
A

C quad ring

43
Q 
Which of the listed pressure control valves would be used to permit the completion of one action of a hydraulic system before a second action would be permitted?
A	Unloading valve
B	sequence valve
C	Counterbalance valve
D	Pressure-reducing valve
A

B sequence valve

44
Q

A casing drain is provided for axial piston and bent axis variable stroke pumps to __________ .

A

prevent damage due to agitation and overheating of oil accumulated in the casing as a result of normal internal leakage

45
Q

If you install a hydraulic hose on a unit and fail to leave sufficient room for expansion, which of the following problems will develop?
A The hose may pull loose from its fittings.
B The components connected by the hose will be damaged.
C The hydraulic unit will fail to acquire any power.
D The hydraulic fluid will overheat and breakdown.

A

A The hose may pull loose from its fittings.

46
Q

Flanged joints in high pressure hydraulic system piping are commonly made leak proof by __________ .

A

incorporating the use of neoprene o-rings

47
Q

In a shell-and-tube type hydraulic fluid cooler, the amount of heat transferred from the hydraulic fluid to the cooling water depends upon __________.
A the temperature of the hydraulic fluid
B the flow rate of both the cooling water and the hydraulic fluid
C the temperature of the cooling water
D all of the above

A

D all of the above

48
Q

Which component in a hydraulic system is commonly used to prevent the stray movements of a vertical load until required?

A

counterbalance valve

49
Q

Which of the following statements concerning the operation of a single-acting hydraulic ram is correct?
A Hydraulic force is applied simultaneously in two directions against the ram by directional ports.
B The single-acting ram is not retracted by means of hydraulic force.
C The single-acting ram is both extended and retracted by means of hydraulic force.
D Hydraulic force applied to a single-acting ram results in a pulling motion.

A

B The single-acting ram is not retracted by means of hydraulic force.

50
Q 
When the tilting box of a variable stroke axial-piston pump is perpendicular to the pump shaft, which of the following conditions will exist?
A	The pistons reciprocate.
B	The "B" end cylinder barrel rotates.
C	There is no fluid flow.
D	Power is transmitted hydraulically.
A

C There is no fluid flow.

51
Q

Before doing any work on a hydraulic system equipped with accumulators, you should __________.

A

bleed off all stored energy from the accumulators

52
Q 
Which of the following problems occurring in a hydraulic system can be caused by using an oil having a viscosity lower than specified?
A	Seal deterioration.
B	Condensation and rust formation.
C	Increased wear of moving parts.
D	Increase in internal fluid friction.
A

C Increased wear of moving parts.

53
Q

The torque rating of a fluid power motor is expressed in __________.

A

inch-pounds at a given RPM

54
Q

Setting the relief valve opening pressure in a hydraulic system lower than the required operating pressure will result in __________ .

A

overheating of the system

55
Q

If the pump in a hydraulic system produces a low rumbling noise while in operation, this is a probable indication of __________.

A

air passing through the pump

56
Q

In a fixed displacement axial piston hydraulic motor, the speed is varied by __________ .

A

controlling the input flow rate

57
Q

If the flow rate to a linear actuator is reduced by half of the original amount, the __________ .

A

speed of the actuator will be reduced

58
Q

Which of the following problems may be encountered by using an oil having a viscosity higher than that specified for an operating hydraulic system?

A

Increased power consumption.

59
Q

The speed of a radial piston hydraulic MOTOR is controlled by varying the __________ .

A

fluid flow rate discharged to the motor

60
Q

The usual number of single-acting pistons used in a variable stroke axial-piston pump is __________ .

A

7 or 9, according to USCG

61
Q 
The pressure of an operating hydraulic system, as indicated by a pressure gauge, is a result of the fluid flow overcoming \_\_\_\_\_\_\_\_\_\_.
A	the load applied to the system
B	resistance of the internal components
C	internal resistance to flow
D	all of the above
A

D all of the above

62
Q

The amount of the cushioning effect developed within a hydraulic cylinder is determined by the __________ .

A

setting of the cushioning adjustment needle valve

63
Q

When normal operating pressure is applied to the hydraulic oil used in a high-pressure system, the oil __________ .

A

volume will decrease

64
Q

The delivery rate of a variable stroke axial piston hydraulic pump is controlled by varying the position of the __________.

A

tilting box

65
Q

Hydraulic pumps most commonly used in steering systems are of the __________ .

A

axial piston type

66
Q

How can the chance of contaminating hydraulic fluid be decreased when working on hydraulic systems?

A

Clean the fittings before they are installed.

67
Q

With an increase in temperature, the volume of hydraulic fluid __________.

A

increases

68
Q

Water allowed to accumulate in the hydraulic system oil will cause an oxidation process producing by-products which are normally __________ .

A

gums, acids, and varnishes

69
Q

New piping and tubing to be installed in a hydraulic system can be safely degreased by using __________.

A

a special petroleum solvent

70
Q

Which characteristic or condition will have the greatest effect on increasing a hydraulic oil’s viscosity?

A

pour point

71
Q

Lint from cleaning rags can be harmful to hydraulic systems because the lint __________ .

A

can clog filters and promote component leakage

72
Q

blank

A

blank

73
Q

Hydraulic machinery failures are commonly caused by misalignment of the system components and by __________.

A

hydraulic fluid contamination

74
Q

Purging air from a hydraulic system is necessary when __________.

A

the system has been drained and then filled with new oil

75
Q

Increased internal leakage, in addition to poor hydraulic system response, and inadequate lubrication, is the result of __________.

A

low hydraulic oil viscosity

76
Q

After installing a new hydraulic pump in a system, what special attention should be given to the hydraulic system?

A

The filters and strainers should be checked frequently.

77
Q

When new piping sections have been fabricated for installation in a hydraulic system, prior to installation the piping should be __________.

A

descaled by using a pickling solution

78
Q

If a radial piston hydraulic pump fails to deliver rated fluid volume, the cause can be __________ .

A

obstructed suctions passage

79
Q

If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be __________ .

A

a blockage in the line between the pump and hydraulic motor

80
Q

In an electro-hydraulic steering system, rudder shock is limited by __________ .

A

relief valves

81
Q

Which of the listed pressure vessels is normally exempt from hydrostatic testing at the regular Coast Guard inspection for certification occurring four years after the initial inspection?
A Firetube auxiliary boiler
B A hydraulic accumulator
C The main boilers
D Air receiver repaired by a certified welder.

A

B A hydraulic accumulator

82
Q

Under normal operating conditions, the rudder is hydraulically locked unless __________.

A

a rudder order is given by the control system

83
Q

A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by __________ .

A

a clogged air vent filter on the oil reservoir

84
Q

Air trapped in the hydraulic fluid of a steering system should be indicated by __________ .

A

an improper rudder response

85
Q

If dirt is allowed to contaminate the sump of a hydraulic deck crane, which of the following problems will occur?
A All the seals in the hydraulic lines will immediately blow out.
B The lifting capacity of the crane will be immediately reduced by 70%.
C The sheathing on the hydraulic lines will fracture.
D The internal parts of the pump and hydraulic motor will wear excessively.

A

D The internal parts of the pump and hydraulic motor will wear excessively.

86
Q

A hydraulic system gear pump being fed from a reservoir frequently indicates signs of excessive pitting after two months of service. Which of the following would most likely contribute to this condition?
A Abnormal pressurization is occurring in the reservoir.
B A partial restriction in the return line has developed.
C A vacuum condition has developed in the reservoir.
D Operating oil temperature is determined to be below normal.

A

C A vacuum condition has developed in the reservoir.

87
Q

If a hydraulic pump is producing a noisy whine when in operation, the cause may be __________.

A

an air leak in the pump suction line above the oil level in the reservoir

88
Q

Which of the devices listed, when used on an electro- hydraulic steering gear, keeps the movement of the rudder closely in step with the steering wheel?

A

The follow-up gear

89
Q

While inspecting the steering system at sea, you should check for __________ .

A

any leaks in the system

90
Q

If the pump for a hydraulic anchor windlass is overheating, the cause may be __________ .

A

excessive pump discharge pressure

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