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
2
Q
A pressure reading of 00.0 psig is theoretically equal to __________.
A
14.7 psia
3
Q
Which unit of measurement is used to measure mechanical potential energy?
A
Foot-pounds
4
Q
Mechanical energy in transition is referred to as __________.
A
work
5
Q
Power is defined as the __________ .
A
rate of doing work
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
7
Q
A compound bourdon tube gauge is capable of measuring pressure and __________ .
A
vacuum
8
Q
A compound gauge is used to measure __________ .
A
pressure and vacuum
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
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
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
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
13
Q
A valve installed in a hydraulic system to control the reversal of fluid flow is called a __________ .
A
directional control valve
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
15
Q
A hydraulic system directional control valve fitted with ‘detent’ will __________ .
A
usually be shifted into three specific positions
16
Q
Return lines to hydraulic systems reservoirs should__________ .
A
end the return line as far as practicable from the pump suction
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
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
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
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
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
22
Q
The rubber bladder or separator bag installed in a hydraulic accumulator should only be filled with __________ .
A
dry nitrogen
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
24
Q
blank
A
blank
25
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
D absorb sudden changes in hydraulic fluid flow occurring in the system
26
A hydraulic fluid flow control circuit, controlling linear actuator speed, with the pump operating below maximum operating pressure is known as the __________.
bleed-off circuit
27
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 __________ .
two to three times the normal flow rate through the system
28
The purpose of an accumulator in a hydraulic system is to __________.
store potential energy in the form of hydraulic fluid under pressure in the system
29
Dry seal threads, typically used for tubing to pipe connectors, and threaded piping in hydraulic systems are __________.
different than NPT as the crest of a matching thread is in contact with the trough of the opposing threads
30
Most solenoid valves are actuated by __________ .
an electromagnet
31
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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
```
B unloading valve
32
Copper is sometimes used for fluid power lines because it __________.
has high resistance to corrosion
33
Hydraulic system tubing should be anchored every three or four feet to prevent __________ .
tube fitting leaks from vibration and pressure surges
34
Plug valves installed in hydraulic systems are most suitable for use as __________.
two position flow control valves
35
Which of the listed pressure control valves would be used to establish the maximum operating pressure of a hydraulic system?
Pressure-relief valve
36
The portion of a hydraulic hose that determines its overall strength is the __________.
braided inner layer(s)
37
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.
D All of the above.
38
To charge a bladder type hydraulic accumulator __________.
remove all hydraulic system pressure and bring the pneumatic pressure to the accumulator preload pressure
39
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Directional control valves used in hydraulic systems may be positioned __________ .
A manually
B mechanically
C electrically
D all of the above
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D all of the above
40
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 __________.
metered-out circuit
41
The size of flexible hose used in a hydraulic system is indicated by __________ .
the numerical designation found on the 'skin' of the hose
42
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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
```
C quad ring
43
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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
```
B sequence valve
44
A casing drain is provided for axial piston and bent axis variable stroke pumps to __________ .
prevent damage due to agitation and overheating of oil accumulated in the casing as a result of normal internal leakage
45
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 The hose may pull loose from its fittings.
46
Flanged joints in high pressure hydraulic system piping are commonly made leak proof by __________ .
incorporating the use of neoprene o-rings
47
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
D all of the above
48
Which component in a hydraulic system is commonly used to prevent the stray movements of a vertical load until required?
counterbalance valve
49
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.
B The single-acting ram is not retracted by means of hydraulic force.
50
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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.
```
C There is no fluid flow.
51
Before doing any work on a hydraulic system equipped with accumulators, you should __________.
bleed off all stored energy from the accumulators
52
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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.
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C Increased wear of moving parts.
53
The torque rating of a fluid power motor is expressed in __________.
inch-pounds at a given RPM
54
Setting the relief valve opening pressure in a hydraulic system lower than the required operating pressure will result in __________ .
overheating of the system
55
If the pump in a hydraulic system produces a low rumbling noise while in operation, this is a probable indication of __________.
air passing through the pump
56
In a fixed displacement axial piston hydraulic motor, the speed is varied by __________ .
controlling the input flow rate
57
If the flow rate to a linear actuator is reduced by half of the original amount, the __________ .
speed of the actuator will be reduced
58
Which of the following problems may be encountered by using an oil having a viscosity higher than that specified for an operating hydraulic system?
Increased power consumption.
59
The speed of a radial piston hydraulic MOTOR is controlled by varying the __________ .
fluid flow rate discharged to the motor
60
The usual number of single-acting pistons used in a variable stroke axial-piston pump is __________ .
7 or 9, according to USCG
61
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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
```
D all of the above
62
The amount of the cushioning effect developed within a hydraulic cylinder is determined by the __________ .
setting of the cushioning adjustment needle valve
63
When normal operating pressure is applied to the hydraulic oil used in a high-pressure system, the oil __________ .
volume will decrease
64
The delivery rate of a variable stroke axial piston hydraulic pump is controlled by varying the position of the __________.
tilting box
65
Hydraulic pumps most commonly used in steering systems are of the __________ .
axial piston type
66
How can the chance of contaminating hydraulic fluid be decreased when working on hydraulic systems?
Clean the fittings before they are installed.
67
With an increase in temperature, the volume of hydraulic fluid __________.
increases
68
Water allowed to accumulate in the hydraulic system oil will cause an oxidation process producing by-products which are normally __________ .
gums, acids, and varnishes
69
New piping and tubing to be installed in a hydraulic system can be safely degreased by using __________.
a special petroleum solvent
70
Which characteristic or condition will have the greatest effect on increasing a hydraulic oil's viscosity?
pour point
71
Lint from cleaning rags can be harmful to hydraulic systems because the lint __________ .
can clog filters and promote component leakage
72
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73
Hydraulic machinery failures are commonly caused by misalignment of the system components and by __________.
hydraulic fluid contamination
74
Purging air from a hydraulic system is necessary when __________.
the system has been drained and then filled with new oil
75
Increased internal leakage, in addition to poor hydraulic system response, and inadequate lubrication, is the result of __________.
low hydraulic oil viscosity
76
After installing a new hydraulic pump in a system, what special attention should be given to the hydraulic system?
The filters and strainers should be checked frequently.
77
When new piping sections have been fabricated for installation in a hydraulic system, prior to installation the piping should be __________.
descaled by using a pickling solution
78
If a radial piston hydraulic pump fails to deliver rated fluid volume, the cause can be __________ .
obstructed suctions passage
79
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be __________ .
a blockage in the line between the pump and hydraulic motor
80
In an electro-hydraulic steering system, rudder shock is limited by __________ .
relief valves
81
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.
B A hydraulic accumulator
82
Under normal operating conditions, the rudder is hydraulically locked unless __________.
a rudder order is given by the control system
83
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by __________ .
a clogged air vent filter on the oil reservoir
84
Air trapped in the hydraulic fluid of a steering system should be indicated by __________ .
an improper rudder response
85
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.
D The internal parts of the pump and hydraulic motor will wear excessively.
86
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.
C A vacuum condition has developed in the reservoir.
87
If a hydraulic pump is producing a noisy whine when in operation, the cause may be __________.
an air leak in the pump suction line above the oil level in the reservoir
88
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?
The follow-up gear
89
While inspecting the steering system at sea, you should check for __________ .
any leaks in the system
90
If the pump for a hydraulic anchor windlass is overheating, the cause may be __________ .
excessive pump discharge pressure
