Hydraulics Flashcards
1
Q
Force is measured in units of In the metric system
A
Newton- meters
2
Q
The mass of an object is
A
A measure of the amount of matter in it
3
Q
The density of a fluid is expressed in terms of
A
Specific gravity
4
Q
The number of pounds of force applied to an area is measured in
A
Psi
5
Q
When calculating the work done by a hydraulic cylinder,you must know the hydraulic pressure and the pistons
A
Area and stroke
6
Q
The theory that states that pressure in a confined liquid is distributed equally throughout the fluid is
A
Pascal’s law
7
Q
If the force ratio between two different hydraulic pistons is a reducing ratio, the piston velocity
A
Increases
8
Q
Fluid flow in a hydraulic piping system should be
A
Laminar
9
Q
Which of the following doesn’t cause turbulence flow in hydraulic systems
A
Large-diameter pipes
10
Q
Bernoulli’s principle states that the total energy of hydraulic fluid is
A
Always constant not the same
11
Q
The functions of a hydraulic fluid include all of the following except
A
Generating heat
12
Q
The viscosity of a fluid is measured of its
A
Internal friction or resistance to flow
13
Q
Hydraulic fluid with a viscosity of 150 ssu Than one with a viscosity of 275 ssu
A
Is less viscous
14
Q
The term that describes the stability of fluid viscosity when it is heated is
A
Viscosity index
15
Q
Hydraulic oils used for low-temperature applications should have a
A
Low pour point
16
Q
The ability of a fluid to maintain lubrication between closely fitted parts under load is determined by its
A
Film strength
17
Q
What type of reaction occurs when a hydraulic fluid oxidizes
A
Chemical
18
Q
It is estimated that the service life of hydraulic fluid For each 18 to 20c increase above 54c
A
Is reduced by half
19
Q
Contamination in a hydraulic system can best be controlled by
A
Good maintenance procedures
20
Q
Corrosion in a hydraulic system generally is caused be all of the following except
A
Cavitation
21
Q
For a hydraulic fluid to function properly over acceptable periods of time, it must
A
Be kept clean
22
Q
The performance rating of a strainer is based on its ability to remove from the system
A
Dirt
23
Q
The point at which a filter allows contaminants to pass through the medium is called the
A
Maximum allowable pressure drop
24
Q
The medium in a strainer usually is made of
A
Porous wire mesh
25
Which of the following is not true of a filter in a hydraulic system
It’s openings gradually increase in size
26
Which of the following is not true of depth filters used in highly contaminated fluid conditions
They can be cleaned and reused
27
Wound-yarn filters are used for heavy contaminant concentrations because they
Have good removal ratings
28
How is a filtration area of paper filter media increased
Pleating
29
Surface filter media made from sintered metal powders can be used for high pressure filtration because of their
Large mass
30
When working on or around a hydraulic system, always remember that the system may be
Pressurized
31
In order to separate contaminants from hydraulic fluid in the reservoir the fluid must be
Moved slowly
32
The bottom of a hydraulic fluid reservoir should not be
Flat
33
A hydraulic reservoir relies on an interior baffle to
Help heat transfer
34
What method is not used to maintain the temperature of hydraulic fluid at an acceptable level
Using reservoir with thick side walls
35
Most liquid cooled heat exchangers transfer heat by means of
Separated fluids moving in the opposite directions
36
For what reason is an air breather installed on a reservoir
Prevent pressure build up
37
An accumulator is used in hydraulic system for all of the following except to
Take the place of the pump
38
Because of their non mechanical design air bottle accumulators should not be used with
High speed pumps
39
Which of the following is the correct procedure to use when charging a bladder accumulator
Preload gas’s then fluid
40
A distinctive characteristic of a differential piston accumulator is that it reduces
Fluid volume
41
A hydraulic pump does all of the following except
Produce the working pressure in the system
42
Which of the following types of pumps is not a positive displacement pump
Centrifugal
43
The volume of delivery of a fixed displacement pump
Can be changed by changing the pumps speed
44
The capacity of a pump maybe specified in all the following except
Pounds per square inch
45
The efficient operating life of a pump is usually given in terms of
Hours
46
Because of their design internal gear pumps are limited to applications having
Small capacities and low pressure
47
A vane pump of the unbalanced design can be identified by its
Off centre rotor
48
The vane tips of vane pump usually are grooved or split to permit all of the following except
A large contact area at the housing
49
Variable displacement vane pumps control fluid flow by
Shifting the cam rings
50
Radial piston pumps generally are designed and manufactured with a
Rotating or stationary block
51
When selecting a hydraulic line the most important factor to consider is the
Fluid flow rate
52
Resistance to fluid flow in a hydraulic system is increased by
Pipe restrictions
53
Which of the following does not contribute to pressure loss in a hydraulic line
Direction of flow
54
Hydraulic lines should not be made from
Galvanized pipe
55
Steel piping may be used for hydraulic lines under all of the following conditions except
When the hydraulic lines are short and contain many bends
56
When tubing is bent which of the following does not apply to the bend
It should be formed by hand
57
Which of the following is a proper procedure for installing hydraulic tubing
Support long tubing runs with clamps or hangers or as close as possible to prevent sagging
58
A disadvantage of hoses in hydraulic lines is that they
Wear from flexing
59
Hydraulic hoses should not be used for temperatures above
450f
60
Most hydraulic hoses are rated with a safety factor of
4
61
Directional control valves do all of the following except
Relieve excess pressure
62
Directional control valves are not classified by the number of
Pipe theeads
63
Some manually operated two way valves are not suitable for hydraulic service because of their
Low pressure ratings
64
The closing force of a solenoid operated valve is usually limited
15lb
65
The pressure at which a check valve will start to open is called its
Cracking pressure
66
Spool valves usually are partially balanced because of their
Construction
67
Three way spool valves are made with three
Primary connections
68
Selector and diverter three way valves differ in their
Internal construction
69
A three position four way valve is referred to as a
Close crossover valve
70
Rotary spool valves can be manufactured to operate as all of the following except
Five way valves
71
A pressure reducing valve is a
Normally open two way valves differ
72
What is another term for the maximum pressure of a poppet relief valve
Set pressure
73
What is the pressure at the discharge outlet of a sequencer valve
Line pressure
74
A counterbalance valve is usually constructed as a
Double poppet
75
Unloading valves usually are made for Operation
Pilot
76
Pressure reducing valves limit pressure
In one part of the system
77
Hydraulic shock in system is controlled by an
Shock supprssor
78
The speed of a hydraulic actuator is controlled by by what characteristics of the hydraulic system
Flow is speed
79
A flow control valve can be positioned to operate in all of the following ways except
Counterbalance
80
A pressure compensation valve senses pressure al the
Downstream valve outlet
81
Hydraulic cylinder convert fluid force into
Straight line motion
82
In a double acting cylinder the thrust is
Greater when the piston forces the piston rod out of the cylinder
83
A double end rod cylinder has a piston surface area that is
Equal on both sides
84
Which of the following is true of a ram cylinder
It usually does not require piston seal
85
The pistons of a two piston cylinder always move
Independently
86
The end caps or heads of most individual hydraulic cylinders are held in place by
Tie rods
87
Cylinders that move heavy thrust loads usually are furnished with
Square flanges
88
To select the proper hydraulic cylinder for use in an existing system you must know all of the following except
Piston speed
89
To determine the total cylinder force you must multiply the load times the acceleration factor and add the
Friction resistance
90
What is the purpose of the cushioning device used with a hydraulic cylinder
Prevent mechanical shock
91
The speed of a hydraulic actuator motor is determined by the fluids
Flow rate
92
All hydraulic motors are Motors
Positive displacement
93
The maximum fluid pressure that a motor can withstand is defined by
It’s pressure rage
94
The force exerted by a hydraulic motor while operating normally is called
Running torque
95
When a new hydraulic motor is installed in an existing system its compatibility must be checked against all of the following except the
Piping material
96
The service life of a hydraulic motor is given in
Hours of operation
97
The pressure of the hydraulic fluid entering an internal gear motor acts on the
Gear teeth
98
Gear motors frequently are equipped with wear plates to prevent
Internal leakage or slipage
99
Which of the following characteristics applies to variable displacement hydraulic motor
High slippage rates
100
How far can vane type rotary actuators rotate
Just under one revolution
101
Pascals law concerns the flow of liquid in hydraulic system
True
102
JIC angel
37
103
Accumulator minimum discharge pressure
90
104
Dc will not burn out
True
105
Unloading valve
15 psi
106
Control accuators speed
Flow
107
Pressure outside atmosphere
Psia
108
What pressure do drain line drain
Low to no pressure
109
Pressure compansate pump
Zero pulse min internal leakage
110
2 types of reliefs valves
Directional and pilot
111
Swash plate
To transfer motion of the rotating shaft into reciprocating motion or vice versa
112
Shoe plat
Transfer motion from the swash plate
113
Pascals law
When pressure is applied to confined fluids the pressure is transmitted equally throughout that fluid and is exerted perpendicular to every surface in the container
114
No Newtonian flow is
When oils are subjected to increased shear rate the viscosity will decrease
115
Absolute (dynamic) viscosity
Resistance encountered when shearing on parallel plans of fluid over another
116
Kinematic (relative) viscosity
Usually used when measuring and comparing viscosity at high temperatures
117
Cavitation
Vapor bubbles occur and implode
118
Bleed off circuit
Requires a pressure compensated flow control to keep the cylinder from slowing as pressure increases
119
Accumulator is
Enables a hydraulic system to cope with extremes of demand using a less powerful pump to respond more quickly to a temporary demand and to smooth out pulsation
