1
Q
hydraulic systems transmit ?
A
power
2
Q
what do control valves do ?
A
allow you to control direction ,speed, and force of the actuator .
3
Q
what does a proportional valve do ?
A
multi function electronically controlled valve. can control direction speed .
4
Q
with electronics on a proportional valve what can you control with extreme accuracy?
A
movement of the cylinder rod .
5
Q
hydraulic systems work on the principles of pressure and ?
A
flow
6
Q
pascals law states pressure acting on any fluid at rest in a container (confined) is transmitted :
A
undiminished
equals in all directions
at right angles to every point on the inside surface of the container
7
Q
note’ pascals law applies when fluid Is not flowing
A
8
Q
pressure is created by ?
A
resistance to flow
8
Q
hydraulic oil compresses about ____ when the pressure is 1000 psi.
A
1/2%
9
Q
what causes pressure ?
A
restriction in the flow path
load acting on the fluid
10
Q
the affect of of the fluids compressibility must be minimized by mounting valves that control the cylinder movement directly on the cylinder to shorten the path of the fluid
A
11
Q
When a cylinder is retracting the pressure acts on the piston area minus the _____area.
A
rod area
11
Q
pressure is described as ?
A
gauge pressure
absolute pressure
atmospheric pressure
11
Q
a larger area provides a larger _____for the same pressure
A
force
12
Q
In a 2 to 1 cylinder the cap end of the cylinder has ___times more area for the fluid to push on than the rod end.
A
2 times
13
Q
flow is produces by either a pump or by a ____ drop across an orifice
A
pressure drop
14
Q
true or false
a pump produces only flow , pressure is produced by a resistance to flow. (such as the load or restriction )
A
true
14
Q
A
15
Q
true or false
flow rate is expressed as either velocity (speed) in feet /minute or feet/second
or flow rate in gallons/minute or cubic inches /minute
A
true
16
Q
A
17
Q
A
18
Q
What does V/t represent in the flow triangle?
A
Flow rate in cubic inches/minute
V/t is a key component of the flow triangle used to solve flow problems.
19
Q
What does S represent in the flow triangle?
A
Speed in inches/minute
S is used to determine the speed of fluid flow within the flow triangle.
20
Q
What does A represent in the flow triangle?
A
Area in square inches
A is essential for calculating the flow and is part of the flow triangle.
21
What is the first step when calculating flow using the flow triangle?
Convert everything into the units listed previously
## Footnote
Proper unit conversion is crucial for accurate flow calculations.
22
Fill in the blank: In the flow triangle, flow rate is represented by _______.
V/t
23
Fill in the blank: In the flow triangle, speed is represented by _______.
S
24
Fill in the blank: In the flow triangle, area is represented by _______.
A
25
what are the most widely used cucuits in the industry
open loop
26
to convert GPM to CI/min use the 231 trick
multiply gallons by 231
27
the regenerative circuit is designed to provide equal ____ and equal _____ when the cylinder extends and retracts
speed and equal force
28
if a hydraulic pipe is changed out and replaced with a pipe with a smaller inside diameter the speed of the fluid will what ?
it will increase
29
a hydraulic pipe is changed out with a pipe with a smaller diameter, the speed of the fluid increases. Area varies with the _____ of the diameter (inside diameter).
square
30
fluid speed _____ as the cross section decreases
increases
31
why is a increase in fluid speed bad for a hydraulic system ?
it wastes energy , robs pressure , and wears out components
31
what causes turbulent flow?
abrupt changes in cross section upsets laminar flow . increases pressure drop and fluid temp
31
the maximum pump inlet velocity =______
the maximum pressure line velocity =____
inlet velocity =2-4 feet/second
max line pressure is 7-20 feet/second
31
true or false
The amount of friction in laminar flow increases as velocity increases (velocity doubles and friction doubles). In turbulent flow if velocity doubles, friction quadruples.
true
32
when hydraulic fluid flows smoothly in parallel lines it is called ?
laminar flow
most desirable flow condition
33
true or false
Cavitation is the violent collapse of entrained vapour (gas) bubbles in the oil. It occurs when the fluid moves from a low-pressure area to a high-pressure area. The imploding bubbles cause a rattling noise and abnormally low pressure at the pump inlet.
34
name some effects of cavitation
erosion of metal surfaces
pump damage
erratic operation of valves
high vibration
35
Clogged inlet filters, clogged tank breathers and high oil viscosities cause ?
cavitation
36
________occurs when air is mixed with the fluid. You can tell aeration from cavitation because the inlet pressure is not lower than normal.
Aeration
37
Aeration is caused by low fluid levels, shaft seal leaking, inlet fittings leaking and gas charged accumulators are leaking.
true or false
true
38
velocity increases when ?
diameter decreases
velocity is highest at the small diameter
39
velocity decreases when ?
diameter increase
40
what is energy
the capacity todo work
41
Work = to force x distance. Power = work/time. 1 hp = 33,000 ftlbs/min or 550 ft/lbs/sec
41
Power in hydraulics can be calculated using formulas such as power = gallons/min x psi.
41
Hp (theoretical) = 1 gal/min x 1psi/1714 or 1 hp (actual) = gallons/min x psi x 0.0007
41
what are the two types of power efficiency
power efiecnticy
volumetric efficiency
42
Power efficiency (%) = output HP/ input HP x 100. This tells us if the system is wasting power or not.
43
Volumetric efficiency (%) = volume output / volume input x 100. This tells us if the pump or actuator is worn out.
44
relief valves are the greatest power wasters in the system true or false ?
true
45
volume efficiency can determine if a ___ is worn out
actuator
46
Volumetric efficiency measures how much fluid an actuator or pump dischargers in comparison to the amount of fluid intake
true or false
true
47
how does pressure affect the output of a cylinder
it affects the force
47
what produces pressure
resistance to flow
47
how does pressure affect the output of a cylinder
it affects the speed
48
what causes a decrease in volumetric efficiency
internal leakage
49
50
this circuit uses a reservoir that holds_______ times the volume of the rated capacity of the pump?
3 times
51
what is the main job of a charge pump?
return fluid from the case drains back to the inlet of the main pump
51
the term conductor is used in hydraulics for what?
piping tubing or hose
52
the hydraulic systems you may be required to work on have pressures up to?
3000 psi or higher can kill you
53
a open top on a reservoir drawing is indicating ?
the vent allows atmospheric pressure to push the fluid into the inlet of the pump
54
The open top on a reservoir symbol indicates that it is ______ to atmosphere.
vented
55
The filter symbol has a _____ line inside indicating it is a filter element.
broken line
55
A pump symbol that has a shaded triangle inside the circle pointing outward (direction of flow). is for what
liquid
56
what is the first valve located right after the pump and is the first valve in the system ?
maximum pressure relief vale
57
the pressure relief valve provides three functions what are they
----overload protection
---diverts excess flow to the reservoir
---sets maximum pressure at which the system operates
58
what does a directional control valve do ?
allows you to direct the flow to either end of cylinder ,or stop flow all together
59
true or false directional control valves can be operated manually, electrically hydraulically or pneumaticlly ?
true
60
what does a flow control valve do
it controls the speed at which the cylinder operates
61
A cylinder is the ____component in the system which does the work. It pushes when it extends and pulls when it retracts.
out put
61
what is the symbol ---this symbol has two curved lines to represent a restriction of flow that flows through the valve , the diagonal arrow across this restriction indicates its adjustable to control the flow rate
flow control valve
62
what is a double acting cylinder
can have fluid acting on either side of the piston to provide movement in both directions
63
what is a pressure reducing valve used for
reduce the pressure on cylinder #2 below the system pressure
64
what does a small dotted Line from the spring to a reservoir mean
external drain line
65
what does a sequence valve do
stops flow to the 2nd cylinder but then releases the flow to the 2nd cylinder when the 1st cylinder reaches end of stroke
65
true or false
Hydraulic sequence valve must be installed so that the inlet of the valve is connected to the first cylinder and the outlet to the second cylinder
true
66
where are sequence valves mounted
between the two cylinders
67
what are meter out flow control used for
can be used to control the speed of retraction
68
what is a tractive load
the load pulls on the piston
69
bleed off flow control can be used to ensure ?
no flow goes over the relief valve when flow to the cylinder is reduced
70
this symbol has fluid triangle facing into a circle
hydraulic motor
70
whaat are the purpose of using cross port relive valves (cushion valves)
protect motor from shock loading during operation
71
motors are often bi-rotational which is indicated by what
double headed curved arrow
72
what is a counter balance valve used for
control movement of a vertical load
73
Deceleration circuits can extend a cylinder at full speed for part of the stroke and then slow it down to a set speed to the end of the stroke. The deceleration valve is operated by an attachment on the cylinder rod that acts against a roller cam to depress a plunger that will shift a valve to direct the flow thru a flow control for the end of the stroke slowing the cylinder down.
74
what are three factors valves control in a hydraulic system
direction
force
speed
74
what is the important reason for using electronic controls
extremely accurate
74
what is the term used for the output component in hydraulic systems
an actuator
75
list 5 main parts of a hydraulic system
reservoir
conductors (piping hoses tubes)
pump
control valves
actuators
76
what is the first main valve after the pump
max pressure relive valve
77
is a pressure reducing valve normally open or closed
open
78
what is the purpose of a sequence valve
stops the flow to the second cylinder
79
which valve would you use to prevent uncontrolled fall of a load due to gravity
counter balance valve
80
why must you attach a an external drain to a sequence valve or to a pressure reducing valve
to prevent the valve from locking up under load
81
three main types of flow controls
metre in
metre out
bleed off
82
what is the purpose of the a flow control
to control the speed of the actuator
83
84
What is the most desirable type of flow in a hydraulic system?
Laminar Flow
## Footnote
Laminar flow causes less wear and energy loss than turbulent flow.
85
Why is laminar flow preferred in hydraulic systems?
It causes less wear and energy loss, produces the least amount of friction, pressure loss, and is the most efficient type of flow
## Footnote
Laminar flow minimizes erosion and energy losses.
86
What are the key characteristics of laminar flow?
* Least amount of friction
* Least amount of pressure loss
* Least amount of energy loss
* Most efficient type of flow
* Least amount of wear and erosion
## Footnote
These characteristics contribute to the overall performance of hydraulic systems.
87
What is the least desirable type of flow in a hydraulic system?
Turbulent Flow
## Footnote
Turbulent flow causes damage and loss of energy.
88
What are the negative effects of turbulent flow?
* Most friction produced
* Greatest amount of pressure robbed from the system
* Reduces efficiency
* More wear and erosion on components
* Common cause of cavitation and aeration
## Footnote
Turbulent flow leads to significant operational issues in hydraulic systems.
89
True or False: Turbulent flow produces the least amount of friction.
False
## Footnote
Turbulent flow produces the most friction.
90
Fill in the blank: Laminar flow produces the least amount of _______.
friction
## Footnote
This characteristic is crucial for efficient hydraulic system operation.
91
What does turbulent flow rob from a hydraulic system?
* Useful energy
* Pressure
## Footnote
This leads to reduced efficiency and increased operational costs.
92
What is a common consequence of turbulent flow in fluids?
Cavitation
## Footnote
Cavitation refers to the formation of damaging bubbles in the fluid.
93
Fill in the blank: Laminar flow is the most _______ type of flow.
efficient
## Footnote
Efficiency is crucial for the performance of hydraulic systems.
94
What is the most desirable type of flow in a hydraulic system?
Laminar Flow
## Footnote
Laminar flow causes less wear and energy loss than turbulent flow.
95
Why is laminar flow preferred in hydraulic systems?
It causes less wear and energy loss, produces the least amount of friction, pressure loss, and is the most efficient type of flow
## Footnote
Laminar flow minimizes erosion and energy losses.
96
What are the key characteristics of laminar flow?
* Least amount of friction
* Least amount of pressure loss
* Least amount of energy loss
* Most efficient type of flow
* Least amount of wear and erosion
## Footnote
These characteristics contribute to the overall performance of hydraulic systems.
97
What is the least desirable type of flow in a hydraulic system?
Turbulent Flow
## Footnote
Turbulent flow causes damage and loss of energy.
98
What are the negative effects of turbulent flow?
* Most friction produced
* Greatest amount of pressure robbed from the system
* Reduces efficiency
* More wear and erosion on components
* Common cause of cavitation and aeration
## Footnote
Turbulent flow leads to significant operational issues in hydraulic systems.
99
True or False: Turbulent flow produces the least amount of friction.
False
## Footnote
Turbulent flow produces the most friction.
100
Fill in the blank: Laminar flow produces the least amount of _______.
friction
## Footnote
This characteristic is crucial for efficient hydraulic system operation.
101
What does turbulent flow rob from a hydraulic system?
* Useful energy
* Pressure
## Footnote
This leads to reduced efficiency and increased operational costs.
102
What is a common consequence of turbulent flow in fluids?
Cavitation
## Footnote
Cavitation refers to the formation of damaging bubbles in the fluid.
103
Fill in the blank: Laminar flow is the most _______ type of flow.
efficient
## Footnote
Efficiency is crucial for the performance of hydraulic systems.
104
What is laminar flow?
A flow regime characterized by smooth, orderly fluid motion, typically at low velocities.
## Footnote
Laminar flow is crucial for maintaining efficiency in hydraulic systems.
105
What are the recommended velocities for laminar flow at the pump inlet?
2 to 4 fps.
## Footnote
Lower velocities help to maintain laminar flow conditions.
106
What are the recommended velocities for laminar flow in the pressure lines?
7 to 20 fps.
## Footnote
Keeping within this range helps reduce turbulence.
107
What type of surfaces should conductors have to promote laminar flow?
Smooth inside surfaces.
## Footnote
This applies to tubing or hoses used in hydraulic systems.
108
What type of bends should be used to promote laminar flow?
Long radius bends.
## Footnote
Long radius bends help maintain smooth fluid motion.
109
What type of fittings should be used to promote smooth changes in diameter?
Swedge-type fittings.
## Footnote
These fittings provide gradual transitions in diameter.
110
What is the minimum requirement for obstructions in a system to maintain laminar flow?
Use the fewest pipe fittings possible.
## Footnote
Pipe fittings can create steps in the flow path that disrupt laminar flow.
111
What characterizes turbulent flow?
High velocities above those recommended for laminar flow.
## Footnote
Turbulent flow is less efficient and can cause increased wear in hydraulic systems.
112
What type of surfaces can lead to turbulent flow?
Rough inside surfaces.
## Footnote
Rough surfaces disrupt fluid motion and promote turbulence.
113
What type of bends should be avoided to prevent turbulent flow?
Short radius bends.
## Footnote
These bends can cause abrupt changes in the direction of flow.
114
What produces abrupt changes in diameters that can lead to turbulent flow?
Reducer bushings.
## Footnote
These fittings can create turbulence due to sudden transitions.
115
What should be avoided to prevent sudden changes in flow direction?
Tortuous flow paths.
## Footnote
Such paths can increase turbulence and reduce system efficiency.
116
What is a common issue caused by pipe fittings in a hydraulic system?
They leave a step in the flow path where they connect to the pipe.
## Footnote
This step can disrupt laminar flow and promote turbulence.
117
Fill in the blank: To promote laminar flow, maintain _______ velocities at the pump inlet.
low
## Footnote
Low velocities are essential for achieving laminar flow conditions.
118
True or False: High velocities are ideal for maintaining laminar flow.
False
## Footnote
High velocities lead to turbulence, which is undesirable for laminar flow.
119
What is laminar flow?
A flow regime characterized by smooth, orderly fluid motion, typically at low velocities.
## Footnote
Laminar flow is crucial for maintaining efficiency in hydraulic systems.
120
What are the recommended velocities for laminar flow at the pump inlet?
2 to 4 fps.
## Footnote
Lower velocities help to maintain laminar flow conditions.
121
What are the recommended velocities for laminar flow in the pressure lines?
7 to 20 fps.
## Footnote
Keeping within this range helps reduce turbulence.
122
What type of surfaces should conductors have to promote laminar flow?
Smooth inside surfaces.
## Footnote
This applies to tubing or hoses used in hydraulic systems.
123
What type of bends should be used to promote laminar flow?
Long radius bends.
## Footnote
Long radius bends help maintain smooth fluid motion.
124
What type of fittings should be used to promote smooth changes in diameter?
Swedge-type fittings.
## Footnote
These fittings provide gradual transitions in diameter.
125
What is the minimum requirement for obstructions in a system to maintain laminar flow?
Use the fewest pipe fittings possible.
## Footnote
Pipe fittings can create steps in the flow path that disrupt laminar flow.
126
What characterizes turbulent flow?
High velocities above those recommended for laminar flow.
## Footnote
Turbulent flow is less efficient and can cause increased wear in hydraulic systems.
127
What type of surfaces can lead to turbulent flow?
Rough inside surfaces.
## Footnote
Rough surfaces disrupt fluid motion and promote turbulence.
128
What type of bends should be avoided to prevent turbulent flow?
Short radius bends.
## Footnote
These bends can cause abrupt changes in the direction of flow.
129
What produces abrupt changes in diameters that can lead to turbulent flow?
Reducer bushings.
## Footnote
These fittings can create turbulence due to sudden transitions.
130
What should be avoided to prevent sudden changes in flow direction?
Tortuous flow paths.
## Footnote
Such paths can increase turbulence and reduce system efficiency.
131
What is a common issue caused by pipe fittings in a hydraulic system?
They leave a step in the flow path where they connect to the pipe.
## Footnote
This step can disrupt laminar flow and promote turbulence.
132
Fill in the blank: To promote laminar flow, maintain _______ velocities at the pump inlet.
low
## Footnote
Low velocities are essential for achieving laminar flow conditions.
133
True or False: High velocities are ideal for maintaining laminar flow.
False
## Footnote
High velocities lead to turbulence, which is undesirable for laminar flow.
134
What is a characteristic of a closed loop system regarding the reservoir size?
Reservoir is approximately ¾ the volume of the charge pump capacity.
## Footnote
This indicates a compact design suitable for specific applications.
135
What is a key feature of closed loop systems in terms of size?
Relatively compact and lightweight in size.
## Footnote
This makes them suitable for mobile equipment.
136
Where are closed loop systems primarily used?
Widely used on mobile equipment, but also on stationary machines.
## Footnote
Their design is often tailored for specific machines.
137
How are closed loop systems typically designed?
Usually designed specifically for one machine.
## Footnote
This specialization can enhance performance.
138
What is a characteristic of an open loop system regarding the reservoir size?
Reservoir is approximately three times the volume of the pump capacity.
## Footnote
This results in a larger system design.
139
What is a key feature of open loop systems in terms of size?
Much larger and heavier.
## Footnote
This can limit their use in mobile applications.
140
Where are open loop systems mainly used?
Mainly used on stationary equipment.
## Footnote
Their larger size is more suitable for fixed installations.
141
What is an advantage of the design of open loop systems?
More versatile design allows for modification.
## Footnote
This flexibility can accommodate various applications.
142
What is a characteristic of a closed loop system regarding the reservoir size?
Reservoir is approximately ¾ the volume of the charge pump capacity.
## Footnote
This indicates a compact design suitable for specific applications.
143
What is a key feature of closed loop systems in terms of size?
Relatively compact and lightweight in size.
## Footnote
This makes them suitable for mobile equipment.
144
Where are closed loop systems primarily used?
Widely used on mobile equipment, but also on stationary machines.
## Footnote
Their design is often tailored for specific machines.
145
How are closed loop systems typically designed?
Usually designed specifically for one machine.
## Footnote
This specialization can enhance performance.
146
What is a characteristic of an open loop system regarding the reservoir size?
Reservoir is approximately three times the volume of the pump capacity.
## Footnote
This results in a larger system design.
147
What is a key feature of open loop systems in terms of size?
Much larger and heavier.
## Footnote
This can limit their use in mobile applications.
148
Where are open loop systems mainly used?
Mainly used on stationary equipment.
## Footnote
Their larger size is more suitable for fixed installations.
149
What is an advantage of the design of open loop systems?
More versatile design allows for modification.
## Footnote
This flexibility can accommodate various applications.
millwright level 3
flashcards
Decks in class (25)
# Cards
-
millwright Manuel chapter 257
-
gas laws and coefficient of linear expansion63
-
cross dial alignment20
-
laser shaft alignment16
-
alignment trade science test38
-
fans58
-
dynamic pumps89
-
postive displacement pumps0
-
hydraulics168
-
hydraulic valves74
-
hydraulic pumps90
-
fluid accessoires and seals65
-
seals part b42
-
trouble shooting and maintenance35
-
compressor fundamentals and b85
-
screw compressors and lobe blowers72
-
liquid ring compressors143
-
dynamic compressors106
-
vane compressors33
-
compressor crankshaft and frame components153
-
compressor cylinder components part b38
-
compressor auxiliary systems28
-
compressor valves13
-
pneumatic system30
-
gas and air dryers10
