Hydraulics Flashcards
1
Q
What are the 4 main dangers of hydraulics?
A
Injection
Toxins
Heat
Material movement
2
Q
What are the dangers of pressures around and above 100psi?
A
Skin punctures
3
Q
What are the dangers of pressures between 2000-7000psi?
A
Amputation
4
Q
What should you use to check for leaks on a hydraulic system?
A
Paper or cardboard
5
Q
Can you check for flow in a hydraulic system by cracking lines?
A
No
6
Q
How large should a hydraulic reservoir be?
A
2-3x greater than systems capacity (not including reservoir)
7
Q
Why does a hydraulic reservoir need to be 2-3x greater than the system capacity?
A
Leaking
Cooling
Air removal
Particulates (contaminants to settle)
8
Q
What is spectromatic in terms of hydraulics?
A
Oil analysis
Testing oil for foreign matter
9
Q
What is oil analysis?
A
Testing oil for foreign matter
10
Q
Why do oil return lines have a 45 degree opening?
A
Natural circulation
Changes velocity
11
Q
Why are filters typically on return lines?
A
Lower pressure = lower wear on filters
That’s where the particles in the oil are
12
Q
Why should you always clean around a hydraulic system prior to opening it?
A
To ensure you don’t introduce any new contaminates
13
Q
What is the difference between a strainer compared to a filter on a hydraulic system?
A
More course
On suction side of system
14
Q
What are the two sides to a hydraulic system?
A
Pressure
Return
15
Q
Why is the return side to a hydraulic system more simplistic?
A
Minimize chances for blockages
16
Q
What type of piping should you NEVER use on a hydraulic system?
A
Galvanized or conducts
17
Q
Why should galvanized or conduct pipes NOT be used on a hydraulic system?
A
You want interior piping to be as clean as possible
18
Q
What is fluid?
A
Any liquid or gas that transmits power
Will take the shape of its container
19
Q
What is the 4 main purposes of hydraulic fluid?
A
Transmit power
Lubricate moving parts
Seal clearances between parts
Cool/dissipate heat
20
Q
How is moisture pulled into oil?
A
Temperature changes
21
Q
Why should return lines be under the fluid line of the supply tank?
A
reduces aeration
Improve circulation
22
Q
What is pour point in terms of hydraulics?
A
The lowest point a oil flows
23
Q
What is viscosity index?
A
Measure of fluids resistance to viscosity change over temperature
24
Q
What is boundary lubrication?
A
The ability for oil to stick to parts acting as a barrier
25
What is oxidation in terms of hydraulics?
Chemical reaction between oxygen and hydraulic fluid reducing the oil life
26
What does viscosity refer to?
Resistance to flow
27
Where should a relief valve always be located on a hydraulic system?
Directly after a pump
28
What are the 4 main valve controls?
Closed
Open
Tandom
Floating
29
If a solenoid fails on a hydraulic system should it be repaired or replaced?
Replaced
30
How should gauges be sized?
So the normal running operations read at 50% of the gauge
31
What is used in conjunction with an accumulator on a hydraulic system?
Shuttle valve
32
What is a shuttle valve?
Dual acting check valve
33
How many inches cubed is 1 US gallon?
231inches cubed
34
How many US gallons is 231 inches cubed?
1 gallon = 231 inches cubed
35
How many inches cubed is 1 imperial gallon?
277 inches cubed = 1 imperial gallon
36
What is 277 inches cubed equal to?
1 imperial gallon
37
How do you find the area of a circle?
3.14 x radius squared
38
What hydraulic symbol is this?
Main line
39
What hydraulic symbol is this?
Return line
40
What hydraulic symbol is this?
Control valve
3 position
41
What does this hydraulic symbol mean?
Line or conductors connecting
42
What does this hydraulic symbol mean?
Conditioning
(Ie. Filter, lubricator)
43
What does this hydraulic symbol mean?
Spring
44
What does this hydraulic symbol mean?
Unidirectional
Fixed capacity
Hydraulic pump
45
What does unidirectional mean?
One direction
46
What does bi directional mean?
Two directions
47
What does this hydraulic symbol mean?
Unidirectional
Hydraulic pump
Variable capacity
48
What does this hydraulic symbol mean?
Bi directional
Hydraulic pump
Variable capacity
49
What does this hydraulic symbol mean?
Bi directional
Hydraulic pump
Fixed capacity
50
What does this hydraulic symbol mean?
Bi directional
Hydraulic motor
Fixed capacity
51
What does this hydraulic symbol mean?
Bi directional
Hydraulic motor
Variable capacity
52
What does this hydraulic symbol mean?
Hydraulic motor
Uni directional
Variable capacity
53
What does this symbol mean?
Hydraulic
Oscillating motor
54
What does this hydraulic symbol mean?
Single acting
Cylinder
Return by un known source
55
What does this hydraulic symbol mean?
Single acting
Cylinder
Spring return
56
What does this hydraulic symbol mean?
Double acting
Cylinder
Double ended piston rod
57
What does this symbol mean?
Double acting
Cylinder
58
What does this hydraulic symbol mean?
Double acting cylinder
Double fixed cushion
59
What does this hydraulic symbol mean?
Double acting cylinder
Double adjustable cushion
60
What does this hydraulic symbol mean?
Check valve
Non return
61
What does this hydraulic symbol mean?
Check valve
Spring return
62
What does this hydraulic symbol mean?
Shuttle valve
63
What does this hydraulic symbol mean?
Flexible hose
64
What does this hydraulic symbol mean?
Electric motor
65
What does this hydraulic symbol mean?
Accumulator
Spring loaded
66
What does this symbol mean?
Accumulator
Gas charged
67
What does this symbol mean?
Accumulator
Weighted
68
What does this hydraulic symbol mean?
Reservoir/ tank
Vented
69
What does this hydraulic symbol mean?
Reservoir / tank
Pressurized
70
What does this hydraulic symbol mean?
Reservoir/ tank
Inlet pipe below fluid level
Vented
71
What type of valve is this?
Brake valve
72
Where in a hydraulic system would you find a brake valve?
Right after the motor
73
What type of valve is this?
Counter balance valve
74
Where is the counterbalance valve in a hydraulic system?
Directly after an actuator
75
What type of valve is this?
Sequence valve
76
Where is a sequence valve located in a hydraulic system?
Between different actuators
77
What valve is this?
Unloading relief valve
78
Where are unloading relief valves typically located?
After actuator on return line to reservoir
79
What type of valve is this?
Direct relief valve
80
Where are direct relief valves typically found?
Anywhere you need to protect the system
81
For what reason would you use a direct acting relief valve?
Anytime you want to protect your system from damage
82
For what reason would you use an unloading valve?
For returning pump output at a lower pressure once system pressure has been reached
83
How do you find force?
Pressure x area
84
What unit is force in?
Lbs
85
What unit is pressure in?
Psi
86
What unit is area in?
Inches squared
87
What is the 3 types of relief?
Cracking pressure
Full flow
Pressure override
88
What is the first main valve after the pump in a hydraulic system?
Relief valve
89
Cylinders are used to create linear motion what are motors used to create?
Rotary motion
90
When fluid flow increases in a system what happens to the pressure?
Decreases
91
Hydraulic fluid that have small viscosity variations when heated are said to have good _______?
Viscosity index
92
Demulsibility is the ability of the fluid to ___________
Eliminate water
93
What is the ratio of the actual delivery rate of a pump to its displacement called?
Volumetric efficiency
94
Mechanical shock is controlled in a hydraulic cylinder by means of a/an?
Cushion device
95
When you first start up a system after you installed a new relief valve what position should the pressure adjustment screw be in?
Turned all the way out
96
What term is used for the output component of a hydraulic system?
Actuator
97
What does the term flow rate mean?
The measure of the volume of fluid that passes a point in a given time
98
What is the purpose of a hydraulic cooler in a hydraulic system?
Keep the oil at an optimum operating temperature
99
What device is used in a hydraulic cylinder to limit the amount of rod extension and steady the rod within the cylinder?
Stop tube
100
Why does a cylinder have a lower load capacity when it retracts that when it extends?
It has less surface area to work with
101
Why must you attach an external drain to a sequence valve?
Prevent valve from locking up under pressure
102
What is the formula for calculating pressure using pascals law
P=F/A
103
How is volume of fluid expressed in a hydraulic circuit
Cubic inches
104
What causes pressure in a hydraulic system?
Resistance to flow
105
What kind of system transmits and controls power through use of a pressurized fluid within an enclosed circuit
Fluid power system
106
What are pressure gauges used for?
Aiding in adjusting pressure control valves
Determining forces exerted
Troubleshooting
107
What are the types of pressure gauges?
Bourdon tube
Schrader gauge
108
How does a bourdon tube pressure gauge work?
Inner tube straightens under pressure moving the dial
109
What are the purposes of a loop on a pressure gauge line?
Extra adjustment
Prevent vibration
110
What fitting should thread sealant be applied to?
Only make side
111
What are the purposes of thread sealant?
Lubrication
Sealing
112
What is hunting in terms of pressure gauges?
When the pressure gauge needle bounces back and fourth
113
Why are some pressure gauges filled with liquid?
To prevent shock loading of the gauge needle
114
What is a schrader gauge?
Gauge that uses and inlet with a spring that moves an armature attached to a needle
115
What’s PSIG read?
Psi gauge that already has atmosphere pressure accounted for (14.7)
116
What does PSIA read?
Psi absolute gauge that does not account for 14.7 atmospheric pressure
117
What are vacuum gauges typically measured in?
Inch/hg (mercury)
118
What is the max vacuum gauge reading?
29 inch/HG
119
What is a compound gauge?
A gauge that reads BOTH vacuum and pressure
120
What is a duplex gauge?
A gauge that reads 2 systems at the same time
121
What is a differential gauge?
A gauge that uses two systems to read the difference
122
What are the 3 types of flow meters?
Typical
Turbine
Transducer
123
What is a typical flow meter?
A flow meter that uses a tube and indicator
124
What is a turbine flow meter?
A flow meter consisting of a wheel connected to a counter
125
What is a gauge snubber?
A filtering mechanism used to prevent surging of gauges
126
What are the 3 types of gauge snubbers?
Porous
Metering
Threaded
127
What are the two places gauges can be installed?
In series (in line)
Dead ending
128
What are the 5 main uses of accumulators?
Emergency supply
Shock absorbing
maintain pressure
Acceleration control
Auxiliary support
129
What is a poppet?
A type of check valve
130
What are the two main classes of accumulators?
Gas
Mechanical
131
What are the two types of mechanical accumulators?
Spring
Weighted
132
What type of accumulator gives consistent discharge?
Weighted
133
What are the 3 types of gas accumulators?
Non separated
Piston
Diaphragm/bladder
134
What type of gas is typically used to charge a gas accumulator?
Nitrogen
135
Why should air not be used in a gas accumulator?
Oxidation
Corrosion
Deteriorate seals
Fire hazard
136
Prior to pre loading an accumulator what should you do?
Ensure all oil is discharged
137
Where should an accumulator be in a hydraulic system.
High up
138
What is isothermal in terms of accumulators?
When the process is slow enough to allow heat transfer
139
What is adiabatic in terms of accumulators?
Process is fast enough to retain all the heat
140
How does true adiabatic discharge happen?
Discharge is started immediately upon fluid reaching the accumulator
141
What gauge is used at a pumps inlet and how is it typically calibrated to zero
Vaccum
0= 14.7
142
What reading can be seen on a typical flow meter scale?
Gpm/lpm
143
What do we use flow meters for?
Check internal leakage
Check pumps volumetic efficiency
144
What is a conductor in terms of hydraulics?
Anything that carries the fluid
145
What are the 3 types of conductor lines in hydraulics?
Piping material
Tubing material
Flexible hose material
146
What is the TYPICAL difference between tubing and piping?
Tubing is typically smaller
147
When is piping typically the conductor of choice?
Long permanent lines
Large flows
148
What type of piping is typically used?
Seamless steel (black) pipe with a clean interior
149
What determines the bursting pressure of a hydraulic line?
Wall thickness
Internal Diameter (ID)
150
What are the 3 most common piping threads?
NPT (American national pipe taper)
NPS (American national pipe straight)
NPTF (dry seal pipe taper)
151
Which threads are self sealing?
NPT (American National pipe taper)
NPTF (dry seal pipe taper)
152
What threads require an O-ring?
NPS (American national pipe straight)
153
What does schedule number refer to?
Wall thickness of a pipe
154
What is the number range for schedule numbers?
10-160
155
What does it mean if a pipe has a larger schedule number?
The wall thickness is greater
156
In terms of schedule number what changes?
Internal diameter
157
How is pipe measured?
From outer diameter
158
What is the advantage of pipe?
Cheap
can withstand a fair amount of physical abuse
159
What are the disadvantages of pipe?
-Leaks at higher pressure
-Can’t be bent
-Requires more fittings
-If a line is disconnected it must be tightened more than previously
-heavy and bulky
160
How does the dash number system work?
16 = 1 inch
6 = 3/8 inch
161
What are the flow control methods?
Meter in
Meter out
Bleed off
162
What is the “safest” flow control method?
Meter out
163
164
What is turbulent flow?
Non uniformed flow of fluid in a hydraulic system
Example sharp bend
165
What type of pump is typically found in a hydraulic system?
Positive displacement
166
What are the 3 classes of hydraulic fluid?
Mineral based
Synthetic
Water based
167
What keeps the bladder in an accumulator?
Poppet (check valve)
168
What is a static seal?
A seal that neither mating surface is moving
169
What is a dynamic seal?
A seal where one or both mating surfaces are moving
170
What are the two types of hydraulic leaks?
Internal
External
171
In terms of copper tubing is M or K thicker?
K
172
In terms of copper tubing is M or K thinner?
M
173
When bending tubing will bends add or take away from a tubes overall length?
Take away
174
What are the 3 types of proportional flow control valves?
Servo actuated spool type throttle
Flapper nozzle pilot control
Proportional solenoid
175
What does metering in control?
Amount of fluid going INTO an actuator
176
What does metering out control?
Amount of fluid going OUT of an actuator
177
What does a bleed off flow control valve do?
Dumps the pressure out of a system back to the tank
178
What do flow control valves control?
Speed
179
What does laminar flow look like?
Consistent moving parallel with the piping (or tubing)
180
In standard pipe threads what comes in contact first?
The flanks
181
What is the compression rate of O rings?
40-60%
182
What are the two types of tubing fittings?
Flared
Compression
183
What are the two types of flared fittings?
Flared
Ferrule
184
What are the two types of compression fittings?
Sleeve
O-Ring
185
What is the angle of a JIC flare?
37 degrees
75 included
186
Why are leakage paths needed in most components?
Lubrication
187
What can excessive leakage cause in a hydraulic system?
Pressure loss
188
What purposes do seals serve?
Make up clearances
Keep contamination out
189
What type of seal would be best suited for rotating shafts in high pressure applications?
Dynamic
190
What affect does high temperatures have on the viscosity of oil?
It makes it lower
191
What are some products produced by oxidation?
Sludge
Foaming
192
What is a non compensating flow control valve?
Throttle valve that does NOT compensate for any variation in pressure or flow.
193
What happens if flow or pressure increases through a non compensating flow control valve?
The flow or pressure will also increase through the valve
194
What is the term of the pressure control valve as it first opens?
Cracking pressure
195
What would you use to control the pressure in a fluid system?
Pressure control
196
What type of accumulator will supply the most constant pressure when discharging?
Weighted
197
What would you use in a fluid system to control the speed of an actuator?
Flow control
198
What type of pressure control valve would you use to have a motor start after a hydraulic vice has clamped the component?
Sequence valve
199
When a hydraulically operated unit is preforming erratically what would be the first thing to check?
Fluid level
200
What type of valve is used in conjunction with an accumulator?
Shuttle valve
201
What type of valve is used in conjunction with an accumulator used in an emergency or auxiliary circuit providing recovery from a power failure or loss of pumping capability?
Shuttle valve
202
What component is added to a hydraulic circuit for shock absorption during operation?
Accumulator
203
What two types of seals are used in hydraulic cylinders?
Positive and non positive
204
What is the purpose of a pressure control valve?
Provides pressure control in a fluid system
205
How would you provide controlled drain down of an accumulator?
Operation of the flow control valve to bleed off
206
What elements in a fluid power system are used to control the speed and force?
Flow and pressure
207
If a hydraulic cylinder is hammering on retraction what can be done to reduce it?
Adjust cushion
208
What is used in a hydraulic system to provide emergency recovery in the event of a power failure?
An accumulator and a shuttle valve
209
Why should you use a strainer instead of a filter on a hydraulic pump inlet
Strainer offers less resistance to flow
