Hydraulics Alberta Modules Flashcards
(102 cards)
1
Q
1psi = _ kpa
A
6.9 kpa
2
Q
1 psi = _ bar
A
0.069. Bar
3
Q
1 bar = _ psi
A
14.5 psi
4
Q
1 bar = _ kpa
A
100 kpa
5
Q
1 atmosphere = _ psi
A
14.7 psi
6
Q
1 atmosphere = _ kpa
A
101.325 kpa
7
Q
Gauge pressure read what when system has atmosphere pressure
A
0
8
Q
Absolute pressure reads what with atmosphere pressure
A
14.7
9
Q
Small piston force pressure vs big piston force pressure
A
Big piston has more pressure because bigger area
10
Q
Force =
A
Diameter square ×0.7854 × pressure
11
Q
If a piston has a rod and you want to know the force what do you do
A
Take cylinder force minus rod force
Force = diameter squared × 0.7854 × pressure
12
Q
Flow is produced by
A
Either a pump or by a pressure drop across an orifice.
13
Q
Pressure is produced by
A
Resistance to flow
14
Q
There is only flow across an orifice if
A
There is a pressure drop
15
Q
Flow is expressed as
A
Velocity in speed ft/min or ft/sec
Or flow rate in gallons/min
Or cubic inches/min
16
Q
Flow triangle is
A
17
Q
A
Multiple gallons by 231
18
Q
Recommend max inlet velocity =
Recommend pressure line velocity =
A
2 to 4 ft/sec
7 to 20 ft/sec
19
Q
A
20
Q
Cavitation effects 7x
A
*Vary rapid erosion of metal surfaces.
* severe pump damage
*generation of high frequency vibration
*erratic operation of valves and actuators
*accelerated fluid oxidation
*interference with lubrication of components.
21
Q
Causes of cavitation 7x
A
- clogged inlet filter
- pump mounted to high above resivor
*fluid is to thick viscosity to high - clogged breathers
*too many bends or fittings
*inlet pipe is too small
*turbulence
22
Q
Work =
A
Force ×distance
23
Q
Power=
A
Force ×distance ÷time
24
Q
1 HP = _ FT pounds /min
A
33 000 ftlbs/min
25
Define cavitation
Cavitation is the violent collapse of entrainted gas bubbles.
26
What causes aeration
Occurs when air gets into the fluid from an outside source.
27
Volumetric efficiency =
Percent out volume/input volume
28
Pressure tubing limited to what size Generally
2 inches larger is ultra tp 12 inches
29
Tube is available in
Steel,copper, aluminum, plastic
30
3 types of copper tube
Plumbing
Oxygen
Air conditioning and refrigeration (acr)
Not used for hydraulic system.
31
Plumbing tube designation
K (thick wall)
L (med wall)
M (thin wall)
32
Oxygen tube designation
K or L tube that has been specially cleaned to avoid spontaneous combustion of hydrocarbons with oxygen
33
Acr tube sized by
Outside diameter it was been cleaned purged and capped
34
Specify following when selecting tubing
Material
OD
wall thickness
Working pressure
Working temperature
35
Tube measurements
Imperial od in fraction of inch wall thickness is thousands of an inch.
Metric
Od mm teo decimal places
36
Tube fittings syle 3x
Flared
Welded or brazed
Flarless
37
Standard flare angles are
45 low pressure
37 high pressure
38
Flarless fittings developed for
Thick walled tubing
39
Hose classification 2x
Pressure
Vacuum
40
The inlet hose on a pump is a
Vacuum hose
41
Pressure hose rating have a ______ pressure and a ______ pressure given in ___ or
Bursting and a working pressure rating given in psi or megapascals 1 mpa= 145 psi
42
Vacuum hose rated in _____
Mercury normal practice to specify 28 inches of Mercury witch is full vacuum.
43
Hose is sized by ___
Pressure hose
Vacuum
ID
Dash number In 16th
Fraction of inch
44
Hose fitting types
Jic
Orb
Npt
45
1 Gallon to inches
1 x 231 = 231 "
46
Jic means
Joint
Industry
Conference
47
Hydraulics tank are made of
9-11 gauge steel that has been picked and oiled
48
A baffle serves what purpose
4x
Prevents turbulence
Promotes cooling
Promote settling of contaminants.
Allows air to escape from fluid to reduce foaming
49
Breather on tank allows
Air to flow in and out as fluid level rises and falls
Prevents to low cavitation
Too high aeration
50
Inlet filter _____ microns
100
51
3 common types of reservoirs
Open
Pressurized
Closed- circuit.
52
Open reservoir size
2 to 3 times pump capacity
53
If open resivorirs vent to the atmosphere, how do pressurized and closed deal with atmosphere
They are sealed from atmosphere and use a supply of regulated low pressure air 1-3 psi above atmosphere.
54
In a closed circuit reservoir most of return flow goes
Directly back to pump from actuator
55
Closed circuit reservoir size
Small reservoir only 15 percent goes back to tank.
56
Resevoir mounting styles 4x
Flat top
L shaped
Overhead stack
Vertical mount
57
Partical counter is set
2,5,15 micron
58
4 locations for filters in a hydraulic system
Pump inlet
Pressure line immediately after the pump
Return line
Off line
59
Locating leaks 3 steps
1. Clean area watch for the leak.
2. Focus on fittings first then hoses and seals.
3. Suspect the fitting that is most difficult to get at would have been hardest to tighten.
60
Minor leaks can cause
Ingested contamination.
61
Difference between cracking
And full flow pressure is called what
Pressure override
Pressure differential
62
Sequence valve
63
Counter balance valves is attached
In the exhaust side of actuator
64
Dirty gritty oil acts as
A grinding compound
65
Air in system causes
Rapid wear in working parts and generation of heat is the result.
66
Positive seals are
Seal that does not allow any leakage
Eg . Flat gasket
O ring between stationary surfaces
67
Non positive seals
Allow controlled leakage for lubrication
Eg vane tips against cam ring
Between valve spools and the bore.
68
Static seals
Provide seal between two surfaces that do not move with respect to each other.
69
Best way to store a oil drum
In temperature control storage.
70
Fluid maintenance keep Fluid below ___ Celsius
60
71
Hydraulic fluid use anti ware
Ep
Anti ware
Ep is harmful, too broze and brass
72
Cim speed area triangle
Cim × ___ = gpm
231
73
Hp -pressure -flow
triangle
74
Hp- tourqe - rpm
Triangle
75
Pressure reduce valve can be identified because it is the only one that is normally
Open
76
MA =
77
When does cavitation occur
When the fluid moves from low pressure area to high pressure area
78
79
System relief valve is always close to ____ and have a ______
Pump
By pass check valve
80
Sequence valve outlet is
Not back to tank
81
82
83
84
85
Gear motors are _____ displacement .____ # of gears connected by output shaft
Fixed
One
86
Vane motors are ____ displacement angel must have ____ for the vanes
Fixed or variable
Springs
87
What is difference between hydraulic motor and pump
Motors are driven by hydraulic fluid
Pumps drive hydraulic fluid
88
What makes a cylinder a ram
The piston rod is more than half the piston face area.
89
Axial motors are ____ displacement
Fixed or variable
90
Types of positive Displacement Pumps
Piston
Vane
Gear
91
How to change output of pump 3x
1:Use flow control and relief valve built into discharge passage
2: change speed of driver (rpm)
3: use variable displacement pump changes volume.
92
Bent axis pump can with stand ____ _____ at the inlet
High vacuum
93
How is the stroke increased on an axial piston pump
By increasing swash plate angle.
94
What is reason to use a pressure limiting or load sensing compensator
To save energy
95
Screw motors are _____ capacity
Fixed
96
Displacement is the amount of liquid handled in _____
One rotation
97
Tourqe output is a function of the system ____
Pressure and motor displacement
98
How to change output of pump 3x
:Flow control and relief valve
:Change speed of driver
:Use variable displacement pump
99
Can an inline piston pump be higher than fluid level
No they cannot tolerate high vacuum.
100
101
What is more the most efficient to least efficient pump
Piston pump
Vane pump
Gear pump
102
