Hydraulics Systems Flashcards
1
Q
_____ relates to the use of confined fluids to transmit power, multiplying force and modifying motions.
A
Hydraulics
2
Q
Hydraulics is based upon a principle discovered by the french scientist _______ in the 17th century.
A
Blaise Pascal
3
Q
Hydraulics is widely used in the CG to perform various functions, including the following:
A
- Steering systems
- Booms/cranes
- Winches and other deck machinery
- Hydraulic presses
- Fin stabilizer systems
- Controller pitch propellars
4
Q
Pressure applied to a confined fluid is transmitted undiminshed in all directions and acts equal force on equal areas and at right angles to them.
A
Pascal’s Law
5
Q
Within Pascal’s Law are found the 3 areas of Hydraulics:
A
- Pressure
- Force
- Area
6
Q
Use the following 3 formulas when working with hydraulic systems:
A
- Force = Pressure X Area
- Pressure = Force / Area
- Area = Force / Pressure
7
Q
______ is defined as the measure of a bounded region or plane.
A
Area
8
Q
______ is expressed in inches square (in2)
A
Area
9
Q
________ is defined as anything which tends to produce or modify motion.
A
Force
10
Q
_______ can push, pull or rotate and is usually expressed in units of weight. In hydraulics it is expressed in pounds (#, lbs.).
A
Force
11
Q
______ is defined as force per unit area and is measured in pounds per square inch (psi).
A
Pressure
12
Q
________ is created by resistance to flow, either by force (load) or restricting flow.
A
Pressure
13
Q
Inside a Hydraulic Cylinder there are two working surface areas?
A
The 1st is the cap end** and the 2nd is the **net area.
14
Q
Hydraulic pressure working on the ______ area forces the piston rod to extend.
A
Cap End
15
Q
Hydraulic forces working on the _____ area forces the piston to retract.
A
Net
16
Q
With the same pressures, the hydraulic cylinder produces greater force _________.
A
extending than retracting
17
Q
What is the formula to calculate the cap end area of a hydraulic cylinder?
A
Area = D squared X .7854
(D = Diameter in inches)
18
Q
Formula to calculate the piston area when the force and pressure are known.
A
Area = Force / Pressure
19
Q
To calculate the amount of force being applied, multiply the pressure by the cylinder’s area. For extending use the cap area. For retracting use the net area. What is the formula?
A
Force = Pressure X Area
20
Q
Calculating force for extension:
A
Extending
F = P X A
F = 200 psi X 6 in squared
F = 1200 lbs
21
Q
Calculating force for retraction:
A
Retracting
F = P X A
F = 200 psi X 4 in squared
F = 800 lbs
22
Q
Calculating maximum force:
A
Extending
F = P X A
F = 2500 psi X 8 in squared
F = 20,000 lbs
23
Q
Calculating maximum retraction:
A
Retracting
F = P X A
F = 2500 psi X 4 in squared
F = 10,000 lbs
24
Q
What is the formula to calculate area?
A
Area = Force / Pressure
25
Calculate the piston area when force and pressure are known.
**_Area_**
## Footnote
Area = Force / Pressure
A = 2000 lb / 500 psi
A = 4 in squared
26
To calculate the system's pressure while moving a load, the force and the cylinder's area must be known. What is the formula?
Pressure = Force / Area
27
Calculate cylinder pressure extending:
**_Extending_**
## Footnote
P = F / A
P = 1500 lbs / 10 in squared
P = 150 psi
28
Calculate cylinder pressure retracting:
**_Retracting_**
## Footnote
P = F / A
P = 1500 lbs / 5 in squared
P = 300 psi
29
When calculating the movement and force on a cylinder with pressure on both sides of the cylinder, the force exerted in each direction calculated first. Then subtract the force retracting from the force extending. View example of a differential pressure formula:
Force extending = Pressure X Area
Force retracting = Pressure X Area
Force extending = 500 psi X 4 in squared = 2000 lbs
Force retracting = 500 psi X 2 in squared = 1000 lbs
2000 lbs - 1000 lbs = Differential Pressure 1000 lbs
30
\_\_\_\_\_ is the ability or capacity to do work.
Energy
31
Also referred to as **_STORED ENERGY_**, _______ is present in a hydraulic system in the form of a **_FLUID PRESSURE_**.
Potiential Energy
32
Also referred to as **ENERGY IN MOTION**, ______ is present in a hydraulic system in the form of **FLUID FLOW**, represented by a **MOVING ACUATOR**.
Kinetic Energy
33
\_\_\_\_\_\_\_\_\_\_ states "Energy can neither be created, nor destroyed, but instead will simply be changed from one form to another"
The Law of Conservation of Energy
34
\_\_\_\_\_\_\_\_\_ energy changes into \_\_\_\_\_\_\_energy as speed is lost-what is gained in one energy form is lost in another.
Kinetic Energy changes into Potential Energy
35
\_\_\_\_\_\_\_ is defined as exerting force through a defined distance. In other words, how much effort is exerted moving something a certain distance.
Work
Formula: Work = Force X Distance
One way to express work is in foot pounds
36
\_\_\_\_\_\_\_ is the rate of doing work. An object is moved a fixed distance either slowly or quickly.
Power
Formula: Power = _Force X Distance_
Time
The faster an object moves over a fixed distance, the more power is required.
37
Formula for Horse Power:
1 HP = _100 lbs X 330 ft_
1 minute
38
In hydraulics, ___________ are used to determine horsepower.
Fluid Flow and Pressure
39
What is the best protection against unsafe practices when working with hydraulic systems?
Common sense and knowledge of the system
40
Where would you find the following components:
* Reservior
* Pump
* Control valves
* Motors (rotary actuators)
* Cylinders (linear actuators)
* Accumulator
* Filters and Strainers
* Fluid conductors and seals
* Hydraulic fluid
Components of a hydraulic system
41
When a hydraulic system is operating incorrectly, the cause is generally traced to one of the following:
* Contaminated hydraulic fluid
* Wrong hydraulic fluid viscosity or type
* Insufficient fluid in system
* Air in the system
* Damage
* leakage
These causes result in a problem with one or more of the following fundamental elements of the system:
* Flow
* Pressure
* Direction of flow
42
A problem with flow, pressure and direction of flow may cause one or more of the following symptoms to appear in the system:
* Excessive heat
* Excessive noise
* Faulty operation
* Incorrect flow
* Leaks
* Vibration
43
The tools most commonly used in the CG for troubleshooting hydraulic systems are:
* Pressure Gauges
* Flowmeters
* Manufactures tech manual
44
Most common cause of failures, especially repeated failures in the same piece of equipment, is fluid \_\_\_\_\_\_.
Fluid Contamination
45
\_\_\_\_\_\_\_, which can cause fluid contamination, is another possible cause of failure in a hydraulic system.
Heat
46
When using a flowmeter, direct the return fluid to the \_\_\_\_\_\_\_\_\_.
Reservior
47
The fluid used in hydraulic systems has four functions:
* Transmit power
* Cool
* Seal
* Lubricate
In order for hydraulic fluid to perform these functions, verify it is the correct type, viscosity and free of contaminants.
48
\_\_\_\_\_\_\_ is the most important factor in keeping hydraulic systems operating properly.
Contamination Control
49
Dirt, sand, gasket/sealing materials, component wear particles or any solids within the hydraulic fluid.
Solid or particle contamination
50
The most common Liquid Contaminant in CG hydraulic systems is \_\_\_\_\_\_.
Water
51
Any dissolved or free air or other gases in the fluid. It causes increased oxidation and reduced lubrication.
Air and gas contamination
52
Chemical, solvent and microbial growth and any other type of contaminants.
Other Contaminants
53
Fluid storage inspection and testing are detailed in \_\_\_\_.
NSTM, Chapter 556, Section 5
54
For petroleum base fluids, such as _______ and ______ fluids, water content is less than 100 ppm is desirable.
MIL-L-17331 and MIL-H-17672 fluids
55
Maximum allowable water content for MIL-L-17331 and MIL-H-17672 fluids is _____ ppm for any sample.
500 ppm
56
\_\_\_\_\_\_\_\_ fluids are somewhat hygroscopic (absorb water) with a maximum water content of 3000 ppm (0.30 percent).
MIL-H-19457
57
For water emulsifying petroleum base fluids, a maximum water content of _______ is allowed.
20,000 (2.0 percent)
58
\_\_\_\_\_\_\_\_\_\_\_\_\_ is a water emulsifying fluid and in an emergency, is authorized for continued use at 100,000 ppm (10 percent) by TYCOM/NAVSEA.
Houghton PR 1192
59
Detailed procedures for handling water contaminated hydraulic systems are found in \_\_\_\_\_\_\_.
NSTM, Chapter 556, Section 8.7
60
Remove water from hydraulic fluid using several different methods?
* Drain and fill
* Settling and draining
* Centrifuging
* Evaporation
* Filtration
* Water absorbent filters
61
\_\_\_\_\_\_\_\_ convert mechanical energy from a prime mover, into hydraulic energy(pressure). This energy is used to operate an actuator.
Hydraulic Pumps
62
Name two broad categories of Pumps:
* Positive Displacement
* Nonpositive Displacement
Nonpositive displacement pumps are not used in hydraulic systems
63
Positive displacement pumps include the following types:
* Gear
* Vane
* Piston
64
\_\_\_\_\_\_\_\_ is the quantity of fluid that passes through a pump in one revolution, stroke or cycle, expressed in cubic inches.
Displacement
65
Output of the pump is considered "\_\_\_\_\_\_\_" because it is not significantly affected by resistance to flow.
Positive Displacement
66
Most pump failures are attributed to one or more of the following:
* Cavitation 10 - 12% frequency
* Aeration 10 - 12% frequency
* Contamination 80% frequency
* Excessive heat 2 - 5% frequency
* Overpressurization 5 - 6% frequency
* Improper fluid 2 - 5% frequency
67
\_\_\_\_\_\_\_ occur when pump inlet vacuum get high enough to pull entrapped air out of the hydraulic fluid.
Cavitations
68
Cavitations occur with as little as \_\_\_\_\_\_.
5 inches Hg
69
\_\_\_\_\_\_\_ is when air enters the fluid on the suction side of the pump.
Aeration
70
Parts affected by contamination in a Vane Pump:
* Vane tip to cam ring
* Rotor to side plate
* Vane-to-vane slot
71
Parts affected by contamination in a Gear Pump:
* Tooth to housing
* Tooth to tooth
* Gear to side plate
72
Parts affected by contamination in a Piston Pump:
* Shoe to swash plate
* Cylinder block to valve plate
* Piston to cylinder bore
73
Name two types of rotary actuators.
* Hydraulic Motor
* Rotary Actuator
74
Provides continuous rotation motion.
Hydraulic Motor
75
Has a limited turning motion of less than 360 degrees. A hydraulic motor converts hydraulic energy into mechanical energy.
Rotary Actuator
76
Types of motors
* Gear motors
* Vane motors
* Piston motors
77
\_\_\_\_\_\_\_\_\_ is used on motors to help prevent the prime mover from overloading.
Pressure Compensation
78
Breakage of a motors output shaft is caused by either:
* Shaft misalignment
* Loads with excessive torque
79
What?
* Stores the hydraulic fluid not currently being used in the system
* Allows space for expansion/contraction of the systems volume due to thermal changes
* Allows gauges to expel from hydraulic fluid
* Allows foreign matter to settle out from the hydraulic fluid
* Allows heat to dissipate from hydraulic fluid
A Hydraulic Resevior
80
A _______ is a type of actuator.
Hydraulic Cylinder
81
It converts fluid power into mechanical force and linear (straight line) motion.
Hydraulic Cylinder
82
The components of a hydraulic cylinder that require the most attention are the \_\_\_\_\_\_\_.
Seals and Pivots
83
The two most common locations for seal failure with a hydraulic cylinder are the \_\_\_\_\_.
Rod and Piston Seals
84
In a \_\_\_\_\_\_\_, the pressure in the net end is greater than in the cap end when extending the cylinder.
meter-out circuit
85
Control valves are divided into the following categories:
* Flow control valves
* Directional control valves
* Pressure control valves
86
Regulates flow of fluid
Flow control valves
87
Controls the driection of flow
Directional control valves
88
Limits or reduces fluid pressure to:
* relief valves
* pressure reducing valves
* pressure sequence valves
* unloading valves
Pressure control valves
89
* no pressure
* low or erractic pressure
* variations in flow
* excessive noise or chatter
* overheating system
* permature movement to second operation
* pump fails to unload completely
* faulty or incomplete shifting
* cylinder creeps or drifts
* overheating hydraulic fluid
What do these symtoms indicate when troubleshooting a hydraulic system?
One or more Valves may be at fault
90
\_\_\_\_\_\_\_\_\_ are furnished in matched sets and are not available for individual replacement.
Directional control valve spools
91
When repairing directional control valves, inspect the valve spools and bores for _____ and \_\_\_\_\_.
Burrs and Scoring
92
The directional control valve spools become coated with impurites from the \_\_\_\_\_\_\_\_.
Hydraulic fluid
93
When scoring or coating on a directional control valve is not deep enough to cause a leakage problem, polish the surface with \_\_\_\_\_\_.
Crocus Cloth
94
Renew the directional control valve's body and spool if __________ is excessive.
Scoring or Coating
95
If a directional control valve's action was erractic or sticky before removal, it may be unbalanced because of wear on the spools or body.
Renew the valve
96
If system checks indicate low pressure, check for a weak relief-valve spring using a \_\_\_\_\_.
Spring Tester
97
Each ______ is stamped with number, a pressure limit and the date of manufacture. Use this code when testing the cartridges.
Relief Valve's Cartridge
98
Test a valve's cartridge for correct pressure setting by installing in a system and operating the system until you reach the valve's \_\_\_\_\_\_\_\_.
Operating Pressure
99
Three main types of accumulators are:
* Spring loaded
* Weight loaded
* Gas charged
100
What kind of accumulator is used most in CG hydraulic systems?
Gas Charged
101
What two components of a hydraulic system are designed to reduce or eliminate certain types of contamination?
Filters and Strainers
102
Properly functioning _______ are essential to a properly functioning hydraulic system.
Filters and Strainers
103
\_\_\_\_\_\_\_\_\_ are devices whose primary function is the retention, by some porous medium, of insoluble contaminants from a liquid.
Filters
104
\_\_\_\_\_\_\_\_ are more course than filters, meaning larger particles will pass through.
Strainer
105
\_\_\_\_\_\_\_\_\_ are normally rated in wire mesh numbers.
Strainers
106
\_\_\_\_\_\_\_\_ are normally cleanable, where filters are not.
Strainers
107
\_\_\_\_\_\_\_\_\_ are most commonly located on the inlet or suction side of the hydraulic pump,but can be found elsewhere, such as resevior fill port or vent.
Strainers
108
Common places filter are located on a hydraulic system:
* In the pressure line just after the pump
* In return line before entering the resevior
* Before or in a component, kidney or bypass loop
* Offline-a separate pump & filter or a portable filtering unit.
109
Filters are located in:
* reseviors
* pressure lines
* return lines
110
\_\_\_\_\_\_\_\_\_ are classified as full flow or proportional flow.
Filters
111
In \_\_\_\_\_\_\_\_, all the fluid passes through a filtering element.
Full-Flow Filter
112
In a \_\_\_\_\_\_\_\_\_\_\_, only a portion of the fluid passes through a filtering element during each cycle.
Proportional Flow Filter
113
Filter elements can generally be classified into two groups:
* Surface Type Element
* Depth Type Element
114
In this type of element, the fluid stream has a straight flow path through the element and contaminants are trapped on the surface of the element.
Surface Type Element
115
In this type of element, the fluid stream is forced to pass through a multiple layer element and the multiple layers trap the contaminants.
Depth Type Element
116
\_\_\_\_\_\_\_ are usually constructed of a fine metal mesh with pores larger than 50 microns.
Strainers
117
\_\_\_\_\_ are most commonly installed on pump inlet lines inside the reservoir.
Strainers
118
Two common types of strainers used in hydraulic systems are:
* Wire Mesh
* Edge Disk
119
A strainer that consist of several layers of wire mesh.
Wire Mesh Strainer
120
A strainer that consist of a stack of metallic disk, separated by metallic spacers.
Edge Disk Strainer
121
The contaminants which are accumulated on the strainer are cleaned off using one of the following cleaning devices:
* Edge Wound Type
* Edge Disk Type
122
Indications that the pump inlet strainer is clogged:
* Pump noise caused by cavitation
* High vacuum pressure at the inlet side of the pump
123
What are a few ways to tell that pressure differential has beem reached and the filter element is clogged and needs replacement?
* Pressure Guages
* Mechanicla and Electrical Indicators
* Bypass Valve Indicator
