engine lubricating oil systems

8/3/2019 Engine Lubricating Oil Systems

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ENGINE LUBRICATING OIL SYSTEMS AND ITS FUNCTION

Lubrication is as important for reliable engine operation as air, fuel, and heat

are to combustion. Lubrication is considered to be one of the most important

factors in the operating life of an internal-combustion engine. The lubrication

requirements of shipboard machinery are met in various ways, depending on

the design of the machinery. It is important not only that the proper type of

lubricant be used, but also that the lubricant be supplied to the engine parts at

the specified flow rate and temperature and that provision be made for removal

of any impurities that enter the system.

After studying the information in this chapter, you should be able to understand

the basic theories of lubrication, the factors affecting lubrication, the functions

and characteristics of greases and lubricating oils used aboard ship, and the

design and function of components in various lubricating oil systems, including

tanks, pumps, coolers, and filtering devices that you, as an Engine-man, may be

required to operate or maintain. You should also be able to understand theimportance of standards and procedures and how they are established and

enforced through the Lube Oil Quality Management Program.

For proper operation of an engine, the contacting surfaces of all moving parts of

the engine must be prevented from touching each other so that friction and

wear can be reduced to a minimum. Sliding contact between two dry metal

surfaces under load will cause excessive friction, heat, and wear. Friction, heat,

and wear can greatly be reduced, of course, if metal-to-metal contact is

prevented. When a clean film of lubricant is used between the metal surfaces,

metal-to-metal contact is automatically reduced. The lubricating film used

between load bearing surfaces in machinery is provided by a specified oil or

grease.


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TYPES OF OIL

Conventional

Conventional motor oil is a byproduct of the crude-oil refining process and is the

least expensive of the three types.

Synthetic

Synthetic motor oil flows better than conventional motor oil, keeps the engine

cleaner and maintains viscosity longer. It is the most expensive motor oil.

Synthetic Blends

Synthetic blends provide some benefits of synthetic oil while not costing as

much.

Single Grade

Single grade is the designation from the Society of Automotive Engineers, such

as SAE30, a measurement of oil thickness and ability to handle high

temperatures.

MultiGrade

Multigrade, for instance, 5W30, indicates the oil's ability to handle both hot and

cold temperatures. In this measurement, "W" stands for "winter," and the lower

number represents the lowest temperature at which this oil performs well.

OIL DISTRIBUTION

SYSTEM CLASSIFICATION

Wet SumpA wet sump system for oil circulation in an engine is commonly found in passenger

cars. In a wet sump system oil is stored in the oil pan, where it is recirculated directly

back into the engine by the oil pump. The main benefit to a wet sump system is its

easy modification for oil control and power since it is the original system included in a

car's engine. The wet sump system is also low-cost, lightweight, simple and common,making it the logical choice for most passenger cars and light racing. However, for

serious racers, there are distinct disadvantages to the wet sump system. It limits

power, is slightly bulky and is inadequate to deal with the extreme shifts in motion.

Dry SumpA dry sump system is most commonly found in race cars for its additional power. A dry

sump system pumps oil from the oil pump and filters it to an outside tank where it is

then recirculated back into the engine. The main advantage to the dry sump system is


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increased power through reduced oil splash, or wind age, and an improved ring seal

between the oil pan and engine block. The dry sump system also allows for lower

engine placement because of its shallower oil pan, increased oil capacity due to the

external oil tank and continuous lubrication. The main disadvantages to the dry sump

system are its complexity, high cost and its limited use as a mainstream oil circulating

system.

Oil system components

OIL PUMP

The oil pump in an internal combustion engine circulates engine oil under pressure to

the rotating bearings, the sliding pistons and the camshaft of the engine. This

lubricates the bearings, allows the use of higher-capacity fluid bearings and also assists

in cooling the engine.

As well as its primary purpose for lubrication, pressurized oil is increasingly used as

a hydraulic fluid to power small actuators. One of the first notable uses in this way was

for hydraulic tappets in camshaft and valve actuation. Increasingly common recent

uses may include the tensioner for aiming or variations for variable valvetiming systems.

PRESSURE RELIEF VALVE

The relief valve (RV) is a type ofvalve used to control or limit the pressure in a

system or vessel which can build up by a process upset, instrument or equipment

failure, or fire.

The pressure is relieved by allowing the pressurized fluid to flow from an auxiliary

passage out of the system. The relief valve is designed or set to open at a

predetermined set pressure to protect pressure and other equipment from being

subjected to pressures that exceed their design limits. When the set pressure is

exceeded, the relief valve becomes the "path of least resistance" as the valve is forced

open and a portion of the fluid is diverted through the auxiliary route. The diverted fluid

(liquid, gas or liquidgas mixture) is usually routed through a piping system known as

a flare headeror relief headerto a central, elevated gas flare where it is usually burned

and the resulting combustion gases are released to the atmosphere. As the fluid is

diverted, the pressure inside the vessel will drop. Once it reaches the valve's reseating

pressure, the valve will close. The blow down is usually stated as a percentage of set

pressure and refers to how much the pressure needs to drop before the valve reseats.

The blow down can vary from roughly 220%, and some valves have adjustable blow

downs

OIL FILTERS

An oil filter is a filter designed to remove contaminants from engine oil, oil,

lubricating, or hydraulic oil. Oil filters are used in many different types ofhydraulic

machinery. A chief use of the oil filter is in internal-combustion engines in on- and off-

road motor vehicles, light aircraft, and various naval vessels. Other vehicle hydraulic

systems, such as those in automatic transmissions and power steering, are often

equipped with an oil filter. Gas turbine engines, such as those on jet aircraft, require
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the use of oil filters. Aside from these uses, oil production, transport, and recycling

facilities also employ filters in the manufacturing process.

OIL COOLERS

Oil coolers are essentially small radiators that are situated in front of an engine's

cooling system in an automobile. Its purpose is to cool the oil as it passes through the

coils and it only operates when the engine is running.

OIL DILUTION

On-line measurement of oil dilution is of interest in light of new

environmental regulations imposed on today's high-performance engines. In particular,

after-treatment devices such as diesel particle filters (D.P.F.) or den Ox systems need to

be periodically re-generated. Such re-generation process is typically performed by

using post-injection cycles that can induce a transfer of fuel to the lubricant, resulting

in oil dilution by fuel (or "fuel dilution"). Oil dilution system combines the services of

both fuel system and the oil system, it was described in the chapter on fuel system.

OIL SEPARATOR

Oil separators are designed to skim oil out of effluent water sources to prevent

contamination from waste water that is not treated in sewage facilities. The American

Petroleum Institute has set a standard for oil separators that prevent spillage of oil from

becoming entrained in effluent water sources and contaminating the environment.

OIL PRESSURE

Oil pressure is an important factor in the longevity of most internal combustion

engines. With a forced lubrication system (invented byFrederick Lanchester), oil ispicked up by a positive displacement oil pump and forced through oil galleries

(passageways) into bearings, such as the main bearings, big

ends and camshaft bearings. Other components such as cam lobes and cylinder walls

are lubricated by oil jets.

Sufficient oil pressure ensures that the metal of the rotating shaft (journal) and the

bearing shell can never touch, and wear is therefore confined to initial start-up and

shutdown. The oil pressure, combined with the rotation of the shaft, also

hydrodynamically centers the journal in its shell and cools the bearings. Such a bearing

is known as a fluid bearing.

Oil pressure is higher when the engine is cold due to the increased viscosity of the oil,

and also increases with engine speed until the relief valve opens to divert excess flow.

Oil pressure is lowest under hot idling conditions, and the minimum pressure allowed

by the manufacturer's tolerances is usually given at this point. Excessive oil pressure

may indicate a blocked filter, blocked oil gallery or the wrong grade of oil. Low oil

pressure indicates worn bearings on the crank shaft or a broken oil pump.

OIL RESERVOIR
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is a subsurface pool ofhydrocarbons contained in porous or fractured rock formations.

The naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped by

overlying rock formations with lower permeability. Reservoirs are found

using hydrocarbon exploration methods.

OIL SCAVENGE SYSTEM

The subsystem of a gas turbine engine lubrication system that collects the oilafter it has lubricated the bearings and gears and returns it to the oil tank.

Scavenging oil system as a part of recirculatory oil system

HYDRAULIC POWER SYSTEM

FunctionA hydraulic system is used in machines that need fluid power to make them work. The

fluid power used for these machines is a high-pressured liquid, called hydraulic fluid.

The hydraulic fluid is transmitted through the entire machine and will reach the

different hydraulic cylinders and hydraulic motors in the machine. There are control

valves that have complete control over the fluid and will automatically distribute it

through the machine's tubes and hoses. The advantage of using a hydraulic machine is

that it can produce large amounts of power that is transferred into the machines tubes

and hoses. All this power is used in the actuators, which is the mechanical device that

is used for controlling and moving a particular mechanism.

Process
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A hydraulic system works because the force that is applied at a point is transmitted to

a second point by using an incompressible fluid. Two pistons are positioned into two

glass cylinders that are filled with oil. An oil-filled pipe connects them to one another.

The pipe can be any shape or length--all it needs to do is separate the two pistons.

Sometimes the pipe will look like a fork in the hydraulic system, so a master cylinder

can have the ability to drive more than one slave if needed. First, one of the pistons

experience a downward force then that force is transmitted to the next piston using theoil in the pipe. This makes the hydraulic system work efficiently, because the oil is

incompressible. Then the all of the force is applied on the second piston, and it

happens all over again.

BenefitsThe benefit of using a hydraulic system is that it is simple to multiply more force if

needed, and get the desired power for your machine. To make this work, all you have to

do is change the size of one of the pistons and cylinder, while still making them relativeto each other. To do this, you need to measure the sizes of the pistons, and plug those

numbers into this formula Pi times r2. Once you determine the difference between the

two, you will know how much force is needed to reach your desired power. After you

have determined the numbers, you will need to raise one of the pistons, while

decompressing the other to reach your optimum power.

PRINCIPLE OF HYDRAULIC POWER

Hydraulic systems use an incompressible fluid, such as oil or water, totransmit force from one location to another. Hydraulic power canmultiply an applied force to permit the lifting or moving of heavyobjects, and because of this ability, there are limitlessopportunities to use hydraulic power in industry.

Pascal's LawAccording to Pascal's Law, an increase in pressure anywhere within a system of

confined fluid creates an equal increase at every other point in system. This allows the

transfer of forces through the hoses and pipes of a hydraulic system.

Force IncreaseA small force applied to a piston of a small diameter will apply a larger force at a piston

of larger diameter elsewhere in a hydraulic system. The larger force equals the smaller

force times the ratio of the areas of the pistons. This allows the moving heavy objects

with minimal force.

Working FluidHydraulic systems require a working fluid to take a force created in one place and apply

it elsewhere. According to Hydraulics & Pneumatics, most hydraulic systems use

mineral oil, but water, ethylene glycol or synthetic fluids are also possible.


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System ComponentsHydraulic systems vary in their design from small lifting pumps to systems that fill

compartments on ocean vessels. Possible components include pumps to create high

pressure and move fluid through the system. Pumps can also charge accumulators,

which use compressed gas to store energy and maintain pressure on the system.

Actuators change the direction hydraulic fluid flows, or stop its flow, to impart

translational mechanical motion upon a component outside the system.

Example ApplicationsExamples of the application of hydraulic power include hydraulic jacks, vehicle lifts,

fork lifts and the control surfaces (like ailerons and rudders) on ships and aircraft.

Hydraulic System Components

Hydraulic systems are built out of five basic components. Pumps move hydraulic fluidand create pressure. They convert mechanical force into hydraulic force. Valves direct

the flow of hydraulic fluid and change its pressure. Actuators, such as pistons and

hydraulic motors, convert hydraulic force into mechanical force. Reservoirs store

hydraulic fluid. Filters clean it.

Hydraulic Pumps and Motors

o Piston pumps and motors (fixed & variable volume, axial, bent axis,and radial)

o Gear pumps (cast iron & aluminum), tandem

o Vane pumps

o High pressure hydraulic pumps (open & closed loop)o Hydrostatic pumps and transmissions,

o Low speed, high torque; geroler, gerotor, torqlink

o Electronic controlled pressure and flow

Electronic Controls

o Electro-hydraulic control of valves & pumps

o Electronic monitoring and control of entire machine

o CANbus / J1939 communication protocol

o Parker IQAN control

o Sensors (rotary, linear, position, speed, proximity, level, & angle)

o Single and multi axis motion controllerso Closed loop position, velocity, pressure and force control

Filtration

o High, medium & low pressure filtration

o Fluid analysis

o Fluid sampling

o Filter carts and portable / offline filtration units

o Kidney loop filtration system
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o Purification units

o Reservoir accessories

o Water removal filters

o Competitive replacement elements

o Moisture sensors

o Laser particle counters

Actuatorso Mobile cylinders, telescopic, welded, single acting

o Industrial cylinders, tie rod, double acting, mill cylinders

o Rotary, rack and pinion, vane

Accumulators

o Piston, Bladder, Diaphragm

o Oil, Water Service

o Carbon fiber

Hydraulic Valveso Directional control valves

o Electrohydraulic servo, proportional valves

o Relief, pressure reducing, sequence valves

o DIN cartridge valves

o Threaded cartridge valves

o Integrated manifolds

Compact Power Units

o Oildyne

o Electrohydraulic actuators, EHA

Winches

o Planetary, recovery and worm gear

PTO's

Heat Exchangers

o Air to Oil

o Water to Oil

From hydraulic mobile cylinders and winches to hydraulic solenoid valves, we have the

parts you need. We also provide kitting, subassembly, custom inventory management,

and basic Kanban value-added services. We design, engineer, and sell hydraulic system

components for many standard and challenging applications. For existing applications,we also provide complete hydraulic repair services. At McCoy Sales, a team of experts

will help you find the specific part that works in your unique hydraulic system

application. Our system design capabilities and extensive line of hydraulic components

makes us a one-stop solution for your hydraulic needs


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HYDRAULIC DESIGN

McCoy Sales is an ISO 9001:2008 registered company providing complete hydraulic

system design, engineering, fabrication, and assembly. We are a Parker designated

Hydraulic Technology Center and Mobile Technology Center. Our breadth of products

provides you with a number of hydraulic system options you cannot get elsewhere. We

work with both MROs and OEMs, mobile and industrial markets, bringing you high

quality hydraulic components to get you going quickly and efficiently.

HYDRAULIC FLUID

Hydraulic fluids, also called hydraulic liquids, are the medium by which power is

transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil

or water.[1] Examples of equipment that might use hydraulic fluids include excavators

and backhoes, brakes, power steering systems, transmissions, garbage trucks, aircraft

flight control systems, lifts, and industrial machinery.

Hydraulic systems like the ones mentioned above will work most efficiently if the

hydraulic fluid used has low compressibility.

Characteristics of a Good Hydraulic Fluid

ViscosityViscosity is a measure of a hydraulic fluid's resistance to

flow. It is a hydraulic fluid's most important characteristic

and has a significant impact on the operation of the

system.

When hydraulic oil is too thin (low viscosity), it does not seal sufficiently. This leads to

leakage and wear of parts. When a hydraulic oil is too thick (high viscosity), the fluid

will be more difficult to pump through the system and may reduce operating efficiency.

All hydraulic fluids must be able to retain optimum viscosity during operation in cold or

hot temperatures, in order to consistently and effectively transmit power.

CompressibilityCompressibility is a measure of the amount of volume reduction due to pressure.

Although hydraulic oils are basically incompressible, slight volume reductions can occurunder certain pressure ranges.

Compressibility increases with pressure and temperature and has significant effects on

high-pressure fluid systems. It causes servo failure, efficiency loss, and cavitation;

therefore, it is important for a hydraulic oil to have low compressibility.

Wear Resistance
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Wear resistance is a hydraulic fluid's ability to reduce the wear rate in frictional

boundary contacts. Antiwear hydraulic fluids contain antiwear components that can

form a protective film on metal surfaces to prevent abrasion, scuffing, and contact

fatigue. Antiwear additives enhance lubricant performance and extend equipment life.

Oxidation Stability

Oxidation stability is a hydraulic oil's resistance to heat-induced degradation caused bya chemical reaction with oxygen. Hydraulic oils must contain additives that counteract

the process of oxidation, improve the stability and extend the life of the fluid. Without

these additives, the quality of the hydraulic oil will deteriorate quickly.

Thermal StabilityThermal stability is the ability to resist breakdown at elevated temperatures. Antiwear

additives naturally degrade over time and this process can be accelerated at higher

temperatures. The result of poor thermal stability is the formation of sludge and

varnish which can clog filters, minimize flow and increase downtime. In addition, as

these antiwear agents decompose at high temperatures, acids are formed which attack

bronze and yellow metals in piston pumps and other hydraulic system components.

Hydraulic oils can be formulated with very high levels of thermal stability to minimize

these issues and help extend the life of the hydraulic fluid and the components of the

hydraulic system.

FilterabilityWater can react with additives in hydraulic fluids forming oil insoluble material. These

contaminants can precipitate from the lubricant and block filters, valves and other

components resulting in decreased oil flow or the system going on bypass. Blockage

can eventually result in unplanned downtime. Hydraulic fluids are designed to be

filtered with modern filtration systems without fear of the additive being depleted orremoved from the system. This enables systems to stay clean without sacrificing

critical performance requirements such as antiwear, rust protection or foam inhibition.

Rust and Corrosion ProtectionIn many systems, water can enter as condensation or contamination, and mix with the

hydraulic oil. Water can cause rusting of hydraulic components. In addition, water can

react with some additives to form chemical species which can be aggressive to yellow

metals. Hydraulic oil formulations contain rust and corrosion inhibitors which prevent

the interaction of water or other chemical species from attacking metal surfaces.

Foam ResistanceFoam results from air or other gases becoming entrained in the hydraulic fluid. Air

enters a hydraulic system through the reservoir or through air leaks within the system.

A hydraulic fluid under high pressure can contain a large volume of dissolved or

dispersed air bubbles. When this fluid is depressurized, the air bubbles expand and

produce foam. Because of its compressibility and poor lubricating properties, foam can

seriously affect the operation and lubrication of machinery.


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Proper foam inhibitors modify the surface tension on air bubbles so they more easily

break up.

DemulsibilityWater that enters a hydraulic system can mix or emulsify with the hydraulic oil. If this

'wet' fluid is circulated through the system, it can promote rust and corrosion. Highlyrefined mineral oils permit water to separate or demulsify quickly. However, some of

the additives used in hydraulic oils promote emulsion formation, preventing the water

from separating and settling out of the fluid. Demulsifier additives are incorporated to

promote water separation from hydraulic fluids.

Hydrolytic StabilityWhen hydraulic fluids come into contact with water, the water can interact with the

additive system of the hydraulic oil resulting in the formation of acids. Hydraulic fluids

that lack hydrolytic stability hydrolyze in the presence of water to form oil insoluble

inorganic salts that can block filters and valves inhibiting oil flow. This can result in

hydraulic system failure. Properly formulated hydraulic fluids are designed to contain

additives that are resistant to interactions with water, helping to extend the life of the

equipment.

Seal CompatibilityLeaking hydraulic fluids can cause many issues from simple housekeeping problems to

more serious safety concerns and lubrication failures. Most hydraulics systems utilize

rubber seals and other elastomers to minimize or prevent hydraulic oil leakage.

Exposure of the elastomer to the lubricant under high temperature conditions can

cause the rubber seals to harden, crack and eventually leak. On the other hand,

hydraulic oil exposure can seals to swell excessively preventing hydraulic valves and

pistons from moving freely. Hydraulic oils are tested against a variety of seal materials

to ensure that the hydraulic fluid will be compatible with seals under various

conditions.

TYPES OF HYDRAULIC FLUIDS

Hydraulic fluid is used to run different machinery such as transmissions in cars, forklifts

and factory machinery. Each type of hydraulic fluid are made of different chemicals and

have different characteristics. Some hydraulic fluids smell while other have no smell at

all and some hydraulic fluids are more environmentally friendly than others.Determining what type of hydraulic fluid to use is mainly a personal preference

decision.

Oil-based Hydraulic FluidMost hydraulic fluids used on ships and are oil or petroleum-based fluids that prevent

corrosion on the different metals used in the ships engine. The petroleum-based

hydraulic fluid do not have foam when running through the system. Ships are not the

only place oil-based hydraulic fluid is used, it can be used in brakes, shock absorbers


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and some aircraft. The petroleum-based hydraulic fluid is the most common fluids in

use today. Besides being flammable, this type of hydraulic fluid also has a tendency of

building up sludge in the gear cases and needs to be replaced more often then the

synthetic type hydraulic fluid.

Synthetic Hydraulic Fluid

Synthetic hydraulic fluid was developed because other oil-based fluids are flammableand engineers wanted to prevent this flaw. The oil-based hydraulic fluid also had a

hazard of exploding under high-pressure situations. The use of synthetic hydraulic fluid

is for highly flammable or other hazards may exist with the use of other types of

hydraulic fluid. Synthetic hydraulic fluid is not made from natural sources like the oil-

based hydraulic fluid and is a combination of different chemicals. This chemical

combination is what makes the synthetic hydraulic fluid flame resistant.

Detergent Additive Hydraulic FluidsDetergent additive hydraulic fluids are considered a flame resistant hydraulic fluid, but

can become flammable at certain temperatures. This detergent type hydraulic fluid is

used when operating the machinery or part causes a build-up of sludge or there is

water present. this type of hydraulic fluid can emulsify water and disperse the water

from the machine parts. The drawback of this type of hydraulic fluid is that it

deteriorates gaskets and seals quicker than the others.

VEGETABLE BASE FLUID

MIL- H- 7644 fluids has been used in the past when hydraulic system isrequirements

were not so severe as they are today

BASIC DESIGN OF HYDRAULIC SYSTEM

A basic hydraulic system consists of a reservoir, pump (either hand, electric, or enginedriven), a filter to keep the fluid clean, selector valve to control the direction of flow,

relief valve to relieve excess pressure, and an actuator.

The hydraulic fluid is pumped through the system to an actuator or servo. Servos can

be either single-acting or double-acting servos based on the needs of the system.

This means that the fluid can be applied to one or both sides of the servo, depending

on the servo type, and therefore provides power in one direction with a single-acting

servo. A servo is a cylinder with a piston inside that turns fluid power into work and

creates the power needed to move an aircraft system or flight control. The selector

valve allows the fluid direction to be controlled. This is necessary for operations like the

extension and retraction of landing gear where the fluid must work in two differentdirections. The relief valve provides an outlet for the system in the event of excessive

fluid pressure in the system. Each system incorporates different components to meet

the individual needs of different aircraft.

A mineral-based fluid is the most widely used type for small airplanes. This type of

hydraulic fluid, which is a kerosene-like petroleum product, has good lubricating

properties, as well as additives to inhibit foaming and prevent the formation of

corrosion. It is quite stable chemically, has very little viscosity change with

temperature, and is dyed for identification. Since several types of hydraulic fluids are


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commonly used, make sure your airplane is serviced with the type specified by the

manufacturer. Refer to the AFM, POH, or the Maintenance Manual.

SIMPLE HYDRAULIC SYSTEM

A simple hydraulic system such as that within a hydraulic jack consists of two different

sized cylinders connected by a pipe.

According to Pascal's Law, pressure exerted on the smaller piston is transmitted

through the fluid to act on internal surface of the larger piston. Pressure is a property of

the system (not the pistons) and is therefore experienced equally by each piston.

Because each piston has a different surface area, the force exerted on each piston will

be different, even though the pressure is the same.

If the larger piston is twice the area of the smaller piston then the force on the largerpiston will be twice as great. In order to create that extra force, the smaller piston has

to be moved by twice the distance.

It was this principle that was understood by Joseph Bramah when he patented the

Bramah Press in 1795.

For the demonstration of how a simple hydraulic system works, Sphaera's interactive

instructor-led CBT is simple yet effective. Buttons on screen provide the instructor with

full control over the amount of force applied whilst pressure and force are clearly

indicated numerically and through use of color.
http://www.sphaera.co.uk/pascalsLaw.htmhttp://www.sphaera.co.uk/pascalsLaw.htm


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HYDRAULIC RESERVOIRThe hydraulic reservoir is the fluid storehouse for the hydraulic system. It

contains enough fluid to supply the normal operating needs of the hydraulic

system and an additional supply to replace fluid lost through minor leaks.Additionally, the reservoir allows the settling of any impurities and separation of

air from the fluid before reuse in the system. The basic hydraulic reservoir has a

space above the fluid even when they are full. This space allows the fluid to

foam, and thus purges itself of air.

HYDRAULIC LINES


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Just like any other part of a machine, hydraulic lines acquire some serious wear and

tear over the life of your motor. Whenever the lines begin to crease, kink, break or leak,

it's easier to replace them instead of repairing them. Replacing hydraulic lines is

relatively easy, so roll up your sleeves and get to work.

SELECTOR VALVES

Selector valves are used in a hydraulic system to direct the flow of fluid. Aselector valve directs fluid under system pressure to the desired working port of

an actuating unit (double-acting), and, at the same time, directs return fluid

from the opposite working port of the actuating unit to the reservoir. Some

aircraft maintenance instruction manuals (MIMs) refer to selector valves as

control valves. It is true that selector valves may be placed in this

classification, but you should understand that all control valves are not

selector valves. In the strict sense of the term, a selector valve is one

that is engaged at the will of the pilot or copilot for the purpose of

directing fluid to the desired actuating unit. This is not true of all control

valves. Selector valves may be located in the pilots compartment and be

directly engaged manually through mechanical linkage, or they maybe

located in some part of the aircraft and be engaged by remote control.

Remote-controlled selector valves are generally solenoid operated

PUMPS

A pump is a device used to move fluids, such as liquids, gases or slurries.

A pump displaces a volume by physical or mechanical action. Pumps fall into three

major groups: direct lift, displacement, and gravity pumps. Their names describe

the method for moving a fluid.

ACTUATING CYLINDER

A cylinder and piston arrangement in which hydraulic or pneumatic pressure is

converted into work. Fluid pressure moves the piston, which, in turn, does the work.

Actuating cylinders having ports in piston rod.
http://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Slurryhttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Slurry

engine lubricating oil systems

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