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Lubricants known as hydraulic fluid are used as the working fluid in
hydrostatic power transmission.
6-Protect against wear:
Lubricant prevent wear by keeping the moving parts apart .lubricant also contain anti-wear or extreme pressure additives to boost their performance.
Good quality lubricants are typically formulated with additives that form chemical bonds with surfaces to prevent corrosion and rust.
8-Seal for gases:
Lubricants will occupy the clearance between moving parts through the capillary force thus sealing the clearance this effect can be used to seal pistons and shafts. The oil supply to the crosshead bearing is boosted in pressure to about 12 bar by a second set of pumps. This oil is also used to operate the hydraulic reversing gear for the engine.
The cylinder liners on a two stroke engine are lubricated using separate injection pumps which use a different specification of oil. The oil which is led to drillings in the liner is able to deal with the acids produced by the burning of high sulphur fuels. On some engines : The oil then drains from the crankcase into the drain tank or sump.
The oil in the drain tank is being constantly circulated through a centrifugal purifier. This is to remove any water and products of combustion plus any foreign particles which may be in the oil
The cylinder liner must be lubricated as well. This is so there will be a film of oil between the piston rings and the liner and also so that any acid produced by combustion of the fuel is naturalized by the oil and does not cause corrosion. Some of this lubrication will be supplied by so called "splash lubrication" which is the oil splashed up into the liner by the rotating crankshaft. However larger medium speed marine diesel engines also use separate pumps to supply oil under pressure to the cylinder liner. The oil is led through drillings onto the liner surface where grooves distribute it circumferentially around the liner, and the piston rings spread it up and down the surface of the liner.
A pre lub pump is sometimes fitted especially to engines where the main pump is engine driven. This pump is electrically driven and circulates oil around the engine prior to starting. On a medium speed 4 stroke engine : Lubricating oil for a marine diesel engine achieves two objectives; it must cool and lubricate.
The oil is taken from the drain tank usually underneath the engine by a screw type pump. It is cooled, filtered and supplied to the engine via the oil inlet pipe or inlet rail at a pressure of about 4 bar. THE LUBRICATING OIL SYSTEM:
The oil pump is the heart of the lubricating system, it forces oil out of the oil pan, through the oil filter, galleries, and to the engine bearings. Normally, a gear on the engine camshaft drives the oil pump. 3-OIL PUMP: 1-OIL PAN :
The oil pan (Fig. 1) may be made of steel, cast iron, or cast aluminum. A shallow or deep sump-type oil pan is used, depending upon the particular engine application.
A one-piece oil pan gasket stamped steel pans. A four-piece gasket is used with the cast oil pan It must be remembered that the lubricating system is actually an integral part of the engine and the operation of one depends upon the operation of the other.
Thus the lubricating system in actual practice Can’t be considered as a separate and independent system , it is part of the engine. LUBRICATING (OIL) SYSTEM COMPONENTS : LUBRICATING (OIL) SYSTEM COMPONENTS 4- Should not react with the lubricating surface.
5- Cleaning ability
6- Non toxic
7- Non flammable
8- Low cost
9- high resistance to oxidation A good lubricant should posses the following properties :
1- high Viscosity:
Viscosity is a measures of the flow ability of an oil under a particular temperature and pressure
2- Flash Point or Fire Point:
The lowest temperatures at which the oil flashes and fires , known as flash and fire points.
3- low Pour Point.
The lowest temperature at which the oil pours is called its pour point. PROPERTIES OF LUBRICANTS: As the load increases on the contacting surface five distinct situations can be observed with respect to the mode of lubrication, which are called regimes of lubrication :
Fluid film lubrication
Boundary lubrication ( boundary film lubrication ) THE REGIMES OF LUBRICATION: 1- Keep moving parts apart :
Lubricants are used to separate moving parts in a system .this has the benefit of reducing friction and surface fatigue together with reduce heat generation and noise.
2- Reduce friction :
The lubricant – to – surface friction is much less than surface-to- surface friction without any lubricant thus use of lubricant reduces the overall system friction .
3- Transfer heat :
Both gas and liquid lubricants can transfer heat .however liquid lubricants are much more effective on account of their high specific heat capacity .
4- Carry out contaminants and debris :
Lubricant cycle in an engine has the benefit of cleaning generated debris and external contaminants that generated into the system to a filter where they can be removed. 1. Keep moving parts
2. Reduce friction
3. Transfer heat
4. Carry away contaminants &debris
5. Transmit power
6. Protect against wear
7. Prevent corrosion
8. Seal for gases
9. Stop the risk of smoke and fire of objects Lubricant functions : Lubrication is the most effective means of reducing friction and controlling wear LUBRICATION SYSTEM : the oil is supplied to the main bearings through drillings in the engine frame to the crankshaft main bearings. Drillings in the crankshaft then take the oil to the crankpin or bottom end bearings. The oil is then led up the connecting rod to the piston or gudgeon pin and from there to the piston cooling before returning to
Oil is also supplied to lubricate the rocker gear operating the inlet and exhaust valves, and to the camshaft and camshaft drive the Crankcase ON A MEDIUM SPEED 4 STROKE ENGINE: The oil temperature regulator is used to prevent the oil temperature from rising too high in hot weather and to assist in raising the temperature during cold starts in winter weather . The regulator makes use of the liquid in the system . It provides a more positive means of controlling oil temperature than does cooling by radiation of heat from oil pan. The regulator unit is made up of a core and a housing . The core through the oil circulates is of cellular or bellows construction, and is built to expose as much oil as possible to the coolant that circulates. 6-OIL TEMPERATURE REGULATOR: registers actual oil pressure in the engine. 5- OIL PRESSURE GAUGE: An oil filter is a filter designed to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil. Oil filters are used in many different types of hydraulic machinery. 4-OIL FILTER: level gauge, also known as a dip stick . It consists of a long rod or blade that extends into the oil pan.
It marked to show the level of oil within pan. Readings are taken by pulling the from its normal place in the crankcase, and noting the height of oil lower or marked end. This should be done with the engine stopped unless the manufacturer recommends otherwise.
It is important that the oil level not drop below the LOW mark or rise above the FULL mark. 2-OIL LEVEL GAUGE : fig.1 COMPONENTS:
1-Oil Pan : reservoir or storage area for engine
2- Oil Level Gauge : checks the amount of oil in the oil pan.
3- Oil Pump : forces oil throughout the system.
4- Oil Pickup and Strainers : carries oil to the pump and removes large particles.
5-Oil Filters : strains out impurities in the oil.
6-Oil Galleries : oil passages through the engine.
7-Oil Pressure Indicator : warns the operator of low oil pressure.
8-Oil Pressure Gauge : registers actual oil pressure in the engine.
9-Oil Temperature Regulator
Mohamed Refaat Abd el-azim Hamama
Amir Ibrahim Abo hashish
Mohamed Kamal Shalaby
Ahmed Magdy Dawood
Mohamed Rabiea El-amawy
Mohamed Abd el-aleem WORK GROUP Lubrication
PRESENTED TO PROF. DR : HAMDY ABD ELSALAM MANSOURA UNIVERSITY
FACULTY OF ENGINEERING
MECH POWER DEPT lubricating oil is supplied to the main bearings and camshaft and camshaft drive. A separate supply is led via a swinging arm or a telescopic pipe to the crosshead where some of it is diverted to cool the piston (travelling up and back through the piston rod), whilst some is used to lubricate the crosshead and guides, and the rest led down a drilling in the connecting rod to the bottom end or crankpin bearing. Oil is also used to operate the hydraulic exhaust valves. On a 2 stroke crosshead engine: SOME OIL FILTER PICTURES Some oil filter pictures Operation LUBRICATING (OIL) SYSTEM COMPONENTS PROPERTIES OF LUBRICANTS The regimes of lubrication Lubricant functions Lubrication system Agenda :