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LUBRICATION_SYSTEM.ppt

The lubrication system supplies oil to moving engine parts to prevent metal-to-metal contact and minimize friction. It is made up of an oil pump, oil filter, oil galleries, and nozzles that supply pressurized oil to bearings, pistons, and other components. The system also cools and cleans the engine by circulating oil through a filter and cooling components like the oil cooler. Lubrication system diagnosis can identify issues like low oil pressure, high oil pressure, or a swollen oil filter through inspection of parts and oil analysis.

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LUBRICATION SYSTEM • Purpose • Parts Of Lubrication System • Types Of Oil Pumps • Pressure Relief Valve • Oil Filters 1. Full-flow Filters 2. Bypass Filters • Oil Coolers • Oil Pressure Switch • Lubrication Of Small Two And Four-stroke engines • Crankcase Ventilation • Classification Of Lubrication Oils • Lubrication System Diagnosis 1
LUBRICATION SYSTEM Purpose The purpose of the engine lubricating system is to: Minimize friction and wear. Thereby reducing power loss. It also performs the following tasks: Act as a seal and prevent leakage between the parts such as pistons, rings and cylinders. Remove the heat generated by friction. This keeps down the temperature of the moving parts and thus prevents seizure. Act as a cleaning agent. Wash away dirt, carbon particles and abrasive metal worn from the friction surfaces. Absorbs shock between bearings and other engine parts, thus reducing engine noise and extended engine life. 2
• The lubricating system performs this job by supplying oil to prevent metal-to-metal contact. 3
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Parts of lubrication system 6
• Oil Pump: The pump is driven by the engine and takes oil from the oil pan through the strainer and pickup pipe. • The strainer is provided to prevent any foreign matter present in the oil from reaching the pump. Oil leaving the pump is directed to the filter. • Relief (or) Regulator Valve: This valve regulates pressure in the system. As the engine speed increases, pump output increases and this must be controlled to prevent excessive pressure in the system. When the specified pressure for the engine is reached, the relief valve opens to regulate the pressure. Excess oil from the relief valve is then bypassed to the intake side of the pump. 7
• Oil Filter: Filters out foreign particles from the oil. The filter also includes a relief or bypass valve which will open if the filter becomes blocked. • Main Oil Gallery: The main oil gallery is a passage that runs full length of the crankcase. A number of drillings and passages from the gallery to other parts of the lubrication system. 8
• Crankshaft Main Bearings: Each of the crankshaft main bearings is supplied with oil through a separate drilling from the main oil gallery. • Connecting Rod Bearings: Oil from the drillings in the crankshaft lubricates the connecting rod bearings. • Oil spray nozzles (Oil Jets) are used to direct a stream of engine oil onto the bottoms of the engine pistons, timing gears or chain, and other moving engine parts. 9
• Camshaft Bearings: The camshaft receives its oil supply from the main oil gallery • Rocker Shafts: Drillings in the rocker shafts provide oil to the rocker arms and these in turn have a small drilling to provide lubrication to the cams. • Timing Chain: Where a timing chain is fitted, oil is provided from the end of camshaft bearing or similar source to that the chain and sprockets are lubricated. • Return Oil: After lubricating the various components, oil from the cylinder head drains back to the oil pan through oil drain holes provided for this purpose. Oil from the camshaft drops directly back to the oil pan. 10
Types of oil pumps 11 1. Gear pump
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13 2. Rotary Oil Pumps
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16 3. Crescent Pump
Pressure Relief Valve • A pressure relief valve limits maximum oil pressure. • It is a spring-loaded bypass valve in the oil pump, engine block, or oil filter housing. 17
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OIL FILTERS Sources of Lubricating Oil Contamination: Abrasive and corrosive particles such as: • carbon particles due to incomplete combustion • Acids formed from condensed crankcase vapors • metal particles from the wear of the metal surfaces • silica or dust enter through the crankcase or carburetor intake 19
Types of oil filters 1. Full-flow filters All the oil delivered from the pump passes through the filter on its way to the bearings and other engine parts, so that only filtered oil is used for lubrication, provided the filter is in good condition. 20
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2. Bypass filters • Bypass filters filter only a portion of the oil delivered from the pump to the oil galleries of the engine. An oil line is tapped into the oil gallery and a restricted amount of oil (5-10%) is allowed to flow to the filter and then back to the oil pan. 23
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2.6 OIL COOLERS • An oil cooler is a heat exchanger which is either air cooled type or liquid cooled type. In air-cooled oil cooler, oil flow through heat exchanger tubes and coolant (air) passing over the tubes where as in liquid cooled cooler, both oil and coolant (water), the two being separated by tubes or baffles, flow through heat exchanger. higher temperature. 25
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OIL PRESSURE SWITCH • The oil pressure switch is mounted in the cylinder block and detects if there is any oil pressure in the main oil gallery.  Low Oil Pressure The points inside the oil pressure switch are closed when the engine is stopped or when the oil pressure is low, causing the warning lamp to light up. 28
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 High Oil Pressure When the engine is started and the oil pressure rises higher than a predetermined value, the pressure acts on the diaphragm inside the oil pressure switch. This causes the points of the switch to open and the warning lamp goes off. 30
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LUBRICATION OF SMALL TWO AND FOUR-STROKE ENGINES • MIST LUBRICATION- The oil and fuel are mixed together in proportion by volume according to manufactures recommendation. • SPLASH LUBRICATION-Oil held in the crankcase is splashed by the connecting rod big end to the cylinder. 32
CRANKCASE VENTILATION • Crankcase ventilation is provided to remove vapors from the crankcase (blow by gas) and prevent their harmful effects. • PCV- blow by gas is directed to the combustion chamber and burned. • NCV- blow by gas is directed to the atmosphere. 33
CLASSIFICATION OF LUBRICATION OILS • Requirements The following properties are required of engine lubricating oil: • It must have an appropriate viscosity. If it is too low, the oil film will be broken easily and seizure of parts will occur. If it is too high, it will create additional resistance in parts movement and cause hard engine starting and loss of power. • The viscosity level must remain relatively stable regardless of changes in temperature. • Engine oil must be suitable for use with metals • It must not corrode or rust parts • It must not foam 34
1. Classification by Viscosity • The American Society of Automotive Engineers (SAE) has drawn up a table of SAE viscosities classes. • SAE indexes are usually determined according to the temperature at which a particular oil may be used. • Engine oil should also be carefully selected according to the expected operating conditions of the vehicle. • Viscosity of an oil is expressed by a number called the viscosity index. The lower the index, the thinner the oil. The higher the index, the thicker the oil. 35
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• Oil whose viscosity indexes are indicated as a range (10 W-30, 15 W-40, etc) is called "multi- grade" oils. Since their viscosity is not affected much by a change in temperature, they are usually used through the year. These oils are easier starting in cold weather and stability at high temperatures. 37
• Viscosity indexes followed by the letter E (10 W, etc) indicate oil's viscosity measured at -20C (- 4F). • Using a low viscosity oil helps to start the engine more easily in cold climates. • Viscosity numbers after a "W" indicate the viscosity at 100C (212F). • For example, "SAE 10 W-30" means that the engine oil meets standards for SAE 10 oil at -20C (-4F) and standards for SAE 30 oil at 100C (212F). 38
2. Classification by Quality • Engine oil is classified by quality according to standards set by American Petroleum Institute (API) and by test methods also set by API. 39
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Lubrication System Diagnosis Condi tion Possible causes Correction Low oil Press ure 1. Oil level low 2. Oil too thin 3. Defective oil gauge 4. Bad sending unit 5. Excessive bearing clearance 6. Worn oil pump 7. Loose or disconnected oil pickup 8. Clogged pickup screen 1. Add oil to engine 2. Add heavier oil 3. Replace gauge 4. Replace sending unit 5. Replace bearings 6. Replace oil pump 7. Repair oil pickup 8. Repair valve in pump or block 9. Clean or replace screen 41
High oil pressur e 1. Stuck pressure relief valve 2. Incorrect relief valve spring 3. High oil viscosity 4. Oil gallery restriction 5. Inaccurate indicator 1. Repair valve 2. Replace spring 3. Drain oil, Replace with recommended viscosity oil 4. Remove blockage 5. Repair circuit Replace gauge or sending unit, if necessary Swelle d oil filter 1. High oil pressure 1. See high oil pressure 42