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Engine Terminology

Engine Terminology. Engine Lubrication Principles Engine Oils Lesson 1. Engine Doc – S. Ruch 2008. Agenda. Primary function Lubrication principles Hydrodynamic action Engine oils Ratings. Primary Function. Separate moving components. Lubrication Principles. Hydrodynamic Lubrication

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Engine Terminology

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  1. Engine Terminology Engine Lubrication Principles Engine Oils Lesson 1 Engine Doc – S. Ruch 2008

  2. Agenda • Primary function • Lubrication principles • Hydrodynamic action • Engine oils • Ratings

  3. Primary Function • Separate moving components

  4. Lubrication Principles Hydrodynamic Lubrication Hydro - liquids - as in hydraulics - engine oil Dynamic - motion - engine parts in relative motion

  5. Hydrodynamic Lubrication • is the wedge shape of oil film that completely separates two surfaces that have relative motion Do you remember the name for engine bearings?

  6. Anti-Friction Bearings

  7. Hydrodynamic Lubrication • occurs between the shaft journals and the bearing inserts. YouTube - SPH BEARING FLOW

  8. Hydrodynamic Lubrication • The engine lubrication system must provide a constant supply of clean oil at a high enough pressures to force oil to the bearings to allow enough flow for cooling of the bearing surfaces • The oil is supplied to the lightly loaded area of the bearing and then the hydrodynamic process takes over • The hydrodynamic oil film pressures developed on the engine bearing surfaces may exceed 1000 psi. • Loss of oil supply will result in bearing failure

  9. Hydrodynamic Lubrication • Normal bearing wear happens when there is a lack of hydrodynamic lubrication. • This occurs when? Initial engine start up • When the engine is off, the crankshaft pushes most of the oil from around it as it settles to the bottom of the bearings.

  10. Boundary Lubrication • Occurs when the oil film is extremely thin and the high spots of the surfaces touch

  11. Engine Oils Purpose • Lubricate all moving parts to prevent wear • Reduce friction • Aid in cooling the engine • Assist the cylinder seal at the piston rings • Neutralize acids formed from combustion process • Prevent rust and corrosion • Clean the engine and hold dirt in suspension

  12. Oil Viscosity • Viscosity is the resistance to flow of an oil • A high viscosity oil has a greater resistance to flow and is said to be thicker than a lower viscosity oil • As an oil cools it thickens and as it heats up it thins out. • Viscosity changes with temperature

  13. Oil Viscosity • Oil must not be too thick at low temperatures or cranking speeds will be low, and hard or no starts will result, due to the increased co-efficient of friction. • Oil must not be too thin at high temperatures or the oil film will not support the loads placed on it and boundary lubrication will occur and increase the co-efficient of friction. • Viscosity is measured by the Say bolt UniversalViscosity Test which measures the number of seconds for a definite quantity of oil to flow through a fixed orifice into a measured container at a specified temperature.

  14. Viscosity Index Improver • Polymer additive that induces thickening of a thin base oil at high temperatures • 10W30 oil starts as a 10W oil and viscosity index improvers are added in sufficient quantity to bring the hightemperature viscosity rating up to the S.A.E. 30 standard. • VI improvers make up between 6 and 15% of the oil • VI improvers breakdown with use • Oil oxidizes and thickens forming sludge YouTube - oil aditives

  15. These oils were chilled to -35C for 16 hours. The photo was taken 30 seconds after the caps were removed from the containers. YouTube - Tech Talk on Engine Oil - with Castrol

  16. S.A.E. Oil Viscosity Ratings • Grade number represents the viscosity range of an oil • A grade number with no letter following means that oil was tested only at 100C (212F) eg. SAE 10, 20 30 • The higher the number the higher the viscosity • Grade numbers that are followed by a the letter “W” indicate that the oil was tested at -18C (0F) and are given a viscosity rating at that temperature. eg. 10W, 20W • Multigrade oils like 10W30 are tested at -18C and 100C and meet the S.A.E. specifications for those temperatures (VI improvers are added to meet these specifications)

  17. A.P.I. Ratings - Oil Quality American Petroleum Institute • Letter Ratings that are applied to oils tested for quality Gasoline engine ratings • “S” means Service (spark ignition) • Ratings from SA (straight mineral oil) to SL. • SL is the highest rated oil starting in 2001. • Use the highest rated oil available (or as specified)

  18. A.P.I. Ratings - Oil Quality Diesel engine ratings • “C” means Commercial (compression ignition) • Ratings from CA (obsolete) to CG4 which is for severe duty high speed four stroke diesel engines. • Always use the correct oil for the application

  19. ILSAC Oil Rating International Lubricant Standardization and Approval Committee • Combination of SAE Viscosity and API Quality ratings • GF1 - pre 1996 • GF2 - 1997 to 1999 • GF3 - 2000 • Starburst Symbol

  20. Synthetic Oils Base Stocks not from crude oil Polyalphaolefins - Mobil 1 Organic esters - alcohol and acid - Castrol Syntec Polygycols - polyalkaline gylcol (PAG oil for 134a A/C) Advantages • remains fluid at very low temperatures • lower internal friction - fuel economy and cooler engine • resists oxidation Disadvantages • $ cost $ - 4 to 5 times more money • may not be compatible - gaskets, seals = oil leaks

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