POWER (Lubrication)

FRICTION
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Terms in this set (20)
FRICTION
Refers to the forces acting between mechanical
components due to their relative motion and to the
forces on and by fluid when they move through the
engine
f = Ft/Fn
f
• Reduce friction and wear
• Seal a space adjoining the surface (ex. piston moving in a cylinder)
• Cool the surfaces by carrying away heat generated by friction
• Clean the surfaces by washing away carbon and metal particles caused by wear
• Coat engine parts to prevent rust and corrosion
PURPOSES OF LUBRICATION
• Flows freely into place
• Effectively reduces friction
• Stands up under working pressures and temperatures
• Does not break down into harmful acids
• Does not form residues such as carbon or gums upon burning
• Does not change its viscosity with service
IDEAL LUBRICANT
VISCOSITY
the most important single property of lubricants, the resistance to flow exhibited by a fluid (thick oil has higher viscosity than a thin oil)
SAE Classification Scheme
• Oils with lower numbers are less viscous and used in cold-weather operation
• Oils with higher numbers are more viscous and use in modern high-speed, high temperature engines
SAE Classification Scheme (Commonly Used Oils)
SAE 5, 10, 20, 30, 40, 45, 60

If oil viscosity is too high, more work is required to
pump it and to shear it between moving parts which
increases friction power and reduces brake power
Multi-grade Oils
Developed so that viscosity is more constant over an
operating temperature range

SAE 5W-20, 5W-30, 5W-40, 5W-50, 10W-30, 10W-40, 10W-50, 15W-40, 15W-50, 20W-50

SAE# with "W" indicates that the viscosity was determined at low temperature (Winter Grade)
Interpretation: the oil has a property of SAE 10 when it is cold (W=winter) and SAE30 when it is hot
SAE 10W-30
VISCOSITY INDEX
Ability of an oil to resist changes in viscosity
as temperature changes
VISCOSITY INDEXCan be enhanced by using oil additivesService Categories--Gasoline Engines- SA, SB, SC, SD, SE, SF, SG, SH are obsolete. - SJ: 2001 and older automotive engines. - SL: All automotive engines manufactured after July 2001.• Service Categories--Diesel Engines- CA, CB, CD, CE are obsolete. - CF: Off road, indirect-injected manufactured after 1994 and with fuels over 0.5% sulfur. - CF-2: Severe duty, two cycle engines. - CF-4: High speed, four cycle engines. - CG-4: Severe duty, high speed, four stroke, with fuels less than 0.5% sulfur. - CH-4: High speed, four stroke engines designed to meet 1998 exhaust standards. - CI-4: High speed, four stroke engines designed to meet 2002 exhaust standards.Lubrication with GREASEEmulsion of mineral oil with soapLubrication with GREASEDo not continually flow through a bearing and do not perform cooling and cleansingLubrication with GREASEReduces friction, serves as a cushion between mating parts and acts as a seal against the entry of dirt and waterSPLASHA small projection (oil splasher/ slinger) on the rod bearing cap dips into the oil pan during each crankshaft revolution and picks up oil and splashes inside the enginePRESSURE FEED and SPLASHA gear pump discharges oil into drilled passages in the engine block and the crankshaftFULL PRESSUREThe same as the pressure feed and splash system except that an oil passage is drilled through the center of each connecting rodSPLASH PRESSURE FEED and SPLASH FULL PRESSUREEngine Lubricating Systems