C H A P T E R 11 Lubrication Systems

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Define friction and explain how it affects the internal engine components. List the functions of lubricating oil. Differentiate between the lubrication systems in two-cycle engines and four-cycle engines. Explain the operation of ejection pumps, barrel pumps, and positive displacement pumps. Explain the function of oil filter systems and differentiate between the three main types. Learning Objectives

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Lubrication Reducing friction between sliding surfaces by introducing a slippery or smooth substance between them Lubricant forms: –Dry (powdered) –Semidry (grease) –Liquid (oil)

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Friction Resistance to motion when one surface rubs against another Even highly polished metal surfaces will create friction if rubbed together –Microscopic roughness will resist movement and create heat

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Friction As friction and heat increase, metal parts expand, causing even greater friction Parts eventually weld themselves together or seize In some cases, excessively worn parts may become too loose to function properly

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Preventing Wear Due to Friction Manufacturers select suitable material for parts in moving contact with each other –Rod and main bearings have a cast babbitt surfacebabbitt All bearing surfaces have oil separating moving parts that are in close contact –Prevent metals from touching

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Permits easy starting Lubricates engine parts –Hydrodynamic lubricationHydrodynamic lubrication –Boundary lubricationBoundary lubrication Protects against rust and corrosion Keeps engine parts clean –Detergent/dispersant additivesDetergent/dispersant additives Cools engine parts Seals combustion pressures Prevents foaming Aids fuel economy Qualities of Lubricating Oil

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Oil Specifications Given in two ratings: –Society of Automotive Engineers (SAE) Viscosity Also called viscosity grade –American Petroleum Institute (API) Engine Oil Service Classification Referred to as type of oil

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Viscosity Viscosity is a measure of an oil’s resistance to flowViscosity –Keeps oil from being squeezed out from between engine surfaces as they move under pressure –Oil used must have viscosity characteristics that ensure satisfactory cold cranking, good oil circulation, and adequate temperature protection

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. SAE Viscosity Grade Developed by SAE All engine oils classified according to this system Used worldwide

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. SAE Viscosity Grade Each oil is assigned a grade that signifies the viscosity range into which it falls –Thick, slow-flowing oils have high numbers –Thin free-flowing oils have low numbers –W before grade number indicates that oil is suitable for use at low ambient temperatures

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. SAE Viscosity Grade Recommendations

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Viscosity Index (V.I.) Temperature effect on viscosity varies with different types of oils Viscosity index is a measure of the relationship between viscosity and temperature –High viscosity number indicates little change in viscosity over a wide range of temperatures

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Multigrade Oils Multigrade, or multiviscosity oils meet the viscosity requirements of two or more SAE gradesmultiviscosity –SAE 5W-20, SAE 5W-30, and SAE 10W-30 Can be substituted for single viscosity grades in four-stroke engines –Should not be used in two-stroke engines

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. API Engine Oils Service Classification System Dynamic method of rating an oil’s suitability for use in various generations of engine New categories created as oil is reengineered to meet growing demands placed on it by evolving engine designs

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. API Engine Oils Service Classifications Divided into two categories: –“C” categories: classify oils suitable for use with compression-ignition engines –“S” categories: classify oils suitable for use with four-stroke, spark-ignition engines Each successive “S” category is a suitable replacement for all the “S” categories that preceded it

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. API Engine Oil Categories for Spark-Ignition Engines

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. API Engine Oil Service Classification Symbol Provides information about oil’s characteristics and applications Typically found on oil container label May also be found on oil fill cap or in owner’s manual

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Divided into three parts: –Top specifies oil’s service classification or recommended application –Center describes the oil’s viscosity –Bottom contains information on oil’s fuel-saving properties API Engine Oil Service Classification Symbol

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Selecting the Proper Engine Oil Always use type recommended by engine manufacturer Shown on engine nameplate, oil filler cap, or label attached to engine –Also found in operator’s manual API categories are not for two-stroke engines or those with wet clutch –Two-cycle oils contain additives that prevent unburned deposits

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Engine Lubrication Systems The way moving parts are lubricated differs in two- and four-cycle gasoline engines –In two-cycle engine, oil is mixed with gasoline and poured in tank –In a four-cycle engine, oil is poured into the crankcase

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Two-Cycle Engine Lubrication Two-cycle engine receives lubrication as fuel mixed with oil passes through engine Clean oil continuously supplied to all moving parts while engine is running –Will get adequate lubrication even when operated at extreme angles Oil eventually burns in combustion chamber and is exhausted with other gases

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Mixing Fuel and Oil The correct mixture of fuel and oil is critical in maintaining a two-stroke engine in good working condition The prescribed type and grade of oil must be mixed with fuel in proper proportion before being placed in tank –Refer to manufacturer’s recommendations

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Mixing Fuel and Oil Amount of oil for given amount of fuel expressed as ratio –A fuel-to-oil ration of 40:1 requires 1 part oil for every 40 parts gasoline Mix oil and fuel in separate container –Empty half of fuel from container –Add appropriate amount of oil –Place cap on container and shake –Add fuel that was removed and shake again

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Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Four-Cycle Engine Lubrication Provided by placing the correct amount and grade of oil in crankcase –Oil sump supplies lubrication for cylinder wall and all internal engine parts –Several methods used to feed oil from crankcase to correct locations Must be operated in upright position for adequate lubrication

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Splash Lubrication System Oil dipper located on connecting rod capdipper –Picks up oil from crankcase on every revolution of crankshaft –Splashes oil on parts Oil slinger used in place of dipper in some enginesOil slinger –Driven by crankshaft or crankshaft gear –Has several blades, or fingers, that pick up oil and splash it onto internal engine parts –Provides more consistent supply of oil

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Constant Level Splash System Contains oil pump, splash trough, and strainer Pump supplies more oil to trough than dipper can remove Oil returning to crankcase passes through strainer System provides adequate lubrication as long as there is enough oil to supply pump Engine can be operated at angle

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Ejection and Barrel Pump Systems Ejection pump system –Forces oil under pressure against connecting rod –Some oil enters connecting rod bearings, while remaining oil is deflected to other parts Barrel pump system –Uses cylinder-and-plunger type pump –Oil is forced through passages in camshaft to the main bearing and connecting rod journals

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Pressurized Lubrication Systems Similar to systems used in automotive engines Used in conjunction with splash system Relies on positive displacement oil pump or rotor pump to supply oil to moving partspositive displacement oil pump –Passages for oil flow are drilled to all critical points –Pressure relief valve prevents excessively high pressures at high engine speeds

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Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Oil Filter Systems Used on engines with pressurized lubrication systems Prevent harmful materials from circulating through engine –Oil filter prevents fine particles from circulating –Oil strainer prevents large particles from entering the filter

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Filter System Types Bypass filter system –Pumps part of oil through filter –Remaining oil pumped to engine bearings Shunt filter system –Part of oil delivered by pump is filtered and directed to bearings –Remaining oil shunted past the filter and back into crankcase Full-flow filter system –Directs all pumped oil through filter and to bearings

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Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Low-Oil Warning and Shutdown Systems Low-oil warning devices –Warn operator –Shut down engine Limited to four-stroke engines

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review The resistance to motion created when one surface rubs against another is called _____. friction

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review To prevent wear caused by friction, all bearing surfaces must have _____ separating moving parts that are in close contact oil

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review List eight functions of modern motor oil. (Any order) Permits easy starting, lubricates engine parts, protects against rust and corrosion, keeps engine parts clean, cools engine parts, seals combustion pressures, prevents foaming, aids fuel economy

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review A two-stroke engine receives its lubrication as _____ mixed with oil passes through the engine. fuel

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review In a four-stroke engine, lubrication is provided by placing the correct quantity and grade of oil in the _____. crankcase

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review In an ejection pump system, oil is forced against the rotating _____. connecting rod

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review In a(n) _____ pump system, an eccentric on a hollow camshaft moves the pump plunger in and out of the pump cylinder. barrel

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review A positive displacement oil pump is used in a(n) _____ lubrication system. pressurized

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review Oil _____ prevent harmful materials from circulating through the engine. filters

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review Name the three basic types of oil filter systems commonly used on small engines. Bypass filter systems, shunt filter systems, and full- flow filter systems

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Review True or False? In a bypass filter system, all the oil is pumped through the filter and directly to the engine bearings. False

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary API engine oil service classification symbol –Symbol that appears on an oil container and provides the consumer with information about an oil’s characteristics and applications. API engine oil service classification system –A dynamic method of rating an oil’s suitability for use in various generations of engines. Babbitt –An alloy of tin, copper, and antimony having good antifriction properties. Used as a facing for bearings.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Barrel pump system –Lubrication system that uses a cylinder-and-plunger lubrication pump. An eccentric on the camshaft moves the plunger in and out of the pump cylinder. Boundary lubrication –Noncontinuous oil film between moving parts allowing intermittent metal-to-metal contact between the high spots on sliding surfaces.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Bypass filter system –Oil filtration system that pumps part of the oil through the filter, while pumping the remaining oil to the engine bearings. Oil pumped through the filter is returned directly to the crankcase. Constant level splash system –Lubrication system that contains an oil pump, a splash trough, and a strainer. Engines with constant- level systems can be operated at an angle while still providing adequate lubrication.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Detergent/dispersant additives –Oil additives that keep engine parts clean by suspending fine particles of the oil contaminants until they can be trapped by the oil filter. Dipper –Arm on the connecting rod that picks up and splashes oil on the moving parts within the crankcase during each crankshaft revolution.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Ejection pump system –Lubrication system in which oil is forced under pressure against the rotating connecting rod. Some oil enters the connecting rod bearings, while the remaining oil is deflected to other parts in the crankcase. Full-flow filter system –Oil filtration system that directs the entire volume of pumped oil through the filter to the bearings. Hydrodynamic lubrication –A complete, unbroken film of oil between surfaces.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Lubrication –The process of reducing friction between sliding surfaces by introducing a slippery or smooth substance between them. Multigrade oils –Oils that meet the viscosity requirements of two or more SAE grades. Multiviscosity –See Multigrade oils.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Oil slinger –Device with several blades that pick up oil and splash it onto the internal engine parts. Because the slinger has multiple blades, it provides a more consistent supply of oil to the moving engine parts than a dipper. Positive displacement oil pumps –Oil pump commonly used in pressurized lubrication systems.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Pressurized lubrication system –Lubrication used on larger small engines that relies on a positive displacement gear pump, or rotor pump, to supply oil to moving engine parts. Shunt filter system –Oil filtration system in which part of the oil delivered by the pump is filtered and directed to the engine bearings, and some of the oil is shunted past the filter.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Glossary Splash lubrication system –Lubrication system that splashes oil onto various engine components as the engine spins. This type of lubrication system is used in small four-cycle gasoline engines. Viscosity –The resistance to flow or adhesive characteristics of an oil. Viscosity index (V.I.) –A standard for measuring the relationship between viscosity and temperature.