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Agricultural Power Systems

Identifying Engine Systems

and Their Components

Engine Systems

What are the major systems involved with small engine operation?

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Engine Systems

Compression system – creates the engine compression and converts the energy of combustion to mechanical energy

Governor system

Fuel System

Cooling and lubrication system

Ignition system

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Purpose of a compression system

To efficiently compress air to increase the potential energy resulting from the combustion of the fuel

Compression Problems

Inadequate Compression (Leaks)

Excessive Compression (Preignition/Detonation)

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Combustion is usually lost in one of three places:

Fit of the piston to the cylinder

Head gasket

ValvesDecrease pressure of charge (unwanted air)

Increase exhaust gas temperature (wear and degradation)

Pre-Assessment

Quick Write- Which parts make up the compression system of an engine?

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Components of the compression system

Piston – machined from lightweight alloys

Piston Rings – made of cast iron and/or steel

Compression rings

Oil rings

Piston Rings

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Components (continued)

Head gaskets – provide a seal between the cylinder head and the cylinder block

Cylinder head – forms the top of the combustion chamber

Cylinder block – houses the cylinders and crankshaft

Cylinder Block

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Components (continued)

Valves – Intake valves – open and seal the intake ports

Exhaust valves – open and seal the exhaust ports

Valve springs – both close the valves and hold them open

Spring retainers – hold the springs on the end of the valves

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Components (continued)

Valves – Valve guides – support the valve stem as the valve moves back and forth

Camshafts – open and close the valves

Pushrods – transfer the rotating movement of the camshaft to the linear movement of the valves

Partsof anenginevalve

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Engine Disassembly

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In pairs, you will disassemble a small engine. Please follow the directions in the packet

given and use proper tools for precise measurements.

Today we will complete questions #1-8. When you have completed #8 please come see me!

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Operating System Components

Air intake system – provides a source of clean air necessary for combustion

Fuel system – delivers clean and adequate amounts of fuel to the cylinder

Exhaust system – removes the exhaust gases and particles from the combustion chamber

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Air intake systemAir must first be cleaned by passing through the air cleaner – a filtering deviceFuel and air are mixed in the carburetor – provides fuel and air to the engine in correct proportions and volumeFuel-air mixture enters the engine cylinder through intake valves

Parts ofan airintakesystem

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Fuel system

Fuel tank stores fuel

Fuel filter cleans the fuel that passes through it

Fuel injection system inject fuel into the combustion chamber

Mechanical fuel injection systems

Electronic fuel injection systems

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Exhaust system

Exhaust manifold – collects gasses from one or more individual cylinders

Exhaust pipe connects exhaust manifold to the muffler

Muffler is the sound deadening device used to quite engine operations

Partsof anexhaustsystem

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Material beyond this slide will not be included in the quiz on Monday September 28th.

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Operating System Components (continued)

Engine cooling system – manages the heat produced by the combustion of the air-fuel mixture

Lubrication system – keeps internal engine parts coated with oil to reduce friction, enhance cooling, seal internal engine components, and clean internal parts

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Engine cooling system

Liquid cooling system – uses a liquid to transfer heat from engine components to the surrounding air

Air-cooled system – transfers the heat of the engine components directly to the surrounding air

Air-cooled system

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Components of a liquid cooling system

Radiator – a heat transfer deviceWater pump – forces the coolant to flow thorough the systemThermostat – a flow control valveWater Jacket- a series of interconnected cavities cast into the engine block & cylinder head for circulation of coolant.Additional components: radiator cap, fan, fan belt, and temperature gauge

Partsof aliquidcoolingsystem

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Liquid Cooled System

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Pressurized system- boiling point of liquid raised significantly

How an engine cooling system works

Lubrication System

Purpose- maintain proper operation by reducing friction and cooling internal engine components.

How it works

Splash Lubrication

Pressure Lubrication

Full Pressure Lubrication

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Lubrication system

Oil filter – removes dirt particles from oil

Pressure regulator – maintains the operating pressure of the system

Sump – a reservoir for the engine oil

Oil pump – circulates oil through the engine

Oil Characteristics

Viscosity- the internal resistance of flow of a fluid. (thickness)

SAE viscosity rating-number based on the volume of a base oil that flows through a specific orifice at a specified temp, atm pressure, time period.• High rating- small volume flow caused by high

resistance.• Low rating- large volume of oil flowing caused by

low resistance.

Multi-viscosity- characteristics of 2 viscosity ratings.

Offers low viscosity in cold. High in hot.

Ex: SAE 10W-3032

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Operating System Components (continued)

Ignition System – starts the combustion of the air-fuel mixture

Starting system – used to turn the engine crankshaft until the engine starts

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Ignition system

Compression ignition system – does not consist of any unique parts

Spark Ignition systems – uses high voltage electrical spark to ignite the compressed air and fuel mixture

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Spark ignition systems

Magneto–type ignition systems – use magnets and coils to generate electrical pressure to ark the spark plug

Battery-type ignition systems - use the energy from a battery and/or alternator to create the ignition spark

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Battery-type ignition systemsBreaker point-type battery system – an ignition switch begins the processIgnition coil – converts low battery voltage to high voltageDistributor – sends the high voltage current to the correct spark plugCondenser – function as a capacitor which stores electrical energy

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Battery-type ignition systems (continued)

Breaker points – provide a switch to initiate the spark in the engine

Distributor cam –controls the opening and closing of the breaker points, and regulates through the distributor rotor the timing of the engine spark

Breakerpoint-typebatteryignitionsystem

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Starting system

Manual – manually turning the crankshaft – rope starter

Electrical – solenoid-type switch controls the voltage going to the starter

Flywheel – a gear which is attached to the crankshaft

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Review/Summary

What are the three categories of internal combustion engine systems?

Identify the components of the primary or compression system

What components make up an engine’s operating system?

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Terms

Accessory systems

Air cleaner

Air cooled system

Air intake system

Battery-type ignition systems

Breaker point-type battery system

Breaker points

Camshafts

Carburetor

Compression ignition system

Condenser

Cylinder head

Distributor

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Terms (continued)Distributor camElectronic fuel injection systemsEngine cooling systemExhaust manifoldExhaust systemExhaust valves

Flywheel

Fuel filter

Fuel injection systems

Fuel system

Head gaskets

Ignition coil

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Terms (continued)Ignition systemIntake valvesLiquid cooling systemLubrication systemMagneto-type ignition systems

Mechanical fuel injection systems

Operating systems

Piston rings

Primary system

Pushrods

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Terms (continued)

Radiator

Spark ignition systems

Spring retainers

Starting system

Thermostat

Valve guides

Valve springs

Water pump