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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
