Agricultural Engineering: Engine Components

Engine Nomenclature, Construction, and Design

• The document is a review of Agricultural and Biosystems Engineering.
• It details engine types, designs, parts, and related terminologies.

Principal Engine Parts

• Cylinder and cylinder block: Provides the space for the piston to operate.
• Cylinder head: Creates a pocket/space above the piston (combustion chamber).
• Piston and rings: Draws in fuel, compresses it, and receives power from the expanding gas.
• Piston rings: Maintain compression and reduce friction against the cylinder wall.
• Piston pin: Connects the piston to the top of the connecting rod.
• Connecting rod: Transfers power from the piston to the crankshaft.
• Crankshaft: Receives power from the connecting rod and transforms reciprocating motion into rotary motion.
• Flywheel: Acts as a balance wheel to ensure smooth engine rotation.
• Crankcase: Supports and houses the crankshaft, camshaft, and lubricating oil.
• Valve system: Provides openings for fuel, air, and exhaust.
• Fuel supply system: Provides clean fuel and air mixture for combustion.
• Cooling system: Controls engine temperature and assists in quick engine warming.
• Lubrication system: Reduces friction and wear on moving engine parts.
• Governing system: Controls engine speed and power at any operating condition.

Engine Types and Design

• Number of cylinders: Single or multi-cylinder.
• Arrangement of cylinders: In-line, radial, or V-type.
• Cooling Method: Air-cooled, water-cooled, or combination.
• Fuel Used: Gasoline or diesel fed engines.
• Electrical source: Battery or magneto.
• Valve System: L-head or I-head valve designs.
• Starting method: Manual or electrical start.

Parts of the Valve System

• Intake and exhaust valves
• Valve spring
• Retainer
• Valve lock
• Valve seat
• Tappet
• Camshaft, cam, cam gear
• Rocker arm
• Push rod
• Intake and exhaust manifolds

Valve System Related Terminologies

• Timing gears: Crank and camshaft gears (belt/chain and sprockets).
• Timing marks: Indicate crankshaft and camshaft gear timing relative to piston movement.
• Valve timing: Arrangement for valves to operate at the correct position.

Parts of the Fuel Supply System

• Gasoline engines: Fuel tank and cap, fuel line, filter, fuel pump, carburetor, air cleaner
• Diesel engines: Fuel tank and cap, fuel line, filter, fuel pump, injection pump, injection nozzle, high pressure line(s).

Fuel Supply System Terminologies

• Air-fuel ratio: Proportion of air and fuel in the mixture used for maximum power and economy (e.g., 15:1).
• Lean mixture: More air than desired (e.g., 18:1).
• Rich mixture: Less air than desired (e.g., 10:1).
• Octane rating: Anti-knock quality of gasoline.
• Cetane rating: Ignition quality of diesel fuel.
• Catalytic converter: Reduces exhaust pollutants (hydrocarbons and carbon monoxide).
• Turbocharger/supercharger: Increases volumetric efficiency of the engine.
• Euro emission standards: Limit exhaust emissions. (e.g, Euro 4, Euro 6)

Parts of the Ignition and Electrical System

• Gasoline engines: Spark plug, breaker system, ignition coil, high tension wire, battery, charging unit.
• Diesel engines: Heat of compression, high pressure, CR.

Ignition and Electrical System Terminologies

• Primary cell: Type of cell that cannot be revitalized after discharging – common dry cells.
• Secondary cell: Type of cell that can be regenerated through opposite-directional charging.
• Lead acid battery: A common battery in tractors, with 2 volts/cell.
• Electrolyte: Solution used in lead-acid batteries (sulphuric acid and distilled water).
• Sulfation: A common battery problem caused by lead sulfate deposits.
• CDI (Capacitor Discharge Ignition): system ignition.
• Ignition voltage: Voltage needed for operation (e.g., 25,000 to 40,000).
• Cold plug: Type of spark plug for high speed and compression engines that dissipates quickly.
• Condenser/capacitor: Prevents arcing in the breaker points of the ignition system.
• Distributor: Distributes the secondary voltage to each spark plug in multi-cylinder engines.

Parts of the Cooling System

• Air-cooled: Cooling fins, shroud, fan.
• Water-cooled: Water tank (or radiator), water hoses and clamps, water jacket, water pump, thermostat.
• Combination: Radiator, water hoses, water jacket, water pump, thermostat, fan.

Cooling System Related Terminologies

• ICE heat balance: Breakdown of engine thermal loss (e.g., 23% thermal energy).
• Range of operating temperature: Operating temperature in Celcius degrees.
• Thermostat: Device that regulates coolant flow based on temperature.

Parts of the Lubrication System

• Mixed lubrication: Oil tank, metering device
• Splash lubrication: Oil pan, dipper or oil ring gear
• Full pressure lubrication system: Oil pan, oil pump, oil filter, oil pressure gauge, by-pass/safety valve, oil lines

Lubricants and Lubrication Terminologies

• Grease: Semi-solid lubricant for bearings, UJs, and shackles.
• Motor oil: Thin, free-flowing lubricant for engines.
• Gear oil: Heavier, high-viscosity lubricant for transmission gears.
• Viscosity: Essential quality of lubricating oils.
• SAE number: Viscosity rating of lubricating oils specified by the Society of Automotive Engineers.
• Single-grade oils: Winter or summer oils using only one viscosity classification (e.g., SAE 30).
• Multi-grade oils: Oils suitable for winter and summer use (e.g., SAE 15W-40).
• API: American Petroleum Institute, for engine oil service classifications, specifying quality for various engines and fuel types.
• Oil additives: Improve lubricating properties (prevent corrosion, rust by inhibiting oxidation, and adding detergents to the oil.
• Synthetic lubricant: Lubricant created through chemical reaction of simpler compounds.

Parts of the Governing System

• Mechanical type governing system (centrifugal): Weights, thrust collar, speed change lever/shaft, control arm, throttle shaft.
• Vacuum governor: Vacuum-sensitive unit, rubber hose, diaphragm, throttle arm.
• Governor Hunting: Uneven or irregular engine speed resulting from the governor.

Basic Engine Data and Measurement

• Bore: Diameter of the cylinder.
• Stroke: Length of piston travel.
• Engine speed (crankshaft speed): Revolution per minute (RPM).
• Piston displacement: Area of piston multiplied by stroke.
• Total piston displacement: Piston displacement multiplied by the number of cylinders.
• Specific fuel consumption: Quantity of fuel that is consumed by an engine in kg per horsepower-hour or lb per horsepower-hour.

Engine Cycles

• 4-stroke cycle gasoline engine: Completes cycle in two crankshaft revolutions- uses gasoline/petrol, uses carburetor/L or I head valve system for air/fuel mixing, intake stroke.
• 4-stroke cycle diesel engine: Completes cycle in two crankshaft revolutions- uses diesel fuel- uses injection pump and nozzle to introduce fuel, intake stroke -uses L-head valve arrangement. increase compression ratio.

Diesel Engine Terminologies

• Direct or solid injection: Mechanical fuel injection into compressed air.
• CRDI (common rail direct injection): Modern diesel engine technology for high speed engines, less noise and higher fuel economy.
• Glow plugs: Electrically operated heaters for cold-weather starting.

Explore the key components of engines used in Agricultural and Biosystems Engineering. This quiz covers the nomenclature, construction, and design of essential engine parts and their functions. Test your knowledge of cylinders, pistons, crankshafts, and more.