Small Engine Terminology This presentation is from Virginia Tech and has not been edited by the Geor

1
Small Engine TerminologyThis presentation is
from Virginia Tech and has not been edited by the
Georgia Curriculum Office.
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Performance Objectives

• Students will be able to define, recognize, and
  utilize terms concerning small engines
  effectively.

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Enabling Objectives

• Students will define small gas engine terms.
• Students will use correct terminology in
  discussion of small engines.
• Students will recognize small gas engine
  terminology and be able to effectively apply
  terms to usage and maintenance of the engine.

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How does this whachamacallit fit into the
whozamathingy?I need a flappy white thing
that goes on the top of the engine.
Effectively communicating your intentions is a
key point to success. Terminology is the key!

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Small Engine Maintenance

• Internal Combustion Engine- Device that burns
  fuel inside a cylinder to create a force that
  drives a piston.
• Piston- A sliding cylinder fitting within a
  cylindrical vessel that receives the force of
  combusting fuel.
• Crankshaft- A shaft with an offset projection
  that converts circular motion to reciprocal
  motion, or vice versa.
• Reciprocating- return move back and forth

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• Horizontal shaft engine- An engine with a
  crankshaft that lies crossways for normal
  operation
• Vertical shaft engine- an engine whose
  crankshaft is vertical for normal operation
• Stroke- the movement of a piston from top to
  bottom or from bottom to top
• Cycle- All the event that take place as an engine
  takes in air and fuel, compresses the air fuel
  mixture, burns the fuel, and expels the burned
  gasses. Also the current produced by one turn of
  a generator armature.

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• Four- stroke cycle- four strokes per cycle
• Two-stroke cycle- two strokes per cycle
• Poppet valve- a valve that controls the flow of
  air and gasses by moving up and down.
• Port- a special hole in the cylinder wall of a
  two cycle engine to permit gasses to flow in or
  out of the cylinder.
• Reed valve- a flat, flexible plat that permits
  air or liquid to pass on one direction but seals
  when the flow reverses.

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• Intake stroke- engine process of taking fuel and
  air into the combustion chamber
• Compression stroke- Movement of an engine piston
  to squeeze or compress the air-fuel mixture
• Compression ratio- the relationship between the
  volume of an engine cylinder at the beginning and
  end of the compression stroke.
• Top Dead Center (TDC)- position of a piston
  when at its highest point (furthest from the
  crankshaft)

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• Bottom Dead Center (BDC)- piston at its lowest
  point ( point nearest the crankshaft)
• Fire- flame to make a spark jump across an air
  gap
• Ignition- a spark igniting an air-fuel mixture
• Power stroke- the engine process in which
  burning fuel expands rapidly but evenly to drive
  the piston down
• Exhaust- burned gasses removed by the motion of
  a piston

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• Exhaust Stroke- Movement of a piston which
  expels burned gases from a cylinder
• Revolution- one complete turn of 360 degrees
• Momentum- turning force of the flywheel and other
  moving parts that carries an engine through
  nonpower strokes.
• Maintenance- doing the tasks that keep a machine
  in good condition

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• Troubleshooting- determining what causes a
  malfunction in a machine or process.
• Repair- to replace a faulty part or make it work
  correctly.
• Adjust- to set a part or parts to function as
  designed.
• Contaminant- any material that does not belong
  in a substance
• Saturate- to add a substance until the excess
  starts to run out.

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• Dual-two
• Precleaner- a device that removes large particles
  from air entering an air cleaner
• Shroud- to cover a cover
• Score- to scratch
• Torqued- A twisting force to twist
• Speed indicator- a device used to measure
  revolutions per minute (RPM) of a turning shaft
  or part.
• RPM-revolution per minute

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• Leaner- a greater proportion of air and lesser
  proportion of fuel in an air-fuel mixture.
• Richer- a mixture with an increased proportion
  of fuel to air
• Labor- to struggle or work hard to keep running

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Small Engine Adjustment and Repair

• Overhaul- complete disassembly with cleaning and
  reconditioning or replacement of most moving
  parts.
• Governor- Speed control device
• Air Vane- type of governor used on small engines
• Carburator- Provides fuel and air to the engine
  in appropriate portions and volume.

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• Needle- A long tapered shaft
• A hole shaped to receive the needle and control
  the flow of fuel.
• Jet or Seat- a hole shaped to receive the needle
  and control the flow of fuel.
• Battery- produces electricity by chemical action.
• Magneto- produces electricity by magnetism
• Condensor- stores and releases current to boost
  current in the Primary circuit

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• Primary circuit- low-voltage circuit of an
  ignition system
• Secondary circuit- high-voltage circuit of an
  ignition system.
• High-tension wire- high voltage wire in a
  secondary circuit
• Electromagnetic induction- conversion of
  low-voltage current to high-voltage current with
  a coil.
• Ignition spark- hot electrical arc across an air
  gap

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• Ignition points- interrupt the flow in the
  primary circuit at the correct time to induce the
  high voltage flow to the spark plug.
• Discharge- loss of power from a battery
• Electrolyte- acid solution in a battery
• Distilled water- free of iron or other parts
• Armature- the rotating part of a motor. Also
  the iron core portion of a magneto.
• Head gasket- seal between the head and the
  cylinder block

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• Valve Spring Compressor- compresses the valve
  spring to remove keepers.
• Valve keeper- transfers spring force to valve
  stem
• Stem- long, round section of a valve
• Margin- outer edge of a valve head
• Face- surface that is intended for use. Also
  tapered section of a valve head.
• Lapped in- grinding valves to fit the seat for a
  perfect seal

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• Lapping compound- gritty material used for
  lapping in valves
• Valve grinding- the process of grinding valves
• Valve guide- holds valve stem in alignment
• Valve stem clearance- air gap between valve and
  push rod.
• Cylinder- engine cavity containing a piston
• Head- flat part of a valve cylinder cover
  containing the spark plug and combustion chamber.

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• Piston- a sliding cylinder fitting within a
  cylindrical vessel that receives the force of
  combusting fuel.
• Rings- complete the seal between the piston and
  cylinder wall.
• Inside micrometer- telescoping gauge used to
  measure inside surfaces of hollow objects.
• Telescoping gauge- inside micrometer
• Cylinder hone- Tool for restoring cylinders

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• Ring expander- tool used to remove and install
  piston rings
• Blow-by- compression leakage past pistons
• Piston ring compressor- used to force piston
  rings into their grooves
• Wrist pin (Crank pin)- pin between a connecting
  rod and piston
• Micrometer- Used to measure outside surfaces of
  round objects
• Plastigage- carefully designed material that
  flattens out uniformly when pressed.

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• Rope starter- rope wrapped around a pulley for
  turning power to start an engine
• Wind up starter- uses a lever to coil a spring
  for cranking an engine.
• Valve pin- Transfers spring force to valve stem
• Head- flat part of a valve cylinder cover
  containing the spark plug and combustion chamber.

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Vocabulary Quiz

• Exhaust stroke
• Power Stroke
• Piston
• Stroke
• Exhaust

• Burned gases removed by the motion of the a
  piston.
• The movement of a piston from top to bottom or
  from bottom to top.
• A sliding cylinder fitting within a cylindrical
  vessel that receives the force of combusting
  fuel.
• The engine process in which burning fuels expands
  rapidly but evenly to drive the piston down.
• Movement of a piston which expels burned gases
  from a cylinder.

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• Doing the tasks that keep a machine in good
  condition.
• Engine process of taking fuel and air into the
  combustion chamber
• Movement of an engine piston to squeeze or
  compress the air-fuel mixture.
• A spark igniting an air-fuel mixture
• Turning force of the flywheel and other moving
  parts that carries an engine through nonpower
  strokes.
• To replace a faulty part or make it work correctly

• Repair
• Momentum
• Intake stroke
• Ignition
• Compression Stroke
• Maintenance

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• Determining what causes a malfunction in a
  machine or process.
• All the events that take place as an engine takes
  in air and fuel, compresses the air-fuel mixture,
  burns the fuel, and expels the burned gases.
• Device that burns fuel inside a cylinder to
  create a force that drives a piston.
• A shaft with an offset projection that converts
  circular motion to reciprocal motion, or vice
  versa.

• Crankshaft
• Troubleshooting
• Cycle
• Internal Combustion Engine

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• Provides fuel and air to the engine in
  appropriate portions and volume.
• Produces electricity by magnetism
• The rotating part of a motor.
• Seal between the head and the cylinder block
• Complete the seal between the piston and the
  cylinder wall.
• Stores and releases current to boost current in
  the Primary circuit.

• Head gasket
• Armature
• Condensor
• Magneto
• Carburetor
• Rings

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• Used to measure outside surfaces of round
  objects.
• Inside Micrometer
• Flat part of the valve
• A twisting force
• Compression leakage past pistons

• Telescoping gauge
• Blow-by
• Torque
• Head
• Micrometer