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Lesson. Using Small Engines. Interest Approach. How could we accomplish lawn tasks without small engines?. Student Learning Objectives. Identify the reasons why small engines are widely used. Describe how small engines can be classified.

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  1. Lesson Using Small Engines

  2. Interest Approach • How could we accomplish lawn tasks without small engines?

  3. Student Learning Objectives • Identify the reasons why small engines are widely used. • Describe how small engines can be classified. • Identify common service jobs performed on small engines.

  4. Terms • Blow-by • Degreaser • Dry-filter type air cleaners • Horizontal crankshaft engine • Oiled-filter type air cleaners • Service intervals • Vertical Crankshaft engine

  5. Small engines • 25 horsepower or less. • Several million are now in use in the U.S. • Accomplish tasks that other equipment cannot do.

  6. Small engine popularity • Compact • Lightweight • Easy to service and repair • Affordable

  7. Reasons for small engine trouble • Dirt and dust leads to rapid wear if not serviced properly. • Abuse by overloading. • Do not receive proper service or regular maintenance.

  8. Classifying small engines • By the position of their crankshafts. • By the number of power strokes per crankshaft revolution.

  9. Position of crankshafts • Vertical crankshaft engine – its cylinder is in a horizontal position. • Horizontal crankshaft engine – may have its cylinder in a vertical, horizontal, or intermediate position. • Multi-position crankshaft engine – operates in any position.

  10. CrankshaftPositions

  11. Number of power strokes • Four stroke cycle engines – intake, compression, power, exhaust. • Two-stroke cycle engines – compression & intake, power & exhaust.

  12. Extremeanglesof operationand oilsupply

  13. Service intervals • The periods of time between the performance of service jobs.

  14. Common Service Jobs • Cleaning the engine. • Inspect and clean the exhaust system. • Degreaser – solvent good for cleaning hard to reach places. • Inspect cooling system for obstructions.

  15. Servicing Carburetor Air Cleaners • Oil-filter type air cleaner – made of a sponge-like filtering material called polyurethane. • Dry-filter type air cleaner – consists of a porous filtering material made of paper or fiber.

  16. Types ofair cleaners

  17. Lubricating Small Engines • Engine oil is vital to engine life. • Blow-by – gases under pressure that leak by the piston rings during combustion and the power stroke. • Four cylinder engines are lubricated from an oil reservoir. • Two-cycle engines are lubricated by specific types of oil in the fuel.

  18. Servicing Spark Plugs • Anything that inhibits the flow of current through the spark plug and across the spark plug gap will affect the operation of the engine.

  19. Sparkplugoperation

  20. Review/Summary • Why are small engines so widely used? • How are small engines classified? • What are some of the common service jobs performed on small engines?

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