Using Small Engines

Next Generation Science/Common Core Standards Addressed! CCSS.ELA Literacy.RST.9 ‐ 10.1 Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions. CCSS.ELA Literacy.RST.9 ‐ 10.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text. CCSS.ELA Literacy. RST.11 ‐ 12.2 Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms. CCSS.ELA Literacy.RST.11 ‐ 12.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on explanations in the text.

Agriculture, Food and Natural Resource Standards Addressed! PST Perform preventative maintenance and scheduled service to maintain equipment, machinery and power units used in AFNR settings. PST b. Develop a preventative maintenance schedule for equipment, machinery and power units used in AFNR power, structural and technical systems.

Bell Work / 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.

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

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

Small engines Implements with less than 25 horsepower. Several million are now in use in the U.S., both two and four cycle Accomplish tasks that other equipment cannot do. New items are continually being developed.

Small engine popularity Compact Lightweight Easy to service and repair Affordable

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. Small engines usually operate at top speed continuously. That would be comparable to you car traveling at 85 mph continuously.

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

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

Crankshaft Positions

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

Extreme angles of operation and oil supply

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

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

Types of air cleaners

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 mixed in the fuel

Lubrication Systems.

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.

Spark plug operation

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?

The End!