Student Introduction to small engines - WikiEducator

Introduction to small engines -- Student Student

Introduction to small engines

What you will learn

When you have finished this introduction module, you should know:

O How small engines work O The main differences between 2-stroke and 4-stroke engines O The main parts of small engines O Why engines need air, fuel and a spark to run O Why engines need maintenance O Technical information about your engine.

Things you need before you start

Materials

None

Tools or equipment

No tools for this module ? but you will need to find out information about your engine

1 Copyright ? Commonwealth of Learning

What is a small engine?

Engines can be in all sorts of shapes and sizes. They are used to power:

outboard motors brush cutters and mowers motor bikes small generators chainsaws concrete mixers

Introduction to small engines -- Student

2 Copyright ? Commonwealth of Learning

Introduction to small engines -- Student

Here are the names for some important parts of an engine.

Spark plug

Cylinder head

Dipstick oil Starter

Air-filter

Carburetor

Crankshaft

Muffler

Crankcase

Fuel tank

Crankshaft

Crankcase and cylinder

Piston Valves

Cylinder head

3 Copyright ? Commonwealth of Learning

Introduction to small engines -- Student

How do engines work?

The power and energy in an engine is made by burning a mix of fuel and air inside a cylinder.

As the fuel burns it explodes and pushes a piston down inside the cylinder

The piston is attached to a crankshaft that turns as the piston moves up and down

Here is the piston going up and down as the crankshaft turns

Piston

Cylinder

Crankshaft

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Introduction to small engines -- Student Think of a person riding a bicycle. Think of one of their legs pushing down on the pedal ? round and round. The leg is just like the piston and the pedal and chain-wheel are like a crankshaft

The engine crankshaft is then connected to what the engine is driving ? a wheel, propeller, cutting blades.

The engine cycle

These are the steps that happen inside the engine: intake. fuel and air is sucked or pushed into the cylinder compression. the fuel-air mix is compressed ? or squashed ? as the piston moves up ignition/power. a spark ignites the fuel-air. The exploding fuel pushes the piston down exhaust. the burnt gasses are pushed out through the exhaust

and then the cycle goes around again. Those are the proper names for the steps. Some people call them:

Suck - Squash - Bang - Blow

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