Objectives Define a small engine Uses of a small engine History of the small engine Types of small...

Objectives• Define a small engine

• Uses of a small engine

• History of the small engine

• Types of small engines

• Commonality of small engines

• Basic Parts

• Different groups of small engines

I. Small Engine –

an engine that produces power by burning a fuel into a mechanical force that is rated under 25hp

II. Equipment used

- lawn mowers, weed eaters, snow-mobiles, 4-wheelers, mo-peds

History

• 1680 was the first small engine

• External Combustion Engine- it derives heat from the combustion of water into steam that in turns powered the pistons inside the engine.

Ex. Steam enginesWhat are some problems with this

engine?Large, not as efficient, very heavy

History

• Internal Combustion Engine –

Burned fuel inside the engine.

Adv

More efficient, power, reduced size & weight

Ex. Cars, lawnmowers

Types of Small Engines

A.) 2 stroke (cycle) engine

- operates on a series of 2 strokes to complete a cycle

B.) 4 stroke (cycle) engine

- operates on a series of 4 strokes to complete its cycle

Commonality of Small Engines

• All engines have these things in common.

1. Intake Stroke

2. Compression Stroke

3. Power Stroke

4. Exhaust Stroke

How a 2 stroke functions• 2 Stroke Engines

2 cycle combined

2 cyles combined

Stroke Paper

• Define Stroke

• TDC

• BDC

• Operation of a 4 stroke Engine

The Engine Consist of 5 Basic Parts

All engines have these parts

1. Block

2. Piston

3. Cylinder

4. Crankshaft

5. Camshaft

Small Engines are Broken up into 5 Different Groups

1. # of Strokes

2. Ignition

3. Shaft Orientation

4. Cooling System

5. Cylinder Design

Ignition Systems

A. Pull Start

B. Electronic

C. Combination

Shaft Orientation

What is this??

- The axis of the CRANKSHAFT

Two Options

1. Vertical

2. Horizontal

Selected for efficiency in driving components

Ex. Push lawn mower – Vertical

Snow blowers – Horizontal

Cylinder Design

What way can cylinders come?

Automobiles are multi-cylinders and are called V-6 or V-8

Why do we use the V option for cars/trucksMore Power than horizontal or vertical

I

Cooling Systems

How is an engine cooled?

1. Air – air fins

2. Water – radiator