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Presentation Topic-

Two Stroke Engine

Stroke

Reciprocating motion used in reciprocating engines and other mechanisms

is back and fourth motion .Each cycle of reciprocation consists of two

opposite motions , there is a motion in one direction and then a motion

back in the opposite direction . Each of this motion is called stroke.

2 stroke

A two-stroke petrol engine is an internal combustion engine that completes

the process cycle in one revolution of the crankshaft . Thus one power stroke is

obtained in each revolution of the crank shaft.

Basic parts of 2-stroke petrol engine

Piston

Piston Ring

Spark plug

Connecting rod

Crankshaft

Spark Plug

Electronic match is used to begun the combustion process of burning air

and petrol to create heat.

It provides the means of ignition when the petrol engine’s piston is at the

end of compression stroke close to Top Dead Central (TDC)

Connecting rod

Connects the piston and piston point to the crankshaft

Piston

A sliding plug that harness the force of the burning gases in the cylinder

Crankshaft

Along the piston pin and the connecting rod is converts the up and down

motion ( reciprocating ) of the engine to spinning (rotary) motion

Working Principle of 2 stroke

Here suction and exhaust strokes are eliminated . Instead of valves , ports are used

The exhaust gases are driven out of the cylinder by the fresh charge entering the cylinder

The intake & exhaust are controlled by movement of piston

The fresh charge enter to cylinder due to difference of pressure

The charge is compressed by the pumping action of the piston due to the design of crankcase

As the piston continues to move upward , exhaust and transfer port get closed and the compression is continued

In the end of the compression the spark is created which ignites the charge and the products of combustion thrust the piston from TDC to BDC

This cycle is repeated continuously

Video clips…….

Advantages

The power developed will be nearly twice that of four stroke engine of

same dimension and operating at the same speed

The work required to overcome the friction of the exhaust and suction

strokes is saved

Low weight

Construction is simple

Low thermal efficiency.

Can run at higher speeds (5000 rpm)

Low maintenance cost

Disadvantages

As working on otto-cycle , a part of the fresh mixture is lost through exhaust

port

Part of the piston stroke is lost

Heavy consumption of lubricating oil

Two-stroke engines are not fuel efficient, so we would get fewer miles per

gallon.

Use of 2-stroke engine Dirt Bike

Lawn mowers

Outboard engines

Chain saws

Line Trimmers

Jet Skis

Snowmobiles

Model Air Planes

Light Motorcycles

Go Karts

Ultra lights

Scooters

Go-Karts

Example picture-

Dirt Bike Jet Skis

Chain sawsLawn mowers