Two stroke and four stroke engines pdf

For a given weight, engine would give For same weight, two stroke engine gives only half the power of two stroke twice the power that of four stroke engine.

All types of speed are possible high Mostly high speed engines are there. It can be operated in one direction It can be operated in both direction only.

In diesel engines only air is drawn into the cylinder. The engine has high compression ratio hence the air in the cylinder attains very high temperature and pressure at the end of the compression stroke.

At the end of the compression stroke, the fuel is sprayed into the cylinder in atomized form using injectors. Due to high temperature, the fuel gets ignited, begins to burn and produce lot of heat. Due to the heat the gases expand, move the piston downward and rotate the crank shaft. The torque available at the rotating crank shaft is used to do any mechanical work Special features of diesel engine 1 Engine has high compression ratio ranging from to It uses petrol gasoline or power kerosine iii It uses diesel oil as fuel.

Operating cost is high. It is the basic part of the engine. It provides space in which piston operates to suck the air or air-fuel mixture. The piston compresses the charge and the gas is allowed to expand in the cylinder, transmitting power for useful work. Cylinders are usually made of high grade cast iron. Liners are classified as : 1 Dry liner and 2 Wet liner. Dry liner makes metal to metal contact with the cylinder block casing.

It is connected to the connecting rod by a piston pin. The force of the expanding gases against the closed end of the piston, forces the piston down in the cylinder.

This causes the connecting rod to rotate the crankshaft Fig 3. Cast iron is chosen due to its high compressive strength. Aluminum and its alloys preferred mainly due to it lightness. Engine components Head Crown of piston: It is the top of the piston. Skirt: It is that portion of the piston below the piston pin which is designed to adsorb the side movements of the piston. They are usually made of cast iron or pressed steel alloy Fig. Piston rings are of two types: 1 Compression ring and 2 Oil ring vii Compression ring Compression rings are usually plain, single piece and are always placed in the grooves of the piston nearest to the piston head.

They prevent leakage of gases from the cylinder and helps increasing compression pressure inside the cylinder. Oil ring: Oil rings are grooved or slotted and are located either in lowest groove above the piston pin or in a groove above the piston skirt. They control the distribution of lubrication oil in the cylinder and the piston. Piston Pin: It is also called wrist pin or gudgeon pin. Piston pin is used to join the connecting rod to the piston.

It transmits the power of combustion to the crankshaft and makes it rotate continuously. It is usually made of drop forged steel. Usually the crankshaft is made of drop forged steel or cast steel. The space that supports the crankshaft in the cylinder block is called main journal, whereas the part to which connecting rod is attached is known as crank journal.

Crankshaft is provided with counter weights throughout its length to have counter balance of the unit. Its main functions are as follows : a It stores energy during power stroke and returns back the energy during the idle strokes, providing a uniform rotary motion of flywheel. It provides a reservoir for the lubricating oil. The upper portion of the crankcase is usually integral with cylinder block.

The lower part of the crankcase is commonly called oil pan and is usually made of cast iron or cast aluminum xii Camshaft: It is a shaft which raises and lowers the inlet and exhaust valves at proper times.

Camshaft is driven by crankshaft by means of gears, chains or sprockets Fig3. The speed of the camshaft is exactly half the speed of the crankshaft in four stroke engine. Camshaft operates the ignition timing mechanism, lubricating oil pump and fuel pump. It is mounted in the crankcase, parallel to the crankshaft. Camshaft gear fig.

For this reason, this gear is commonly called half time gear. Timing gear controls the timing of ignition, timing of opening and closing of valve as well as fuel injection timing. It is fitted by the side of the cylinder head. It is capable of withstanding high temperature of burnt gases. In two stroke cycle engine both the sides of the piston are effective which is not the case in four stroke cycle engine. Entire burnt gases do not go out in normal stroke, hence some type of blower or compressor is used to remove the exhaust gases in two stroke cycle engine.

In general, this ratio varies between 1 to 1. Swept volume - It is the volume A x L displaced by one stroke of the piston where A is the cross sectional area of piston and L is the length of stroke Fig.

Bore and stroke of IC engine Compression ratio - It is the ratio of the volume of the cylinder at the beginning of the compression stroke to that at the end of compression stroke, i. The Compression ratio of diesel engine varies from to and that of carburetor type engine spark ignition engine varies from to Power - It is the rate of doing work. In metric unit the power can be expressed in kg.

Horse power HP - It is the rate of doing work. Indicated horse power IHP - It is the power generated in the engine cylinder and received by the piston. It is the power developed in a cylinder without accounting frictional losses.

It is measured by a dynamometer. In general, the belt and PTO horse power of a tractor will approximately be the same. It is that power which is available for pulling loads. As we all know the there are two types of engines although there are various kinds of engines are available however these are some popular engines we are talking about one is four-stroke another one is two-stroke.

We call an engine 2-stroke when the four successive strokes, i. Suction, Compression, Power, and Exhaust are completed in 1 revolution of the crankshaft, which means in the degree rotation of a crankshaft all the successive strokes are completed.

And again we call an engine 4-stroke when the same successive strokes Suction, Compression, Power, and Exhaust are completed in the 2-revolution of the crankshaft. I will suggest you to reading those articles too. So these are the quite few difference between the 2-stroke engine and 4-stroke engine, let me know in the comment section if you know more differences between these engines, I will love to show more.

And yeah, if you have any doubts regarding this topic, feel free to comment down below, I will reply here. Suction, Compression, Power, and Exhaust are completed in 1 revolution of the crankshaft. Your email address will not be published. Save my name and email in this browser for the next time I comment.

The spark plugs fire once every single revolution, and power is produced once every 2-strokes of the piston. Two-stroke engines also require the oil to be pre-mixed in with the fuel. Two-stroke engines are typically found in smaller applications such as remote-controlled cars, lawn tools, chainsaws, boat motors and dirt bikes. Four-stroke engines are found in anything from go-karts, lawnmowers and dirt bikes, right up to the typical internal combustion engine in your vehicle.

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Check out our website and Facebook page for accurate information and quality products you need to handle your most common vehicle issues. Recent Posts. Watch this quick video for a further description of how the 4-stroke engine works: 2-Stroke: In a 2-stroke engine, the entire combustion cycle is completed with just one piston stroke: a compression stroke followed by the explosion of the compressed fuel.

This is due to the fact that fuel is consumed once every 4 strokes. Typically, a 2-stroke engine creates more torque at a higher RPM, while a 4-stroke engine creates a higher torque at a lower RPM.