FOURSTROKE DIESEL ENGINE

                                                        FOURSTROKE DIESEL ENGINE

The fourstroke diesel engine works as here in.When the piston is moving upward and is close to TDC,the inlet valve is opened.As the piston moves downward vacuum is created in the cylinder.Air is alone sucked in.The piston after reaching BDC begins to rise.At this point the inlet valve is closed,and the exhaust valve is already in the closed positions.Now the piston moves upward  and compresses the air to a great extent compared to that in a petrol engine.Due to compression,temperature and pressure of air increase.At the end of the compression stroke,Fuel is into the hot compressed air,in the form of fine spray.The heat of compression in the air ignites the injected fuel.Combustion takes place.High pressure thus develeped forces the piston to move downward.The piston is connected to crankshaft by the connecting rod.As such the crank shaft is rotated .After the powerstroke,piston rises up.Now the piston pushes combustion products out of the cylinder.As the piston approaches close to TDC intake valve is opened.Atmospheric air begins to enter the cylinder.The cycle of operations g

ets repeated again and again and the engine continues to work.


To watch the working of fourstroke dieselengine-click here

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TWO STROKE PETROLENGINE

                                                       TWO STROKE PETROLENGINE

In the two stroke engine,ports(intake,exhaust&transfer ports)of different sizes and shapes are there in the cylinder wall at different levels and positions.The piston as it moves up&down in the cylinder  opens and closes these ports.Piston controlled port two stroke engine is used widely in two wheelers.
                                                                                                                                       In the piston controlled port two stroke engine,as the piston descends from TDC(power stroke)just before BDC,the piston crown opens the exhaust port.Expanding combustion products rush out.The downward movement of the piston compresses the mixture that has been previously sucked into the crankcase.Further downward movement of the piston,causes the piston crown to open the transfer ports.The transfer port and the transfer passages connect the cylinder with the crankcase.As such the mixture compressed to some extent and confined in the crankcase,now rushes through the transfer ports and fills the cylinder.The entering mixture sweeps the combustion products that may remain in the cylinder.After the piston reaching BDC,it begines to rise.Now the piston first closes the transfer ports and then the exhaust port.
                                                                                                               From the instant of the closure of the transfer ports,the upward movement of the piston creates partial vacuum in the crankcase.As the piston moves further upward,at some instant,the bottom of the piston opens the intake port.Now because of the vacuum in the crankcase,airfuel mixture is sucked into the crankcase.Then the airfuel mixture is passed through the transferport and it will compressed in the cylinder by the piston.it will ignites by the sparkplug.Its the simple working of a two stroke petrol engine.


Watch the working of twostroke petrol engine:-ClickHere

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FOURSTROKE PETROL ENGINE

                                                     FOURSTROKE PETROL ENGINE


The fourstroke engine is also called sometime as four cycle engine.The main components of the four stroke engine are piston assembly,connecting rod,cylinder,cylinder head,crank case,crank shaft,inlet and exhaust valves,valve operating mechanism and ignition system.The operation of the four stroke engine is illustrated.The four stroke petrol engine is works as herein.when the piston is moving upward and is close to TDC,the inlet valve is opened.As the piston move downward vacuum is created in the cylinder.Air fuel mixture is sucked in.The piston after reaching BDC begins to rise.At this point,the inlet valve is closed,and exhaust valve is already in the closed position.Now the piston moves upward,and compresses the charge temperature and pressure of the charge increase.
                                                                         At the end of the compression stroke,an electric spark is produced .This ignites the mixture,combustion take place.High pressure thus developed forces the piston to move downward.The piston is connected to the crank shaft by the connecting rod.As such the crankshaft is rotated .After the power stroke,piston rises up.Now the piston pushes the combustion products out of the cylinder.As the piston approaches close to TDC.Intake valve is opened.Fresh charge begins to enter the cylinder.The cycle of operations gets repeated again & again and the engine continues to work.

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CONSTANT MESH GEARBOX

                                                     CONSTANT MESH GEARBOX

In these case all the gears are in mesh and engagement between the gears which are freely rotating on the transmission main shaft and transmission main shaft is effected by moving the dog clutches as explained below.
        The gearbox shaft is integral with a pinion.The pinion meshes with a wheel on the layshaft.The layshaft is therefore driven by the engine shaft.There more wheels are fixed to the lay shaft as in the sliding mesh gearbox.These gears rotate with the layshaft.The transmission main shaft is just above the layshaft and in the line with the engine shaft.The three gears in the main shaft are perfectly free on the mainshaft.These gears are in constant mesh with the wheel on the layshaft through an idler wheel which is mounted and freely rotating on a pin fixed to the gearbox casing.The three main shaft gears are therefore constantly driven by the engine shaft,but at different speeds.

Watch working of constant mesh gearbox

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SLIDING MESH GEARBOX

                                                            SLIDING MESH  GEARBOX

The sliding mesh gearbox which is the simp

lest and oldest historically consist of three shaft and a set of gears and gear selecter mechanism and gear shift lever.The engine is coupled through the clutch and clutch shaft,to short gearbox input shaft.this shaft carries a pinion.a lay shaft or counter which is arranged parellel to the gearbox shaft carries five wheels of different sizes.These are the driven gear,third speed gear.second speed gear,first speed gear and reverse gear.The gearbox shaft pinion meshes continuously with the driven gear on the lay shaft.There is a transmission main shaft(gearbox output shaft)in the line with the gearbox input shaft.This shaft is supported at one end in a ball bearing housed in the casing,and at the other end by the spigot which is part of transmission shaft and which fix in a bushed hole in the gearbox input shaft.There are 2 gears on the main shaft.These gears maybe shifted back and fourth along the splines on shaft,by operating gear shift lever in the driver compartment.The splines are matching internal and external teeth that permit end wise movement of the gears but caused gears and main shaft to rotate together.The transmission main shaft is connected by the propeller shaft,gears in the final drive and differential mechanism and axial shaft to the wheels of the vehicle.

watch working of sliding mesh gearbox

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GEAR BOX

                                                        GEAR BOX

                       In simple words gear boxes are used to vary the speed and torque.When driving a vehicle  usually there will be slops,curves or sudden breaking situations.So there will be a speed variation occurs.To overcome these type of situation the shifting is used.In straight roads we need accurate speed and low torque & when the vehicle slows down the speed is low and the torque need to be high.

WORKING

   Gear box has a series of gears and shaft to vary the speed and torque of the output shaft compared to the engine speed.Commonly there are two parellel shafts known as layshaft and main shaft.They are connected with a series of gears.The main shaft is a joined form of another two shafts whose ends are in geared form.These formation is used to maintain the maximum speed(top gear).The main drive from engine is  straightly connected through the lay shaft.There are a series of gears in varying size.In first gear position the smaller gear of the layshaft will meshed with the larger gear in the main shaft,and maintain the lower speed and higher torque,respectively 2^nd,3^rd gears also meshed with their pairs.In the top gear position the drive

shaft will directly meshed to the driven shaft.The gears may be spurgear or bevelgear.

Types of gear boxes

*Sliding mesh gearbox

*constant mesh gearbox

*Epicyclic gearbox

How a gearbox works?-Video-https://www.youtube.com/watch?v=Gf5tQfEBj0M

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DIFFERENTIAL

DIFFERENTIAL

                                                           The differential receives the drive from the shaft called propeller shaft.It has the following puposses

*It receives the drive from shaft and then send to axle then the wheels,that means means perpendicular rotation to parellel rotation.

*It rotates the two road wheels in the same speed in the straight roads.

*It rotates the wheels in different speeds when occurs a curve

                   A differential system consist of a crown wheel

,spacerblock,sun gears and star gears.Son gears receives drive from propeller shaft,the two sun & star gears are connected in square shape respectively.This whole system connected and also rotates with the crownwheel.A spacer block is provided between the bevelgears(sun&star)to maintain the stability and their formation.When the curves occures one wheel have to rotate less and the other one needs more.In these situations the sun&star gears make these difference in the axles.


working principle of differentilal-video(direct link):-https://www.youtube.com/watch?v=gIGvhvOhLHU

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ENGINES

                  ENGINES

It is the heart portion of a vehicle,in other words driving portion.It’s an assembled form of many other parts like oilsump,cylinder,piston,valves etc.When the engine starts a fly wheel(a wheel of high mass)begin to rotate,it will rotates in high speed crank and it’s connected to the crankshaft which drives the piston,the piston is placed in a cylinder.The other end of crankshaft is joined to timing gear or pulley.This portion controls the valve timing.Then a shaft called camshaft driven by this timing gear,it controls the opening and closing of the inlet and outlet valve.This drive is given by a special part called tappet and push rod.The returning force to the valve is given by a spring.Its the simple working of a  engine,there are many other operations like cooling and lubricating.There is an additional oil sump is used to store the oil and to distribute it.When all these processes works properly then its called an engine.

Parts of an Engine:

1-Fly wheel

2-Crankshaft

3-Timing gear or pulley

4-Cam shaft

5-Tappet & push rod

6-Piston

7-Cylinder

8-Oil sump

9-Cooling system

10-Valve mechanism

Classifications

According to strokes:

                   Fourstroke engine

                   Twostroke engine

According to position of cylinder:

                   Vertical engine

                   Horizontal engine

                   Inclined engine

According to fuel used:

                   Petrol engine

                   Gas engine

                   Diesel engine

According to the combustion take place:

                   Internal combustion engine(IC)

                   External combustion engines(EC)

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SPARKPLUGS

                                                         SPARKPLUGS

Sparkplug controls the ignition system,as the name indicates it sparks the petrol air mixture.There's an electrode placed in it,the electrode is used as the conducter.When high current passed through it from a battery  current will jump from the electrode to the conducter which shaped like hook.This current jump is known as the spark.The spark can combust the compressed air fuel mixture.The spark system is also well timed as the valve mechanism(sparks in the power stroke).The spark plug has a great part in the engine efficiency,if the plug can combust the fuel completely then the spark plug is ideal.So the duel sparking is placed in the newer engines.Spark plug have to be well maintained(clean alternately).The figure shows simplest working of a spark plug.

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STEAM ENGINE

STEAM ENGINE:

STEAM ENGINE

     Steam engines are huge in size and are used in railways,factories and machineries.There is a boiler must for this steam engine.Because the steam is produced by the boiler.There is always a fuel having high calorificfactor,because there is a need of an extralarge amount of steam.In some cases the steam will again converted into liquid form.So there is no fuel wastage.The steam from the boiler will be passed through a pipe or tunnel to the engine cylinder.The cylinder consist of a piston.The steam will force the piston to make reciprocating movement.The power produced is very high.It's construction and working is as same as the external combustion engine.But it's difficult to use in moving situations.

ADVANTAGES:

>more powerful engine

> Any suitable form of energy can be used to make steam

>Not affected much by high altitudes 

DISADVANTAGES:

>need more space to stay

>more expensive parts

>maintanance is high

>skilled workers are needed

>dangerous because of the high pressure and heat

for video-watch

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