KNOW WHAT YELLOW OR WHITE STRIPS ON COACHES OF INDIAN RAILWAY MEAN !!

On 16 April, 1853, Indian Railways started its services and the first train travelled at a distance of 33 km from Mumbai to Thane. While travelling through train, you may have seen coloured coaches and different coloured stripes on the train coaches such as yellow or white etc. Have you ever thought why these coloured stripes are given to some of the train coaches, what does it mean? Let us study through this article about the stripes and about the colour coaches & their significance.

On the blue ICF coach, the lines or stripes of yellow or white colour are placed on top of the window at the end of the coach, which is actually used to separate the coach from another coach. These lines indicate the unreserved coach of the second class. When a train arrives at the station, there are many people who are confused about the General Bogie, but by looking these yellow stripes, people can easily understand that this is the General Coach. Coach with white strip shows reservation class.

Similarly, the yellow stripes on blue / red are used for the handicapped and sick people. Similarly, green stripes on the grey indicate that the coach is for women only. These colour patterns are included only for the new Auto Door Closing EMU in Mumbai, Western Railway.Similarly, the red colour stripe indicates the first-class coach.

KNOW WHY TURBOCHARGERS ARE MOSTLY USED IN DIESEL ENGINE !

Turbochargers are rarely used with petrol engines but mostly used in diesel engines.We will discuss the reason behind this in this article.

A turbo charger is a device which uses exhaust heat from an Engine to get more air into the Cylinder during Induction stroke.More air translates to increased ability to burn more fuel which in turn increases the Power output (brake horse power) of the Engine.Turbocharging is common in modern car and truck Diesel engines to produce higher power outputs, lower emissions levels, and improved efficiency from a similar capacity of engine. Turbo-Diesels in automobiles offer a higher refinement level than their naturally aspirated counterparts.

Basically turbocharger compresses the air and forces into the engine cylinder so in short, we are putting more air into cylinder which results in more power.Compression of air by TURBOCHARGER INCREASES THE PRESSURE AND TEMPERATURE INSIDE THE CYLINDER.

Now, let us take the case of Diesel Engine:

Diesel as a fuel is not as combustible as petrol. The air-fuel mixture inside the cylinder should be at higher pressures for effective combustion of diesel. To withstand higher combustion pressures a diesel engine is built with strong, heavy parts.So,heavier parts can withstand higher pressure generated by turbocharger.Also,the heavier components of a diesel engine cannot rotate at higher RPMs.Lesser RPM means lesser air intake into combustion chambers. Hence a turbo charger helps a diesel engine to get more air into the combustion chamber.

Now come to Petrol Engine:

Petrol is more combustible than diesel and hence at lower pressures combustion can take place.If we add turbocharger to petrol engine then rise in pressure inside the engine cylinder may lead to problem of knocking.Also the parts of petrol engine is lighter than diesel engine so they may not withstand the pressure rise inside the engine cylinder.These are the reasons why turbochargers are not used with petrol engines. 

Also read:

DIFFERENCE BETWEEN KNOCKING AND DETONATION EXPLAINED !!

KNOW WHY THESE EQUIPMENTS ARE USED ON THE ROOF OF FACTORIES??

 You might have seen this type of rotating equipment on the roof of factories.In this article we will discuss what is this,what is does and how it works.

These are known as roof extractors. 

In summers, high temperatures build up inside small workshops and factory units making them extremely unpleasant to work in. As a temporary measure portable fans are installed to provide relief for workers, however while portable fans cool small areas of the building, the rest remains stiflingly hot.

Roof extractor fans provide a simple, low cost method of cooling for small buildings or rooms of upto approximately 1400 cubic meter (50,000 cubic feet).

It provides ventilation, fresh air and remove stale or contaminated air.Hot air is exhausted from the building and cooler outside air is sucked in though open doors and windows. As a result the temperature inside the building is held close to the outside temperature.

Using roof extractor fans to cool buildings of upto 1400 cubic meter has proved to be a very cost effective. By rapidly removing hot air from the building and sucking cooler air in through open doors and windows, the temperature inside can be kept close to the ambient (outdoor) temperature. 

KNOW WHY WIND TURBINES ARE ALWAYS PAINTED WHITE !!

You might have noticed that almost every wind turbine is painted white in colour.We will discuss reasons behind the white colour in this article.

1.)Generally wind turbines are painted white to be more aesthetically pleasing than otherwise. Painting them white or light grey helps the entire structure "blend" into the background, especially when the sky is cloudy. By making the entire structure white, the wind turbine is less visually obtrusive, in theory at least. White, after all, is a pretty neutral color.

2.)White, with an absence of colour, reflects sunlight and therefore reflect heat. Heat causes expansion, drying up of lubrication, and blistering. Consequently any colour would either shorten the life of a wind turbine by introducing increased wear and tear, or be more expensive in terms of maintenance. 

3.)Third reason is to make them visible from the sky.From the sky looking down, planes and aircraft will be able to see them standing out in the grass below them. This rule was implemented for safety reasons, and it is actually required by law that pilots must have a clear view of all wind turbines from above to avoid any accidents. 

 So these are the basic reasons why wind turbines are painted in white colour.If you liked this article then share it with your friends and if you have any doubt then feel free to ask in comment section.

KNOW WHY CARBON FIBER IS EXPENSIVE !!

Stronger than steel and a fraction of the weight, carbon fiber is a brilliant invention. Since its first use as a motor case on space rockets in the 1960s, it's often proclaimed as the ticket to better performance. It costs enough that it better. Despite 50 years of advancements carbon fibre remains expensively high end. But 50 years later, carbon fiber is still rare and expensive (starting at $10/pound.The rate of steel is $0.38/pound.)

FEW FACTS ABOUT CARBON FIBER:

1.)Carbon fiber -- sometimes known as graphite fiber -- is a strong, stiff, lightweight material that has the potential to replace steel and is popularly used in specialized, high-performance products like aircrafts, racecars and sporting equipment.

2.)The next generation of carbon-fiber composites could reduce passenger car weight by 50 percent and improve fuel efficiency by about 35 percent without compromising performance or safety.

3.)Carbon fiber can be woven into a fabric that is suitable for use in defense applications or added to a resin and molded into preformed pieces, such as vehicle components or wind turbine blades.

WHY CARBON FIBER IS EXPENSIVE: 

The main reason for high cost of carbon fiber is its manufacturing process.Let us see how it is made and what makes it expensive.

Before carbon fiber becomes carbon fiber, it starts as a base material—usually an organic polymer with carbon atoms binding together long strings of molecules called a polyacrylonitrile(similar to the acrylics in sweaters and carpets).To get the carbon part of carbon fiber, half of the starting material's acrylic needs to be removed. "The final product will cost double what you started with because half burns off,"This is responsible for a big part of the costs.

Then there are two major processing steps. The first is called oxidization stabilization. Here the fibers are fed through very long ovens with temperatures of several hundred degrees. The process takes hours to complete and is therefore a massive energy eater.

The second step is carbonization where the material is again placed in an oven, but this time the temperatures rise over thousand degrees. This step will also increase the power bill. It doesn’t end there.

Manufactures also have to take care of the off-gases to make sure they do not poison the environment, which needs lot’s of energy, real estate and large equipment. All steps are just for the manufacturing of the individual filaments themselves.

To get to the final product, the fibers and the resin have to be shaped and cured in an autoclave, again a time and energy consuming process.

So,the process of manufacturing is time taking and energy eating also only half of the raw material is used in final product.This leads to the high cost of carbon fibre.

IMPORTANT TERMS OF CASTING EXPLAINED !!

1.)AIR GATE – A vertical channel for the removal of gases from the mould;
checking of the filling of the mould cavity with metal and feeding up
the casting with metal during solidification.

2.)BACK DRAFT – Taper or draft which prevents removal of pattern from the
mould.

3.)BINDER – Material used to hold the grains of sand together in moulds or
cores. May be cereal, oil, clay, resin, pitch etc.

4.)BLEED – Molten metal oozing out of a casting stripped or removed from
the mould before solidification.

5.)CAVITY, MOULD or DIE – Impression or impressions in a mould or die
that give the casting its shape.

6.)CHILL – A metal object placed on the outside or inside a mould cavity to
induce more rapid cooling at that point and thereby produce hard zone
i.e., hard, unmachinable surface.

7.)COPE – The upper or top most section of a flask, mould or pattern.

8.)DRAFT – Taper allowed on the vertical faces of a pattern to permit removal
of it from the sand mould without excessive rapping or tearing of the
mould walls.
 
9)DRAG – The lower or bottom section of a mould or pattern.

10.)FLASH – Thin fin or web of metal extending from the casting along the
joint line as a result of poor contact between cope and drag moulds.

KNOW WHY FILLETS ARE PREFERRED ON EDGES !!

In mechanical engineering a fillet is a rounding of the interior or exterior corner of a part. On the inlet fillets are concave while on exterior corners these are convex.We generally use fillet on the edges of almost every product.In this article we will see why fillets are used at corners.

We generally use fillets due to following reasons:

1.)Fillets are mainly used to reduce stress concentration compared to chamfers. These can easily distribute stress more uniformly.

2.)Fillets give a part better flow and less resistance. Using a fillet also eliminates any sharp edges that can be easily damaged, or that could cause injury when the part is handled. This means there is less risk of failing an inspection for having a burr or sharp edge.

3.)Industrial designers tend to prefer fillets compared to chamfers as these are considered to be visually pleasing.

4.)One of the other reasons is that protective coating like paint are more uniformly distributed over a fillet compared to chamfer. Thickness of coating is reduced on sharp corners of chamfers so coating is lost first on these spots. Fillets have no such issues due to uniform distribution of coating.

But when it comes to comparison with chamfer in terms of cost then fillet is costly due to following reasons:

1.)A chamfer requires less machining time that a fillet radius.

2.)For fillets different radii of tools has to be stocked to create different radii, but a single tool can be used for creating different chamfers.

Still fillets are more preferred as compared to chamfers by industrial designers due to its advantages.Comment down your views in comment box.

KNOW THE FUNCTION OF LINES ON REAR WINDSHIELD !!

You have probably noticed the lines on the rear windshield of your vehicle.Have you ever wondered what those thin lines running across the length of your rear window are for? We will discuss about these lines in this post.

These lines are called defoggers. These lines are electrified filaments which dissipate heat in the case your rear windows begins to fog up.A small current is passed through those embedded wires or lines, and as the current is conducted, it heats up the glass slightly—just enough to melt any snow or ice blocking your view, or eliminating any fog/condensation that was built up.Your front windshield comes equipped with defoggers, too. But since driving with a bunch of thin lines obstructing your view probably isn't ideal, it instead comes in the form of vents near the base of the glass.

All of these small details on a car may not seem to add up to much, but they are integral to the safety and comfort of the passengers, as well as the structural integrity of the vehicle itself. Next time you sit down for a long drive, pay attention to those tiny details and be grateful that someone in the car manufacturing industry thinks about the small stuff!

DIFFERENCE BETWEEN FORCE AND PRESSURE EXPLAINED !!

Force and Pressure are the two important concepts of physics which are often erroneously interchanged by the people. But, these two are not same at all, as there is a vast difference between force and pressure,we will discuss about the difference between them in this post.

FORCE:

Force is the pull or push on an object which can change the velocity of the object on which it is applied. We can say that if force is applied on an object from one direction and there is no opposing force, then the object will move. If it’s already moving, it will either get faster or slower depending upon the direction of the applied force.

PRESSURE:

Pressure can be explained as force applied on a unit area.When the force is applied over a large area, then the pressure developed.

Now have you ever wondered, why tools which are made to cut, chop, trim or pierce always have sharp edges? Or why heavy vehicles always have fat tyres? This is only due to pressure, which refers to the physical force per unit area.

The difference between force and pressure is summarized in the table given below:

 

WHY SMALLER WHEELS ARE USED IN SCOOTERS ?? KNOW HERE !!

Scooters are often used as a way to get around that’s both good on fuel as well as easy on the pocket. They generally weight less than motorcycles but are also slower. However, the type of wheels that you have on a scooter, whether they’re big or small, can make a lot of difference.

More common these days are that scooters are getting 12” and 13” inch wheels. So what is the advantage? 

Using small tyres in a scooter provides additional space between the seat and tyre, where you can mount the engine and transmission. Because of small size only, this space is available. Hence the scooter is compact, has under seat storage and space at front for keeping your legs and goods.

Also, small wheels and tyres helps in incredibly quick steering. But again it leads to poor handling at higher speed.

So,the main reason for giving smaller wheels to scooters is to reduce the weight of the vehicle, increase the space requirement, and to offer a great manuvarity in city traffic.When it comes to poor handling at higher speed, scooters are not designed to run at high speed that is why smaller wheels are provided.

WHY TRACTORS HAVE 2 BRAKE PEDALS? CHECK OUT HERE !!

Tractors are equipped with 2 brake pedals. There is a specific reason behind this. 

In tractors, each pedal controls one side of the tractors rear-drive wheel.y using one pedal this allows the tractor to lock that wheel on the spot forcing the other rear-drive wheel to swing in an arch around the locked wheel.

During filed operations, a tractor should take a turn as minimum radius as possible. So, two brakes are provided in tractor because by pressing left side brake, left wheel stops rotating, the right wheel rotates around left wheel and vice-versa. Thus, turning radius decreases. A simple mechanism always provided in the tractor to lock both brakes for on-road operations to avoid accidents. Below figure shows two brakes with locking mechanism. B and C are two brakes for each wheel, while A is locking mechanism.