## Differential – A hidden wonder of automobile

While driving a car have you ever wondered how does the engine drive the wheels? How only one engine drives all the wheels of the car? How does the system manage to transmit the power to the wheels? Let’s have a brief look under the hood and understand a very important concept of an automobile, that is “DIFFERENTIAL”.

Engineering of an automobile is a very vast subject. On an average, about 30,000 parts are used for the manufacturing of a single car. Hence to study automobile, the whole subject is divided into 6 major systems: Chassis, Engine, Transmission, Steering, Braking, Suspension. Differential is a part of Transmission system.

Main aim of transmission, as the name suggests is to transmit the power produced by the engine to the wheels so that the vehicle moves. A transmission in general consists of an input shaft, an output shaft, gears and a differential. The input shaft gets power directly from the engine, which is manipulated according to our needs by gears and finally the output shaft carries the final power.

The differential then comes into action. The differential transmits the the power produced by the output shaft sideways.

As shown in the picture, the differential is situated between the two wheels and it transfers the motion of transmission shaft/output shaft to the rotary motion of the wheels. The transmission shaft rotates the driving pinion, which in turn drives the ring gear (crown wheel). This ring gear is attached to a small sun gear/side gear. This side gear is meshed via the differential pinion gear(planet gear). Both the side gears are connected to the half shafts(axle) connected to the wheels.

Why to use the side gears pinion assembly when we can directly connect the ring gear? Also this work seems to be easy. But this is not all a differential does. A differential is designed for a far more greater purpose.

Whenever an automobile turns, there is a difference in the speeds of the inner and the outer wheels.

As you can see, the outer wheel of the automobile has to travel a larger distance than the inner wheel in the same amount of time while turning. Hence the speed of outer wheel is more. This can be achieved by unequal and proportionate distribution of power to the wheels. The outer wheel needs more power than the inner wheel and this unequal but proportionate distribution of power is done by the differential.

The inner half shaft in the figure indicated the part of the shaft connected to the inner wheel while the outer half shaft to the outer wheel. Both the shaft move in anticlockwise direction when moving on a straight road. Hence the power is distributed equally and both the side gears hence the shaft rotate at same speed.

While turning, both shafts do rotate in the same direction. The outer wheel has to move at higher speed than the inner wheel. This produces a couple moment at the differential pinion. This force drives the pinion gear to rotate. Due to this rotation, the side gear of the outer shaft rotates at a rate higher than the inner wheel. The side gear of outer shaft gets an additive rpm while the inner shaft gets a subtractive rpm. Hence due to this production of different speeds in both the wheels, the system is called a differential.

Hence for different turns, different torque is applied on the differential pinion and according powers are provided to the wheels. This was the basic information about differential and transmission. Further the differentials are classified into different types differentials like open differential, locking differential, limited slip differential, electronically controlled limited slip differential, torque vectoring differential etc. But for basic understanding of the differential, this much knowledge is enough.

## Roadmap for Computer Engineering Students

Hey, Guys!

Some of you might’ve got an internship or training somewhere while some of you haven’t. Internship or not, vacations are a great time to learn. There’s a plethora of stuff that you can do. From developing websites, smart phone apps and games to studying a subject that you are really interested in and maybe get started with some research work (though it is easier said than done).

In the end of the third year, you all will be looking for a serious internship and in the final year, a job.  Your resume is the first thing that will help you get noticed by recruiters. Your resume should reflect what your ambitions are and what you have done to achieve them.

Before you start building your resume, ask yourself what is that you want to do when you get out of college. Is it higher studies (for MBA or M.Tech. or MS…) and research that you want to pursue or do you want to join an organization and write code for them, or maybe you aspire to become an entrepreneur, maybe become a freelancer or  some other plan that you have for yourself.   If you are in 2nd year, NOW is the time to start thinking and drawing out a plan; if you are in the 1st year, a head start is always great. I don’t pretend to be an expert on this, even I am trying to find my path; I’ll just tell you what I know and hope that it’ll help you.

First of all, understand that the goal of studying, participating in competitions or developing software is not (or rather SHOULD not be) to make a good resume. A resume is just a by-product of the actions that you take to achieve your ambition. You want to achieve something and for that, you study stuff, you do stuff, you develop stuff, and that stuff is what goes on your resume. Trust me if you think of it this way, it’ll be much more fun.

Many of you took Computer Engineering by choice and many of you got it because you didn’t get your first choice. The fact is that you are now in a field that has innumerable possibilities of innovation and vast space for new stuff. All you need is a laptop and you can make the next big thing! Some other branches of engineering have the constraint of availability of resources. They have to wait in turn to get some time on equipment. They might not even have some equipment in their institute. But we all have the equipment in our rooms!

Okay, so let’s get to the point.

If you want to pursue higher studies in Computer Science abroad, then your goal should be to gain research experience. Because that’s what the universities see. They want to know if you really are into something or are applying only because you have nothing else to do.

Research might sound like a big word. Because it is a big word. It requires lots of hard work before you can start saying “Research”. But to get started, identify your area of interest and talk to the professors in our department. They’ll tell you what to read. The list of research areas of all faculties is given on the SVNIT website. Use Google to find the currently active areas of research. Join courses on edx.org and coursera.org to understand the subject you are interested in.  Even if you can’t decide your area of interest, just go and talk to a faculty and they’ll help you out.

For those who want to do Masters in India, you’ll have to give GATE exam. Go online, check out its syllabus. It’s mostly what we have in our curriculum. So just make sure that you understand each topic well.

If you want to join an organization and code for them, then START CODING! Many organizations ask questions like those in competitive programming in their hiring process. So keeping your skills sharp will be advantageous. Not only that, good companies also require experience. Eg. they may ask for experience in web development or system programming or some other field. Prove yourself worthy of hire by developing some useful software.

Contribute to Open Source. Google Summer of Code is a very popular internship related to OSS. If you are aiming at that, START NOW. GSoC doesn’t only need apply. It’s not so easy to get it. Google “how to prepare for GSoC” and start now. There’s nothing called early start.

An organization will be very happy with you if you show them that you know stuff and they won’t have to spend much time training you. Even if what you have developed is not related to what a company does, they’ll still acknowledge that you made something and you know how to develop stuff.

A few possibilities related to development are Android or iPhone app development, Web browser extensions development, Web designing, Web development, Windows Desktop app development and Java Applet development.

There’s a lot to learn out there. A LOT we don’t know. Online learning website like edx.org and coursera.org are invaluable. Needless to say, there are a lot of worthy courses. Join a course, be regular. Just don’t be stagnant. College is the time when you have plenty of time to learn stuff.

Whatever doubts you have, we at CEV are always there to help you out. You just need to reach out to us or seniors in your department.

I feel that, as Computer Engineers, we have the power to make anything we want. Whatever is going on in your head, you can materialize it. Make it right and people will use it and appreciate it. People will use something that was once just a figment of your imagination and you materialized it out of nowhere.  This is what motivates me 🙂

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