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  • Mehra Saab

    In a single cylinder in si engines the power stroke starts in which degree rotation of crankshaft
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  • DrD  »  MayankBambal

      "I think the human race made a big mistake at the beginning of the industrial revolution, we leaped for the mechanical things, people need the use of their hands to feel creative." - Andre Norton"
    Feel free to reject all the products of the industrial revolution in your own life. Do not ride in automobiles, do not use electricity, do not use any machine of any type, and of goodness sakes, do not use a computer. Just go live in a cave or a mud hut, (no lumber, nails, screws, or glue allowed), burn only wood or cow chips, and do not eat anything cultivated or processed by machinery. This would be a good start, and then I'm sure you will find ways to improve on this beginning. Enjoy your life!!!
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  • MayankBambal

    "I think the human race made a big mistake at the beginning of the industrial revolution, we leaped for the mechanical things, people need the use of their hands to feel creative." - Andre Norton
    · 0 replies
  • neelk

    difference between square thread and v-thread in terms of strength
    · 0 replies

Image Comments

  • Shown here is the battery ignition system.there are others like magneto ignition systems and various other ignition methods.the battery is connected to primary winding via ignition switch which when turned on completes the there are breaker points in the circuit that is operated using a cam connected to the engine. This essentially determines the ignition timing.when the breaker points come into contact the current flows into the primary winding inducing a magnetic field in it.Now when the breaker points open the current flows into the capacitor. Now the primary winding induces a current in the wire which flows in same direction of primary current. Hence this helps in charging capacitor to a higher voltage than battery .now current starts flowing from capacitor and not the battery. This reverses the magnetic field in the primary winding.the sudden reversal induces a high voltage in secondary winding which then carries current to distributor.the distributor decides the time at which each spark plug must activate
  • I feel that electric cars are the  next revolution that is going to happen in automotive industry.this is because wide sources of energy is available that can be converted to electricity efficiently.Moreover the rapid improvement in battery technology with promotion of nano cell technology will the pave the path for these vehicles.Emissions will hence decrease when multiple renewable energy sources are used. Second, electric cars make less noise and are going to be more economical in future.they have fewer moving parts thus avoiding wastage of energy and leading to high efficiency.
    The electric cars don't require any power train units like gearbox thus enabling a single pedal drive.This will make the driving of a car simple.Just imagine a car with just one pedal and no gears to is phenomenal
  • What is the Length of the crankshaft????
  • The flywheel does not store force; it stores kinetic energy. This is the source of energy to keep the crank turning during the compression strokes when the cylinder pressure is retarding crank rotation.
    Imagine that you start a small, single cylinder engine, such as a lawnmower engine, With the lawnmower blade in place, the engine runs just fine, but in many cases if you remove the blade, the engine will not run at idle speed. Why? Because the blade acts as a part of the flywheel, storing energy for the compression stroke. If you remove the blade, there may not be enough energy stored to complete the compression stroke.
  • Flywheel is storing device because during ignition strokes its stored a power and due to suction stroke there is no power generated in engine so these type energy for rotation is provided by the flywheel.....

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    1. Many research and development have been conducted  to meet society needs for safer vehicles. Particularly, occupant protection system such as air bags, developed and introduced in order to reduce occupant injuries in crashes, are currently installed in most vehicles making significant contribution to safety.


      Meanwhile, many studies have been made into the development of active safety technologies that help to avoid crash accidents. Unfortunately the current situation is that the active safety technologies are not sufficient spread. Adaptive cruise control has been commercialized since 1995, but its primary use has not been convincing.Some audible warning system  are also being offered, but have not yet reached widespread use.


      Toyota Motors corporation has explored the possibility of producing an active safety system employing Intelligent Transport System (ITS) technologies,through participation in the Advanced Safety Vehicle (ASV) projects started in 1991 and led by ministry of land , infrastructure and transport.


      Critical basis ITS technologies for application to ASV includes a surround monitoring sensor and an obstacle determination algorithm which combines information from the surround monitoring sensor with other information to identify obstacles with which the vehicle is likely to actually crash.


      The sensors and crash determination algorithm for an active safety system should be capable of reliably determining that  a crash will not occur in non-crash situation. Advanced technologies are required to make these predictions and judgments correctly while also taking into account the driver's operation and behavior and this has hampered widespread of active safety systems.


      Pre-crash safety system has been developed which operates only when it is judged that a crash cannot be avoided by most drivers under normal driving conditions. Determining unavoidable crashes is restricted to a short time period immediately before the crash so as to improve the reliability of the judgement. In addition the pre-crash system is made with a mechanism and system that will not place the driver and the running vehicle in an unsafe condition even if the system is operated unnecessarily. As a result the world's first commercial system has been achieved.








    2.     Mechanics Corner
          A Journal of Applied Mechanics and Mathematics by DrD
          © Machinery Dynamics Research, 2017

      Last Post
      Time to Hang It Up

      This will be the final post of Mechanics Corner here on Mechanical Engineering Forums. It has run almost exactly two years, and there have been ups and downs along the way. In this final post, I want to reflect a bit on my original goals for the blog, and also on what has actually happened.

      When our host first proposed to me that I might write a blog for ME Forums, I was excited about it. About half of my career had been spent in engineering education, and I always loved working with students. It seemed like a way to get back to something that I had long enjoyed, and so I accepted his suggestion.

      A long time ago, back when I was about 14 or 15 years old, in Junior High School, my shop teacher mentioned, in an off-hand way in class, that various curves could be described mathematically. I’d never heard that before, but I thought immediately, “This has interesting possibilities.” Moving ahead a few years, I discovered that I wanted to study and build my career around was the area known as Applied Mechanics, although it was a time before I first heard that term. In my freshman physics class, I discovered the laws of motion, and thought to myself, “This is great stuff! I can use math to describe how things move!” All of that happened back in the 1950s, and I’m still doing the same thing today (some might say I am in a rut!).

      As a teacher, I taught mostly undergraduate engineering courses, although I taught my share of graduate courses as well. It was the undergraduate courses that I liked most, because I firmly believe that the economy of a nation is strongly dependent on the quality of the baccalaureate level engineers produced in that nation. Engineers with graduate degrees are valuable as well, but the vast majority of the national engineering workload falls to BS level engineers.    Thus, I envisioned Mechanics Corner as a sort of continuation of the several undergraduate courses I most enjoyed teaching — kinematics, dynamics of machines, vibrations, and mechanics of materials. For the most part, I have stuck to the plan, so that most of the technical posts I have made have dealt with problems that I considered suitable for undergraduate engineering students, say perhaps, junior level. I have posted a few topics from my industrial experience, but those have been situations that baccalaureate level engineers would be expected to handle.

      Now I knew it would not be exactly like continuing to teach my classes. In particular, you would not have any homework or tests, and I would not have any grading to do – a win-win, or so I thought. I did hope, that even with no assigned homework, readers would take an interest in the problems discussed, even to the point of working through the details for themselves (I was terribly naive, apparently!). I knew from my own experience that the only way I ever really learned a new idea was to get in and work with it, work some problems, make some numbers, plot some curves, until I really understood what it was all about. I’ll venture to say that nobody ever learned any technical material simply by reading only.

      In actual fact, in the early days, I had one or two folks say that they would in fact work through the problems, so I was encouraged. What I was not prepared for, however, was the fact that the vast majority never seemed to even read very carefully, much less work through the problems! The questions that have come, and there have been a few, have largely been about matters totally unrelated to the posts. The most common question has been, “Suggest a topic for my final project,” which relates to not a single post. Needless to say, that aspect of my vision was totally unfulfilled.

      But there is another side. I ventured to write a few “philosophical” articles, items dealing with academic integrity and cheating, with how to ask for help, with how to write a report or a paper, and various other matters. I really thought all of this would be considered obvious and trivial, so I was completely unprepared for the excitement that some of these articles generated. There were, in some cases, many, many comments, and people seemed to really be interested. I’m left to wonder: why? Are these ideas foreign to the culture of India and SE Asia? Are these things not all taught at home and in the public schools? I don’t know, but there was a lot of interest in these matters.

      But Mechanics Corner was intended to be primarily a technical blog, and there, it just did not excite the interest of the readership. As time passed, there was less and less interest. First, the comments dropped off to just about zero, and later, there were fewer and fewer who even bothered to “like” the articles. Finally, the number of reads has dropped to almost nothing (there may be no one left to read this final note). Well, there could hardly be any more clear indication that it is time to stop.

      I asked for opinions about this from some of the administrators, and was told that the blog was just over the heads of the readership. That makes me sad; that was never the intent. If it is true, I do not see how engineering has a very bright future among this readership. Even so, I wish all of you the best for your careers. I hope that you are able to find rewarding and beneficial work in which you will be happy and make a real contribution to your societies.

      To use an old cowboy metaphor perhaps familiar to many of you from Bollywood, “It is time to hang up the bridle and saddle, and say, ‘Adios’ (Adios is literally, “to God”).


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    3. Hydraulic cylinders haven’t really changed a lot over the years. The manufacturing processes are much more streamlined and the tolerances are much tighter, but for the most part cylinders are still the hard working push/pull tools they have always been. These things have literally shaped the world around us. Anything that gets lifted, pushed, hauled, dumped, dug, crushed, drilled or graded has gotten that way by some truck, crane, dozer or tractor using a hydraulic cylinder. But how do hydraulic cylinders work?
      The amazing amount of force a cylinder exerts is due to the simple mechanical principle of pressure exerted on the surface area of the
      piston . Simply put, the larger the diameter of the cylinder, the more it will lift. 

      Cylinder cutaway.png


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