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Mechanical Engineering


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Everything posted by DrD

  1. Mechanics Corner A Journal of Mechanics & Mathematics by Dr.D, #54 B Mine Hoist Problem, Hint #2 Introduction The original Mine Hoist Problem was posted 25 August 2020, and the first Hint was given on 8 September. We are now almost one month into this problem, and thus far no one has sent me even so much as a question other than Tim Dennison's request for a video. I'm not quite sure how to understand this. I see two basic possibilities: 1.The problem is so dull and uninteresting that no one could possibly
  2. Sounds like you are narrowing your question to friction losses in the rack and pinion only, exclusive of the guide mechanism. This depends upon the details of the tooth design (arc of approach/arc of recess) and upon the lubrication. If done well, these will probably be small relative to the friction in the guides. DrD
  3. Friction will be a major problem, and it all depends upon how you guide the moving member. What do you plan to use as a guide? There is simple sliding contact, various ball or roller guides, etc. A lot depends upon your budget, but the better the guide quality, the easier your system will work. DrD
  4. It appears that only a very few folks are even attempting these problems, but it also appears that no one has sent me a solution. For that reason, a small hint seems to be in order. Hint: Turn the picture upside down. For most of us, it is conceptually easier to think about the problem if the X-axis goes to the right and the Y-axis is upward. Of course, if you do this, you must recall that gravity then acts up, not down. Don't be shy; give it a try!!
  5. Was there supposed to be a question or a comment hidden in there? DrD
  6. You question is not very specific, and after three tries, no one has answered you. Please be more specific. DrD
  7. Do some internet searches on impact absorption, collision absorption, energy dissipation in metal foams. DrD
  8. DrD

    Mine Hoist Problem, #54

    And just how would I do that, Timothy? 1)Do you want a video of the system (which only exists on paper at this time) and is therefore impossible to do? or 2) Do you want a video of me talking about the problem? What would be the point of that? the written words "hold still" and can be read and re-read as many times as necessary. What do you have in mind, Timothy? DrD
  9. DrD

    Mine Hoist Problem, #54

    Well, here we are on 31 August with 151 views (presumable this first page only), and only 4 downloads (necessary to really see what the problem is). That is just slightly more than 2.5% of people bothering to actually look at the problem. How could this group be more lacking in curiosity? DrD
  10. Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, # 54 © 25 August, 2020 Mine Hoist Problem Introduction As we saw in the previous problem (A Hoisting Problem for Engineers, #53), hoisting problems can be fun. This has gotten me to thinking about some other hoist related problems, and here I present three variations on a new problem. The problem is much the same in all three cases, with only small changes in the geometry. These changes do appear to significantly modify the system resp
  11. James , You have identified in your own statement why no one is interested. You said, "one way is to do my project to make speed and torque increase that will violate a law of engineering and open many new doors for millions for all of history." No doubt many folks would like to open new doors and make history, but when you talk about violating the laws of engineering (physics), you are asking for the impossible. The laws of physics are not man-made laws that can easily be replaced with other man-made laws. Rather the laws of physics are the distillation of observed truth in the natu
    I was unable to open the file, so I cannot comment on the content.
  12. Dear Bruce, As you well know, that's how things go at times. Better luck next time! DrD
  13. Perhaps you might start on a research problem, and when you think you have something publishable, look for a "sponsor" to co-author with you? This "sponsor" might be a faculty member or a working engineer, but someone who already has some publications and knows the process. As I read your original request, you are asking another person to identify a promising research problem and then let you do a part of the work to get your name on the paper. The big problem with that, as I see it, is the very limited value of your contribution. Suppose for example that I propose a problem that I'm
  14. You say that you are a ME student working on a bachelor's degree. If you are already in college, why are you seeking a scholarship? Are you trying to change universities? DrD
  15. Everything JAG said is correct. Further, you have not allowed for wheel slippage, varying load weight, wet or slippery rails, etc. Not a great idea. DrD
  16. So, are you looking to get your name on a published paper? Is that the point here? It is pretty rare for undergraduates to publish papers, and I don't think I've ever seen such required for university admission. Perhaps you might tell us more about what you have in mind here. DrD
  17. Why not just do your own analysis and write your own code? This is cheap, gives you complete control, and let's you analyze any device you can understand. Take a look at my book, Mechanics of Machines, Ver. 2.1, available here at ME Forum without cost, for the way to do these things. DrD
  18. Mechanics Corner, #53 A Journal of Applied Mechanics and Mathematics by DrD A Hoisting Problem for Engineers A Learning Experience in Machine Design There is a document available on the Internet at several locations with the title 2.003 Problem Archive by MIT Professor David Trumper, Last Updated April 19, 2005. It is a collection of engineering problems, some with Matlab solutions. One thing that particularly caught my eye is 4.4 Hoisting Problem for Enginee
  19. Still cannot open any of your pdf files. Your claim to increase both speed and torque implies that you are increasing total power output = speed x torque. Where is the extra energy coming from? DrD
  20. Is there a guide or surface supporting the bar AB? This is a poorly stated question. DrD
  21. I cannot open your picture files. What is the .rar format? A PDF would be a lot better idea. DrD
  22. Is any information given about friction with the wall at the right side? DrD
  23. Timothy, it seems to me that your idea violates the essential idea of the railroad track, namely to have a flanged wheel to assure that it stays on the tract. The flange is only there as a backup; the wheel is actually conical and will tend to stay centered with no flange, providing there is no disturbance. It sounds like you want the front truck to reach sideways to an adjoining track and then leap over. Woul all the trailing wheels be required to follow the same sidewise leap? DrD
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