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Help on a knuckel crane idea

  1. May 21, 2012 #1
    I need to figure the load on a knuckel boom for a idea I have . it is like the ones that are located on the frames of trucks right behind the cab to be able to unload the truck or trailer. This will be of a smaller stature. The arm would pivot in the middle and rotate. and use hydralic cylinders to move and lift the load. closer to a robot. I am looking and 5" X1/4" sq tubing and I need help on how to figure the max load on the tubeing to see it the application will even work. where it will be located I am restricted by weight and room and the need for an assy on the end to perform a function I have a pdf sketch which is pretty bad View attachment Full page photo.pdf the length of the tubing the longest is 78" shorter one is 60" the angle lines are the points the hydralic cylinders attach roughly like I said it is a rough sketch
    Last edited: May 21, 2012
  2. jcsd
  3. May 21, 2012 #2
    Designing a crane requires a large body of engineering knowledge and skills.

    And that is just a starting point.

    After that, it also requires a detailed understanding of applicable standards and codes. Certain laws in your area may also apply.

    The reason for all these standards, codes, and laws is that lots of folks thought they could home build a crane and ended up killing people. It really requires not only a professional engineer, but one who has a detailed understanding of all the requirements and how to meet them.

    All this is extremely expensive. That is the reason it is so much cheaper to just go buy a crane than to build one yourself.
  4. May 21, 2012 #3
    Check out Autodesk Force effect. Pretty sweet for a starting point if you have an ipad or iphone.

    But I agree with Pkruse. Get your idea going, then hire an engineer to polish it up.
    Last edited by a moderator: Sep 25, 2014
  5. May 22, 2012 #4
    I know what you are saying I am familar with the codes and the factors of building a crane. It is close to one I am just looking for info to see if it will work at all like I said there is hieght and wieght restrictions I am looking at. so I just want to know the ball park number if I can't come close with this it will not work. If I can then it will require futher engineering to really know. This is only 1 of 3 options I am looking at. this one requires the least space to perform its funtion as compared to the other 2 If i can not safly build it to not break I don't build it no matter what it is Just researhing options here
  6. May 22, 2012 #5
    But I agree with Pkruse. Get your idea going, then hire an engineer to polish it up.[/QUOTE]

    That is better advice than I gave.

    Post a sketch and a free body diagram of what you have in mind and perhaps we can start an interesting discussion.

    The normal way to start this is to define how much load you need to lift, at what radius, and to what height. Selecting material comes much later.
  7. Jun 8, 2012 #6
    Like I said it was researching an option which I am pretty sure will not work . There are going to be stability problems that I think can't beovercome due to it's placement so it is a dead issue. Was trying to cover all the bases before jumping in to fullblown engineering to insure the concept had a chance and to not waste time and money. I do thank eveyone for there help and input
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