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Basic Engineering design of a small lift need help

  1. Jul 25, 2009 #1

    I need a little help on figuring out what size square tubing and thickness I need to make a basic lift for taking the body of a car on and off of a frame. I have included a small drawing of what I am trying to build.

    I am going to need to support a maximum of 1000 pounds. All off the force will be vertical with no side loading.

    The two vertical post will be bolted to the floor and attached to the ceiling. The distance between posts will be 7 feet. The load will be lifted directly in the middle of the horizontal tube.

    Can you please help with what size square (or rectangle) tubing and thickness I need for the verticals and the horizontal to support this weight? Would it be better to use rectangular tubing for the horizontal?

    I understand moments of inertia, Youngs modulus have to be figured in just having a little trouble.

    Thank you



  2. jcsd
  3. Jul 25, 2009 #2


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    So you have an applied midspan load of P = 4450 N. For the horizontal member, using a yield factor of safety of FSy = 1.70, it currently appears a 63 x 63 x 4.763 mm square steel tube, or a 76 x 51 x 4.763 mm rectangular steel tube, would work. Comparing these two options, there is no significant advantage of one versus the other. I haven't looked into the columns, so far.

    Is your value for P the actual, static weight of the object to be lifted, meaning it can have a maximum mass of 454 kg? If so, can this mass be suddenly applied, or dropped, or stuck and then pop free?
  4. Jul 26, 2009 #3
    Thank you for the reply on size for the horizontal.

    There where be no force or acceleration, deacceleration of the load.

    I appreciate all the help


  5. Jul 26, 2009 #4


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    Using an ultimate factor of safety of FSu = 2.0, it currently appears a 51 x 51 x 4.763 mm square steel tube would work for the upright members (columns).
  6. Jul 27, 2009 #5


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    There are differences between square and round bars. The round ones flex more while square flexes only in some planes.

    Use square for horizontal ( with the sides vertical or horizontal to ground) and round for vertical.
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