Engineering help needed.

Mac5005

Mac5005

Well-Known Member
Joined
Oct 19, 2005
Location
Rocky Mount
I need to build a gantry,

It will not have wheels or casters,

The vertical uprights will be welded to the horizontal feel with gussets.

The horizontal “beam” will bolt to the uprights, also with bolted on gussets.

Plan to run a tube truss over the top if necessary.

Single point load in the center. Chain hoist from the single point.

I need to be able to pick up safely 2 ton, most likely used for picking up half that.

Roughly 8 feet tall, 9 feet wide. Minimum span between uprights is 96”. Ideally 103” clear inside uprights.

Gussets can be inside the “span”.

For lifting an engine out, picking heavy things up off a trailer, pull the trailer out.

I need help with engineering the size of the steel, and the loads seen.

I’ve googled a ton, not much definitive that I can find as far as load v span and size of steel. Most places are saying “copy someone who already makes one”

Initial thought is 4 x 4 x .250” wall square tubing for feet and uprights, and then some type of w beam or square tube for top span.

I really don’t care about analyzing the deflection and stress, just want to be able to pick up heavy stuff safely.

Thanks in advance.

Generic picture for attention.

7f5c23e56f48a83a39af2cd89c4f3ab2.jpeg
 
So it’s not going to be permanently fixed to the ground? I can check what my steel charts say tomorrow.


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Are you set on single uprights or willing to entertain triangular legs? Theres no reason to make the legs the same size as the crossbar unless you just have extra material.

I have a spreadsheet from when I designed my loft, but it's not on this computer. I'll try to remember to look at it when I get home, but feel free to PM me a reminder.
 
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That isn't really a lot of weight, I think a better question would be " I have this beam and some 2" square tube laying around, will it support 4klb?" Especially seeing as 8" web or larger structural beam isn't all that cheap. And if you don't plan on using a trolley it can really be any shape steel.
 
I think 4x4x.250 may be a touch of overkill for the uprights but if you have it then roll on. If not .188 would probably be fine and save almost 50 lbs over .250 wall. The I beam I use 4x8x18.4# as that's what a 4 ton crane of that width uses. I'd definitely run a gusset for the the upright to the feet
 
This is a way back, burner for me but...
HF = LOL, YMMV
I looked at materials that i could get locally, 2x4 vs 4x4
and weather 'C' channel both single faced or double up would be sufficient vs beam 'I' or
weather a 2x4 or a 2x4x2 (2x8) would meet my needs... [3/16",1/4"]
and how i braced them, vs the legs, 1 or 2 under each side,
I also look at how heavy are the pieces, ie. could one person assemble it or would i need the engine crane (2 ton) or 2 persons....
I looked this model of cranes for different reasons.
[two legs per side, (triangle) up to a beam, ]
some samples pic of cranes [they were on a different computer]
..
oh look for 'beambuddy' its an old app, vintage win3.11 but it works :)
I may have it on my old CDs of backups.
.
Beams - Supported at Both Ends - Continuous and Point Loads (math, ugg)
online calc, Beam Calculator - Free Online Shear and Moment Diagrams
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b-3ton-unit-01.JPG

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nice-2x4tube-100_0350.jpg

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intestion-IMG_5771.jpg
 

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WTH...Why has no one consulted the ancient writings on this?!?!


John Fuller said:
this is where we get into the Hypathetical mathematics of metals and science
Click to expand...
 
braxton357 said:
That isn't really a lot of weight, I think a better question would be " I have this beam and some 2" square tube laying around, will it support 4klb?" Especially seeing as 8" web or larger structural beam isn't all that cheap. And if you don't plan on using a trolley it can really be any shape steel.
Click to expand...

I’ll be buying whatever I build it with. Nothing large laying around, or it would be together and “in service testing”.

The shape of the steel matters none to me.

Don’t really want to have fully triangulated legs, definite triangulated large gussets at bottom of uprights to the feet. This is mainly for transportation purposes. I do want to be able to unbolt the top horizontal span to be able to transport and set up anywhere if needed.

That’s the main reason against fully triangulated legs/uprights.

I just hope this doesn’t turn into yatfr....
 
I’d do something similar to what @yager posted but with bolted and pinned connections. That way you get the strength of the triangulated frame but some form of mobility at the same time.
 
You can do simple (non-triangulated) legs, but you'll need bigger material to get the stiffness and resistance to bending/buckling. Triangles go a long way towards keeping the crossbeam and legs from twisting as a unit, and you won't have them.. Compressive strength for legs is easy, but keeping things stable with 8-foot-long unbraced straight legs and a 2-ton load is slightly more involved.
 
Something like this.

76067589afa6727d3723854e5f97fe15.jpg


Then bolt on 24”(guessing) “gussets” (pieces of tubing with flanges on ends) at a angle from the end of each “foot” up to the vertical column somewhere.

Similar “gussets” to triangulate the horizontal beam to the vertical columns.

Ideally upper and lower “gussets” all interchangeable.
 
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SO you want Adam to be your mobile pit guy?

I mean if you have Doc's money, no problem!
 
Tried to use some of the online beam calculators.

4 x 4 x 3/16 , a500 steel sq tube.

102” span, center point load, 4 kips? I googled that and understand it as 4 kips is 4000 lbs.

Not really sure how to interpret the results, but I’m thinking that’s not large enough and I think it said it had too much deflection at 1.7”, but I’m not positive I’m inputting the info correctly or interpreting the results correctly either.

I’d really like to just find a chart of loads vs structurals vs spans
 
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