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Gantry Crane

Posted: Tue Oct 16, 2018 10:08 pm
by Glenn Brooks
Finally getting around to building a small gantry crane for the shop and rail yard. I’ve been sourcing materials on and off since last year and now have most of the components.

Crane dimensions will be just over 8’ wide x 10’ tall, with 72” horizontal beams that the casters mount to. Also “3x3” square tubing for the uprights, and heavy gauge 2.5” x 2.5” tubing for a short vertical extension. It fits nicely inside the square tuning. My working load will usually be 1500# or less, and Max point loading probably never exceed 2000 pounds. The frame will be a modified T frame style with heavy gauge support beams welded to 6x6 I beams on the bottom and stout 6 bolt connection plates welded to the top of the vertical support posts. The cross beam on top will be bolted to the verticals for disassembly, as needed.

Primary use will be loading and unloading my locomotives onto work benches for winter maintenance, and the occasional lifting and repositioning of a lathe or mill.

One big question. which beam should I use for the overhead? I have two available. One is 5”h x 3”w x 9’ beam that previously saw duty in a front end alignment machine. I do not know it’s structural rating.

The other is 6”x6” high strength structural beam, rate at 65000#. Just about twice the rating of an A36 beam. For this light weight crane the 6x6 seems like overkill. If I don’t use it, I could save it and build a 2 ton gantry at a latter date.

Any engineers out there might be able to say if the 5x3 would be suitable for a 2000# point load? I tried running a a couple of on line calculators, but got stumped on some of the input criteria.

Not much to look at, but so far have cut and drilled most of the vertical supports and support beams. As mentioned the bottom of the angle supports in the picture will get welded to horizontal I beams.
544F18BA-F8CE-4C02-A0F9-73F5CA6B2621.jpeg
Cutting the structural support members with the old power hack saw - awhomp, awhomp, awhomp, awhomp - music to my ears!
C82E05BB-9001-4AD6-A3C7-4C146F043D69.jpeg
Thanks

Glenn

Re: Gantry Crane

Posted: Wed Oct 17, 2018 10:25 am
by rkcarguy
What's the thickness of the flanges and web on the 5" beam?
I'm showing a 5" beam in the book that is 10# per foot, and 3" wide. Web should be .210".
I just had our engineer do a napkin calc on a pair of W6x12's @ 8' long for "something" and it was good for 5K #'s in the center.
I would say if you have a 5x10x.210 beam there you should be good for around 1800-2000#'s, but this is my opinion only.

Re: Gantry Crane

Posted: Wed Oct 17, 2018 11:28 am
by 10KPete
I was going to figure out the SWL but I could not find a dimension for the span of the beam. You mentioned you had a beam 9 feet long but I don't know if that is your intended span?

I do need to know the dimensions of the beam and if it's a wide flange or standard beam

Pete

Re: Gantry Crane

Posted: Wed Oct 17, 2018 12:13 pm
by rkcarguy
There is no 5" wide flange, only the standard beam 5"x10#, at least in my books here at work. I bet that is what it is, the 3" width matches also.

Re: Gantry Crane

Posted: Wed Oct 17, 2018 12:39 pm
by Glenn Brooks
Yep, 5” height, the flange is 3” wide overall

Re: Gantry Crane

Posted: Wed Oct 17, 2018 12:42 pm
by Glenn Brooks
Hi Pete, the dimensions are 5” h x 3” w. Span could be 9’ but I only need 7’ if the span makes a difference.

Thanks ,

Glenn

Re: Gantry Crane

Posted: Wed Oct 17, 2018 1:30 pm
by 10KPete
Glenn Brooks wrote: Wed Oct 17, 2018 12:42 pm Hi Pete, the dimensions are 5” h x 3” w. Span could be 9’ but I only need 7’ if the span makes a difference.

Thanks ,

Glenn
Thanks, I'll get back this after noon.'

Pete

Re: Gantry Crane

Posted: Wed Oct 17, 2018 3:29 pm
by 10KPete
OK, I get 2862 lbs. max SWL with load in middle of beam.

1795 A D /9 A= area of beam=2.87 sq. in. D= depth of beam= 5"

25758/9 = 2862 lbs. That should do it for you!

This beam has a .210" thick web.

It's been a while since I did this calc. so I had to get out the book and refresh myself. :roll:

Pete

Re: Gantry Crane

Posted: Wed Oct 17, 2018 5:33 pm
by Glenn Brooks
Thanks Pete. This is very reassuring. I’ll go with the 5” beam and save the big boy for latter.

Actually if I interpret your numbers correctly if I went to 8 foot span that I would a bit over 3000 pound max load. Which is even better. Nice safety factor.

Glenn

Re: Gantry Crane

Posted: Thu Oct 18, 2018 10:37 am
by rkcarguy
Nice:)
So Pete are you the man to ask for member size vs. span loading?

Glenn, trucks and trailers can be up to 102" wide, unless you have other concerns I'd use the whole 9' beam. You never know what you'll end up unloading with it and it would be a shame to have it not be wide enough by an inch or two.

Re: Gantry Crane

Posted: Thu Oct 18, 2018 12:49 pm
by Glenn Brooks
Ryan, Hey thanks! Actually I woke up in the middle of the night last night, wondering if 7’ was to narrow for a full size PU, which I might be in the market for this winter.

Glenn

Re: Gantry Crane

Posted: Thu Oct 18, 2018 1:42 pm
by rkcarguy
My boss at my prior workplace had one at his house/barn/shop. His son used it for a frame off restoration on a car, he'd back his boat in under it and use it to remove the outboards and trolling motors and work on them, and we received several pieces of equipment on Semi-trucks and had them back in under it.
My F350 is 8'-6" wide from mirror to mirror, and would be more if I had the wider towing mirrors.