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hp246
02-11-2010, 12:00 PM
I would like to build a Gantry type lift. I figure about 9 foot high for my purposes. is there a formula for the base to determine length for stability? I would like to mount the whole thing on wheels to be able to move it about the shop. I figure I will be lifting about 600 pounds. The primary purpose will be to lift the bed off a pickup truck, and suspend it over the frame.

transit
02-11-2010, 12:28 PM
By the time you get all the materials you can buy one and just assemble it.

http://www.northerntool.com/webapp/wcs/stores/servlet/NTESearch?storeId=6970&N=0&Ntk=All&Ntt=gantry+cranes&Nty=1&D=gantry+cranes&Ntx=mode+matchallpartial&Dx=mode+matchallpartial

Metarinka
02-11-2010, 03:57 PM
bingo, we don't build mobile gantry or boom cranes. we buy them. It's cheaper. did I mention we are a full production shop that has all the capabilities and material to do it in house.

We do build our own stationary gantry cranes, but mostly because they are all custom jobs anyways.

hp246
02-11-2010, 04:56 PM
I appreciate the thought guys, but I already have all the materials, and I expect I'll only use it once or twice, then tear it down. I'm not a production shop. I just want it to be safe.

transit
02-11-2010, 05:37 PM
The problem is there is no one formula.
The over head beam [ I beam] is suspended at the ends with the load anywhere, middle or near one end. The beam will tend to sag, so we need stiffness. The load will most likely be hoisted and move along the beam by a trolley riding on the beams bottom flanges, the flanges need to be able to carry the load or bend.
The end supports for the beams are columns, the longer and the thinner the column, the more likely it will buckle, complicating the column loading is twisting. All the welds must be capable to carry all the loads at the joints.
If you plan on 600 lbs. the rated load should be 1,000 lbs. and then you need a safety factor, no less than 3 x 1,000 lbs.
Forgot, live load and dead load. Now its getting complex, if you weld two 1/8 “ plates, T joint, that carry 1,500 lbs that try to slid the leg along the top of the T with ER70S-6 how long must the beads be?

tapwelder
02-11-2010, 09:03 PM
trailer jacks

59halfstep
02-11-2010, 09:32 PM
Check out this unit. You can use it inside or outside.

http://bbs.homeshopmachinist.net/showthread.php?t=33998
Post #2

Sandy
02-11-2010, 11:05 PM
Look at some of these numbers and see how your materials figure in. Should give you an idea without all the hassles of juggling numbers.

http://www.wallacecranes.com/triste3.htm

hp246
02-12-2010, 07:41 PM
59halfstep and Sandy. Thanks for the links. They were helpful.

jatt
05-08-2010, 08:15 AM
Here is what I put together.

http://madmodder.net/index.php?topic=1693.0

Admittedly I took ideas from what others had done before. Used what was lying around the shop for the legs, gussets and plates. Stumbled across an offcut I beam at the steelyard for a reasonable cost.

I wouldnt roll it around with a weight hanging off it, its simply used to straddle my tandem trailer for loading/unloading purposes.

On the to do list is to fit up some better casters.

grnxrymnky
05-11-2010, 08:45 PM
here's one i made a couple years ago. the gantry that i built spans about 10 feet -- wide enough to back my trailer under and unload.
i forget the beam size, but the verts are 4" x 1/8' sq tubing. the beam is prolly a 8 @ 12 or 16 joined together from two shorter pieces. i have a 2 ton chain hoist and have had over 3k pounds suspended several times (42" 320 cat excavator bucket.) i wouldn't make a habit of taking a nap under it while loaded, but if i had no confidence in it i wouldn't use it either.

there is a set of formulas you can use, but for me (simple minded) they are kind of complicated. it depends, of course, on the weight being suspended and the span of the beam and the distance between the points of the beam where the load will be suspended (i.e. wheel to wheel center of the trolley) and the deflection. i think the deflection is more for id the beam is supporting a load over it like a bridge. you'll have a HARD time finding someone to help you with sizing a beam (unless you pay an engineer) because of liability. :confused:

the reason i know about the formulas is i want to build a bridge crane in the shop that i want to build one day. of course i couldn't get any free advice and i just can't afford to hire an engineer so a-researching i went.

if all else fails, go and measure an engineered one, and don't be afraid to over build.....and, of course, any of my advice is worth what you've paid for it.

William McCormick Jr
05-11-2010, 10:03 PM
Here are chain hoists like ones I made a long time ago. They easily lifted a forty foot cigarette ocean racer with twin Siamese Oldsmobile blocks.


Sincerely,


William McCormick

norite
08-23-2010, 09:33 PM
I built a gantry crane years ago but eventually took it out of the shop, it takes up too much room. It was meant to be temporary and to spare every expense. I used 3 pieces of 4" x 10' l heavy wall pipe out of the scrap pile.

I just welded a 5 ft heavy wall 4" pipe to a 10' piece, like an inverted T (fishmouth joint).

I weldedmatched 3/8 plates to the tops of the 10' pipes and the bottom of a 6" x 12' I beam at the ends. These had matching holes in the corners allowing the beam to be bolted to the top of the pipe.

I also welded 1" pipes into the ends of the bottom pipes which allowed installation of a set of scaffold casters.

The thing proved to be tremendously strong with a beam crawl and 2 ton chainfall installed. I was able to lift lathes, engines, compressors and auction treasure etc. out of the truck.

I wouldn't use this in any commercial, construction or industrial environment but it got the job done when I had nothing better available.

wc870
08-28-2010, 06:09 AM
if you have a engine crane your all set. I just take a piece of 4x4 (wood) and put it under the bed rails (somewhere over the wheel wells is usually the balance piont) come in from behind with the engine crane. I just use 1 chain in the middle. It takes a couple of tries to get it balenced just right. works like a charm!

daddy
08-29-2010, 08:33 PM
Just helped a friend lift the bed off his pickup a few weeks ago. We laid a couple long planks across the bottom chords of several of the roof trusses, hung my chain hoist and picked it up. Rolled the truck out from underneath. Easiest way to change a fuel pump.

Pickup beds are not real heavy.