I am restoring some rather large military vehicles and am thinking that a 1-3ton Gantry type crane (mobile, of course) would fit my shop better than numerous lifts/hoists.
ANyone have any general DIY guidlines for a setup in this size? Nothing really fancy, just enough to lift the load and have wheels.
I built a gantry about 20 years ago. 7" 15 lb "S" beam held up by "A" members from 3" channel. Has four diagonals to control any tendency towards side to side flex. About 8 feet span. Clears ten foot ceiling joists. Used surplus bomb cart casters from the USAF. These are sprung 10" casters that I rebuilt including machining off rubber tread on wheels. They have Timken bearings on 1 1/4" axles.
Lifting handled by rebuilt Wright "Army" 1 1/2 ton chain fall These are the "low head room" jobs with the built in trolley. Has a tag on it that says tested to 5500. Rebuild included new 7/16" section chain (rated for load lifting) and 5 ton safety hook.
I have had 4700 hanging on it.
Welded together when all I had was the Lincoln cracker box. "A"s are bolted to beam so the joint is in compression.
I built my own 1.5 ton crane. Pictures of the process are here.
Gantry Crane Pictures
Look under files named Gantry Crane.
I added a couple DXF files for people that requested them. If I was to do it again, I would make the A frame section on the end taller to extend the telescoping height of the crane to better unload truck/trailer.
If you intend to roll it under load, the casters can quickly become the weak link. They need to be large enough to roll over small obstructions and also rated for the load...a swivel caster can quickly fold up under an overload.
I made my gantry so that the major pieces could be unbolted if I ever moved which proved to be valuable in the recent past.
Headroom is a very important calculation once you add in the trolley, and hoist. Chainfall (hand-over-hand) hoists will be much faster and less stress on you but eat up valuable headroom. A lever chain hoist takes up less headroom but takes many many many pulls on the lever to raise the load.
Other considerations are making it able to roll outside the garage door (mine cannot) and to straddle a trailer or truck (just barely got that one). Also 98% of the time it will be stored/not used, I made it 8'-3" wide so it could "park" sitting over top of my 40 x 96" workbench when not needed.
A gantry comes in super-handy when unloading lathes from trailers, too.
Lots of commercial gantries on a Google search - pretty easy to find one you like & use their dimensions. My gantry & Matt's are almost identical, just wide enough to back the truck under (9' on mine).
Selection of casters is important. I used four swiveling casters with locks, 8" diameter wheel. They came from Clark Caster, Model 38M-S, $36.20 each, click here. Those may or may not be the best ones for your gantry, so a phone call to the company is probably the best way to select the correct one.
My chain hoist & trolley came from Hoistsdirect.com, click here. Great service, nice people to deal with, well-made items.
As has been pointed out, casters are usually a weak link in a gantry crane.
My rule of thumb is to select casters as large as you get (larger the wheel, the easier they roll) and make sure that they are sized appropiately for the load (weight of crane and load) that you plan on them carrying.
Use closed members (tube or pipe) on the supports to resist torsional vectors on the crane.
My policy is to overbuild any lifting device...cheap insurance considering the price of the device failing.
The ability to break the gantry crane down is well worth having.
Making it as high as you can is another plus while remembering to widen the base to allow for the change in CG.
If you look at commercial offerings for ideas, remember that lifting devices such as those from Harbor Freight seldom are engineered with adequate safety margins in mind.
I built mine back in 1990 after I bought a planer in Wisconcin and realized I couldn't afford to pay a rigger to move it for me.
Tip 1: It doesn't need to have four casters. Two are sufficient, though a little less convenient. The first thing mine did when I got it up on its feet was start down the hill on me.
Tip 2: Set it up so the vertical structure will telescope.
Tip 3: Be absolutely certain that the top corners are very well braced. Like Matt's.
Post some pics when you start building it. WWQ
you thinking something sorta like this?
Also, the connection from the legs to the top beam needs to be as square as possible in both directions (use a large carpenter's framing square).
As it is loaded up, it's quite important that the load be transferred axially into the legs and doesn't impart any significant bending moment into them.
A month ago I bought a used 5 ton Wallace gantry crane that has a 35 foot span and 19 feet under the beam! Maybe a bit big for you but just right for me. [img]smile.gif[/img]
Anyways it rolls on two fixed wheels and two swivel casters. They are made by Albion and can be purchased. They have a groove for running on inverted angle iron track or can be rolled on a flat surface.
I was amazed at the simplicity of construction of this quite large gantry. Mostly all rectangular and square tubing and a big I beam.
As a designer of this sort of stuff, that is a really great looking gantry crane.
Regards from Melbourne,Australia,
It has to be red ...
IMO, four swivel casters give the crane the ability to turn within it's own circle. That allows moving a good sized crane inside a small garage. Total height is important as well - mine has fully half an inch of clearance with the garage door in the raised position
Gravity is evident when the I-beam isn't dead level ... the loaded trolley easily rolls towards the low side. You'll want to buy or make a couple of I-beam clamps to prevent this.
If you've ever seen a heavy load fall, which takes only a heartbeat, you understand why no body part can ever be under the load. Lifting devices are usually built with some extra capacity, the human brain being the
Thanks for the nice comments, AAB, I added a couple details I though you'd enjoy [img]smile.gif[/img]
(Oops, those are old and blow the page wide )
On your gantry crane, what are the casters rated?
They look a bit light compared to the rest of the crane (which looks great).
TMT, I think they are 1600lbs each caster, total of 3200 lbs per end, which yes, theoretically if I put all of the 4000 lb design load on 1 end then I could be in trouble.
It was somewhat of a cost vs. function decision, and before I owned any forklifts [img]smile.gif[/img]
oh for godsakes,, just go out and buy a "cherrypicker"!!!
couldn't help myself [img]smile.gif[/img]
"TMT, I think they are 1600lbs each caster, total of 3200 lbs per end, which yes, theoretically if I put all of the 4000 lb design load on 1 end then I could be in trouble."
Actually the concern I would have is if with an unevern floor three of the wheels would end up carrying the load as the crane rolled across an uneven floor.
Since with three wheels bearing it would mean that on one end of the crane only ONE wheel would be supporting a load meant for two. And if the item being held in suspension were located on that "one caster" end of the gantry, that single caster would be under considerable loading. Add in a possible dynamic impulse that can occur to a caster if you hit a crack in the floor as the crane rolled and you have a recipe for disaster.
It's one of the reasons why I try to use casters rated for the static load of the crane for each caster...and yes they are expensive.
It also gives one an idea how dangerous the popular Chinese engine crane with its small fragile wheels is when fully loaded while rolling.
Something that I haven't seen either mentioned or pictured are screw down legs/feet like jacks at each corner to compensate for working on an uneven surface/acting as a brake. Unfortunately I have no pictures to post to illustrate what I mean.
I guess that most gantries are designed for the workshop environment only and obviously Matt's is specifically for moving machinery.
I have used gantries for heavy lifts where crane access was not possible (fo'c'sle of a ship working on a capstan) and would always prefer to have the gantry jacked up slightly rather than free on wheels either chocked or locked.
A gantry placed on a slightly uneven surface will flex in torsion to conform to the shape that is supporting it. This will load each corner accordingly. In no way is the torsional stiffness enough to lift one corner off a an uneven floor while it's loaded.
An I beam is design to take loads in bending. The I shaped beam is an open section and is actually pretty poor in terms of torsional stiffness.
99, that's my experience with the torsional flexure of the beam too, all wheels planted under heavy load.
I suppose the floor could warp enough, (driveway for example) to daylight one of the wheels but it will always be opposite the more heavily loaded end and thus one need never worry about transfer of weight to one wheel only.
Worst possible sceanario; centered heavy load, extreme surface warp, virtually all load on TWO diagonally opposed wheels. That would test the vertical to I-beam connection and bottom flange stiffness! Might make a case for vertical extention of the legs to the top of a boxed-end I-beam and fasteners there as well, creating an "L" shaped cradle at each end.
This especially for a purpose-built, lighter, transportable crane.
Strong second to Barry's trolley clamps. Don't need 4,000 lbs slamming against one end. Might overcome gravity on the other end, ugly!