Yet Another Gantry Crane Question

alskdjfhg · Nov 25, 2014

For those that don't know, I have a 15,500 lb lathe that is occupying a trailer that I need to get unloaded.
I was planning to unload it by making two gantry cranes and using chain hoists.

I went to the scrap yard that is about a mile from the farm and they have about 20 W14x43 beams (I just measured them with a ruler so they could be up to W14x53, but let's just say they are the lighter ones). I went to McMaster and looked up what size beam they use for a 10,000lb capacity gantry crane, they says it's a 5x12 beam. So I assume with these beams being larger they they would be up the task (I want them to be able to handle a minimum of 10k, but I would like more).

But when I used this calculator; WebStructural, it says that the beams will fail*. So I would like someone to check this, preferably tell me how I would go about calculating the strength of beams, but all I need right now is for someone to tell me what a W14x43 beam with a 9ft span will do under a 10k load.

Thanks for any and all help.

*They fail when I specify that beam is going to be unbraced.

matt_isserstedt · Nov 25, 2014

I crashed the macro trying to make it work for a point load, ended up with a 2" long distributed load. Its sort of a dangerous thing because unless you are designing building steel its hard to get the right conditions.

There's sort of a bigger problem. You get the roughly 10' long beams and that's 430# apiece. That probably need to go up 8-10 feet in the air on top of a set of columns, or tilt up an assembly made on the ground. This is not a trivial thing. You need a crane (or forklift) to assemble the crane...a 5 ton chainfall isn't a lightweight little thingy either and it has to hang from the beam as well...

This is the best double check for your design because its sold with PE certification and manufacturer's liability included.
http://www.wallacecranes.com/thrftste_fixed.htm

Also not trivial are the column sizes, the base size, and how all this steel is attached (and braced) to each other. Its not a good time to try to expand your welding skills. Bolted connections are more reliable where possible. Make sure the manner in which you hang the hoist does not compromise the flanges.

I didn't comment on the beam strength because its only a single piece of the pie, every other thing mentioned above is not trivial and can kill you or your machine. So I'm trying to get you to understand the seriousness of the project and the attention to details involved when lifting overhead.

motion guru · Nov 25, 2014

Time to rent a 20,000lb capacity boxcar special and save your time and money while very likely preserving your lathe and limbs.

stonehaven · Nov 25, 2014

I was in need of a gantry and was going to build one, but happened to look at our Kijiji listings(like Craigslist) and found a Vesteel gantry for 5 ton with trolley and chain hoist, for $2000. It's a 10 ft. High x 16 ft width and the beam is 12 inch. Couldn't build one for the price I paid considering the trolley, hoist and casters. You might try finding one that is approved rating for your needs.

alskdjfhg · Nov 25, 2014

Matt, thanks for the tip, used it and the beam works. Thanks a bunch.

And just for the sake of discussion, let's assume that I'm not a complete moron. I don't want to come off as a arrogant person who's ignorant of the dangers of what I'm going to do. But I do understand what's going on and the crane will be built will safety first.

matt_isserstedt · Nov 25, 2014

alskdjfhg said:
Matt, thanks for the tip, used it and the beam works. Thanks a bunch.

Theres a lot to ASS_U_ME when using an "easy button" online calculator. Be very careful. In situations such as this it can easily make one's ass into a dead ass.

johnoder · Nov 25, 2014

Section Modulus 62.7 in AISC for W14 X 43 (Axis X-X - the one you are interested in)

Case 2 in MHB - point load of 10,000

108" span

(10,000 X 108) divided by (62.7 X 4)

1,080,000 / 250.8

4306.2 psi at center

Material yield about 7 times that

But note points posted above

alskdjfhg · Nov 25, 2014

johnoder said:
Section Modulus 62.7 in AISC for W14 X 43 (Axis X-X - the one you are interested in)

Case 3 in MHB - point load of 10,000

108" span

(10,000 X 108) divided by (62.7 X 4)

1,080,000 / 250.8

4306.2 psi at center

Material yield about 7 or 8 times that

As usual, thanks a bunch.
I should just start emailing you directly.

And yes, above posting are noted.

motion guru · Nov 25, 2014

alskdjfhg said:
Matt, thanks for the tip, used it and the beam works. Thanks a bunch.

And just for the sake of discussion, let's assume that I'm not a complete moron. I don't want to come off as a arrogant person who's ignorant of the dangers of what I'm going to do. But I do understand what's going on and the crane will be built will safety first.

Matt, thank you indirectly answering the question.

Matt, a couple of years ago, I purchased a pile of used steel for scrap price and did exactly as you are intending to do. You can read about it here (not sure why the photos don't show up) http://www.practicalmachinist.com/vb/general/bridge-crane-revisited-need-stretch-i-beam-205484/

I have a mechanical engineering degree with a few decades of experience and I have worked with crane manufacturers designing test equipment to destructively test hoists under extreme load conditions as well as fully automated crane systems that pick up loads and move them around completely without any human interaction . . .

Putting together a gantry from scratch for the purpose of lifting nearly 8 tons can be done - but knowing what I know I wouldn't even consider it even if I had all the steel and gear sitting in my shop ready to go.

Heavey Metal · Nov 25, 2014

A crane trolley is a dynamic load and the beam will fail by buckeling the top flange.

Best to hat a chanel on the beam.

If you brace the beam you have to figure kick also (you dont gain much by braceing if you dont stop the kick)

swatkins · Nov 25, 2014

A Gantry Crane would be the last thing I would be building on a farm with lots of space... I would spend my money on a 3/8 to 1/2 inch 4' x 10' sheet of metal and build one of these near the future shop.

Make a sled out of the metal plate, place the lathe, and all future lathes, on top and slide the machine and sled off the trailer, down the ramp and over to door of the shop....

Just remember while Fort Bend EMS is good its a LONG way to the nearest trauma center....

swatkins · Nov 25, 2014

Looks like Bill types faster than I do,,,,, Well, In my defence I did have to go looking and steal a ramp picture

CWB · Nov 25, 2014

If you REALLY want a crane, used industrial cranes are usually pretty dam cheap compared to the steel necessary to build one and one helluva lot safer. If you buy a modern one from a manufacturer still in business you might even get their recommendations for foundations, loading, etc.

bukwerm · Nov 25, 2014

alskdjfhg said:
Matt, thanks for the tip, used it and the beam works. Thanks a bunch.

And just for the sake of discussion, let's assume that I'm not a complete moron. I don't want to come off as a arrogant person who's ignorant of the dangers of what I'm going to do. But I do understand what's going on and the crane will be built will safety first.

Being an incomplete moron may not help your case....

motion guru · Nov 25, 2014

bukwerm said:
Being an incomplete moron may not help your case....

I don't care what anyone says - that there is funny . . .

And Matt, if you have your heart set on building a gantry crane rated to 8+ tons - a little bit of ribbing from the interwebs wont stop you.

Just make sure you have a clear understanding of the engineering and there need not be any risk.

swatkins · Nov 25, 2014

thermite said:
Get you a copy of the legendary "Junior Woodchuck manual" carried by "those damned Beavers".

US Army Corps of Engineers pub. Water-proof, battle-dress pocket size.

Skip the parts on land-mines and use the rigging tricks and load calculations.

Our tax dollars have been paying for its generation and update since around the time of the Revolution. Even then, we were copying from Sumer and Babylon onward.

Bill

We used to build dirt ramps out in West Texas when we needed to unload tractors off of trailers at construction sites.. Came in mighty handy.. I was going to build one here at the farm but luckily I have the use of a trailer that has a tilt bed that allows trucks, tractors and machines to be loaded easily...

Around Mat's farm they get a lot of rain, 45 inches a year. Pit ramps need a sump pump thus the suggestion for an elevated ramp... If I ever need to build one here I'll sink some 6x6 treated posts, nail on some 1x6 treated fence boards for a bulkhead and pile dirt on the board side.. Not counting the dirt, less than 150.00

matt_isserstedt · Nov 25, 2014

motion guru said:
Just make sure you have a clear understanding of the engineering and there need not be any risk.

Thanks MotionGuru, well-stated, that was my intent. Not trying to beat up a young guy but just reinforce the need for research about what is actually happening in the structure and how to visualize the forces. And in general...detailed thinking. Building the device in question is well within the range of possibilities.

jdavi581 · Nov 25, 2014

mobile loading ramp,container loading ramp,yard ramp,Haide Machinery Company Ltd
I would use some steel and build something like this.
A gantry is nice, but when you build your shop I am sure (wink wink) that you will incorporate a crane system into the structure of your new shop.
a hole in the ground will work too, a couple of railroad ties to finish it off right. Could also pull the wheels off of the trailer, to get it close enough to work.
Good luck
Joe

ratbldr427 · Nov 25, 2014

Talk about re purposing truck, trailer beds.A friend bought an old car hauler trailer to convert it into a hay wagon.They have enough steel and a lifetime supply of hydraulic cylinders to make a tilt trailer or ramp.Never dawned on me how much hydraulics are used on one until he started stripping it down.

Keelan · Nov 26, 2014

Having watched one guy move a house across the street almost entirely without assistance, I'd suggest going from underneath.

Block the lathe up enough on the trailer so that you can slide a couple skookum beams under it, one at the headstock end, one at the tailstock end. Get beams long enough to clear the sides of the trailer, and then build cribbing from the ground up to meet the overhanging beams. Use that cribbing to jack & block up the lathe enough to clear the trailer, remove the trailer. Now very carefully remove the cribbing a little at a time until the lathe is on the ground. I recently used a very similar process on a smaller scale to swap out the skids on a 2700 pound printing press, using 2x4 cribbing and 3/4" plywood shims. Worked very nicely, and for an amateur machine mover such as myself it's very comforting never having anything suspended by cables or hydraulics more than 3/4" from any solid surface at any time.

The good thing about this approach is that it is non-destructive to the beams, so you can just borrow them for the duration of the project and return them un-harmed when the lathe is back on terra firma. House movers have a very good selection of beams.

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