Preliminary Workup

[farmersamm]

Starting a materials list for a gantry crane.

I have a couple of 3500# axles on hand with hubs. One set of idlers, one set of brake hubs. Hate to pull the hubs off those axles, but I guess it's a way to save money. Only problem is..........have to move the axles to inside storage once the hubs are removed to prevent damage to the spindles.

I have some 15" wheels/tires on hand from an auction........brand new 10yrs ago, but stored in the shade so still good.

The real rub is the spindles. None of the spindles for sale, have a long enough stub to go through the tubing I intend to use. Probably have to make those. 1018 cold roll should suffice.

In preliminary decision mode about the "front" set of wheels................either fixed, caster design, or steerable. I'm leaning towards steerable with a quick disconnect tie rod. But this makes the damn spindles/kingpins more complex. Casters would be easier, but they're pretty much one way travel.........have to lift the crane to back it out, because you'd have to reverse the casters.

The trolley has to be controlled, it can't just freewheel. The beam will never be level. Coupla cable winches ought to do the trick.

Another rub is deciding how much to derate the beam..........again due to the fact that damn thing will never be level, and will likely always have a twist on it. S beams don't like twist...............any time an I beam is out of plumb, it wants to buckle. Have to decide whether to use rectangular tubing for the main beam....better behavior when twisted. Without the proper software, it's a matter of eyeball engineering.....which I DON'T like. I have I beam trolleys on hand.......I don't want to have to make trolleys for tubing. This one's gonna take some noodling.

My software will tell me the moment stress at the connection between uprights, and beam.............but it won't analyze the stress on any particular design. Being out of plumb, the structure will place huge stress on these connections...........it will want to fold.

I don't see any reason to provide any means of leveling the crane...........this defeats the need that it be mobile. Leveling requires jacks, which have to be fixed in one spot.......ain't gonna happen. Only way around it is to over design at the stress points. Not terribly much more expensive, but ya better get it right the first time.

Uprights are pretty much plug 'n chug..............boils down to a matter of thickness, and dimension. You can go thicker with smaller dimensions, or thinner wall with larger dimensions. It all boils down to which design involves the least number of pounds of steel. We're talking about 13' clearance beneath the beam. Wheels will take up a bit of this clearance, so overall.....the uprights are shorter than a conventional crane with steel casters. At this point, it's a toss up between 3x6, or 4x6, tubing........wall thickness to be determined. Actual free length can be reduced by designing the base to eliminate length of the actual single upright.

At this point.............the target capacity is only 3000#, but could handle more due to the multiX safety factor. Depends on how much of a risk you're willing to take.

This is the hard part...............building it is a piece of cake. Long as the Oliver tranny holds out.........it's the only running machine we have right now.

Half tempted to either upfit the jib crane that's been made for the Oliver, or build a stouter one....................but I'm not confident that the top link will take the load. 3pt load ratings on tractors are only for "close in" loads..............not extended cantilever loads. The top link will have to take a lot of stress.........which I feel is hazardous. let's say you have a 1700# engine hanging out about 5' beyond the rear of the tractor..........the cantilever places a huge amount of stress on the connections. You're looking at a 5X multiplier. A guy could do a Ksi analysis on the top link connection on the tractor, but it's iffy at best.

 

[Mule Meat]

Sounds to me as if you are trying to see just how complicated you can make a simple tool.

 

[farmersamm]

Sounds to me as if you are trying to see just how complicated you can make a simple tool.

Except..............it's over my head..................

 

[Janicholson]

With respect, you are asking for comments, so here goes. Why use it on uneven ground or sloped surfaces. If it needs to be used on sod OK, but moving the item to be lifted is easier than building a difficult to move device. If on surfaces that will twist the beam, the wheels/tires will need to be far enough apart, in the direction they roll, to stay on the surface. I would suggest 10ft between wheels in that direction!! The twist could be eliminated if a free floating hub from a medium hub rear axle was used at the top on one end. this would have the rigidity needed for the span, and keep the beam from twist.
I believe spending time making the work pad level is time well spent and economical. Making an all terrain system doesn't seem practical. Jim

 

[farmersamm]

With respect, you are asking for comments, so here goes. Why use it on uneven ground or sloped surfaces. If it needs to be used on sod OK, but moving the item to be lifted is easier than building a difficult to move device. If on surfaces that will twist the beam, the wheels/tires will need to be far enough apart, in the direction they roll, to stay on the surface. I would suggest 10ft between wheels in that direction!! The twist could be eliminated if a free floating hub from a medium hub rear axle was used at the top on one end. this would have the rigidity needed for the span, and keep the beam from twist.
I believe spending time making the work pad level is time well spent and economical. Making an all terrain system doesn't seem practical. Jim

We've gone down that road. Penciling the cost to put a slab in, considering it's about 500' from the nearest place that a concrete truck could work, got a bit pricey. Not to mention the cost of the slab + a nice crane. A crane that would have to be moved off the slab anyway. That portion of the "shop" has to handle stuff that's up to 16' wide. And this portion of the "shop" often has equipment either pulled in, or backed in. The area has to be accessible from both sides. Any crane would have to be parked in a corner of the yard somewhere, or out in the pasture.

 

[Janicholson]

We've gone down that road. Penciling the cost to put a slab in, considering it's about 500' from the nearest place that a concrete truck could work, got a bit pricey. Not to mention the cost of the slab + a nice crane. A crane that would have to be moved off the slab anyway. That portion of the "shop" has to handle stuff that's up to 16' wide. And this portion of the "shop" often has equipment either pulled in, or backed in. The area has to be accessible from both sides. Any crane would have to be parked in a corner of the yard somewhere, or out in the pasture.

I did not suggest concrete, though ideal, or gravel road base, not needed. just some earthwork to make a levelish playing field. Jim

 

[farmersamm]

My container, where the machine tools are, slopes mondo to the running foot.

That's over 40". Imagine what it would be over the length of a slab..............and the fill, and mud, it would take to offset that. Gets a bit on the spensive side. This is where the "shop" is located.

30yrs ago, it would have made sense to do the dirt work, and mud work. Now.............it doesn't. I'm approaching my expiration date.

 

[farmersamm]

All of this was to be done with the front end loader.................but it had the temerity to crap out on us before we could do the work.

 

[farmersamm]

If I thought this fella could do it, I'd gladly use it.............but I don't trust it with something pushing a ton. What you're seeing here is about a 1200# pick.

EDIT..................half a ton to ton

 

[urbancase]

If you want specific for steel I look it up on company’s website that supply beans, it will give you info how much load rating it will handle. Also I do a 2 to 1 ratio for safety. Around here O’Neal steel and others you can get the info.

 

[farmersamm]

If you want specific for steel I look it up on company’s website that supply beans, it will give you info how much load rating it will handle. Also I do a 2 to 1 ratio for safety. Around here O’Neal steel and others you can get the info.

I use BeamBoy 2.2 which will give me analysis for any structural shape, and load. But it's not sophisticated enough to analyze the moment connections beyond the amount of the moment. Won't give me any specific analysis for a particular design.

 

[farmersamm]

It's the connections that give people fits............it involves liability. Hard to find anybody, other than an engineer, that will give you a definitive answer as to how your connection will behave.

 

[urbancase]

It's the connections that give people fits............it involves liability. Hard to find anybody, other than an engineer, that will give you a definitive answer as to how your connection will behave.

I agree nobody wants to say for sure unless they are getting paid. That’s mostly likely why when I build something it’s over built. I am a EHS guy and there a ANSI standard for everything and each one cost money. I buy a fair amount for work dealing with power presses and related equipment. Good luck if there a way I can help ask.

 

[UAFitter]

i think you are flirting with disaster here. Moving a fabricated wheeled assembly with a load suspended from it on sloped, uneven ground is a very tall order. Every force on it is going to try and fold it up. Even something as simple as a flat tire could be life or death.

 

[caterpillar guy]

I think you are over thinking it . I worked for a guy that had a similar crane set up in his shop with caster wheels . It had 4 tubes/pipes about 4 or 6 inch in diameter running up at an angle like a capital A they set on a piece of channel a bit wider than the tubes were set apart at the bottom. the channels had casters under it. Then an I beam set on top of these tubes where they came together at the top . The bottom channels were about 8-10 feet long for each side then the span across for the I beam was about 10-12 feet. You could work inside the uprights while pulling an engine out of a semi. So we lifted old Detroit's out of trucks with it or other things which were in the 2000-3500 or a bit more with it and then would push it to get the engine out of the chassis and set it down so we could hook the new one and pick up to set in. This was of course on cement in the shop and it never left the shop or cement. We also pulled a DT 466 out of a 4366 with it and set new parts in with it. The shop ceiling was 16 foot or so and it would just clear the middle beam of the shop if you got it just right in the shop. It also had braces from about 3 feet down up to the beam from the angled vertical tubes there was room enough for the chain fall to run from one end of the beam to the other even behind the braces. There was an angle welded across the tubes about 6 or seven feet up so chains could be hung on it to keep them picked up off the floor. With the flanges of the channels up we used to lay some parts or bolts in there while under something then pick them up and put in a can to keep track of them while working on the item. it had steel/cast iron casters. If you want to lift on bare ground why not just set up a jib crane with a support leg to help with the weight then with a 20 foot arm you could do most work with it and if set right could swing some stuff in under the door so it would be inside or at least so it would be slide able on the floor to work on. Or even put the jib just in the door and swing it out the door when you need to lift things just out side the door. To make a crane you could pull around on dirt or even road pack would be quite a feat with sinkage of tires and bounce/squash of them unless you used some pretty heavy side walled tires and then it will be hard to move by hand. For the twist you could weld your tubing to an I beam for the trolley to run on this would help with the twist factor and make it more rigid with a smaller beam. Now the beam could be on top with a slung hoist under the tube. Or put underneath with the ends on top of the verticals to hold the weight easier. though this would now let the beam twist easier again as the tube would now be primarily a stiffener for the beam instead of the load bearing Thus the beam could roll sideways in a twist under load. No I'm not an engineer but have built a lot of things with thought put into them before building. For tires I would use something like 15-20 inch tires with heavy side walls like lowboy tires in nylon because of the stiffer sidewalls. Though radials might have a larger load limit on them. Like our grain cart has 24.5-32's on it with only about 8800 rating the one we replaced one of them with was a radial and it had a 13,000 rating both 12 ply tires. Unfortunately my brother put a cornhead nose through the side wall of the new tire on it so back to the lighter tires that are over loaded when full. Those lowboy tires are usually in the 14-16 ply rating or air plane tires and 16 inch are in the 16-20 ply rating . Will hold an empty gravity wagon up flat.

 

[Welding man]

I may be out in left field, but why not buy a rough terrain fork lift. I have 2. A case 586 and a Massey 6500. I can pick up 3 tons with either one of them and go through mud, snow or whatever. The 6500 has a tall mast and will easily lift up 14 ft or more. I got a great deal on both of them. I use them daily. I also have a gantry crane inside the shop that rolls on steel wheels another one outside to remove truck beds etc. They get used very little compared to the forklifts.