I had a job today where I had to lift a piece that weighed 28,000 lbs, which was exactly at capacity at appx. 14.5 ft load radius. (verified with charts and measuring tape). What surprised me was how "easy" the lift felt in the operator seat, the crane was not even heaving or moving almost at all, sitting tight on outriggers. Some pictures here http://www.machinerymoverschicago.com/blog/Unloading-and-Installing-Amada-CNC-Punch-Press/ I was lifting over the front, so the load was evenly shared between two outriggers. i
Nice job ichudov ! Keep up the good work .
That's the laws of physics at play, within the load chart, lifting a capacity load tight against the machine puts exactly the same strain on all the parts as lifting a much lighter capacity load at maximum radius. Nicely done! Only thing I would question is your cribbing, on asphalt like that i would have used something with more surface area on the ground and then cribbed over that, but hey it worked fine for you, no worries.
Nice job! Do you use an LMI or a dynamometer to determine lifting weight? Looking at a Ron 25t wireless system myself. Hey, for outrigger pads....thought about taking some hard wood 4x4's and sandwiching between 3/4" ply?
I appreciate your comment about cribbing, because I do not have the proper experience with cribbing and want to learn to do it properly. The wood you see on the picture is two 8x8 timbers, one 3 feet long and another 4 feet long. The same on both front sides. I used a lot less on the rear, because the rear was not carrying any additional weight. The square footage for each front cribbing setup (for the two outriggers in the front) is 4.6 square feet.
For this job, the weight was specified in sales literature, it was a new piece of machinery with documentation. I have some wood timbers, 8x8's that you see on the pictures, and also several 8x6s that I salvaged somewhere. The 8x6s are basically new and come from a giant shipping crate for some machinery that I unloaded. I also have some hardwood premium plywood and wanted to glue together a 5" or so sandwhich, and to make four of those, 30x30 inches. Makes sense? Re: scale. I recently bought this 50,000 lbs scale on ebay for $202.50. See ebay item 371489259040: http://www.ebay.com/itm/Martin-Decker-Crane-Scale-/371489259040 This scale also has a plywood glass cover for safer handling. This Ron system looks nice, I hope that it is rainproof.
My physics and geometry are a bit rusty, but if you think about it, you have about 14 ton on the hook in front of the outriggers, which means you have more than 14 ton behind the outriggers as counterweight (including the weight of the entire crane) so essentially you have more than 14 ton on each front outrigger when the pick is in the air. So you had roughly 6,000 pounds per square foot on the asphalt. Looks like your forklifts had no problems and they're a lot higher ground pressure. Don't know what the rule of thumb would be for loading on various materials, like asphalt, rock, dirt, etc.
lantraxco, you are asking a great question. I am definitely not a person with the best answer to it -- I am just beginning to learn this. What I do know is that my guy looked at the outriggers as I was making a lift. He said that the asphalt has not visibly heaved or deflected at all when I lifted the entire load. It was perfectly solid. He also said that the crane did not move on the outrigger at all, as well.
That's a big machine you moved there! Nice work! :drinkup
Absolutely fantastic! Let me know if you're going to make a set...I'm in process of doing same. That scale was a steal!
Perfect. The thing that always worried me back when I did the odd crane pick, was damaging soft asphalt and/or having a void or soft spot under the asphalt or concrete. A while after I left, the construction company I had worked for did the sitework for a concrete tiltup panel warehouse, huge Frito-Lay distribution warehouse. The crane company had set up inside on the slab and was tilting the walls up when one of the outriggers punched through the concrete floor slab. Like dominoes the crane, wall panel, and all the standing wall panels with the braces came tumbling down. Miracle nobody died. Stuff happens... fast! Stay safe, you're doing fine.
Lantraxco, scary story! One second you think that everything is perfect, the next second everything comes crashing down! Did he use any wood at all? What I read about that sort of stuff, concrete breaks from "point pressure" when wood is not used at all, because outrigger legs are not perfectly flat and only little bits push on concrete, and concrete cracks. With wood, the wood works as a cushion to spread the point load to a wider area.
I honestly don't know, just heard the story through the grapevine. Everybody on the job was pointing fingers at everybody else and the customer was looking to sue somebody for damages. Possibilities: 1) Crane company didn't rig and crib properly 2) Concrete company didn't use correct concrete, and steel spacing. I was told the mesh was all laying at the bottom instead of being halfway up in the slab. 3) Concrete provider delivered incorrect mix, though samples were of course taken 4) Concrete testing lab screwed up 5) Dirtwork contractor (My old employer) failed to properly compact subsoil and gravel base. 6) Testing lab screwed up compaction tests. Pick one, or several. The stabilizer punched through the concrete, but the soil underneath didn't hold up, even though the concrete fractured it should have just subsided a bit and stopped. Of course if you're near the limit of the load chart and the cran tips a few degrees, that's all it takes.
It sounds like "all of the above"!
You mentioned you had the manufactures weight. Do not believe it at all if you lift a pressure vessel sometime. Pressure vessels are stamped with the weight before any piping or accessories are added. They often weight thousands of lbs more. Just a tidbit to store in the back corner of your mind. If you make your outrigger pads round they are a lot easier to handle as you can roll them around. Just size them to get the ground coverage you want.
If you make them 34" diameter they will have the same area as the 30x30 square ones that you were planning, and as OIH points out, a great deal easier to move around. TBH I would make them an even 3ft in diameter.
old-iron, thank you for a GREAT tip on making the outrigger pads round, I will do that, did not think about it!
We also drilled 2 ea 1" holes in each side of them about 8" apart. We would stick 3/4 rope in tying a knot on the back side of each end to make a loop on each side of the pads. They did not interfere with rolling and gave a handle to drag them under the pad and adjust them with.