yep. There isn’t any “this may work” involved in this sort of lift. The accidents are always, always, always because people who know better, cut corners to save money on the job.
At least in the case of the 3rd video, heavy metal seems entirely appropriate for, you know, heavy metal.
I have had the occasion to do quad crane lifts, which is a fairly tense experience. The geometry is constantly changing, and the failure of any of the four cranes is likely to cause the others to fail as well. I have not had that happen to me yet.
But what happens is that you get into a situation where delays can cost hundreds of thousands of dollars per hour. In my case, the operation is happening in Liberia or someplace, over the course of several days and a bunch of lifts. In the normal world, when the cranes start leaking fluid, you can just shut down and get the tech people in.
But in my situation, you often have to accept some degree of mechanical issues. The cranes are just not going to be perfect. The person in charge of the operation has to decide where that line is where shutting down is the only safe option.
When we work the cranes with heavy loads over long periods in hot weather, they will start to develop leaks. I have done lifts with people literally pumping hydraulic fluid into the cranes from drums full time during heavy lifts, and others standing by the brake drums with solvent to keep the brakes from getting soaked and slipping from hydraulic fluid leaking from above. It is not a fun situation.
So, without knowing all the details of this particular lift, it does look to me like the weight of the counterweight plus the lift was very close to the operating limits of the crane (or they would have used more weight). The counterweight was heavy enough to balance the lift at near vertical boom angle, but not when the boom was lowered a bit. Even a slight down slope could bring the counterweight closer, and the load further away. that shifts the geometry. But it is clear they exceeded the limits of the crane. Possibly they could not get a larger crane to the work site. Or the load was heavier than anticipated.
One thing that can happen is that cranes do get certified with test weights heavier than the rated capacity of the crane. So you know the crane can lift a load heavier than the rated lift. The operator gets out there and sees that the load is slightly beyond what is allowed. But he knows that it made a lift even heavier a few weeks ago at the certification, however he forgets that the test lift was done under perfect conditions. But of all the things that you don’t want to happen, someone getting badly hurt is the worst, but close behind is some sort of accident where you were found to have deliberately exceeded the capacity of the crane, especially when it requires you to bypass limits to do so.
sometimes you need to bypass the limits. But only in very limited circumstances. And you had better be prepared to defend the decision to do so.
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Could the aqueduct section have been jacked up instead? I know that obviously jacks only go so high but the advantage is that forces are always in compression. I suppose that a crane could be used at the end of the lift to move the load horizontally onto the structure, hopefully over a small distance.
I have not seen where they have published either the actual weight of the section, or exactly how high it was being lifted. Also, they were moving with the load, which you want to avoid if possible. I have a lot of questions that I just do not have the answers to. It looks like they cast the section on-site, if those are the forms on the left side of the image. I would assume that they are making a bunch of those sections. They probably need to move the forms frequently, and balance the difficulty and time loss of doing that vs. moving the sections farther with the crane.
Remembering the limits of my knowledge of this particular job, if someone asked me how to do it, I might suggest two cranes. One at the casting site, and one at the assembly site, and a heavy lift truck to move between the two. The assembly crane would need to be moved every time, but it could be set up for a lift straight up, rotate, and set into position. No swinging loads, no changes in geometry. But there may be good reasons why they chose otherwise.
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I just want to point out that in this other view, you can actually see the crane operator. He seems to duck underneath the huge counterweight and get out just before it hits the ground! (1:22) Holy crap!
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Seems like a dangerous move to me. One way or another he is at risk of being squished. At least if he stays put he has structure around him.
No kidding!
I like the point in the video about a second later, where he looks behind to check, sees “ok, i’m not in danger anymore” and is like, “eh, I’m gonna just keep running anyway…”
That counterweight can come up and just destroy the cab. I bet he had an escape plan figured out when he started the lift, and just pulled the trigger on that when things went south.
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My guess would be that the geometry of the lift was changed from design, not that the weights were unknown. The crane was likely positioned further away than planned due to site access issues, necessitating lowering the boom, thus increasing turning moment on the whole rig. The soil failure was clearly secondary as the rear of the tracks were clearly unweighted prior to any real movement.
This one is an interesting failure. I have sketched the configurations for engineers who generally are unable to quickly see the issue with the unauthorised re-design of the tie-rod configuration until it is pointed out. Of course, any competent engineer, if designing the modified system from scratch would get it right.
Complicated by the fact that the original design didn’t really make sense. I looked like it would have required either threading the entire length of the supports or getting larger diameter supports, putting them on a lathe and then reducing the diameter EXCEPT where it was to be threaded for the nuts to hold the skyway. I guess that machinery exists to lathe a rod that long, but I’d guess that you’d have to get that done custom at a shipyard. because you can’t just thread a section in the middle of a rod and put a nut on there.
Agree that the original design was inelegant and awkward to install, leading to the disastrous change. With the benefit of hindsight, I can think of many alternative designs.
Right down at the diametric opposite of the “lift-y toy operating experience” spectrum, my family had a scrap metal yard my whole childhood.
Our “big boy” was a secondhand Hyster , rated for two tonne when it left the factory, subjected to various “modifications” over the years, and (my dad owning a scrapyard and being both very very mechanically minded and descended from Scots stock) frequently repaired with things cannibalised from very similar machines . . .
Interestingly, the exact same [quote=“Max_Blancke, post:23, topic:100918”]
of all the things that you don’t want to happen, someone getting badly hurt is the worst, but close behind is some sort of accident where you were found to have deliberately exceeded the capacity of the crane, especially when it requires you to bypass limits to do so.
sometimes you need to bypass the limits. But only in very limited circumstances. And you had better be prepared to defend the decision to do so.
[/quote] trade off/punishment incurring calculation took place.
We never got to the point of pumping fluid in as we lifted, but you did gauge remaining grunt by the amount of oil spraying out of various connections. and there was a little bucket of sand in the footwell, for times the oil you dripped made the concrete floor too slick for traction.
Bitterly saying “If you spent some fucking money on new hydraulic lines, dad . . .” was no defense for having dropped a pallet of drums down the driveway.
Tricky to do on a moving crane.
I bet you learned how to work on hydraulic systems, which is a valuable skill.
What can be maddening is when someone sets the limits well inside the operating parameters. Because the company will accept jobs based on those limits. Sometimes the equipment to be moved is designed specifically to fit within our lifting or loading capacity. That might be some sort of power generating or water purification equipment, which likely needs to be offloaded in primitive conditions. So part of the design is the consideration for transport, and the equipment will be designed to be assembled from parts manufactured just inside of our capacity to handle them. Usually the weight limit is 140 tons, and of course there are size limits. I have honestly loaded an object nearly 300 feet long, which fit with less than 2 inches clearance on each side.
But the weight limits are based on manufacturer specs of the cranes when new. The limits of the cranes are supposed to be set at those weights, and min and max boom angles, as well as max lift heights. There are also limits set to keep the booms from striking other cranes or objects. Often we need every bit of that capacity. Sometimes a bit more. I have never personally had a serious disaster. But I have seen some.
I have sometimes been flown out to some really rugged place, and been given a blueprint for an object, and had to go around measuring and inspecting, with the goal of deciding if offloading the thing can be done at that place. When I say “yes”, they almost certainly will expect me to take charge of doing it. I like the challenge of it, and it is much more interesting than delivering food aid, but you only get to screw up badly one time.
I used to have a mentor in the business who always said “One minute you are walking around in a fancy uniform thinking you are king of the world, but as soon as you screw something up, you get to be Joe Shit, the rag man.”
So in that last video, how do so many dump trucks end up on their backs?
Why are they hauling flaming stuff, I assume coal?
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