Just re-found these photos... At a location where we were working, an unrelated crane experienced boom failure. I saved up a couple of pictures. http://www.machinerymoverschicago.com/blog/Crane-Fail/ Just wondering, do you think that the operator purposely overrode load moment indicator? Overall, I think, booms snapping due to overload is better than the crane toppling, as far as consequences go. Makes sense?
Based on the photos with that much boom telescoped out the crane was in the part of the load chart where an overload should have tipped the crane over rather than break the boom. IMHO that boom had a defect in the structure already and the load it was lifting caused it to become over-stresed and ultimately fail.
All I know is that, 1.5 years later, there is still multiple lawsuits in progress. This is all I know.
They did not extend boom sections equally . Notice the crane still had lower sections in boom not extended . Looks like they jammed out the last 3 sections for the lift , notice the main boom still has two sections in it .
td25c, I am just wondering about something, is that how pinned booms are supposed to work? Extend one section fully, then another, etc etc? I tried to understand what "pinned boom" means and this is my best interpretation that I could come up with.
That's my understanding ichudov . One cylinder in the base section jack's it all out & pin's each section . Then backs up to grab another section . Advantage being the cylinder stays in the lower base section . They would have been better off to re position & get closer to the lift if possible . And read an old Grove operators manual .
Pin and Latch system is much different than a conventional Hydro crane. Our 165 will pin each section at 0%, 50% or 100%. Our 100 ton will pin at 0%, 46% 92% or 100%. To achieve a certain boom length, there's several combinations to get there. It's amazing the capacity differences between the different options. It's common practice for us to study the load charts and pick the right combination based on boom length, radius and weight to be lifted. If the operator of that rig didn't pick the best boom configuration, he doesn't need to be operating. Either way the LMI should have shut him down before he overloaded.
He had the wrong sections out. I'll bet the operator saw someone else make a pick at the same weight and radius with the right boom configuration and thought he could do it as well. On our 110 there's a 20k difference in capacity at one point depending on the boom configuration. And it's not even a true pin latch boom. On those newer AT crane there's no room for error.
I would guess that the LMI had the wrong configuration plugged in to it. I've seen more that one problem come up because the operator didn't know that the amount of counterweight, on tires or outriggers, outriggers fully extended, wrong hook block, wrong number for parts of line and so on and so forth made a big difference to what the LMI would limit in the actual situation.
It should have known what configuration it was in. I don't think it's like an older one where you set the crane up then tell the computer how it's configured. I think you punch the boom configuration you want into the LMI then the crane runs the boom out in that order. I'd say that Impact would be the one who would know that.
Not even sure of what model crane that is ? From the photo it looks like they are between 50 to 60 foot radius on the lift . Lets say it's at full capacity /load chart ..... Would the crane be best to have all boom sections equally extended ?
You would think so but no. For long radius picks you usually run the lighter, outer sections out. For heavy short radius picks you run the inner stronger sections out. We just bought a Krupp 5090 and while it isn't a pin and latch boom it's definitely different. If the boom sections are not at 50% or 100% it cuts the capacity in half. The best chart for 40k is with only the third section at 100%. For example I set a modular home the other day. The first section weighed 33k so I ran 3 out to 100%. Set the section and then needed more boom to stand the roof up so I just ran 4 out to 100%. Got all that done and swing Around to lift the next section and looked at the computer. I think I was good for 28k. The peice weighed 30k. I ran 4 in all the way and ran section 2 out to 100%. Same boom length and radius but now I was good for 46k. It's definitely a lot different then the old tms300 we have.
So the load chart shows the capability of the boom sections whenever it is less than the tipping load, that's cool. The old lattice booms were almost entirely compression load, the hydraulics there's a lot of moment load on the boom out past where the cylinders attach.
You mean the "old way" of "correcting" for a tipping problem of putting the bucket of a 988 Cat on the counter weight is not an acceptable procedure these days? What about four guys standing on the back of the fork truck to move that 1710 Cummins engine? Next thing you guys will be saying is that it's not acceptable to cut a couple holes in the side of an old oil drum and hook on it with the crane to get Pete up to that head pulley!
Too funny khansen
Thing is those are the kind of things that were almost common years ago! At least around the quarry. Or riding around with two men in the bucket of a 988 Cat picking up rocks off quarry road? Or leaving the cover open on a breaker with fan blowing at it to keep the breaker from tripping. Probably should stop before I go too far as don't know if there is a "Statue of Limitations" on MSHA violations!
Git 'er done! LOL
The first year I worked construction the bridge outfit I worked for would hang a 450JD equipped with a backhoe on the back of a 30 Ton P&H to lift out old county bridge sections. Once we got the crane hooked up the 450 bucket filled with gravel would be tied to the crane counterweight and then the backhoe boom would be extended way back and pushed down lifting the whole crawler off the ground for more hanging weight. Then yours truely, the new dumb 17 year old kid fresh out of high school, that stupidly told the truth when they asked him if he could run a cutting torch, crawled out there and made the last cut while setting on the piece of the bridge that was supposed to stay. If the crane would have tipped I was directly on the down hill side. Fortunately it handled the pieces and I lived and learned.