Big crane safety fail today, a 60 ton crane snapped its boom - Page 2
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  1. #21
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    Quote Originally Posted by dgfoster View Post
    Used to work in the summers in the '60's on the "Test Pad" at a large Midwestern crane manufacturing plant -- it will remain nameless. As the name suggests the test pad was where the cranes were setup in a engineering-specified configuration with a certain counterweight, length of boom, cable size and hook block(s). Besides doing the assmebly the three of us on the pad applied and wired strain gages in various locations of interest to the engineers and wired them to readout (analogue in those days) equipment. The crane operator would then raise the boom which, by the way, put enormaous strain on the boom and crane as it raised the first few degrees from horizontal. Unlike the pictured crane in the OP, ours were raised by cable backstays that were in turn hooked to a gantry and more cables to improve mechanical advantage---like a gin pole on a sailboat mast. We kind of held our breath as a long boom bounced and flexed under the strain despite the skilled operators most gentle coaxing to get through those first 5 to ten degrees. Clumbsy operation could fold the boom. After that things settled down and it was easy to get to 80 degrees or so. At that point we hooked up a stack of cast iron slabs of known weights and changed boom angle specified amounts, swung the load, raised and lowered the load with sometimes vigorous braking to test the whole works. All done according the engineers direction as they came to the pad for these tests to observe how the crane and hoisting mechanism behaved. Overall it was pretty routine and somewhat boring stuff. By the way there were no load calculators or other fancy equipment on cranes in those days. The fanciest piece of technology on that crane was a very simple hinged rod with a degree scale to indicate boom angle. Gravity made the rod hang straight down and the operator could look at it to double sheck where he thought he was. That was it. All there rest depended on his experience, skil, and feel for what was going on.

    However, I will never forget the day we had our newest and largest crane set up with the maximum boom it was rated for---300 feeet of combination square and round tube boom and 60 feet of "stinger" cantilevered at the top of the 300 foot section. We had made a few lighter lifts without incident and then went for the calculated max lift when, without warning, there was a creaking and bang and the whole works started twisting and falling. Usually we stood back fifty or so feet from the crane as a general safety precaution. But with 360 feet of boom up there along with the 1" diameter back stay cables and the many 50 to 75 pound cable links, gantry, hook block, and lifting cable all falling every which way, each of ran as fast as we could. Luckily no one was hurt, not even the crane operator whose only real option was to sit tight and hope. Needless to say, the relatively light sheet metal cab of the crane would have crumbled like wet cardboard had anything substantial hit it. But luck was on his side that day.

    I never heard what the cause of the failure was. Suspicions were that a faulty weld might have been the cause or a tiny ding in any of the boom tubes could have been at fault. Maybe a tube had an extrusion defect.

    Anyway, we did not get much done the rest of that day. The engineers beat a hasty retreat after doing a quick survey of the damage.

    Once they were gone we retreated to the test pad shack for a break to let our knees stop rattling. Good times.

    Denis
    Back in 1890 we...........
    has just as much relevance as your post. There is no comparasom of lattice boom and hydraulic cranes.
    Hydraulic booms may extend equally or sequentially . There is every reason for sequential extension since hydraulic booms are very heavy.
    The posted failure is due to computer failure or most likely deliberate defeat of the system. the boom has a massive safety factor designed in.

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  3. #22
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    Quote Originally Posted by tdmidget View Post
    Back in 1890 we...........
    has just as much relevance as your post. There is no comparasom of lattice boom and hydraulic cranes.
    Hydraulic booms may extend equally or sequentially . There is every reason for sequential extension since hydraulic booms are very heavy.
    The posted failure is due to computer failure or most likely deliberate defeat of the system. the boom has a massive safety factor designed in.
    Gee, I am sorry for recounting that incident. I thouught it might be of some interest.
    Denis

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  5. #23
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    Interest, yes. Relevance, no. There is no relationship between hydraulic booms and lattice booms. Modern hydraulic cranes are rated on a theoretical weight. Virtually no way you can actually get that weight that close to the center of rotation unless it is a long cylinder of lead or such. Back in the day , lattice boom cranes had to pick with head and heel at the highest boom angle which actually allowed that weight at the crane. Today that weight is actually over the crane. But today a computer will not allow the machine to attempt the pick if outside the capacity. Unless overiden by the operator.

  6. #24
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    Quote Originally Posted by tdmidget View Post
    Interest, yes. Relevance, no. There is no relationship between hydraulic booms and lattice booms. Modern hydraulic cranes are rated on a theoretical weight. Virtually no way you can actually get that weight that close to the center of rotation unless it is a long cylinder of lead or such. Back in the day , lattice boom cranes had to pick with head and heel at the highest boom angle which actually allowed that weight at the crane. Today that weight is actually over the crane. But today a computer will not allow the machine to attempt the pick if outside the capacity. Unless overiden by the operator.
    Sorry again! Can't be too careful about posts that really add to the subject at hand and are specifically and precisely relevant. That is a long and revered tradition on PM, I would agree.
    Denis

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  8. #25
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    Sounds like somebody needs a nap

  9. #26
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    Looks like they where picing a silo off the side.

    My guess is the didnt have it clear the anchor bolts and went to maxine on there puter to clear it.

    Crane stood on its toes, bolts let go (prolly one hung).

    In other words force that did the damage was stored energy.

    Modern crane anti fall valving dosnt have circuit relief.

    Looks to me like the failure happened correctly (the boom didnt fall).

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    In the few crane failures Ive been around the operator has been blamed.
    It wouldn't surprise me to hear it was operator failure.

  11. #28
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    Assuming the pic was taken in the as-failed position.....

    Seems to me the crane would have had a lot more capacity had the lower boom sections been extended and the uppers retracted. (Collapsed might be the wrong word ) Perhaps this is what loggerhogger and ichudov were saying. Can't the operator control that manually?

    Neil

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    Interest, yes. Relevance, no.
    bullshit
    the subject is a crane failure

    Big crane safety fail today, a 60 ton crane snapped its boom
    Denis described one he knew of

    the op made no mention of who, how or what. that was you that changed the parameters of the discussion to theoretical summation of the event with no facts what so ever other than a picture of a bent boom.
    my theory is they drove that boom under a railroad trestle at 60 mph last week and the guy that welded it back together forgot to preheat the base metal

    take your meds and go on to bed next time

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  14. #30
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    That usually happens to me after a long night of drinking.

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    Quote Originally Posted by L Vanice View Post
    Personally, I object more to the opposite situation, when someone verbs a noun. Not to say that nouning a verb is good.

    Larry
    Douglas Hofstadter had a contest for self answering questions. The winner was "What sentence no verb?"

    Bill

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    Quote Originally Posted by tdmidget View Post
    Interest, yes. Relevance, no. There is no relationship between hydraulic booms and lattice booms. Modern hydraulic cranes are rated on a theoretical weight. Virtually no way you can actually get that weight that close to the center of rotation unless it is a long cylinder of lead or such. Back in the day , lattice boom cranes had to pick with head and heel at the highest boom angle which actually allowed that weight at the crane. Today that weight is actually over the crane. But today a computer will not allow the machine to attempt the pick if outside the capacity. Unless overiden by the operator.
    So you are saying that a hydraulic crane needs no extra force to lift it unloaded form a horizontal position? I kind of thought the geometry of angles and forces followed the same rules regardless of the method of applying the force. But I guess the cable crane is all pull while the hydraulic is pushing to lift the boom.
    Bill D.

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    No. A lattice boom is mostly in compression. A hydraulic boom is subject to bending, very little compression until almost vertical. the hydraulic crane as in the picture has a very heavy tubular telescoping boom with the cylinder inside. This weight reduces its capacity rapidly as radius increases. Thus the inner , lighter sections extend first. It could have been overloaded due to defeating the computer or as previous mentioned the load could have snapped loose and caused a shock load . Either way there is an operator error. If the weight on the crane display exceeded the known or estimated weight of the lift then the lift should have stopped until the cause was determined.

  20. #34
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    Tdnidget, thanks for clearing that up. i never really thought about cranes I just figured a crane is a crane whatever the means of moving it around.
    Bill D.

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    Quote Originally Posted by Bill D View Post
    Tdnidget, thanks for clearing that up. i never really thought about cranes I just figured a crane is a crane whatever the means of moving it around.
    Bill D.
    Well there is nothing wrong with your definition of a crane. A crane is a crane is a crane... It's simply a matter of each different style of crane being a trade-off taking into account the specific site needs. The big advantage of the extending-boom crane is quick setup, but the massive cross section of the box beams that make up the boom along with the needed hydraulics also weigh a lot for a given length of boom. That said, you can roll up to a site, put down your outriggers, hydraulically raise the boom, make a lift or two, and get back into a mobile configuration very quickly---in a matter of an hour or two presumably. And it is (usually) all self-contained. Really big extending cranes have to carry the boom separately for reasons of maximum over-the-road loads.

    The lattice type boom is much much lighter for a given length allowing bigger payloads for the same basic crane body size. But, I mentioned above that it could take a crew many hours to unload the boom sections (ours were 10, 20, or 30 foot sections) from possibly several trucks, string out and connect the the boom guy wire cables, pin together the boom sections and bolt in the keeper pins, assemble and connect the stinger etc. But once all put together it could make heavier lifts for a given gross weight as it was not having to counterbalance as much weight in the boom. http://toptenpk.com/wp-content/uploa...r-LR-13000.jpg

    So, for just a few lifts you will usually see an extended boom type crane. For many lifts and very high lifts the lattice will usually win out. It simply a matter of time and money.

    But both styles of crane have to obey the same balance principles and in either style if you are booming out (lowering the boom) with a load and the crane starts to tip, all you can do is release the load or ride it over as it tips. (Makes for not a good day for the operator and perhaps the ground crew as I have witnessed.) The box beam style boom is built more like a cell phone tower and the lattice more like a TV tower.

    Denis

    PS as a youngster working for the company I was surprised that there was a specified clearance on the lattice boom ear/pad that specified around 20 thou by feeler gauge clearance between the pads that took up the compressive load between each section. This being true when the boom was strecthed out on the ground. Once the boom was vertical those gaps closed quickly. That was before I learned that "everything is made of rubber." Makes all kinds of sense now.

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    Nice picture... It's that the crane version of those Russian dolls?

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    Good definition of lattice verses squirt booms. This was a structural failure that could have had many causes. After 35 years of operating cranes I will agree it is operator error no matter the cause. Because if I don't get in the seat it will not happen.


    Quote Originally Posted by tdmidget View Post
    No. A lattice boom is mostly in compression. A hydraulic boom is subject to bending, very little compression until almost vertical. the hydraulic crane as in the picture has a very heavy tubular telescoping boom with the cylinder inside. This weight reduces its capacity rapidly as radius increases. Thus the inner , lighter sections extend first. It could have been overloaded due to defeating the computer or as previous mentioned the load could have snapped loose and caused a shock load . Either way there is an operator error. If the weight on the crane display exceeded the known or estimated weight of the lift then the lift should have stopped until the cause was determined.

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    These scary accidents happens when you simply don't take precautions. sometimes blind spots are not visible and become reason for lost of life. Crane is used for heavy equipment where the risk is higher. A crane sis never complete without an efficient crane camera system that removes operator blind spots and enhance work safe.

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    Spammer alert...

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    Quote Originally Posted by ChloeDion View Post
    These scary accidents happens when you simply don't take precautions. sometimes blind spots are not visible and become reason for lost of life. Crane is used for heavy equipment where the risk is higher. A crane sis never complete without an efficient xxx that removes operator blind spots and enhance work safe.
    I seriously doubt you are from Georgia. Your IP 185.230.62.161 seems to suggest your out of mainland China. Good luck with lying like that. We treasure frauds.

    ​Spam Alert.

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