Quote:
Originally Posted by wilnj
I wouldn’t rule out mechanical failures. It happens even with the proper controls.
Modern cranes won’t lift something they’re not capable of but if something shifts once the laid is in the air, all bets are off.
In this case it looks like the panel started to go away from the crane and once that momentum headed in the wrong direction there was no bringing it back.
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DISCLAIMER: I do not currently have an active crane license but was licensed in the past and operated cranes in the 80's while employed as a millwright.
There are two main parts of a load chart: structural and tipping.
There are also parts for "on outriggers" and "on rubber". There's over the front and over the side.
Lots of stuff to check before making a critical pick.
A trained operator knows the weight of the load and can calculate the radius and plot it on the chart whether it's over the front outriggers, over the side, on rubber, etc.
A crane like that is likely forbidden to ever pick on rubber, and rarely allowed to travel without breaking down the stick. Ground compaction etc. comes into play.
If a load is over 50% of capacity, a full lift plan should be developed and signed off by people who KNOW the weight and don't guess.
That prevents stuff like this from happening.
It's possible the operator had a load cell on the crane and was relying on that to tell him if he was over-loaded, but that would be wrong.
And an operator can over-ride anything he wants in the cab. it'll pick whatever he tells it to.
The operator in the video went past the tipping capacity of the crane. Pure and simple.
As he boomed down, the radius increased slightly and was enough to over-load the crane, causing it to tip. There was no load shifting or mechanical malfunction.
It's a Bragg crane, conventional stick, didn't see a jib. Bragg typically employs the best operators around but aren't cheap.
If it were a big hydro it's have all sorts of computers and alarms but it's a conventional.
He was on outriggers but picking over the side.
If I had to bet, I'd bet that was the problem.
From the video is appears that either he underestimated the weight, or used the load chart for over the front instead of over the side.
Scott Bragg is the prez and CEO of Bragg Companies, he was on the school board for St. Paul's Lutheran school many years ago when my kids went there.
We worked together on many occasions and are still members of the same church, next time I run into him I'll ask about it.