Thursday, September 24, 2009

July 22nd, 2009

Russia? The title of this video indicates that Russia was the location of this accident. Russia is slightly large and just because it was a Slavic accent doesn't prove that it was Russia or establish where in Russia. But that's not really important.
The link is to a vid of a self erector tower crane coming down in the wind. It also strikes the luffing pendant of a second crane taking the jib down on it.
What I see are cranes weather vaned together. The winds are flat out howling. Then we have a quick change of direction that side loads one of the cranes. The side loading overwhelms the tower and/or it's connections and down comes the crane.
Tower cranes are designed to spin in the direction of the wind. The front jib should be pointing with the wind, indication where the wind is going. This allows the back moment of the crane to face the wind. Essentially the crane is leaning into the wind like you would when you walk in 60 mph winds. The change of direction at the rate shown in the vid appears to be incredible. Sometimes the brakes drag a bit but the crane normally weather vanes say after 20 mph. The rate of direction change may have simply been too much for this crane. Another possibility is that the crane was not put in weather vane mode and the crane was not spinning with the change of direction... or at least not fast enough.
It's a cool vid and if you can't see the link... go up to the word link above, and click on it. I know it's hard to see the highlight, but the link is there.

No comments: