Tuesday, October 12, 2010

August 9th, 2010

Salvador, Brazil A crane collapsed with three workers on it killing two and burying one whom was rescued and appears to have survived. The employees are employed by the crane erector whom was also responsible for the operation of the crane. Unfortunately nothing indicating a potential learning moment crops up from the story.

The crane appears to be a small top slewing crane and from the two pictures that I've found I don't see any mast, yet both the tip and the counter jib of the crane. It should be safe to say that the entire super stucture has dismounted the tower. There are a number of things that can cause that. Old technicians have told me uncomfortable stories about testing the slewing brakes on the old cranes. On some of the old cranes you'll see "toppling hazard" stickers in reference to closing the brakes without slowing the swing. Well, that used to be a method of testing the brakes on some cranes. You closed all of the brakes simultaneously and timed the braking. Fortunately I've never seen that... intentionally. I've seen a faulty bearing cause an immediate stop and I don't ever want to see that again. We had five of us up top and before we swung a second time, three of us were below the turntable... of course we were just listening and not terrified... right? We dismantled that crane and installed a new bearing.

The crew may have been inspecting the crane to determine what the problem was. Bearings and broken welds are often difficult to determine. We often hear noises in our cranes and we should pay attention to them. Having a second set of eyes is critical to seeing the whole picture. I had a crane on a cross base once that was fracturing the counter weights because the base was flexing excessively. Age and slop on the pins? I don't know. We welded in some beams that ran horizontally and stiffened the structure. The popping stopped when the beams were added and I ended up being safe. Is it possible that they were searching for a problem and were too late in finding it?

colapso do guindaste de torre

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