Monday, November 29, 2010
November 24th, 2010
Downpatrick Ireland. Getting back after a long US Holiday weekend and I find that Vertikal.net is reporting a Self-Erecting Tower crane having suffered a jib collapse. It's one of those stories that never made the news and is only known because of a reader. Likely the accident caused no injuries, but what could have caused it?
Vertikal notes that winds can cause this. It's true. When you have the jib only partially folded out or stacked, the torsion on the jib is higher than when it's profile is lessened and the entire jib is folded out. But this isn't what sticks out to me. The jib being partially folded in or out is relevant, but what really sticks out to me is the trolley position.
If this were an overload, the hook would not be at the jib. If it were winds at night and the crane were simply weather-vaned, the trolley should be back next to the mast. But the position of the trolley and hook height leads me to think that the crane was being folded up to be removed from the site. The position is where many popular models require the trolley to be placed during erection or dismantling. If a person were to become complacent, and not put that trolley in the right place and span both the eventual horizontal and vertical jibs and continue to fold up the crane, you could easily bend that small jib section.
An odd potential is the Queen's Post suffering a structural failure due to binding during or an undetected detected defect. The big picture is that Self-Erectors need to be treated with care as well. Often contractors and users view them as a toy, but the reality is that they can be dangerous if not handled with care. You have to carry out maintenance and inspection. You need qualified operators and technicians. Follow the manuals and make sure to go back and read it periodically. We get used to doing things one way and a refresher from time to time may expose that you are making a mistake that could be avoided.
Vertikal notes that open discussion is critical to crane safety. I couldn't agree more and that's why I do this blog. It's not to cause fear or hesitation but to insight thought in the process of handling cranes. To cause the operators, and those responsible, to realize that laziness and complacency leads to death. Take that extra moment to do things right. In the end everyone wins. First and foremost, everyone goes home. The equipment lasts for decades. Insurance rates are kept to a minimum which means more money available for tools and wages. And finally, no one's reputation is damaged which can be a really large and unseen expense.
Posted by Gaytor Rasmussen at 7:25 AM