26.01.2008

Crane splits during lift

A 45-year-old man escaped serious injury yesterday afternoon after the superstructure of the crane he was operating as part of a multiple lift at a St. Petersburg, Florida construction site parted company with the chassis.
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The crane operator escaped serious injury

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The superstructure and base parted company

The crane was one of six carrying out a multiple lift to move a large steel pipeline that apparently serves as a conduit for electrical services.

George Huffman, an operator with Kelley Crane Equipment Co, was thrown from the cranes cab and found awake and alert when the emergency crews reached him shortly after the incident happened.

Huffman was taken to the Bayfront Medical Center and was reported as suffering from non-life-threatening injuries.

The cause of the crane accident is under investigation.

Kelley Crane Equipment is based in Clearwater Florida and was founded in 1984 by Garen Kelley who owned a steel erection business at the time. The company runs a fleet largely made up of Manitowoc crawler cranes and Grove mobiles.

Vertikal Comment

While it may be a sensitive issue, it has to be said that there only one or two reasons why a crane superstrucure breaks free of its chassis.
they all relate to the slew-ring retaining bolts.

There are a wider number of reasons why such bolts can work loose but the fact is that loose and missing or incorrect bolts are just about the only reason why a superstructure comes off like this. In the case of extreme overload it is the boom or outrigger beams that buckle, rather than the slew ring bolts 'popping'.

The problem is that well torqued slew ring bolts rarely shift, (although there has been a number of notable exceptions) making the daily inspection and regular torquing appear to be a tedious and unecessesary job. However the repercussions of a problem in this area are so catastophic that a regular check is essential.

Most cranes and access machines are reasonably forgiving when it comes to slew ring bolts and a even a visual and finger tip test is better than none at all.

In most cases of susperstuctures parting company with their bases, one or more bolts are discovered to have been missing for some time, while others have been loose prior to the accident. So that even a visual check would have prevented the accident.