Liebherr tower crane expert Christoph Schneider presented the findings of the manufacturer’s investigations into components manufactured to resemble original Liebherr parts, at Cranes Today’s Crane Safety conference in London in June.
He said that the look of some of these products was deceptively good. “In some cases we couldn’t tell on the outside that the unit was a copy, or that there were any problems with it,” Schneider, Liebherr Biberach head of project management told the conference. “They looked good. The exterior of the welds looked fine. It is only when you get inside that you see the problems.”
Schneider’s presentation came after Liebherr-Werk Biberach issued a technical note warning of the dangers.
“Our investigations have shown that these counterfeits, among other things, possess greatly reduced tensile strength, display much lower impact toughness and have inadequate weld joints,” according to the Technical Information TI 684/2007, dated 16 April.
In particular, tower crane section materials did not measure up to Liebherr static strength requirements, even at room temperature. The picture is even worse at cold temperatures. They were shown to become brittle in cold temperatures. “Ductile steel gives a warning before it fails – it creaks. Brittle steel will fail without warning,” Schneider said at Crane Safety.
One measurement of brittleness is how much energy it takes to notch a section of steel with a mechanical test hammer arrangement. “It normally takes 27J of energy to notch a sample of our steel at -20°C (-4°F). One sample tested had a strength of 3J,” Schneider said.
Although welds of these imitations may have looked good on the outside, testing revealed a different picture, according to the document. “The weld joints on the tower section counterfeits analysed, and especially those on the transverse [diagonal] connections, do not come up to standard, and the workmanship is so bad that in some cases only 50% of the transfer cross-section is present.”
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“Christoph Schneider, Liebherr” |
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Up to now, copies were in Asia and not in Europe; this is no longer the case |
The transverse connections help share the loads placed on corner sections. If the transverse members fail, then the corners will be overloaded, Schneider said. “In the tests, some of the corner posts of the tower section counterfeits analysed cracked after just a third of the loadings demanded of an original Liebherr tower section.” And the manner of cracking was worrying too, with cracks propagating deeply into the steel. “This was very unusual,” Schneider said.
Marketing
“Up to now, copies were in Asia and not in Europe; this is no longer the case,” Schneider said. He said that copycat sections’ corners, and identification plates, show subtle differences from the Liebherr originals. But he added that the company will not publish a list of telltale signs of copies because then copycats will change their manufacturing techniques to make it harder to tell them apart. He did say that Liebherr would be happy to work with customers one on one. But he said: sometimes the only way to be sure is a destructive test.
And although the document mentioned investigating the possibility of legal action against the counterfeiters, Schneider said that there is no clear answer about how to take copies out of the market. Although the safest route may be a new tower section direct from the manufacturer, Schneider acknowledged that people will buy secondhand tower crane sections. Copies, he said, are selling for about a third of the Liebherr price, which might tempt any company.
“If you buy a new crane, it is clear what parts are original. With secondhand cranes, there are always doubts- particularly with secondhand cranes bought unseen,” he said. “A detailed visual inspection is necessary, at latest when it arrives. Contracts should specify original parts only.” The company document added that tower cranes using counterfeit components do not necessarily conform to CE marking criteria, and are not covered by the Liebherr warranty.
Peter Hegenbart, head of the Wolffkran technical support department, who was also speaking at Crane Safety, gave his support to Schneider’s comments. “Please do not use copies. We know of an ex-dealer in Germany
who is producing copies of Wolff cranes,” he said. “He has the drawings. We hope he does them in the right way. But we don’t know.”
Beware of the griffin
Liebherr has also issued a technical note warning users not to combine tower crane sections from different manufacturers. In 1993, the German industry’s liability insurance association argued that combinations of components from different manufacturers required these cranes to be certified by a third party expert.
Anyone who combines crane parts from different manufacturers puts a new machine in circulation – and that
person, in legal terms, becomes a manufacturer and is responsible for declaring that the crane conforms with CE safety standards, the document said. Traditional manufacturers base their safety standards on large-scale testing, which only they have access to, it said. One cannot reason that if every single part conforms, the entire machine conforms, because the combination of the parts creates new risks.
In other words, cranes made up of components bodged together from several different manufacturers are not street-legal in Europe.
Christoph Schneider, Liebherr
