You don’t get something for nothing. That’s what logic might tell us, but on a recent trip to the Liebherr-Werk factory in Nenzing, Austria, I was surprised to find that Liebherr’s mobile harbour crane design team had found a way to do just that.
At the end of April, Port Technology International was fortunate enough to be invited to visit the factory, where Liebherr designs, tests and develops all its maritime cranes. The Liebherr team had been secretive about the purpose of the visit, only hinting that they had “something special” lined up – and the reveal did not disappoint.
The Pactronic® system
Liebherr’s design team revealed they have come up with a new hydraulic hybrid drive system – called Pactronic® – which promises 30 percent less fuel consumption and 30 percent more turnover. Admittedly, at first this claim sounded too good to be true, but – as with all the best ideas – ingenuity sprang from simplicity.
Usually, a hydraulic motor, a pump and a diesel or electric engine drive the hydrostatic hoist system in a Liebherr MHC. With Pactronic, a secondary energy source is added to the drive system. While lowering the load, the reverse power is regenerated, which charges the accumulator along with surplus power from the primary energy source.
When the crane requires peak power during hoisting, the stored energy of the accumulator is transferred back to the system. As a result, the total hoisting power provided by the accumulator is the sum of the conventional hydrostatic power and the secondary energy. Depending on the operational conditions of the crane, this boost in power can be as much as 100 percent.