Liebherr to present new subsea crane

By Laura Hatton19 December 2012

The Liebherr RL-K 7500 at sea

The Liebherr RL-K 7500 at sea

Liebherr will present its new subsea crane, the type RL-K 7500, in Rostock in January 2013.

The type RL-K 7500 is a knuckle boom crane which can lift up to 260 tonnes in the air and handle loads down to a water depth of 3,400 metres. The maximum rope diameter is 100 mm and the maximum load moment of the crane is 75,000 kN-m. The boom configuration can also allow working radii of up to 50 m.

The crane has a number of hydraulic and electronic features and loads can be lowered to the water surface with a short rope length between crane boom head and the water line. It also has an active heave compensation (AHC) system to automatically recognise the vessel’s motion and adjusts itself according to this information.

Up to 70% of the power required to operate the AHC system is obtained from Pactronic, a hydraulic hybrid drive system, which has been adapted for subsea applications. The system serves as a pressure storage reservoir incorporating a gas in conjunction with hydraulic fluid.

The subsea crane has a vertical winch frame lifting system where two hydraulic cylinders allow for the adjustment of the lifting height without moving the drum of the hoisting winch. Adjustments for load and water depth can be made by exchanging the Lebus winch drum shells and by adapting the width of the winch to the actual rope diameter.

The RL-K 7500, which has been built according to the latest rules and regulations, can be installed on =drill vessels and heavy lift vessels, Liebherr said.

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