Harnischfeger To Build World's Largest Dipper/Clamshell Dredge

Harnischfeger Corporation of Milwaukee has announced that it has been awarded a contract to build the world's largest dipper/ clamshell dredge for Great Lakes International Corporation of Oak Brook, 111. The dredge will consist of a P&H 5700 electric excavator mounted on a self-propelled 220- by 75-foot hull. It will operate with either a 27-cubic-yard dipper or a 50-cubic-yard clamshell bucket for excavation of harbors and river channels. The excavator will be readily convertible from shovel configuration to clamshell boom operation for maximum versatility.

The operating weight of the 5700 excavator, excluding the hull, will be about 1,000 short tons. The unit's slewing rim (turntable) will be attached to the hull on a large adapter mounting designed by Harnischfeger using CADAM-NASTRAN computer engineering technology. This design capability not only optimized the configuration and costs of the hull adapter, but also reduced manhours significantly to speed the design process.

As a dipper dredge, the 5700 has a 92-foot shovel boom equipped with a 92-foot handle and 27-yard dipper.

The boom is set at a 25-degree angle to accommodate an underwater digging depth of more than 70 feet and a maximum dumping radius of 113 feet.

The clamshell has an even more impressive working range. The 155- foot-long, lattice type boom is equipped with a 50-yard bucket that has a maximum digging depth of 150 feet below the water surface.

Maximum dumping radius is 120 feet.

A pair of diesel generator sets mounted within the hull will provide power for operation of the electric excavator. Each generator will be driven by a 4,400-bhp GM Electro- Motive' Division EMD20-645 diesel engine. The dredge will be controlled by a P&H Electrotorque® solid-state system. Total connected DC rated power of the electric motors aboard the 5700 is 5,625 hp.

For further information on P&H excavators, Circle 61 on Reader Service Card

Maritime Reporter Magazine, page 18,  Dec 1985

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First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.