Volvo Construction Equipment challenges conventional pipelayers — side booms on bulldozers — with its excavator-based PL4611 and PL4608 pipelayers. The 360-degree swing capability suggests significant pipe-handling advantages including keeping the operator facing the pipe, and Volvo claims better stability with wider track gauge and lower center of gravity than tractor pipelayers. Longer booms and the ability to be converted to a conventional excavator and back are features that further distinguish the first models in Volvo's PL line.
The PL4608 has a maximum tipping capacity of 176,400 pounds and the Volvo PL4611's tipping load is 242,500 pounds. The two form the center of what Volvo plans to be a four-machine line. The largest pipelayer, the PL7015, is expected to have a 330,700-pound maximum tipping load.
Positioning a load with tractor side booms often requires jockeying the whole machine. Each Volvo pipelayer model offers full lifting performance and functionality at all radius positions around its 360-degree swing.
In addition to wider gauge and lower center of gravity, the Volvo pipelayer's boom is mounted inboard of the track frame, closer to the machine's centerline than tractor pipelayers with the boom mounted on one track frame. The resulting improvement in lift capacity and stability allows the Volvo pipelayers to wield longer booms than tractor side booms. Boom lengths range from 30 to 38 feet, depending on model, compared to typical dozer side-based booms of 20 to 28 feet. This allows higher hook height or working further away from the trench to avoid caving in trench walls.
An electronic Load Management System (LMS) constantly computes load charts for 360-degree rotation and infinite machine geometries up to a 35-degree grade. The operator interacts with the system via a graphic display on a monitor in the cab. Load-indicating lights on the boom tip warn the operator and ground personnel if the load exceeds the pipelayer's tipping capacity. A standard anti-two-block device is designed with auto kick-out at full winch-up.
Visibility is substantially improved thanks to elevated cabs and an asymmetric boom design. Because the operator is always facing the load, there is little visibility disadvantage to operating from an enclosed cab.
The larger pipelayers have variable track gauge or easily removed track frames, counterweights and booms. Volvo says these models can either self-disassemble or reassemble in less than one hour without the need for assistance from another lifting machine.
Volvo patented several combinations of excavator design and lifting technology in the new pipelayers. Prototypes of the Volvo PL4611 and the PL4608 have been in the field this spring and summer, and the company expects production units to be available before October 2008.
Volvo PL4611 Specifications
