2,000 tonne Manitowoc flagship

Manitowoc will build a 2,000 tonne capacity lattice boom crawler crane to meet demand for larger cranes to erect bigger refinery vessels and other components.

A primary feature of the design is an innovative moving counterweight tray to “drastically improve• the operation of a heavy-lift crawler crane.

The quad-track Model 31000 was launched at the March ConExpo 2008 exhibition in Las Vegas, US.

Larry Weyers, Manitowoc executive vice president of the Americas region, said that Manitowoc is “creating the mega-sized Model 31000 to meet the challenging demands of global construction, where major projects require ultra high capacity cranes.

“For some time we’ve been receiving feedback from our heavy lift customers that the vessels and other components used in refineries, petrochemical plants and fabrication yards are growing in size,• Wyers continued. “With the introduction of the Model 31000, Manitowoc has once again applied its superior engineering capabilities and knowledge of the market to design an innovative and unique lifting solution.”

Combinations

The single boom on the Model 31000 has FACT connection technology and a range of configurations. Main boom is from 55 to 105 m (180 to 344 feet). Fixed jibs range from 24 to 42 m (78 to 137 feet) giving a maximum main boom and fixed jib combination of 95 m (311 feet) plus 24 m (78 feet). Luffing jibs range from 36 m (118 feet) to 102 m (334 feet) and the maximum main boom and luffing jib combination is 90 m (295 feet) of main boom plus 102 m (334 feet) of luffing jib.

The 31000 is designed to be transported in 85 truck loads. Other than the main boom, all components are designed to be less than 3.5 m (11.5 feet) so transport is easier and permits are easier to get.

On site the 31000 can be erected using a 300 tonne crawler as an assist crane, a 24 m (80 foot) aerial work platform and a telehandler. Engineers estimate that with 60 m (196 feet) of main boom and 60 m (196 feet) of luffing jib and excellent site conditions, the Model 31000 can be assembled in 12 days with minimal crew and equipment.

Counterweight variation

Variable Position Counterweight (VPC) is the “unique lift enhancer• system that automatically extends the rear counterweight radius when more counterweight moment is needed during a lift. It then mechanically locks to prevent the counterweight from moving during operation. The mechanical actuator is controlled by the crane’s EPIC control system and is deployed according to boom angle and applied load.

The VPC allows for pick and carry of all rated loads to make it easier to manoeuvre around a job site. It never touches the ground under normal working conditions so less ground preparation is needed than with other types of counterweight system. The VPC extends from the rear of the crane from 8.38 m (27 feet 6 in) retracted to 28.95 m (95 feet) fully extended.

Another obvious difference from other heavy lift crawlers is that it is mounted on four separate crawler tracks instead of the traditional two. Benefits include “the lowest possible ground bearing pressure with reduced matting requirements and site preparation time,• according to Bill O’Neil, lead engineer on the product development team.

The four tracks are mounted on trunnions, O’Neil said, “This not only provides an efficient means of crawler assembly but also allows the crawler tracks to oscillate during travel to provide uniform load distribution.”

The slewing assembly uses a roller path system instead of a typical turntable bearing. The outside diameter of the roller path is just over 12 m (40 feet) and is a design that helps maximise load distribution and decrease ground bearing pressure. Wear plates on the top of the roller path help protect its surface.

The Model 31000 is powered by a pair of 447 kW (600 hp) Cummins engines. This configuration is designed to give ample power for multifunction operation, O’Neil, explained, and the redundant design allows for single engine operation.