In September, Manitowoc hosted an open house and tour of its manufacturing facility in Manitowoc, Wis. The highlight of the open house was a preview of the company’s new mega 2,535-ton Model 31000 crawler crane. The massive lower carbody—which looked more like a transporter for a space shuttle than a crane—and crane block were on display. The crane is expected to be ready for testing by the end of 2009. Delivery of the first crane to Bulldog Erectors, Newberry, S.C., is scheduled for late 2010.
According to Larry Weyers, executive vice president of Manitowoc’s Americas region, the 31000 boasts at least 17 patents on various designs, including the Variable Position Counterweight (VPC), which is central to keeping the crane’s ground bearing pressure low. “Maximum ground bearing pressure with full load—even over the front of the crane—will be 120 psi,” he said. This is no more ground bearing pressure than experienced on the 250-ton Model 999, he said. This is possible, in part, because all the counterweight for the crane resides on the VPC, which will maintain the center of gravity of the load and crane within the circle of the crane.
No boom was yet installed on the massive crane, but main boom lengths will range from 180 feet to 344 feet. Various fixed jib setups will also be available, but the maximum configuration available is 295 feet of boom with 334 feet of jib.
Building the Model 31000 required Manitowoc to rework its manufacturing facility to accommodate the assembly of the four-story crane and allowed for other upgrades to enhance overall workflow. More than 130,000 square feet of additional manufacturing space have been added to the facility in the past two years and major changes have been made to boom assembly, plate burning and processing, the machine shop, large assembly, and final paint and block.
One of the more significant changes came in the boom assembly area. “By implementing lean manufacturing practices we were able to reduce manufacturing times in that area from 45 days to five days,” said Weyers. Likewise, “By bringing all drum fabrication in house, into one consolidated area, manufacturing times have been reduced from 13 weeks to 3 weeks,” he said.