Spotlight Rigging By Seth Skydel

The Manitowoc 31000 crane is equipped with two independent load hoist drums grooved for 50 mm wire rope. Its standard line pull is 110,230 pounds.

The crane, which can be outfitted with a maximum 2,126,000 pounds of counterweight, also features a unique self-supporting Variable Position Counterweight( VPC) system. The patented VPC system minimizes footprint and ground preparation needs by automatically positioning counterweight between fully retracted and fully extended positions.

“ On a crane that big, the wire ropes are necessarily large, long and expensive,” said B. Tad Dunville, managing director at Lifting Partners, agents for Unique Group, the U. S. importer for AMC Instruments.“ Where many fleet owners typically replace wire ropes on a time or usage basis, in this case it pays to have another solution, one that lets you understand the state of the cables, including and most importantly the core because that is typically where most faults occur.”

For testing the hoisting, boom and whip lines on a Manitowoc 31000, Maxim Crane Works hired Certex Rigging who brought in Unique Group to supply the

Rope 65 system from AMC Instruments and two magnetic resonance testing( MRT) tools.

For the test, which included evaluating the crane’ s three 50 mm cables for the hoisting line and 34 mm cables for the boom and whip lines, the Rope 65 MRT tool was affixed to each line. The lines were run across their full length while the Rope 65 tool remained stationary.

The Rope 65 system evaluates the wire in the cable from jacket to core by inducing a micro-current in the rope and analyzing changes in the property of the current, which can indicate breaks or corrosion anywhere in the cable. The results are displayed on a laptop or tablet at the site, or a skilled technician can remotely diagnose

30 CRANE HOT LINE ® December 2024 • www. cranehotline. com