Patent ID: 6213319
Filing Date: 2001-04-10
Classification: B66C

Abstract:
A method for lifting a multi-ton package comprising the steps of:a) supporting first and second booms respectively from first and second carriages, wherein the lower end portion of a first boom is pinned to said first carriage and the lower end portion of a second boom is pinned to said second carriage each boom having upper and lower end portions;b) supporting third and fourth booms from third and fourth carriages, wherein the lower end portion of the third boom is pinned to the third carriage and the lower end portion of the fourth boom is pinned to the fourth carriage each boom having upper and lower end portions;c) pinning the upper end portion of the first and second booms together to define a first boom apex;d) pinning the upper end portion of the third and fourth booms together to define a second boom apex;e) suspending a lifting beam from the upper end portions of the respective pairs of booms; andf) lifting the package with rigging that depends from the lifting beam by tightening a first cable that links the first and second carriages and by tightening a second cable that links the third and fourth carriages, thus increasing the angle of inclination of the booms and raising the apex of each of the paired booms.