Patent ID: 8684197
Filing Date: 2014-04-01
Classification: B66C

Abstract:
1. A lift crane comprising: a) a carbody; b) ground engaging members elevating the carbody off the ground; c) a rotating bed rotatably connected to the carbody; d) a boom pivotally mounted at a first end to the rotating bed with a load hoist line extending adjacent a second end of the boom; e) a boom hoist mechanism that can be used to change the angle of the boom relative to the rotating bed during crane operation; and f) a boom raising assist structure connected to the boom between the first end of the boom and the center of gravity of the boom comprising: i) at least one ground engaging member in contact with the ground; and ii) a boom elevating member extending between the assist structure ground engaging member and the boom, the boom elevating member supporting at least a part of the weight of the boom and being positioned so that it help supports the boom when the boom is at a horizontal position relative to the ground; and is configured to help raise the boom while the boom is raised to an angle of at least 5°; iii) wherein the weight and length of the boom are sufficient to generate a moment that would tip the crane if the crane boom hoist mechanism were to attempt to lift the boom off the ground without using the boom raising assist structure.