Patent ID: 7331476
Filing Date: 2008-02-19
Classification: B66C

Abstract:
1. A tower crane for lifting and handling loads with an orientable articulated placing jib, comprising: a mast with a rotating pivot; an articulated jib comprising a jib foot, articulated at its first end on the top of the mast by means of a horizontal rotation shaft, and a jib head member articulated for rotation by means of a horizontal articulation shaft on the second end of the jib foot; a jib holding assembly comprising at least one stanchion attached to the mast or the pivot and extending above the mast, a jib holding cable attached on the jib and guided over a pulley on said stachion, and a moving counterweight connected to the jib by the said jib holding cable; and, a guiding track rigidly secured to the rotating pivot opposite to the jib, said guiding track having a varying slope, wherein said guiding track has at least a first portion and a second portion, said first portion being closer to the mast than said second portion, with the proviso that the slope in the first portion is smaller than the slope in the second portion, said guiding track supporting the said counterweight, and wherein variations in said slope are such that the counterweight exerts a set of variable forces on the said jib and on the structure of the said machine, contributing to balancing the machine during movements of deployment/retraction of the jib in articulated working mode.