Patent ID: 6843383
Filing Date: 2005-01-18
Classification: B66C

Abstract:
1. A load limiting device for an extension attached to a lifting boom of a lifting apparatus that lift loads by means of a lifting cable; said load limiting device comprising: an insert adjacent the remote end of said extension and pivotally mounted to said extension at a first location; a cable sheave mounted on said insert at a second location for receiving and supporting the lifting cable of said apparatus during lifting operations; a force measuring device associated with said extension, said force measuring device engaging said insert at a third location for measuring the force imposed on said sheave by the lifting cable; an angle transducer associated with said insert for measuring the angle of orientation thereof; a calculating device which receives a signal from said force measuring device and a signal from said angle transducer, said calculating device comprising means for determining the load on said extension based upon said force and said angle of orientation; and control means for determining if an overload condition is occurring in said extension and for controlling operation of the lifting apparatus.