Hydraulisk kran med organ för registrering av lyftning och nedsättning av last, förfarande för sådan registrering samt förfarande för beräkning av utmattningsbelastningen hos sådan kran

摘要

A hydraulic crane (1) comprising an inner boom 5, a hydraulic cylinder (8) for operating the inner boom (5), and a pressure sensor (34) arranged to measure the pressure in the hydraulic cylinder (8), which crane (1) further comprises a means (36) connected to the pressure sensor (34), which means is adapted to register the lifting up and putting down of a load by detecting the velocity of the pressure variations in said cylinder (8), the means (36) being adapted to register a lifting up and a putting down, respectively, of a load when the velocity of a detected pressure variation exceeds a predetermined value. The invention also relates to a method for registration of the lifting up and the putting down of a load in a hydraulic crane (1) and a method for calculation of the fatigue stress of a hydraulic crane (1) based on the number of registered liftings up and puttings down of load.