Patent ID: 6328173
Filing Date: 2001-12-11
Classification: B66C,E02F,F15B

Abstract:
A crane comprising:a hydraulically actuatable jib system;at least one cylinder-piston assembly for actuating said jib system; said cylinder-piston assembly including a cylinder a piston guided for movement in said cylinder;a valve to regulate a feed flow of hydraulic fluid to said cylinder;a drive to vary a cross section of said valve and thereby the feed flow;a lever-actuated control system to produce a first control of said drive to thereby achieve a first change of said cross section of said valve;at least one sensor to monitor pressure in said cylinder and to generate a signal representative of loading on said crane;a control unit, operable in response to said signal, to generate an output signal representative of variation of said pressure in relation to time, and thereby of loading of said piston in said cylinder in relation to time, and to produce a second control of said drive to thereby achieve a second change of said cross section of said valve in a manner to reduce the variation of said pressure; andsaid first and second controls of said drive being superimposed and independent of each other.