Cranes

Claim 1

AN OVERLOAD WARNING DEVICE FOR A LUFFING CRANE HAVING AN ANGULARLY MOVABLE JIB AND A LIFTING ROPE, COMPRISING A LOAD MEASURING DEVICE FOR MEASURING THE LOAD ON THE LIFTING ROPE, A FIRST INDICATING MEMBER CONTROLLED BY THE LOAD MEASURING DEVICE AND ARRANGED TO MOVE PROGRESSIVELY FROM ONE END OF AN INDICATING PATH IN RESPONSE TO INCREASE IN SAID LOAD, A SLAVE JIB ADAPTED TO MOVE ANGULARLY WITH THE JIB OF THE CRANE TO POSITIONS REPRESENTATIVE OF THE WORKING RADIUS OF THE CRANE, AN ARM EXTENDING FROM THE SLAVE JIB AND ARRANGED TO MOVE IN UNISON THEREWITH, A TRANSMISSION MEMBER ACTUABLE BY THE SLAVE JIB AND ARRANGED TO EXECUTE A LINEAR MOVEMENT WHICH IS PROPORTIONAL TO THE ANGULAR MOVEMENT OF THE SLAVE JIB, MEANS FOR CONFINING THE MOVEMENT OF SAID TRANSMISSION MEMBER TO SUCH LINEAR PATH, MEANS FOR SLIDABLY COUPLING THE TRANSMISSION MEMBER TO SAID ARM AT DIFFERENT POINTS ALONG THE LENGTH OF THE ARM CORRESPONDING TO CRANE JIBS OF DIFFERENT LENGTH, A CAM COOPERATING WITH SAID TRANSMISSION MEMBER FOR TRANSLATING THE MOVEMENT OF SAID TRANSMISSION MEMBER FOR TRANSLATING THE MOVEMENT OF SAID TRANSCAM, A SECOND INDICATING MEMBER, MEANS OPERATED BY SAID CAM FOR MOVING THE SECOND INDICATING MEMBER PROGRESSIVELY FROM THE OTHER END OF SAID INDICATING PATH IN RESPONSE TO INCREASE IN THE WORKING RADIUS, SAID CAM BEING SHAPED TO CAUSE SAID SECOND INDICATING MEMBER TO MOVE TO POSITIONS IN SAID INDICATING PATH INDICATIVE OF THE SAFE LOAD AT ANY PARTICULAR WORKING RADIUS OF THE CRANE, AND MEANS OPERABLE BY APPROACH OF THE TWO INDICATING MEMBERS TO ISSUE A WARNING SIGNAL WHEN AN OVERLOAD CONDITION IS APPROACHED.