Programmed handling apparatus

Claim 1

A CONTROL SYSTEM FOR AUTOMATICALLY OPERATING A MATERIAL HANDLING DEVICE, SUCH AS AN ORE UNLOADER, FOR UNLOADING MATERIAL FROM A SHIP''S HOLD, HAVING A TROLLEYSUPORTING TRACK, A TROLLEY DISPLACEABLE ALONG SAID STRACK, A GRAB SUSPENDED FROM SAID TROLLEY, A FIRST HOIST FOR HOISTING AND LOWERING SAID GRAB, A SECOND HOIST FOR CLOSING AND OPENING SAID GRAB, A CROSS TRAVERSE DRIVE FOR MOVING THE TROLLEY ALONG THE TROLLEY-SUPPORTING TRACK IN A SHIPWARD DIRECTION TO A POSITION ABOVE A HOLD OF A SHIP AND IN A LANDWARD DIRECTION TO A DISCHARGE POSITION, COMPRISING CROSS TRAVERSE POSITION MEANS RESPONSIVE TO THE POSITION OF THE TROLLEY ALONG THE TROLLEY SUPPORTING TRACK, SELECTOR SWITCH MEANS FOR SELECTING INNER AND OUTER LIMIT POSITIONS OF THE TROLLEY IN A SHIPWARD DIRECTION, INCREMENT SELECTOR SWITCH MEANS FOR SELECTING INCREMENTS OF CROSS TRAVERSE FOR THE TROLLEY, CYCLIC CONTROL MEANS FOR OPERATING SAID FIRST AND SECOND HOISTS AND SAID CROSS TRAVERSE DRIVE IN A SUCCESSION OF CYCLES, EACH CYCLE COMPRISING OPERATING SAID SECOND HOIST TO CLOSE THE GRAB, OPERATING SAID FIRST HOIST TO HOIST THE GRAB, OPERATING THE CROSS TRAVERSE DRIVE TO MOVE THE TROLLEY IN A LANDWARD DIRECTION TO BRING THE TROLLEY TO SAID DISCHARGE POSITION, OPERATING SAID SECOND HOIST TO OPEN THE GRAB, OPERATING THE CROSS TRAVERSE DRIVE TO MOVE THE TROLLEY IN A SHIPWARD DIRECTION INTO A POSITION ABOVE THE HOLD OF THE SHIP, AND OPERATING THE FIRST HOIST TO LOWER THE GRAB, LIMIT CONTROL MEANS RESPONSIVE TO THE CROSS TRAVERSE POSITION MEANS FOR ARRESTING THE CROSS TRAVERSE DRIVE MEAN IN THE SHIPWARD DIRECTION, AND PROGRAMME CONTROL MEANS RESPONSIVE TO SAID LIMIT SELECTOR SWITCH MEANS AND TO SAID CYCLIC CONTROL MEANS AND TO SAID INCREMENT SELECTOR SWITCH MEANS FOR CONTROLLING SAID LIMIT CONTROL MEANS TO AUTOMATICALLY DETERMINE A SUCCESSION OF POSITIONS OF THE TROLLEY AT WHICH SAID CROSS TRAVERSE DRIVE MEANS IS ARRESTED DURING SHIPWARD MOVEMENT OF THE TROLLEY WHEREBY TO ENABLE THE GRAB TO DIG MATERIAL AUTOMATICALLY A PRESELECTED MEMBER OF TIMES AT EACH OF THE POSITIONS SO DETERMINED BETWEEN SAID INNER AND OUTER LIMIT POSITIONS.