SYSTEM FOR SYNCHRONIZING HOISTING AND LOWERING FOR BLOW OUT PREVENTER GANTRY OFFSHORE CARNE

The present invention relates to a system to synchronize hoisting with lowering for a blow out preventer (BOP) gantry offshore crane. A technical objective to be solved is to provide a system to synchronize hoisting and lowering speeds with each other between a main motor winch installed in the crane. In order to accomplish this, the system to synchronize hoisting with lowering for a BOP gantry offshore crane in accordance to an embodiment of the present invention comprises: a first encoder installed in a wire drum of a first motor winch unit, sensing a rotational speed and a rotational number of a first hydraulic motor; a second encoder installed in the wire drum of a second motor winch unit, sensing a rotational speed and a rotational number of a second hydraulic motor; a first proportional direction control valve to adjust a pressure, a flow rate, and a direction of working oil supplied to the first hydraulic motor from a hydraulic pump; a second proportional direction control valve to adjust a pressure, a flow rate, and a direction of working oil supplied to the second hydraulic motor from the hydraulic pump; and a programmable logic controller (PLC) which receives motion data on the rotational speed and the rotational number of the first and second hydraulic motors from the first and second encoders respectively, and controls each of the first and second proportional direction control valves such that the rotational speeds and the rotational numbers of the first and second hydraulic motors come to be the same based on the received motion data.