Motion compensation winch

A motion compensation winch having an automatic launch mode, a motion compensation mode, a free wheel mode and an automatic recovery mode, as well as a manual operating mode, the winch comprising:

• a cable drum for winding a cable thereon;
• a secondary gear reduction to rotate the drum;
• a primary gear reduction between a motor drive shaft and the secondary gear reduction;
• a hydraulic motor on the motor drive shaft;
• a primary clutch to engage and disengage the primary gear reduction and drive the cable drum through the secondary gear reduction eliminating the primary gear reduction, thus increasing rotational speed of the cable drum;
• a rotational sensor to sense direction of cable drum rotation;
• a load sensor to determine when a tension on the cable is above or below a predetermined value;
• a secondary clutch to disengage the cable drum and permit the cable drum to rotate freely, and
• a control system to provide:
• the automatic launch mode wherein the load sensor senses when the tension on the cable is below the predetermined value and disengages the secondary clutch to place the winch in the free wheel mode;
• the motion compensation mode wherein the rotational sensor senses when the cable drum is paying in, selects a preset high pressure oil supply for the primary clutch to increase friction and still permit some clutch slippage to retain tension in the cable, and senses when the cable drum is paying out, selects a preset low pressure hydraulic oil supply for the primary clutch to permit clutch slippage to retain tension in the cable, and
• the automatic recovery mode wherein the directional sensor senses the cable drum is paying in, and when the load sensor determines the cable is taut and the tension on the cable has increased over the predetermined value, the secondary clutch engages so full torque is applied to the cable drum through the primary gear reduction and the secondary gear reduction to raise the load.