Focus of the DIGIWIN project is to drive large winches with digital hydraulic motors. The winches are used in cranes to lift loads up to 900t in maritime and offshore operations. They can compensate for ship movements in high waves, so that loads are kept in a steady position - Automatic Heave Compensation (AHC).

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Rotation and control of such heavy duty winch drums require extreme torque and precision at low speed. The traditional solution is to use multiple, variable displacement high-speed hydraulic motors mounted on planetary gearboxes that drive the winch drum through a gear ring. Smaller and simpler winches are often driven by low speed, fixed displacement hydraulic motors with no gearboxes. This is simpler and less costly, and the motors are robust and energy efficient. Though, as motors have fixed displacement, energy consuming valves or expensive hydrostatic pumps are needed to control them.

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Digital valve technology makes the low speed hydraulic motors controllable and increases their efficiency. Proven, fixed displacement high torque low speed motor design is combined with electronic controlled valves that connect each individual motor cylinder to either high pressure or low pressure.

In AHC winches digital motors promise significant energy savings, and in addition ship movements can be compensated with heavier loads in higher waves (increased operating window). New control features can make operation safer and easier and improve the quality of work.

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MacGregor and the project partners Diinef, University of Agder and Imenco Bauer Hydraulics will adapt the digital motor technology to winch drives and develop their potential as well as investigate and handle limitations. Results will be demonstrated on a test-winch with 6 digital motors.

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The project is co-funded by the Norwegian Research Councils Maroff program and is expected to conclude by the end of 2019.

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More details are found at the Research Councils homepage

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