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Stromag Vector® couplings up to the challenge for tugboat winch application

August 16, 2018
Tugboat Winch

Tugboats are used to manoeuvre extremely large vessels and offshore equipment; their winches need to operate reliably under harsh conditions.

Tugboat winches operate under extremely harsh conditions. Often towing vessels that are many times the size and weight of themselves, their winches must overcome rough seas and extreme loads. Typically hydraulically driven, high pressure pumps are used to convert power from the ships’ engines to the winch. One manufacturer relies on high quality Stromag Vector couplings to accommodate the shock loading and misalignment inherent in the application.

Tugboats are used to transfer, position and hold extremely large vessels and offshore equipment; either in harbour, through canals and narrow passages or even on the open sea. The nature of the application means that the winches are not only expected to tow extreme loads, they will also experience incredibly high levels of shock loading as the movement of the two vessels will be affected by the water current and waves. With this in mind, hydraulic winches are typically specified over mechanical systems as the design will accommodate these challenges more readily.

For a leading designer and manufacturer of tugboat winch systems, the decision to specify hydraulic winches was simple. However, the next challenge was specifying a reliable coupling solution to connect the winch’s hydraulic pump to the tug’s engines. The manufacturer wanted to harness 450 HP from one of the tug’s twin 1,500 HP diesel propulsion engines. The coupling would need to accommodate a large amount of radial and axial misalignment due to the sway of the resilient mounted engine. Further, it would be required to transmit extremely high torque loads reliably while also offering easy maintenance.

Stromag Vector 20

The Vector® coupling utilises Stromag’s GE elastic element concept with high tensile strength fabric embedded into the rubber.

The system designers approached Stromag to recommend a suitable coupling solution. Founded in 1932, Stromag is a leader in the development and manufacture of innovative power transmission components for industrial and marine applications. Forming a part of Altra Industrial Motion Corporation, one of the world’s largest manufacturers and suppliers of mechanical power transmission equipment, Stromag’s customers benefit from a global service network and local engineering support. The expert knowledge and global network allows Stromag to offer high quality, engineered solutions for some of the world’s toughest industrial and marine applications.

After careful review of the application’s requirements, Stromag engineers identified the Stromag Vector® 20 coupling as the best fit. The Vector® coupling utilises Stromag’s GE elastic element concept with high tensile strength fabric embedded into the rubber. This extremely durable material allows the coupling to transfer up to 19,800 Nm of torque with practically zero backlash. The flexibility of the elastic material accommodates high levels of misalignment in all directions while absorbing torque shock loads.

The coupling’s flexible element is incorporated in a radial arrangement which allows for installation and removal without the need to displace the connected equipment. This simple installation and maintenance procedure makes it suitable for marine applications where maintenance and repair operations may occasionally have to take place away from shore.

The Vector® coupling makes up one component of a winch system that is relied upon to tow massive cargo vessels through harbour channels as they move in and out of port. Since being specified, the couplings have performed as required, reliably connecting the propulsion engine with the hydraulic pump.

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