New National Supply Anchoring Windlass

A new heavyweight anchoring windlass offering major advances in braking capability and load control has been developed by National Supply Company for semisubmersible d r i l l i n g r i g s and drillships. The company says the D-520-E has been engineered to assure stability and safety under the higher loads resulting from the trend toward larger drilling vessels, greater operating depths and more severe offshore environments.

The D-520-E is a double wildcat, electrically powered design.

Key improvements that contribute to greater load control are: Almost twice the wildcat braking area of the largest windlasses previously available from National Supply; a new, optional hydrodynamic auxiliary brake for controlled chain payout in deepwater mooring; and more positive, easier- to-set chain stopper mechanism.

The water-cooled band brake area on the wildcat pinion shaft has been increased by 92 percent, with substantial gain in thermal performance.

A second band brake operates on the motor pinion shaft and releases releases automatically when the motor is energized.

The combined capacity of the two brakes is 926,000 pounds. National says the rating is a "real" figure based on a friction coefficient of .33 typical with moisture conditions on working rigs. Computed at a coefficient of .40, the rating would approach 1,500,000 pounds, the company notes.

For additional braking control, National Supply offers as an option the newly developed auxiliary brake. Fitted to the gearbox, the brake is a hydrodynamic-type of essentially the same design as used on the drawworks. It was selected for its proven performance and the familiarity of oilfield people with its operation and maintenance, says National Supply- National Supply manufactures the widest range of drilling, production and related equipment in the oil and gas industry. It produces a complete line of windlasses, winches and fairleaders for marine and drill rig mooring system.

For literature on National Supply's complete line of mooring equipment, write William D. Marmack, National Supply Co., Division of Armco Steel Corp., 1455 West Loop South, Houston, Texas 77027.

Maritime Reporter Magazine, page 31,  Sep 1977

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Maritime Reporter

First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.