High-Efficiency Gearbox Upgrades Pearl Harbor Operations

Dec. 9, 2009
New planetary speed reducers produce more power with smaller motors.
Bonfiglioli USA, www.bonfiglioliusa.com

Most Americans are aware Pearl Harbor played a pivotal role during World War II. Many, however, are surprised to learn that today, Naval Station Pearl Harbor is the U.S. Navy’s busiest port as home to the Pacific fleet. The base annually handles about 65,000 boat runs and transports approximately 2.4 million passengers and 200,000 vehicles.

To keep facilities up to date, early this year the Navy began refurbishing a large dry dock and upgrading its capstans — the powerful winches used to pull vessels into dry dock.

Navy contractors tapped Schoellhorn-Albrecht Machine Co., a St. Louis-based firm, to design and fabricate 16 replacement capstans. Thirteen will sit along the refurbished dry dock, and three larger ones will be used in specially outfitted area for demagnetizing, or “degaussing,” submarines.

Navy specs dictated capstans in the demagnetizing area be capable of maneuvering a submarine as close to the dock as possible and have an added safety margin in case extra capacity is ever needed.

To match the requirements, Schoellhorn-Albrecht engineers selected compact and powerful planetary speed reducers from Bonfiglioli USA, Hebron, Ky., for both the demagnetizing and dry-dock capstans. The three Size 315 units used with 40-hp motors for demagnetizing have a 172:1 ratio and generate 360,000 lb-in. of torque. Of the remaining reducers, three are Size 313 used with 25‑hp motors and have a 346:1 ratio producing 300,000 lb-in. of torque; and 10 Size 311 units with 15-hp motors have a 341:1 ratio producing 180,000 lb-in. of torque, says Greg Schulte, president and CEO of Bonfiglioli USA.

A key factor in selecting these reducers, says John Richardson, sales and marketing manager for Schoellhorn-Albrecht, is the efficiency of Bonfiglioli units compared to competing designs. “Efficiency comes up a lot in our business,” he says, “and Bonfiglioli’s speed reducers are so efficient that the new capstans meet the Navy’s power requirements with smaller motors than those on previous versions.” For instance, in the dry dock, motor size dropped from 30 to 25 hp. Units are also built for severe duty because shock loads and impacts are more the rule than the exception, Richardson says.

Another benefit: The new reducers can be configured in a variety of ways, Schulte explains. This gives customers several options for mounting, gear layout, output shafts, and motor interfaces. In this case, they are right-angle reducers with horizontal-mount motors, says Schulte. ”This is a standard design, and we just adapt the motor and gear size per the required pulls,” he says.

The Bonfiglioli speed reducers have the added benefit of increasing the capstan’s overall life. Heaters in the electric motor engage whenever the motor is activated to help dissipate condensation build-up. And synthetic lubricants improve load capacity and gearbox efficiency.

The 13 capstans for dockside use are undergoing testing and audit by the U.S. Navy. They are expected to be installed in early 2010. The three capstans for the submarine-demagnetization area are slated for completion and installation by mid-2010. They should all have operational lives well over 20,000 hr.

About the Author

Kenneth Korane

Ken Korane holds a B.S. Mechanical Engineering from The Ohio State University. In addition to serving as an editor at Machine Design until August 2015, his prior work experience includes product engineer at Parker Hannifin Corp. and mechanical design engineer at Euclid Inc. 

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