Components used in yacht racing, such as winches, must meet speed, reliability, and weight requirements. Developers of the BMW ORACLE racing trimaran chose crown gears and splines made of special high-strength, lightweight, and corrosion-resistant titanium for use in the engine and winch system.
The necessary components were made from durable Ti-6-4, a popular alloy often found in aerospace applications. The gears and their corresponding spline components were hobbed and shaped, respectively. The crown radius was the point of main concern, owing to the extreme stress and motion present when such gears are in use.
As Jon Williams, a member of BMW ORACLE Racing’s shore team explained, “During the build-up to the previous America’s Cup in Valencia, Spain, we developed our own transmission components for the winch systems. After careful study, we determined these components were critical for improving our performance on the water.” The racing team wanted to reduce mass and increase mechanical efficiency of the gear and spline assembly. A prototype project proved successful and the team undertook a complete redesign of the gearboxes for their USA87 and USA98 yachts. These new gearboxes were manufactured in New Zealand and used by the team in the America’s Cup.
The current edition of the America’s Cup sees different rules than previous Cup programs. Under these rules, all equipment for the yachts must be constructed in the country the team represents. In the case of BMW ORACLE Racing, who races under the flag of the Golden Gate Yacht Club of San Francisco, Calif., this means all equipment must be made in the USA.
Williams continued, “Our project called for a fairly wide selection of gears, splines and driveshaft components, some of which were non-standard sizes. Two vendors we selected to produce these components were Arrow Gear and Forest City Gear.”
For Forest City Gear, Jared Lyford and Tom Christenson ran the project. The gearbox casings and other associated parts were manufactured by RB Enterprises of Everett, Wash. For Arrow Gear, Joe Arvin ran the project to deliver the bevel gears. Final assembly of the gearboxes and their installation occurred at BMW ORACLE Racing’s structural R&D facility in Anacortes, Wash.
At the conclusion of five weeks intensive testing on the waters off Seattle, Wash., and San Diego, Calif., the gearboxes were removed for inspection. The gears showed only the first signs of polishing on flanks. It was concluded that the gears were a significant improvement on the New Zealand sourced gears used by BMW ORALCE Racing in their previous America’s Cup program.
Forest City Gear Co., Inc.
Filed Under: Gears • gearheads • speed reducers, Mechanical