The Fuji Double-lock Nut

The Fuji Double-lock Nut is designed to prevent loosening by using an eccentric top and bottom nut.

Fuji Seisakusho meets the need for secure nuts, and has developed them with thread sizes ranging from M10 to M100 and can produce them with any sort of steel. In vibration testing by the Japan Quality Assurance Organization, the Fuji Double-lock Nut lasted more than 17 minutes before loosening, an amazing feat particularly when compared to the mere 13 seconds of a standard nut.

For even further protection against loosening, the company also produces the Fuji Triple-lock Nut, which has a patent pending.

Such anti-loosening nuts are used in such applications as railroads, bridges and heavy machinery.

When Fuji Seisakusho introduced the Extra Long Nut in 1997 in newspaper and other advertisements, it generated a great deal of attention.

This special fastener is used primarily in such applications as base-isolating (earthquake-proofing) devices, the joints of reinforcing bar (rebar) in high-rise buildings and when assembling heavy machinery. It thus plays a part in providing critical support in places often invisible to the eye.

The technology for fastening such long screws was developed by experts at Fuji Seisakusho dedicated to creating better products.