The Enduralock Tidal Lock fastener is designed to be a lower cost permanently locking, high vibration resistant fastener, that for maintenance is reversible and reusable. The components can be manufactured through a forging and stamping process to greatly reduce the cost in production. This allows technology, that originally was developed for the aerospace industry, to be introduced into the automotive industry.
The Enduralock Tidal Lock fastener employs a mechanical lock, which does not rely on friction, and it is highly vibration resistant. The fastener consists of a bolt with 2 machined flats down to the root of the thread. There is a 2-component assembled washer that has flats on its inner circumference which prevent rotation of the washer relative to the bolt. The second washer component has teeth on the end of arms. These engage with teeth on a serrated gear that is keyed into the nut. When a socket applies axial force, the two-piece washer is flattened which disengages the teeth. The fastener is then free spinning, so an accurate preload can be applied. It is ideal for critical applications, as it remains locked even with total loss of preload. In aerospace, the requirement of a self-locking nut (NASM 1312-7) is to withstand 30,000 cycles of vibration. The Tidal Lock fastener withstood 300,000 cycles of vibration without failure. It has also been cycled on and off 250 times. A key attribute of the fastener is that it reduces the time and cost of maintenance. In critical applications, a narrow range of torque will be spec'd for a desired preload. Current castle nuts only allow for 6 gradations of torque per revolution. If the mechanic applies a castle nut to the prescribed torque, and the slots do not align, the mechanic will try a different nut. With the Tidal Lock fastener, there can be 30 - 50 (depending on size) gradations of torque per revolution. This greatly improves the chances of success with the first torque application of the fastener. As all of the components of the fastener are metal, it is also ideal for applications in extreme environmental conditions.
The Tidal Lock fastener is available in a locking bolt version and in a bolt-washer-nut version (as explained above). In the locking bolt version, the flats on the bolt and the washer are eliminated. Instead, there are axial tabs on the washer that constrain the washer in rotation. Otherwise it functions in the same fashion as described above.
In summary, the Enduralock Tidal Lock fastener is a mechanically permanently locking, high vibration resistant fastener, that for maintenance is reversible and reusable.