Washer

Types

Lock washer

Lock washers do not lock, they resist loosening with varying effectiveness. They're designed to be a spring between the bolt head and what it's fastened in, but they are quite weak.

Wedge lock washer

One of the few types of washer that actually do resist vibration effectively. The washers incorporate a wedge shape with a slope angle greater than the angle of the threads, meaning that any rotation of the fastener results in increased clamping rather than reduced. "Nordlock" is the main brand of wedge lock washer.

However suitable they seem for fastener locking, they can be harder to inspect than safety wire and will generally not pass scrutineering (at FSG at least).

Further Reading

• NASA Fastener Design Manual
• Carroll Smith'sScrew to Win

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