How is the Wedge Principle Employed in the HL (Hard Lock Nut)?
In general, forcing a wedge into the gap between a cylinder and its surrounding tube makes it possible to create a powerfully locked assembly (as shown in the figure). Likewise, creating matching key grooves in both a nut and a bolt, and then using a hammer to drive a wedge into those grooves can be used to produce a powerful self-locking effect. However, this method is unsatisfactory from the standpoint of operability. The solution employed in the Hard Lock Nut is to use two nuts to play the roles of the hammer and wedge respectively. A small eccentricity in the sliding part of the convex top surface of the lower nut acts as the wedge. When the upper nut with its concave bottom surface is tightened, the effect produced is exactly the same as that produced by a hammer driving in a wedge.
