Spiralock® wire thread inserts feature a unique thread form that maintains bolt tension under severe vibration conditions. They are used in applications where maximum integrity is essential. Examples included helicopter gearboxes and rotor hubs, high pressure lightweight compressors, oil industry drill bits and underground train gearbox casings.
How does it work?
Spiralock® radially centres the male member to the female member and compressively loads each engaged thread on the wedge ramp, resulting in an even distribution of the bearing load on the entire wedge spiral. Fatigue failures due to high stress concentration on the first engaged thread experienced by standard thread forms are virtually eliminated.
With HEICO-LOCK® any bolt loosening results in the internal cams separating and their movement across each other results in an increase in tension and clamp load. During removal, only the cam surfaces move, resulting in low off torque force.
Differing Friction Coefficient between HEICO-LOCK® cams and radial ridges
The cams on the separation plane (joint face) of the individual washers of the pair show a much lower friction coefficient (µi) than the friction coefficient on the radial ridges on the outside of the pair of washers (µo).
Any loosening through a dynamic load will always lead to movement only across the face of the cams of the washers.