Sterling Instrument’s 21 inch and 27 metric size stainless steel adaptors, referred to as the S52FCY (-, M) Series, offer precision, tight bore tolerances as well as shank and bore/shank concentricity. The adapter’s female end is designed to fit 14 shaft diameters from 0.1200" to .4998" (3 mm to 12 mm) features the Fairloc integral fastening system. The male side of the adapter features shafts in diameter from 0.1247" to 0.4997" (3 mm to 12 mm).

The Fairloc patented integral hub fastener does away with marred shafts, permits frequent phase adjustment, timing and position adjustment, and Fairloc adds positive metal-to-metal fastening strength along each hub section.

The integral hub fastener has two slots machined into the hub, radially and angularly. This produces a transverse wedge attached to the solid portion of the hub on one side. A cantilevered clamping section results, which has a taped hole to accept a cap screw passing through a clearance hole in the solid part of the hub. The cap screw passes into a threaded hole in the transverse wedge section. Once the screw tightens, the cantilevered section clamps the shaft. The screw tightens and releases without damaging the shaft or altering the torque-transmitting abilities.