| 摘要 |
A shock and vibration-proof fastener of general application and particularly suitable to hold dual wheels demountably assembled to a cargo vehicle hub. The fastener is designed to isolate the threads thereof from radial and torsion stresses utilizing a split collet encircling the shank of the fastener with its periphery converging toward the collet ends at angles of the order of 4 to 1 relative to the collet axis and having a nesting interference fit with a similarly tapered bore through the parts or wheels to be clamped together. The fastener shank has a threaded well in one end mateable with a cap screw having a self-aligning conical surface on the underside of its head engaging the rim edge of a loose fitting washer. The self-aligning surfaces are preferably provided with a ring of teeth and notches interengaging along helical surfaces having a pitch substantially greater than that of the fastener threads. This feature, acting in concert with a ring of shallow teeth on the washer face in contact with the parts being clamped, positively safeguards against loosening unless unwrenching forces are applied to the washer.
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