Global Fastener News

1993 FIN – New Washer Design Locks Bolts Without Marring Workpieces

November 04
00:00 2010


December 31, 1993 FIN – An improved spring-tab lock washer has been developed which is said to be able to replace cotter pins, lock wires, and split-ring lock washers to secure parts without digging into the material.
Designers at Marshall Space Flight Center, Huntsville, Alabama, developed the spring-tab lock washer, concave lozenge-shaped, with three wing-like spring tabs and three alignment pins that press into mating dimples in the surface of the part to be fastened. Fabricators can make the dimples using a ball-end drill bit and an alignment jig.

The spring-tab lock washer inserts onto the bolt like a standard washer, under the bolt head or nut. The lock washer turns with the bolt until the washer pips align with the dimples in the part. Continued tightening secures the pips into the dimples. During tightening the corners of the bolt pass over the spring tabs; the washer tabs spring up to prevent the bolt head from counter rotating. In the fully tightened position, the bolt cannot loosen by more than one-sixth turn before hitting the washer tabs. ©1993/2010 Fastener Industry News.

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