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PEM® S-RT™ free-running locknuts are free-running until clamp load is induced. A modified thread angle on the loaded flank provides the vibration resistant locking feature.
  • Screw turns freely until a clamp load is applied.
  • Resistant to vibrational loosening.
  • Back side of panel is flush or sub-flush for screw installation.
  • Locking feature reusability is not affected by number of on/off cycles.
  • Uses same mounting hole and installation tooling as standard S™ nut fasteners found in PEM® Bulletin CL.
Unit of Measure

Thread Size

 N/A .250-20 (1/4-20)

Thread Code

 N/A RT0420

Shank Code

 N/A 2

A (Shank) Max.

 N/A .087 in RT-Drawing.jpg
Rec. Min. Sheet Thickness1 N/A .090 in

Hole Size in Sheet + .003 - .000

 N/A .344 in

C Max.

 N/A .343 in

E ± .010

 N/A .440 in

T ± .010

 N/A .170 in

Min. Dist. Hole C/L to Edge

 N/A .34 in

For Use in Sheet Hardness

 N/A HRB 80 / HB 150 or less

Thread Specification

 N/A Modified thread form on loaded flank. Will accept a maximum material 6g screw.

Fastener Material

 N/A Hardened Carbon Steel

Optional Finish

 N/A Zinc plated per ASTM B633, SC1 (5µm), Type II, yellow

CAD Supplier

 N/A PennEngineering® (PEM®)
  • 1 For maximum performance, we recommend that you use the maximum shank length for your sheet thickness.