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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

Unit of Measure

Specifications

Thread Size	N/A .250-20 (1/4-20)
Thread Code	N/A RT0420
Shank Code¹	N/A 0
A (Shank) Max.	N/A .045 in Loading zoom
Rec. Min. Sheet Thickness²	N/A .047 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 Edge³	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 Finish⁴	N/A Zinc plated per ASTM B633, SC1 (5µm), Type II, yellow
CAD Supplier	N/A PennEngineering® (PEM®)
Inventory

¹ Other shank and screw lengths available.
² For maximum performance, we recommend that you use the maximum shank length for your sheet thickness.
³ To minimize sheet distortion and maximize product performance, use a centerline-to-edge value greater or equal to the value specified.
⁴ “BL” suffix will be added to part number to designate DuraBlack™ finish.