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Online literature contains the most current information available.
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 x Pitch

N/A M8 x 1.25

Thread Code

N/A RTM8

Shank Code

N/A 1

A (Shank) Max.

N/A 1.38 mm RT-Drawing.jpg
Rec. Min. Sheet Thickness1 N/A 1.4 mm

Hole Size in Sheet + 0.08

N/A 10.49 mm

C Max.

N/A 10.47 mm

E ± 0.25

N/A 12.7 mm

T ± 0.25

N/A 5.84 mm

Min. Dist. Hole C/L to Edge

N/A 9.65 mm

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.