Castle Nut / Slotted Nut (DIN 935 / DIN 937)
Castle nuts (also called slotted nuts) have radial slots cut across the top of the nut. After tightening, a cotter (split) pin is passed through a transverse hole in the bolt and through one of the nut slots, mechanically locking the nut in place. Standard for axle, kingpin, and steering tie rod end applications.
Specifications
| Standards | DIN 935 (regular height), DIN 937 (thin), ISO 7036, ISO 7037 |
|---|---|
| Size Range | M5 – M48 |
| Material | Carbon steel, Stainless |
| Common Application | Vehicle axles, kingpins, tie rods, agricultural machinery |
Frequently Asked Questions
How is a castle nut installed correctly?
Tighten the nut to the specified torque, then continue tightening (never loosen) until a slot in the nut aligns with the cotter pin hole in the bolt. If the next slot is not yet aligned, you may need to use a thinner washer or different nut height. Bend the cotter pin legs back over the nut to retain it.
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