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Castle Nuts in 304 Stainless Steel
Locking Nuts for use with a Cotter Pin or Safety Wire
Castle nuts are used in conjunction with a cotter pin to prevent loosening. This nut has slots (notches) cut into one end. The name comes from the nut's resemblance to the parapets of a castle.
Castle nuts are installed much like any other hex nut, simply being fastened to a bolt or axle. The installation differs in that the bolt or axle has one or two holes drilled through its threaded end. If the castle nut's slot isn't aligned with the bolt or axle's hole, the nut is rotated to the nearest slot. The nut is then secured with a cotter pin or safety wire to the bolt or axle. This cotter pin is then bent to secure the castle nut to the bolt. This completes the locking action.
Castellated nuts are used in low-torque applications, such as holding a wheel bearing in place.
Stainless Steel
18-8 or 304 grades of Stainless steel are suitable for many general purpose applications, especially freshwater and non-salt water wet environments. Corrosion-resistant and durable, 18-8 stainless steel is equivalent to the A2 grade of stainless steel.
| Nut Sizes | Width Across Flats | Overall Height |
| #10 | 0.375" REF | 0.248" REF |
| 1/4" | 0.434" REF | 0.281" REF |
| 5/16" | 0.499" REF | 0.326" REF |
| 3/8" | 0.562" REF | 0.410" REF |
| 7/16" | 0.686" REF | 0.456" REF |
| 1/2" | 0.745" REF | 0.569" REF |
| 5/8" | 0.934" REF | 0.724" REF |
| 3/4" | 1.125" REF | 0.820" REF |
| 7/8" | 1.126" REF | 0.814" REF |
| 1" | 1.498" REF | 1.005" REF |
FAQs
What is a castle nut used for?
Castle nuts, or castellated nuts, are used in low-torque applications as a kind of lock nut. They, combined with a cotter pin, lock an assembly down. A notable example of their use is in holding a wheel bearing.
What is the difference between a slotted nut and a castle nut?
The main difference between the two is that castle nuts have a round section at the top where the slots are. Slotted nuts have their slots cut into the nut itself. While functionally the same, the added rounded top of the castle nut allow the installed cotter pin to be installed closer to the nut, almost flush, for added secureness.
What fasteners are used to lock castle nuts?
Tradiationally, castle nuts are locked with cotter pins or split pins. R-Clips and safety wire have also been known to be used for installing castle nuts.
What is stainless steel good for?
Stainless steel is good for general purpose applications, especially those involving water or freshwater. Suppose you need stainless steel for more corrosive environments, such as marine or salt-water applications. In that case, we recommend the 316 grade of stainless steel.
Can I use stainless steel nuts with bolts of a different metal?
Depends on the material. Some materials, such as zinc plated steel, are safe to mix with stainless steel. However, aluminum is not safe to use because it risks galvanic corrosion of the materials. We recommend keeping like-metals together in applications.
