A castle nut used with the cotter pin and the bolt with drilled hole
The bolt need drill a hole in appropriate position，the hole size should be suitable with cotter bin.
The Cotter Pin must be long enough to be wrapped over the nut and bolt end, as seen below. Advance the nut over the threads. The nut should be tight.
If the hole doesn't line up with the nut notch, tighten the nut more rather than loosening it. Insert the Cotter Pin all the way into the hole so that the loop fits snuggly in the notch of the castle nut.
Next,bend over the split ends of the Cotter Pin， one is over the nut face and the other is over the shaft.
