I
> >The authoritative is important. You must think of that crank pin (you'll
> never hear us call it a cotter either, those resemble bobby pins and are
> secured
> by inserting and spreading, at least through my old schools of training,
> including '71 Schwinn Factory School and manual.<
Strictly speaking, a cotter is a vague term meaning anything which passes through a hole and is used to fasten something to a shaft. It could be split pin, a parallel sided pin like a bolt with no thread, a taper or the bicycle type which uses a taper and a threaded end. Confusingly, the one you are calling a cotter pin is also sometimes called a clevis pin which strictly speaking is a pin through the two ends of a clevis which is a U-shaped piece of metal used to support one end of a beam. Here in darkest rural sussex, we call a split pin a split pin, a parallel sided pin, with or without a threaded portion at the end, a clevis pin. A pin with one flat side to make a taper, we call a cotter pin. If the pin has a round section and is uniformly tapered, it is a tapered pin. A crank pin is the parallel sided part of a crankshaft on which a connecting rod big end bears.
This has damn all to do with bicycles, but it illustrates again how imprecise technical language can be. Actually, unless I am buying them, I call my cotter pins Desmond and Ruby. They never seem to mind,
Stuart (wishing he had not started this) Tallack