Cotter
From Wikipedia, the free encyclopedia
In mechanical engineering a cotter is a pin or wedge passing through a hole to fix parts tightly together.
Typical applications are in fixing a crank to its crankshaft, as in a bicycle, or a piston rod to a crosshead, as in a steam engine.
[edit] Popular Usage
Formerly, it was common to mount bicycle crank arms using a cotter, though now usually a more easily maintained arrangement is used such as a square tapered or splined interface. These cotters have a short threaded section at the narrower end of the taper, which is used to hold the cotter in place with a washer and nut.
Cotters in bicycles are frequently referred to as cotter pins, which correctly refers to a split pin, so named for its use in retaining a cotter. Because bicycle cotters were normally retained by a nut and washer, the distinction was unimportant in this context.[1]
In other contexts, the distinction is important: a cotter is intended to take considerable shear loads, while a cotter pin is not, having to be soft enough to allow it to secured by being bent.
