Cotter Joint

a detachable joint that is fastened or adjusted by a wedge; such joints are usually under tension (stressed). The low chamfer angle of the wedge assures tightness of the joint and provides self-braking, which prevents the wedge from falling out.

A cotter joint is a simple and compact connection and is easily assembled and disassembled. Cotter joints may be used in areas subject to corrosion during operation, resulting in difficulty in turning rusty bolts and nuts of threaded connections. Cotter joints use a transverse wedge with cylindrical or conical surfaces, and a longitudinal wedge. They are widely used to fasten bits and cutters of assembled metalcutting tools, such as boring bars, countersink reamers, and milling cutters.