cotter slot: meaning, definition, pronunciation and examples

They are very similar and often used interchangeably in casual technical speech. Strictly, a keyway is for a rectangular 'key' that primarily transmits torque, while a cotter slot is for a 'cotter pin' or 'split pin' used for securing and safety-wiring, often in conjunction with a castellated nut. The slot's geometry and application have subtle differences.

Typically, a milling machine with a slot drill or end mill is used to machine a precise cotter slot. In some cases, a broaching tool might be used. For softer materials or repairs, a precision file can be used by hand.

Yes, but it requires skilled machining. Common repair methods include welding the slot closed and re-machining it to the correct dimensions, or machining the slot wider/deeper and using an oversized (or 'oversize') cotter pin. The component may need to be heat-treated again after repair.

Cotter pins and slots provide a positive, vibration-resistant lock that is simple, inexpensive, and visually inspectable. They are often used in critical, rotating applications (like bicycle pedals or aircraft controls) where a loose nut could be catastrophic. The pin can be wired ('safety-wired') for added security.

A narrow, rectangular slot in a shaft or rod, designed to receive a cotter pin or key that prevents rotational movement between components.

Cotter slot is usually technical/engineering (mechanical design, machining, maintenance) in register.

Cotter slot: in British English it is pronounced /ˈkɒtə slɒt/, and in American English it is pronounced /ˈkɑːt̬ər slɑːt/. Tap the audio buttons above to hear it.