Key, keyway, keyseat - a mechanical system used for coupling a cylindrical shaft to other cylindrical part. There are several types of key shapes: rectangular, rounded, round, semi-circular, tapered, etc.^1)2)3)4)

Correct naming is such that the slot in the outer surface of the shaft is called keyseat, and the the slot in the inner surface of the part coupling to it (hub or bushing) is called keyway. The key is the element engaging with both of them.⁵⁾⁶⁾ The key has to withstand all the sheering forces to be able to transmit the torque, from the motor to the load, or from the mover to the generator.

In a common language, it became popular to use the word “keyway” to refer to the keyseat too.⁷⁾⁸⁾⁹⁾

Rotors are balanced in order to eliminate vibrations. Keyseat has some material removed from the shaft and therefore during the balancing a half-key should be used to compensate for it.

• Shaft
• Torque
• Mechanical coupling