A key is a piece of mild steel inserted between the shaft and hub or boss of the pulley to connect these together in order to prevent relative motion between them. It is always inserted parallel to the axis of the shaft. Keys are used as temporary fastenings and are subjected to considerable crushing and shearing stresses. A keyway is a slot or recess in a shaft and hub of the pulley to accommodate a key.
Types of Keys
The following types of keys are important from the subject point of view:
§ Sunk keys,
§ Saddle keys,
§ Tangent keys,
§ Round keys,
§ Splines.
