Keyed Shaft, what is a keyed motor shaft. In mechanical engineering, a key is a machine element used to connect a rotating machine element to a shaft. A machine runs by the power supplied to it by a prime mover such as motor, engine, etc. The power is then transmitted from the prime mover to the machine through a coupler which couples the shafts of the prime mover and the machine.
Connecting a shaft and a part is most commonly done by driving a small piece of metal, which is known as the key between the shaft and the hole that has been created in part mounted over it. The key settles in between the shaft and is partly into the part mounted over it. Axial grooves, otherwise known as key ways are cut in the shaft and then in part mounted on it. Then, the key is fitted between the shaft and the attached portion.
To ensure the complete functioning of the key, both the shaft and rotating machine must have a keyway and keyseat. The keyseat refers to a slot and pocket in which the key fits. However, this whole system is what we call the keyed joint, and this allows relative axial movement between the parts.
There are five major kinds of keys:
1. Sunk: These keys are set half in the keyway of the shaft and half in the keyway of hub or boss of the pulley. They come in following six types:
• Rectangular sunk key
• Square sunk key
• Parallel sunk key
• Gib-head key
• Feather key
• Woodruff key
2. Saddle: Basically, there are two types of saddle keys: the flat saddle key and the hollow saddle key. The flat saddle key is a taper key that fits into a keyway in the hub and is flat on the shaft. It is most times utilised for light loads. The hollow saddle key is a taper key that fits in a keyway in the hub. The bottom of the key is shaped to fit the curved surface of the shaft.
3. Tangent: These keys are used in large, heavy-duty shafts. Pairs of these keys are set in right angles to withstand twisting from applied torque, in just one direction.
4. Round: These are used mostly for low power drives. They are circular and fit into holes drilled partly in the shaft and partly in the hub. Round keys are usually considered to be most appropriate for low power drives. These are not as popular as the rounded edge is much more prone to shearing than a square edge.
5. Splines: Splines are ridges or teeth on a drive shaft that mesh with grooves in a mating piece and transfer torque to it, maintaining the angular correspondence between them. A gear mounted on a shaft might use a male spline on the shaft that matches the female spline on the gear. The splines or serrations are milled or hobbed to size and shape and then heat treated.
Spline keys are usually made on the shop floor by mechanics by published standards.
