Shaft Key- Types, Advantages and Disadvantages

Are you curious to know about Shaft Key?

Don’t be concerned, you arrive at the proper location. You’ll find everything you need to know about it here, From the beginning to the end. Let’s get started now, without further ado…

Let’s go through the basics…

What is Shaft Key?

The shaft key is a small metallic component that connects the shaft and hub to other rotating components like gears and bearings. The axial of the shaft is always parallel to the shaft keys.

Shaft keys are available in a variety of materials and forms and sizes. Rectangular or tapered keys are the most common, and they are typically designed of steel.

The entire component is referred to as a keyed joint when the hub and shaft are joined by the key. For the installation of a key in the Shaft and hub, there must be a specific space. Keyways are the spaces in the shaft and hub where keys are installed.

Any machining process performed on the Shaft and hub for the specified dimensions can be used to build keyways.

shaft key

Types of Soft Key-

There are different types of shaft keys. They are-

  • Parallel key
  • Square Key
  • Tangent Key
  • Round Key
  • Tapered Keys
  • Flat Key
  • Sunk Key
  • Saddle Key
  • Gib Head Keys
  • Woodruff Key
  • Kennedy Keys
  • Splines Key

Parallel Key-

At both ends of the key, the height of this kind of shaft key is uniform. Because of their inefficiency, availability, and convenience of installation, parallel keys are extensively employed in mechanical and automotive engineering.

parallel key diagram

Square Key-

This key’s cross-section has the same height and breadth as the square and looks to be a square cross-section.

The width and thickness of the key, as well as the diameter of the hole in the hub or the diameter of the shaft, are all in standard proportions. They are mounted in shafts to transmit gear from one shaft to the next, as well as to other components.

square key

Tangent key-

A tangent key is a pair of rectangular keys on the shaft that are positioned at a right angle to each other. It’s called a tangent key or tangential key since it’s located on the tangential surface of the shaft.

It has the ability to transmit a large amount of torque, making it suitable for heavy-duty applications. A single tangent key is used to transfer torque only in one direction.

tangent key diagram

Round key-

A cylindrical pin-type key, the round key is cylindrical in form. The pin key and the Nordberg key are other names for it.

These keys are round in shape and partially drilled in hub holes and partially in shaft holes. The main benefit of employing a round key is that the key drilling is repeated after the mating element has been assembled. They’re ideal for low-power applications.  Torque transmission is improved by the usage of round keys.

Tapered Key-

This buried key type does not have a uniform height; instead, it is tapered at the upper surface in a 1:100 ratio. As a result, they’re referred to as tapered keys. These tapered keys are hammered on one end for the perfect fit.

Flat Key-

This key’s cross-section does not have the same height and diameter as the rest of the key; instead, it seems to be rectangular. It has a smooth surface at the bottom as well.

Sunk Key-

Sunk keys are fitted in both the shaft and hub keyways. The top half goes on the hub keyway, while the bottom part goes on the shaft keyway. The sunk key also keeps the shaft and hub from moving together.

They’re made for industrial and heavy-duty purposes.

Saddle Key-

Saddle keys are one of the shaft key kinds that are mounted on the shaft’s surface rather than in the keyway. This shaft key installation necessitates the use of a keyway on the hub but does not need the use of a keyway on the shaft.

The saddle keys are divided into two categories:

  • Flat saddle key
  • Hollow saddle key

Flat saddle Key-

These are taper keys that fit into the keyway in the hub and rest flat on the shaft. They’re often utilised to transport light loads.

Hollow saddle Key-

The bottom of hollow saddle keys has a curved surface rather than flat surfaces.

Gib Head Key-

Gib keys, also known as gib head keys, are tapered and notched machine keys used to secure pulleys and gears on keyed shafts in power transmissions. The key’s head acts as a concussion point, allowing you to hammer without damaging the shaft.

The gib head’s purpose is to make removal easier. In comparison to other keys, they are simple to remove. The Gib key is another name for this key.

Woodruff Key-

The woodruff key is a key that can be adjusted simply. In front perspective, it’s a portion of a cylindrical disc with a segmental cross-section. This key is commonly used in the manufacture of machine tools and automobiles.

Read More About: Woodruff Key : Types | Why Used | Advantages and Disadvantages

Kennedy Key-

The Kennedy key is made up of two square keys. This set of square keys is 90 or 120 degrees apart. At both square keys, the torque is distributed evenly.

It’s simple to put together this key. This key may be used to position the shaft and hub correctly. The Kennedy key looks a lot like the flat key.

This key is used in industrial purposes.

Splines Key-

Splines, also known as the splines key, are a type of key that is built parallel to the shaft’s axis. The shaft prepares integrated keys, also known as splined shafts, by fitting into keyways broached in the hub.

These shafts commonly have four, six, ten, or sixteen splines. Shafts with splines are significantly more reliable than shafts with only one keyway.

Know more about: The Splines Key

Now, let’s move to the Benefits and limitation of the soft keys.

Advantages of Shaft keys-

  • The cost of construction is lower.
  • Reusable as well as easily removal
  • Transmission ranges from high to moderate
  • Standardized to perfection

Disadvantages of Shaft keys-

  • For transferring axial force, a stop lock is required.
  • Unbalances the shaft
  • Not recommended for Shaking and alternating directional loads
  • It’s difficult to get rid of a joint after a long period


Here’s a video to help you understand it better: Take a look-


Wrapping Up-

That concludes the Shaft keys section; I hope you liked your stay and learned something new. Please pass this important information on to your friends and coworkers.

Here are some other articles worth reading:

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