woodruff key

Everything You Need To Know About Woodruff Key

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When it comes to drill and precision tools, there’s nothing more important than knowing your tools. Woodruff keys can get a bit confusing without some background. Would you like to learn more about woodruff keys and their uses? If so, this guide is perfect for you. This guide will cover what you need to know about woodruff keys. This guide includes tips and tricks for using them, their advantages and disadvantages, their different types, and what you could use them for. If you’re interested in learning more about woodruff keys, read on.

A woodruff key is a small, usually metal, tool used to attach the pulley from a belt drive, or any other pulley, gear hubs or other component to shaft and prevent them rotate freely. It is also used to connect flywheel to crankshaft. Its semi circular in shaped and shaped like a key, with one end shaped to fit into the groove of the pulley and another that fits into the grooves of the shafts on which it’s mounted. These keys are typically used with an impact gun or ratchet wrench to quickly break loose stuck pulleys without damaging them.

Woodruff keys are named after Charles H. Woodruff, who invented them in 1869 while working for the Warner & Swasey Company in Cleveland, Ohio. They were initially called “universal keys,” but this name was changed when they became popular among mechanics who needed them to work on many different machines.

woodruff Key

Till Now we have discussed about what woodruff key is and where it is used. But now one most common asking about why woodruff key is used for?

Why woodruff key is used for?

The Woodruff key has some advantages over other types of keys. The main one is that it can be used in places where there is a lot of stress on the shaft and many places where concentricity is important, such as high-speed operation.

Woodruff keys are used in machine tools, such as lathes and milling machines. They also help secure the flywheel of a small internal combustion engine to its crankshaft by fitting into a conically bored hole in the flywheel hub.

An extra advantage is that it can be removed from the shaft with a hammer blow, and the circular profile will push the key out of its slot instead of needing to be pushed axially or pulled from it.

Typical applications include machine tools, automotive applications, snow blowers, and marine propellers.

When Woodruff key Replacement should be done?

Woodruff keys can become worn out over time if you don’t take care of them properly. If you notice that your key is not working correctly or has stopped moving smoothly in the gearbox, it may be time to replace it immediately. You should also replace worn-out keys as soon as possible because they can cause severe damage to other parts of your engine if they continue working improperly for too long.

Pro and Cons:


  • Easily adjustable: The Woodruff Key is a small steel key holding the bearing. It is easily adjustable, which means you can tighten or loosen it to ensure that your bearings are correctly aligned.
  • Woodruff Keys Are Stronger Than Other Types: Woodruff keys are made from high-quality steel that is stronger and more durable than other types of keys. This makes them ideal for use in industrial settings with a lot of wear and tear on equipment.
  • The advantage of using woodruff keys is that they can accommodate any taper in the hub keyway, so there is no need for an exact match between them unless it is required for centering purposes during assembly.
  • The keyway reduces play and stress concentrations, improving the key’s reliability.
  • It is essential for high-speed operation.


Woodruff keys have several limitations:

  • Keyway depth weakens the shaft: The keyway is deeper than the thickness of most shafts, which means that it weakens the integrity of the shaft. This can lead to breakages and splintering when a lot of force is applied to the shaft.
  • It cannot be used as a feather: Woodruff keys cannot be used as feathers because they do not have any feathers on them; therefore, if you want to use something as a feather, then you should look for another type of tool which does have feathers, like, for example, a hammer
  • Require Special Tools: Woodruff keys also require special tools for removal and installation. If you ever need to remove a woodruff key from your engine, you will likely need professional help because there is no other easy way to do it safely without damaging the metal key or camshaft.
  • It can’t carry too much load.: Woodruff keys are designed for small loads, not heavy-duty applications. They’re also unsuitable for high-speed applications because they’re prone to wear and tear. This is because they don’t have bearings or any other lubrication mechanism.
  • Woodruff keys have been around since 1907 and have been used on many vehicles. However, they will not fit all vehicles because they cannot adapt easily to changing configurations or designs.
  • They Are Hard To Find: Woodruff keys are not easy to find at your local auto parts store; instead, you need to order them online or search for specialty shops that carry them in stock to buy one when needed.


Woodruff keys are a significant component of the modern manual transmission system. They help synchronize gear movement and are often the weakest point in a system subject to constant stress. Because of their relative importance, you must understand their operation and maintenance needs.

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