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A woodruff key is installed in the hub of a pulley or gear so that the pulley or gear does not slip off the shaft it is attached to or spin freely. These keys are found in motorized devices such as lawn mowers, motorcycles, and cars and are held in place by a threaded fastener. By removing a key, you can remove and modify other parts of your vehicle or replace a bad key to improve performance. [1] X Research source
Steps
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Apply penetrating oil. Put this directly onto the pulley and shaft area to loosen any corrosion that will make the pulley hard to move.Those that come in spray bottles are handy and will still be effective for getting into and breaking up rust on metal.
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Remove the threaded fastener. This holds the pulley in place and can be undone with a tool such as a crank remover or wrench. If the threads are damaged, more tools and methods will have to be utilized, such as pliers.Advertisement
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Clean the shaft. If there is any rust or dirt on the shaft, lightly sand or brush it. The hub of the pulley usually is fit well to the shaft, so the debris can prevent a loosened pulley from sliding off.
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Loosen the pulley nut. Do whatever you can to stop the pulley from turning, then use a tool such as a socket or ring spanner on the nut until the pulley can be removed. [2] X Research source
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Pry off the pulley. Place a pry bar or a large screwdriver behind the pulley, if there is a surface behind it to use as leverage. If not, you can try striking the back of the pulley with a hammer while applying pressure with the pry bar or screwdriver. [3] X Research source
- Use a soft-faced hammer to avoid damaging the components. If you use a normal hammer, hold a wood block against the fastener and shaft.
- Tap the pulley shaft with the hammer. Don’t use too much pressure. For steel hammers, insulate the shaft, nut, and bolt before striking.
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Take out the key. On the now freed pulley, look for a semicircular piece inset into the shaft. This is the Woodruff key. Grip the sides of the key with pliers and remove it. If pliers don’t work, try to wedge it out with a small screwdriver. These keys are delicate, so force can easily damage them, but keys are easily and cheaply ordered in hardware and auto part stores or online and replaced. Remove any shredded key bits in the machine so they don’t cause damage later. [4] X Research source
- You can try tapping a nail on one end of the key, drilling into the center of the key and removing it with a nail, or even heating the key up with a blowtorch and letting it cool repeatedly to loosen it.
- Remember that damaging the key is a far better alternative than damaging the shaft or other part around the key.
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Select the right size. These claw-like devices come in different sizes. You can use measuring tape to find out the diameter of the pulley so that you can buy or rent one that expands to fit over the pulley.
- You’ll need an appropriate socket wrench to adjust the forcing screw on the gear puller.
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Fit the arms. Once the gear puller is set, the center bolt should engage the pulley shaft in proper alignment to prevent slippage. Adjust the arms so that the puller’s jaws are set at about right angles against the pulley or gear. [5] X Research source
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Tighten the forcing screw. Use the socket wrench to tighten the screw at the end of the gear puller until the screw touches the pulley shaft. Continue turning until the pulley can slide free.
- You can strike the exposed end of the gear puller with a hammer to try to loosen the pulley. [6] X Research source
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Remove the Woodruff key. On the freed pulley, locate the semicircular shape in the shaft. This is the key and it can be removed by gripping the sides with pliers or wedging one end with a screwdriver. The key may be stuck. If that is the case, alternative and possibly damaging measures need to be taken. Remember to remove any shredded key bits.
- Try tapping down on one end of the key with a hammer and nail. Another option is to drill into the center of the key and remove it with a nail.
- Rapidly heating the key with a blowtorch and letting it cool can help loosen it.
- Remember that these keys are cheap and readily available online or at hardware and auto part stores, so causing damage to it may be necessary. Damaging the parts around it is a more costly idea.
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Community Q&A
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QuestionWhat if I can't remove the key from the shaft?Community AnswerYou can try to tap out the key with a chisel or pin puncher. You can also quickly heat up the key with a torch and try to remove it again when it cools. You can also drill into it and use a screw or other device to take it out. Whatever you do, avoid damaging the shaft around the key.
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QuestionI have a Predator 500. Will the Woodruff key make it not start?Community AnswerIf the key is on your flywheel, yes, as it controls the engine's spark via the magneto.
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Tips
- Lawnmowers have a "shear" key, which prevents damage to the crankshaft, located in the hub of the flywheel or magneto. These often cause the engine to refuse to run but are easily replaced when you learn how to remove them.Thanks
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Warnings
- Wear safety glasses when using a hammer to strike another metal surface or tool.Thanks
- Use care using lubricating oils. They are often flammable and harmful to skin and eyes.Thanks
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Things You'll Need
- Wrenches
- Prying tool
- Soft-faced hammer
- Penetrating oil
- Gear puller, if needed
References
- ↑ http://www.scooterhelp.com/tips/engine/flywheel.old.vespa.html
- ↑ http://www.vw-resource.com/pulley_removal.html
- ↑ https://www.howacarworks.com/electrical-systems/removing-and-refitting-a-dynamo-pulley
- ↑ https://aylo6061.com/tag/morini/
- ↑ http://www.ebay.com/gds/How-to-Use-a-Gear-Puller-/10000000178758751/g.html
- ↑ https://www.ccohs.ca/oshanswers/safety_haz/hand_tools/gearpullers.html
About This Article
Article Summary
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Woodruff keys are found in motorized devices and are installed in the hubs of pulleys or gears so they don’t slip off the shaft or spin freely. If you need to remove a woodruff key, you can do it using pliers. Start by removing the threaded fastener that holds the pulley in place, loosening the pulley nut, and prying off the pulley with a pry bar or screwdriver. Then, grip the key, which is the semicircular piece inset into the shaft, with pliers and pull it off. You can also use a gear puller to remove the key. Adjust the arms so its jaws are at right angles against the pulley or gear. Tighten the forcing screw until the pulley slides free and you can locate the key. Then, remove it with pliers. To learn how to remove dirt and grime that may make the pulley hard to move, keep reading!
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Reader Success Stories
- "I didn't know which side of the key went to the shaft. This was exactly what I needed."
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"I didn't know which side of the key went to the shaft. This was exactly what I needed."
"Got to know what a woodruff key is. Explanation was clear and simple. "
"Illustrations were clear and directions were concise. Great info!"
