Gib Key Removal

Gib key removal made easier with gib key removal tool

| June/July 1986

  • Rough outline of a gib key removal tool
    Rough outline of a gib key removal tool.

  • Rough outline of a gib key removal tool

The sketches show the rough outline of a gib key removal tool. These tools were commonly available in convenient sizes from 1 to 2 feet in length. They may still be manufactured but, if so, I have no idea where. This tool is particularly effective at gib key removal if the key hasn't been mutilated by someone using a wrecking bar, etc., trying to get the key out.

To remove a flywheel secured with a gib key (a gib key has a small vertical ab on it to permit withdrawal) I use the following approach. First I dig out all rust, grease, dirt, etc. with a sharp tool paying particular attention to the joints where the key and shaft mate. If I can get in behind the inboard end of the flywheel keyway I clean it as well as possible. The tab on the gib key should be carefully examined to insure that the face toward the flywheel is clean, square and not badly damaged. It is most important that the inner face of the key not be angled away from the face of the flywheel. If it is it should be filed so it is at least parallel with the face of the flywheel hub. It is important that no more than necessary metal be removed as this weakens the key and all you may do is cause the tab to bend away from the flywheel when you try to pull the key if you remove too much.

Once the key and keyway are cleaned up examine the keyway for burrs and nicks that must be removed if present. While normally I would use a chunk of bronze or lead when hammering on steel or cast iron, in this case, I believe it better to use a short piece of steel key stock the same width as the keyway in the shaft to drive the gib key into the flywheel just enough to break the rust loose that is probably holding the key very tightly. Once the key has been rapped with several sharp blows examine the joint between the shaft and the key to see if the key has moved at all. It helps to mark the key with a scratch close to the flywheel hub so slight movement may be easily detected. Once it is clear that the key has moved, however slightly, apply one of the rust penetrating oils to the key. (Try to orient the flywheel so the oil will penetrate the joints.)

At this point the gib key removal tool is used to pull the key. This tool is a forging, and a particularly tough one at that, as the stresses are extremely high at "A." The tool is inserted between the tab on the key and the flywheel hub. The tool is intended to be rotated from a point more or less parallel to the shaft toward the rim of the flywheel. If there is too much space between the tab on the key and the flywheel hub, the initial phase of removal will not take place at "A" which is critical. If the gap is too great, a piece of steel stock should be placed between the flywheel hub and point "A." Once the gap has been correctly filled raising the tool should cause the key to withdraw. Increasing the gap as the key is withdrawn will soon require a larger shim between the flywheel hub and point "A." Once the key has been withdrawn sufficiently to lower the pressure required to move the key, point "B" will probably be sufficient to move the key. The point "C" end of the tool is useful in the final withdrawal process. (The flat side of point "C" is laid on the crankshaft.) Point "B" should not be used in the initial withdrawal phase as the pressures are too great for the tool. The difference in torque between "A" and "B" is so large there is no comparison in the effectiveness of the tool in the early withdrawal process.

After the flywheel has been separated from the crankshaft the bore and shaft should be thoroughly cleaned and when reassembled one of the available "anti-seize" compounds should be liberally applied to the shaft and keyway so rust cannot form in the joint.

What to do if the gib key cannot be removed as described above will be the subject of another short article in a future issue.


Gas Engine Magazine A_M 16Gas Engine Magazine is your best source for tractor and stationary gas engine information.  Subscribe and connect with more than 23,000 other gas engine collectors and build your knowledge, share your passion and search for parts, in the publication written by and for gas engine enthusiasts! Gas Engine Magazine brings you: restoration stories, company histories, and technical advice. Plus our Flywheel Forum column helps answer your engine inquiries!

Be sure to take advantage of the Square Deal Subscription Program.

  • No Missed Issues.

  • No Renewal Notices.

  • No Additional Cost.

The Square Deal Subscription Program is designed as a paperless transaction with automatic renewals at a preferred low rate.   With advanced electronic notification, a 100% satisfaction guarantee and an easy opt-out plan, the Square Deal Subscription Program is the best value, risk free, eco-friendliest way to subscribe.

Facebook YouTube