

| Subject: | Re: WTB: woodruff key |
| From: | George Goff |
| Date: | Mon, 22 Aug 2005 20:55:17 EDT |
In a message dated 8/22/05 5:26:35 PM, conradk@MAC.COM writes: << I'm concerned that without a woodruff key, that there would be some movement that would cause wear, etc. >> As you well should be. In a message dated 8/22/05 11:54:28 AM, dhaynes@OPTONLINE.NET writes: << they stopped using the woodruff key. I guess they figure that the pulley being driven will further tighten the pulley nut if it should slip. >> Of course, unless it slips in the opposite (righty tighty, lefty loosey) direction whenever you snatch a downshift. Dispencing with the key does not make sense to me. A nut alone fixing a hub relative to a straight shaft cannot be depended on to maintain the relationship of the two components. The shaft and the bore of the hub have a sliding fit. If only the clamping force of the nut is locating the pulley relative to the shaft, then it is really the coefficient of friction of the sides of the pulley hub which is generating the force opposing independent rotation. A key may not be needed for a shrink fit or an interference fit, but it is necessary for this application. Even some taper fits use keys. Unkeyed the to-and-fro inertial tug-of-war between the alternator and the crankshaft would act to loosen the nut as well as to tighten it. If the hub of the pulley is broached with a keyway and the shaft has a Woodruff keyseat cut into it, then I think the Woodruff key itself simply fell out of the shipping box somewhere along the way. George
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