It’s definitely fretting fatigue on the spring pins. I’m thinking the pins are subject because they’re moving and lack lubrication. Whatever goes in there has to be press fit and can’t move or it will be subject to the same fretting and may potentially shear. A bolt will rotate if used in the pin holes and failure might still occur because there’s no lubrication to keep the contact area lubricated. In many of the engineering designs I see, in order to mitigate fretting a consideration is made in preventing movement and provides adequate lubrication. In this case we can only have one because there no localized oiling so I’m thinking two possible solutions; 1. Welding castle nuts to the forks and using bolts with tappet holes and pins. 2. Pressing in stainless taper pins and locking them with stainless cotters pins/stainless tie wire.
In any effect, I was thinking this could also be a large contributor as to why high horsepower cars crack transmission cases. Roll pin works itself out and drops into the gears, gets munched, and pushes them apart. Drives the shafts right thru the bell housing or endcover when the helicals spread?
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