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Restoring 2" Case Reverse Slide Issue

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Old 06-16-2019, 12:12:06 PM
Bob N Bob N is offline
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Default Restoring 2" Case Reverse Slide Issue


Anyone out there who has built a 2” Coles Case, I am rebuilding the valve gear. Things are moving along well. I have most of the new tight pins made and the holes that were egg shaped cleaned up and bushed. I am keeping all the linkage tight ie minimal (no) play. The cylinder valve face has been ground down smooth and a new valve will be made.

My question for the day is the slide that runs in the bronze reverse block. The one on this engine was made of a real hard plastic. It appears to have little wear. It tore up the bronze reverse block, the sides were all gouged out. I am not sure how this was caused. It is likely the fit was loose so the slide just dug in on each stroke. One side was the worse, which made sense as the engine was run 95%+ of the time in the CCW direction looking from the Crank end. This engine was used a lot and run at 600RPM most of the time, running a silage cutter. See video to get idea of speed.

My issue is the material for the slide. The drawings call out steel. This one was a really hard plastic material. Both make sense ie. hard running on soft. The Coles instruction sheets recommend wood for easy replacement.

What have you used in building yours?

Any other advice on the Woolf valve gear that will help in the rebuild would be appreciated.

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Old 06-17-2019, 10:53:51 AM
chrsbrbnk chrsbrbnk is offline
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Default Re: Restoring 2" Case Reverse Slide Issue

I have a 1/3 scale but the wolfe gear seems to have a pretty high wear rate and any lost motion really hurts on a small model
I'm thinking they went bronze for the the bearing characteristics, so then the choice is something way harder like steel at 62 -60 rockwell or the opposite direction like a plastic with a built in lubricant effect some of the reinforced teflon kinda stuff
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