If you can avoid anything that turns the rollers on the chain, you may
get a little better life in a dirty environment. Even though the
bushings are hardened (and sometimes the rollers, sometimes neither in
really crappy chain), you have a steel against steel wear point.

We use what we call a "follower wheel". Basically, it's a UHMW wheel
with a bump that sticks out for some guiding between the chain sidebars.
The bump doesn't stick out quite to the point of touching the rollers.
The sidebars of the chain sit on the shoulders of the UHMW follower
wheel. Sidebars can wear down quite a lot and still not cause sprocket
engagement problems whereas if the rollers wear even a little, you can
start having problems.

I'm not sure of the speed of the chain or the overall tension so cannot
say if UHMW would be adequate for your application. A spring system
will probably be enough to apply the tension you need.

Oh yea...go as large as possible on any tensioner so that the chain
doesn't have to bang it's way around a small diameter bend.

Koz

Old Nick wrote:

Back to my post hole digger. I want to spring-tension the main drive
chain (5/8"). I was wondering if anyone has any useful ideas about
putting a chain tensioner together. Part of the reason is that I wll
have to use 2, because the chain fouls the mounting (my build :- ) if
I just tension one side.

I have thought of actually using a little sprocket, or a ball bearing
on a shaft (no drive needed, of course). But there was one picture
that appeared to simply use a piece of plastic! Presumably delrin, or
some other slippery, hard material? It looked quite narrow. I assume
it sits only on the chain rollers.

The chain is in exposed, dusty conditions, I might add. That was why
the dragging plastinc idea did not appeal.

Any ideas appreciated.
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