JoeNova:
The cable is in a nylon tube so nothing comes in contact with the cable itself.
The cable is at roughly a 180 degree angle because the output gear is facing towards the ground.Its a relatively small project. Savings is roughly $1200/year after the cost of the components for the digital gauge, but if it works, I'll get buy-in on much larger projects I would like to do.
The face of the gear that the cable slides into is flat. There are no spokes, and you cannot see the teeth of the gear. An optical sensor isn't an option in this case. I need something to physically spin.
I am guessing, but if wear is involved, something is touching something. Anyway, how fast is the gear revolving? Is the gear clean enough to glue a bit of reflective tape to it? Then an IR LED could light the reflector and a sensor could pick up the light and signal an Arduino that the gear made one revolution.
Paul