I have an application which would work very nicely using a rack-and-pinion. The problem is: the environment is inherently very dirty. A typical rack-and-pinion arrangement would quickly seize.
Does anybody know of a self-cleaning rack-and-pinion design?
1) What about turning the rack and pinion sideways?
Have the pinion axle go up & down vice horizontal. The dirt/rocks/debris/shavings/particles will fall out of the gear teeth on both rack & pinion because the grooves are now vertical.
2) Eliminate oil or grease (use a dry system) and expect to replace the pair more often.
We have a plasma cutting table that makes use of rack and pinion linear drives. I will be anxious to see what solutions are posted here, as well, as it is a time consuming bugger to keep clean.
How about a relief (deeper root) in the root of one or both elements? I've seen this used on roller chain sprockets in agricultural applications. Rather than debris packing hard in the root, it squirts out the side through the relief. In this case the debris is primarily soil and crop residue.
Give us a schematic of the problem/your solution, you will get much better feedback for the problem you specifically have and any critical nuances that may be apparent.