@__el__toro__ The rack and pinion is self cleaning, regular gear and rack would gum up in no time.
Check out Haag-Streit slit lamp Model 900, (introduced around 1958-1959) it also has other very neat design features that later was copied by Topcon and other knock-off brands.
I Sverige blir folk skitnödiga när det diskuteras gårdsförsäljning medans man i Ungern obehindrat köper 5liters flaskor med vin (10%) till extra pris på motsvarigheten till ICA.