Simple Rack and Pinion Zero Backlash (no springs)

[deemoss]

Hi Guys,

I was getting ready to share my "great invention" with you when I decided to do a patent search. Sure enough, someone had a similar idea way before I did :) On the positive side, it will spare me from a lengthy write up.

The patent has now expired so if you are looking for a simple belt reduction with zero backlash between the pinion and the rack check this out. It considers gear on gear but you can substitute the large gear (26) with a rack and two pinions (28 and 30).

The principle is that you have two pinions riding on the rack with each of them having an opposite tooth pre-load applied by the tension of the belt. Each time direction change occurs, the preloaded tooth/pinion drives the rack so no backlash. There are no torque limitations, which can be a problem with split pinion system demanding high accelerations.



Instead of driving one of the pinions (28) directly, as illustrated, I have a small pulley driving the two larger pulleys via a belt which offers 1:3 reduction.



I made a 3d printed prototype, which works great. Iill be ordering the machined parts soon.



The green idler barely touches the belt. The red and motor pulleys are the ones providing tension for tooth engagement on the respective pinions.