You've probably heard enough about solving first design problems of my pivot joint braking system but while waiting for the larger bearings and shaft to arrive I just had to review alternate fixes and to see how things work for my own satisfaction. The shafts ball bearings are needed for a easy return of the brake lever. The springs that do this are on the brake shoes. It works very well without supplementary return springs.
Even though the design actually works there is a flexing of of the 1/4" shaft of the original prototype design which is being updated with larger shaft and bearings along with stainless steel levers for appearance. Part of the flexing is due to the fact that the bearings gimbal which wasn't considered in the beginning which is what prototyping is all about at least for me.
More thinking on this while the new parts are in transit. With a healthy push on the rear brake lever the deflection of the 7" shaft is about .020" between the bearings, enough to be noticed at the pivot joint. All quite useable but not a perfect prototype design. My first thought was an additional support with yet another bearing in the middle. Hmm, bad design. The shaft is only bending under heavy braking and has stopped rotating. Only a stop in the center would be needed and as braking subsided the shaft would be free to return.
A quick working model was built and the clearance was set at a few thousandths. Quite an improvement when tested but still a slight deflection noticed at the pivot joint. Part of the culprit is the gimbaling bearings which still allow some bending in that part of the shaft. All of this confirms that we need a stronger shaft and/or non-gimbaling bearings. Hey, this is how I learn, I was probably taking an Art class at the time.
I hope I'm not boring everyone with my amateur research but I have learned several things about motion, physics, design and materials. Beats the hell out of TV.
Maxie