Quote:
Originally Posted by Kevin Ainsworth
Great design!!!
The more designs someone does the more they learn and the better they get.
Your designs get more compact and innovative every time, keep them coming.
What is shifting the gears? I don't see an air cylinder or servo in there.
I prefer the Vex Versa gearboxes also, due to the fact the output shaft has a flange. The Banebots gearbox doesn't have a flange on the output shaft and that can cause problems if not used correctly. We tried using a round sleeve and a screw/washer to pull the gear up against the Banebots gearbox bearing with bad results last year. We switched to clamp collars and everything ran smooth after that. I agree they're lighter and that's a benefit.
I am a little nervous about retaining the steering balls with a single clip at the top. We went through a discussion about using a clip on our 8WD setup and found they can take about 600lbs of force for a 1/2" shaft so the clip isn't the issue. I am more concerned with the strength of the upper plate that will be seeing that load. I think there are more forces there than you are considering. In normal operations the weight of the robot will bear down on the balls and this will be a non-issue. When the robot is pushed to the side and the balls try to climb out of their grooves you will see vertical load that might cause issues. Again you might be fine.
The other consideration is contamination getting into the steering ball tracks. We had issues with aluminum chips from drilling on the robot, debris from the field and the carpet fibers getting kicked up from the tires getting in the steering grooves. This is the reason that we are switching to sealed ball bearing on our 2nd generation swerves. We disassembled our units and replaced the balls multiple times last year. I would guess Bomb Squad doesn't have this issue because they leave the steering bearing setup above the wheel and not right next to the carpet. I would be interested to hear from them if they have seen this issue also. Maybe consider a labyrinth seal (a winding path to the balls instead of a straight slot between the plates). I was considering using two opposing L-shaped walls instead of two round grooves.
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This is a single speed design. sorry if the description doesn't make that clear.
As far as the retaining clip, in order to cause the balls to try to crawl out their grooves and push up on the robot, the robot would have to pull several Gs of horizontal acceleration.
Thanks for warning about grit getting in the bearing. There is only 0.04" of clearance between the turning gear and the bottom plate, but I'll start thinking about ways to seal that gap.
What bearing did you use on your most recent module?