pic: Single Stage Ballshifter

[s_forbes]

Originally Posted by jkelleyrtp

Edit: Did not realize a description had been posted. Your teeth count does not line up 71 vs 72, is that okay to use?

Vexpro sells a pinion gear that has 11 teeth, but the profile is set up so that it is used as a 12 tooth gear (as far as spacing between shafts is concerned).

One thing that I would double check with this kind of design is that the motors are spaced around the shifting shaft in a way that prevents the pinions from over constraining the shifting gears and binding. With the shifting gears being 54 and 60 teeth (both divisible by 3) I don't think there would be an issue with the motors being spaced evenly around the gearbox, but it doesn't look from the render like they are spaced that way.

[Rob Stehlik]

Originally Posted by s_forbes

One thing that I would double check with this kind of design is that the motors are spaced around the shifting shaft in a way that prevents the pinions from over constraining the shifting gears and binding. With the shifting gears being 54 and 60 teeth (both divisible by 3) I don't think there would be an issue with the motors being spaced evenly around the gearbox, but it doesn't look from the render like they are spaced that way.

You make a good point about over constraining things. It's not so much the location of the motors in the gearbox, but the angular alignment of the 11T and 18T gears on all of the motors have to be the same. This is probably not easy to do...

[s_forbes]

Originally Posted by Rob Stehlik

You make a good point about over constraining things. It's not so much the location of the motors in the gearbox, but the angular alignment of the 11T and 18T gears on all of the motors have to be the same. This is probably not easy to do...

After some more thought, I guess there's 3 main requirements:

• Spacing of the motors (easy peasy)
• Correct alignment of both pinions on each shaft (hmm, tricky)
• Assembly such that the pinions of each motor are in synch with every other motor (this part would be fun!)

For what it's worth, the Penguineers used a shifting design with two pinions per motor successfully in 2012. Their solution to these issues was apparently to make 4 gearboxes, one for each wheel.