Swerve drive questions

[nathannfm]

Originally Posted by Gdeaver

The max velocity of the vertical shaft can be > 1200 RPM and while the load is with in tolerance of bronze thrust washers, the ball thrust washers are lower friction. We have yet to see any signs of wear with the ball thrust bearings. Our design pushed us to needle bearings for the vertical drive shaft. They also have provided a low cost durable solution. My only complaint with the needle bearings Is the shaft. Because the needles run on the shaft, the shaft needs to have good surface hardness. I would prefer a case hardened precision shaft. How do you cut a key way in a case hardened shaft? You don't. You can grind one. To avoid the time and hassle we use a 4140/4142 steel shaft. Rockwell B90. After a season there is some wear but very tolerable. We have used Igus bushings for many apps and they have worked very well If you follow Igus design guide lines. The hex shaft on the vex miter gears do not fit our current design and I would not change for them.

For the shafts you might try ceramic coated aluminium shafts from McMaster they have a surface hardness much higher than the steel ones you are currently using and being aluminium are lighter and even easier to machine.

As for the thrust bearings since the inner race of the ball bearing, the miter gear and the shaft should all be spinning at the same speed I don't see where friction comes into play. I was wondering if anyone knows a way to calculate the force along the axle that would be applied to the inner race of the ball bearing by the back of the miter gear if the thrust bearing were not there, and if this would be enough to damage the ball bearing. I understand that with the thrust bearings being as inexpensive as they are it can't hurt to have it, but I was curious if calculations could be done to prove its worth.