Bevel/Miter Gear Mounting Distances

[Aren Siekmeier]

Originally Posted by AdamHeard

There is a little bit of hand waving here, but for the typical FRC swerve that uses 12DP 15T bevels with some reduction after to the wheel (the rough size modules 118, 1717, 973, 1625, etc... have run ) it's okay to use the radial bearing (typical an FR6/FR8 here) to handle these axial loads. If doing this make sure the gear is necked down such as the Vex bevel so it's not rubbing the outer race.

Starting fresh, and not having a massive pile of anecdotal data for these exact bevels to reference, I'd design in better thrust management (or do the match for what thrust you bearing can take and compare that to the loads generated).

A 1" diameter bevel gear driven at the same speed as a 2" wheel delivering 100lb of force to that wheel still only sees a 50 lb thrust load. Increasing wheel size or reduction after the bevel stage, or reducing final force output, reduces this thrust load. Since the radial bearings typically take several hundred pounds radially, sounds reasonable that the groove is deep enough (min. ~30 degree span) to support that small of a thrust load as well. Sounds like some of those swerves did rely on the radial bearing in this way.

Edit: did wheel to bevel diameter ratio backwards. Fixed by multiplying thrust loads by 4.