Drill “Rivet” for Emmett's Automatic Transmission Model

This is a “rivet” (don't know the exact word) for spinning the gears of Emmett's awesome automatic transmission model.

My printed model was quite tight when I put the gears together. After oiling it, I printed this piece and used a drill with a flat screwdriver end in slow-speed mode to make the gears spin for a while in both directions from both suns, and it's now rotating quite freely.