NEMA 17 Roller Traction Ring Housing
A gearless roller-traction reducer housing that bolts to a NEMA 17 face (31 mm M3 pattern, 22 mm pilot recess). Three 608 bearings (22 mm OD) work as planet rollers, squeezed between the bare 5 mm motor shaft and a 48.8 mm ring bore. The ideal fit would be 5 + 2×22 = 49 mm, so the 0.2 mm undersize adds preload and the drive has no backlash and no teeth to strip. With the output taken from the carrier, the ratio is 10.8:1. The part is 64 × 64 × 18 mm and has four M3 heat-set bosses for the carrier cover.
mechanism nema17 traction-drive 608-bearing