HTD generator drive: 210 T crank gear and a 2208 bracket (14 : 1) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/htd-generator-drive/  (CC BY 4.0)
Basis: Module 1, 20° involute (ISO 53) as the site's spur gears; the catalog's 15 T pinion, its 2208 adaptor and the 2208 envelope
Catalog version: 2026-10-20

Sizes: see table below
- 210 : 15 = 14 : 1 at 112.5 centre distance: at 150 rpm the 2208 (KV 128, 14.4 Ω, published) turns 2100 rpm and makes 16.4 V open circuit.
- The bracket bolts to the seal cap's outer face with three M4; the motor's base takes four M3 countersunk screws from the bracket's back.

part  teeth  tip_mm  ratio
gear-m1-210t-b12  210  212.0  14.0
motor-bracket-2208-3in      

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- ISO: ISO 53 cylindrical gears, standard basic rack (20°, addendum 1 m, dedendum 1.25 m) — standard — dimensions are facts [verify license at link] — https://www.iso.org/standard/22952.html
- T-Motor (maker's store page): GB2208 gimbal motor KV128: internal resistance 14.4 Ω — web — maker page; values are facts [verify license at link] — https://store.tmotor.com/goods-447-GB2208.html
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/htd-generator-drive/index.json
API: https://xemstudio.com/api/geometry?object=htd-generator-drive