Round-groove pulley Ø40 × 10 for a Ø5 round band, Ø8 bore — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/round-groove-pulley-40-band5-bore8/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
Catalog version: 2026-10-20

Overall (mm): length 40.0, width 40.0, height 10.0
- Ø40 × 10 pulley with a semicircular R2.5 groove centred on the rim: a Ø5 round band lies in it with its centre on the Ø40 circle, touching the groove over half its section.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
outside Ø  40 mm
groove  R2.5, centre on the rim
band  Ø5 round
width  10 mm
bore  Ø8

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala
- 507movements.com: Brown's movement No. 257: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_257.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/round-groove-pulleys-round-band-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/round-groove-pulley-40-band5-bore8/index.json
API: https://xemstudio.com/api/geometry?object=round-groove-pulley-40-band5-bore8