Cone pulleys (speed cones) for gradually varied speed — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/cone-pulleys-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 9 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- Two identical cones mounted head to tail: sliding the belt along them changes the ratio smoothly, from r_small/r_large to r_large/r_small, while the sum of the two radii — and so the belt length, nearly — stays the same.
- Here Ø24–Ø56 × 64 cones at 110 mm; at 20 mm along, Ø34 drives Ø46, ratio 0.74. With straight cones an open belt is -1.54 mm slacker near the ends than in the middle (No. 10's curved cones fix that).
- Brown's No. 9 (cones for gradually increasing or decreasing speed, as in cotton machinery). The belt section lies flat on each cone; its strands twist between the two tilts.
- Parts (each has its own page): cone-pulley-24-56x64-bore8, flat-belt-10x1-5-cone-pulleys-c110.
- Brown's movement No. 9 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
pulleys  2 × Ø24–Ø56 × 64, head to tail
centres  110 mm
ratio range  0.43 – 2.33
drawn at 20 mm  ratio 0.74
belt  10 × 1.5, 345.99 mm

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. 9: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_009.html

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/cone-pulleys-mechanism/index.json
API: https://xemstudio.com/api/geometry?object=cone-pulleys-mechanism