Scotch yoke: slotted yoke and crank disc, 20 and 30 mm stroke — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/scotch-yoke/  (CC BY 4.0)
Basis: Textbook Scotch yoke: slider displacement = r·sin θ, stroke = 2r; slot sized to a 623 bearing (OD 10) on a Ø3 crank pin, Ø5 shaft
Catalog version: 2026-10-20

Sizes: see table below
- A crank pin rides in a slot across the yoke, so the yoke moves as a pure sine of crank angle with no connecting rod and no rod angularity.
- Stroke is twice the pin offset: the 20 mm crank has its pin hole at 10 mm, the 30 mm crank at 15 mm.
- The slot is 10 mm wide for a 623 bearing (OD 10) on a Ø3 pin through the crank disc; the rod end has a Ø3 hole for the next link.
- Shorter than a crank and con-rod for the same stroke; used to drive displacers and pumps.

stroke  parts  slot  crank pin offset
20 mm  yoke + crank disc  10 × 30 mm  10 mm
30 mm  yoke + crank disc  10 × 40 mm  15 mm

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Scotch yoke — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Scotch_yoke
- Long Earth Society: Engine and rig builds on extrusion frames — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 4 parts): https://xemstudio.com/files/hardware/scotch-yoke/index.json
API: https://xemstudio.com/api/geometry?object=scotch-yoke