Technical sheet
The 3 Hz Miyota workhorse since 1977: automatic, date, an exposed gilt balance.
Features
Going train
| Arbor | Wheel | Pinion | True speed |
|---|---|---|---|
| Mainspring barrel | 72 | — | 1 rev / 6 hours |
| Center wheel | 75 | 12 | 1 rev / hour |
| Third wheel | 80 | 10 | 7.5 rev / hour |
| Fourth (seconds) wheel | 96 | 10 | 1 rev / minute |
| Escape wheel | 15 | 8 | 12 rev / minute |
Disclaimer
An approximation of the Miyota 8215 layout from public drawings and photographs, not a manufacturer-accurate replica. 21,600 vph (3 Hz), 21 jewels, a running time of more than 42 h, 11½‴, Ø 26.00 mm and 5.67 mm height are Miyota’s published figures. Stop-seconds (hacking) follows Miyota’s current specification; older production was non-hacking (Time+Tide, Caliber Corner). The sources consulted do not name the escapement type: the 3D lever escapement is a generic illustration. Tooth counts, the barrel and train positions and the shapes of the bridges are an approximation; the tooth counts give the published rate and a seconds wheel turning once a minute. The real rotor winds in one direction only; the shared animation winds on both swings. The escapement motion is a kinematic model, not a physics simulation.
Sources