MST 521
Mechanical
c. 1973
Date
Hacking
No photos yet
Notes
1973-1976
last MST designed family
Except the calendar discs all parts are usable for each family member.
hacking by stopping the 4th wheel, not as common the balance.
indirectly driven minute allows a big balance and low profile
option: excenter device mounted on regulator (Fig.3)
attention: right handed crown-wheel screw
Dimensions
| Width | 25.6 lignes (57.75 mm) |
|---|---|
| Height | 3.9 mm |
| Stem height | 1.25 mm |
| Hands (H × M × S) | 1.5 × 0.9 × 0.25 mm |
Technical data
| Beat rate | 21,600 vph (3 Hz) |
|---|---|
| Lift angle | 50 ° |
| Power reserve | 56 h |
| Jewels | — |
| Shock protection | — |
| Mobile stud carrier | No |
Complications
| Self winding | No |
|---|---|
| Date | Yes (quick set) |
| Day | No |
| Hacking | Yes |
| Chronograph | No |
Mainspring
| GR code | Zf873 |
|---|---|
| Height | 10 mm |
| Thickness | 0.11 mm |
| Length | 320 mm |
| Barrel diameter | 1.3 mm |