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Helvetia 31
Manual · 18.5‴ · Switzerland · 1930
Dimensions
41.7 mm
Height
4.20mm
Jewels
15
Power reserve
—
Timegrapher
Beat rate
18,000bph
Frequency
2.5Hz
Reference: healthy amplitude ≈ 270–315° fully wound (>200° at 24 h); beat error ideally < 0.5 ms.
Movement
| Movement type |
Manual
Purely mechanical movements wound by hand via the crown, which tensions the mainspring to store energy. As the spring unwinds, it drives the gear train at a controlled rate set by the escapement and balance. Typical power reserves range from 38 to 80 hours, requiring daily or near-daily winding to keep the watch running.
|
|---|---|
| Winding type |
Stem Winding (Crown)
Winding the mainspring by turning the crown attached to the stem, transmitting torque through the winding pinion. Patented by Adrien Philippe in 1842, it replaced key winding and remains the standard manual winding method for both pocket watches and wristwatches.
|
| Setting type |
Stem Set (Crown Pull)
The dominant modern system: pulling the crown out to a setting position engages the hand-setting mechanism. Introduced in the late 19th century and refined into multi-position crowns (date, time, GMT). Used in virtually all modern wristwatches and most 20th-century pocket watches.
|
| Escapement type |
Swiss Lever
The undisputed standard of modern mechanical watchmaking. Through an elegant interplay between escape wheel, pallet fork, and balance, it delivers reliable impulses with the safety of 'draw' to keep the lever locked. Refined since the 18th century, it powers almost every quality mechanical wristwatch made today.
|
| Control type |
Balance Wheel
The heart of mechanical timepieces, the balance wheel is an oscillating component that, together with the hairspring, forms a harmonic oscillator regulating the gear train's pace. Its steady back-and-forth motion ensures the even release of energy from the mainspring, governing the watch's accuracy.
|
| Regulator type |
Pinned Regulator (or Index Regulator)
The most traditional regulator, consisting of a movable index pointer fitted with two curb pins (or a pin and a boot) that embrace the hairspring. Sliding the index along its scale changes the spring's active length, adjusting the rate. Simple, reliable, and easy to service, it remains the workhorse standard across countless mechanical movements.
|
Specifications
| Lignes | 18.5‴ |
|---|---|
| Shape |
Round
It is the most common form that we can find.
|
| Complications |
Sub Second
A small seconds hand typically located on a sub-dial and is separate from the central hour and minute hands. Originating from early pocket watches where the main balance wheel drove the seconds hand, it offers an elegant way to track the passage of time without crowding the main display. It remains a testimony to the watch's mechanical precision and history.
|
| Hand count | 3 |
| Hand sizes | 1.92 x 1.15 / 0.26mm |
| Further measures | Mounting Diameter (Dm): 41.1mm |
Origin & References
| Manufacturer | Helvetia |
|---|---|
| Country | Switzerland |
| Launch year | 1930 |
| COSC certified | No |
| Signature | ca. 1930: Helvetia, 32A, Swiss Made, 15 Jewels - 2832
(Helvetia 32A) |
Notes
Remarks: open face calibre
different bridge shapes (cf. Helvetia 32A)
Other data: balance staff: U2026 stem: W1592 mainspring / battery: Zf3135, 1.60 x 16.0 x 0.21 x 440mm balance staff ronda: 1244 (18,5) stem ronda: 250 (18,5) Mainspring: 1.600 x 16.500 x 0.210 x 480.000 mm
different bridge shapes (cf. Helvetia 32A)
Other data: balance staff: U2026 stem: W1592 mainspring / battery: Zf3135, 1.60 x 16.0 x 0.21 x 440mm balance staff ronda: 1244 (18,5) stem ronda: 250 (18,5) Mainspring: 1.600 x 16.500 x 0.210 x 480.000 mm
Family
Series 30 - suffix S
30: H= 3.62mm
31: H= 4.2mm
32: H= 4.8mm
33: H= 5.3mm
suffix A, B, I: meaning unknown
Suffix L: open face
suffix S: hunter
Not all possible variants were made; here only variants, known from literature or reality, are listed.
31: H= 4.2mm
32: H= 4.8mm
33: H= 5.3mm
suffix A, B, I: meaning unknown
Suffix L: open face
suffix S: hunter
Not all possible variants were made; here only variants, known from literature or reality, are listed.
Related calibers
Helvetia 30
Helvetia 31
Helvetia 32
Helvetia 32A
Helvetia 32BL
Helvetia 33LI
Helvetia 33SI
Compatible Parts
22 other catalog sources can supply compatible parts for this caliber.
23 compatible parts catalogued · find a donor to harvest a scarce part.
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