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Unitas 158
Manual · 10.5‴ · Switzerland · 1940
Dimensions
23.7 mm
Height
4.05mm
Jewels
15
Power reserve
37h
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 | 10.5‴ |
|---|---|
| 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.
,
Perpetual Calendar
An engineering masterpiece, it accounts for month variations and leap years. It's a testament to horological excellence, programmatically tracking the intricacies of the Gregorian calendar.
|
| Hand count | 3 |
| Hand sizes | 1.30 x 0.65 / 0.21mm |
| Further measures | Mounting Diameter (Dm): 23.3mm Stem height (T): 2.0mm Mounting Height (F): 0.4mm |
Origin & References
| Manufacturer | Unitas |
|---|---|
| Country | Switzerland |
| Launch year | 1940 |
| COSC certified | No |
| Signature | ca. 1940: Arsa, 15 Rubis
(Unitas 150) |
Notes
Remarks: varying bridge shapes (cf. other calibres of the family)
differences not known between 148, 150-152, 154, 156-158, 160, 165
Other data: balance staff: U585 / U1908 (L= 3.44 / 3.6mm) stem: W1259 mainspring / battery: Zf1211, 1.50 x 9.0 x 0.10 x 290mm balance staff ronda: 2390 (10,5) stem ronda: 711 (10,5) Mainspring: 1.500 x 9.000 x 0.105 x 280.000 mm
differences not known between 148, 150-152, 154, 156-158, 160, 165
Other data: balance staff: U585 / U1908 (L= 3.44 / 3.6mm) stem: W1259 mainspring / battery: Zf1211, 1.50 x 9.0 x 0.10 x 290mm balance staff ronda: 2390 (10,5) stem ronda: 711 (10,5) Mainspring: 1.500 x 9.000 x 0.105 x 280.000 mm
Family
Series 148 - 152A
148: sub second
159: sweep second
152A: digital display
159: sweep second
152A: digital display
Related calibers
Unitas 148
Unitas 149
Unitas 150
Unitas 151
Unitas 152
Unitas 152A
Unitas 153
Unitas 154
Unitas 155
Unitas 156
Unitas 157
Unitas 158
Unitas 159
Unitas 160
Unitas 165
Compatible Parts
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