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Longines 25.173
Manual · 8‴ x 11.5‴ · Switzerland · 1939
Dimensions
17.8 mm x 26.55 mm
Height
4.00mm
Jewels
17
Power reserve
43h
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 | 8‴ x 11.5‴ |
|---|---|
| Shape |
Rectangle
Popular in dress watches and certain iconic wristwatch brands.
|
| 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 | 1.33 x 0.76 / 0.20mm |
| Further measures | Mounting Diameter (Dm): 17.8 x 26.0mm Stem height (T): 1.8mm Mounting Height (F): 1.25mm |
Origin & References
| Manufacturer | Longines |
|---|---|
| Country | Switzerland |
| Launch year | 1939 |
| COSC certified | No |
| Signature | 1939: 5882638, 25.17, Longines - Longines
(Longines 25.17) |
| US import codes |
Notes
Remarks: indirect sub second
Breguet hairspring
Other data: balance staff: U1550 stem: W737 mainspring / battery: 1.60 x 10.0 x 0.10 x 360mm Mainspring: 1.600 x 11.000 x 0.100 x 380.000 mm
Breguet hairspring
Other data: balance staff: U1550 stem: W737 mainspring / battery: 1.60 x 10.0 x 0.10 x 360mm Mainspring: 1.600 x 11.000 x 0.100 x 380.000 mm
Family
Series 27.17 - 9LT
27.17, 9L: bimetallic balance, Breguet hairspring
27.173: monometallic balance, Breguet hairspring
base plate, barrel bridge, regulator modified
27.17, 9L new: bimetallic balance, Breguet hairspring
27.17ABC, 9LT: monometallic balance, flat hairspring
27.173: monometallic balance, Breguet hairspring
base plate, barrel bridge, regulator modified
27.17, 9L new: bimetallic balance, Breguet hairspring
27.17ABC, 9LT: monometallic balance, flat hairspring
Related calibers
Longines 25.17
Longines 25.17 new
Longines 25.173
Longines 25.17ABC
Longines 9L
Longines 9L new
Longines 9LT