Need a part for this caliber? Supporters unlock the parts catalog, factory equivalents, and the donor finder that shows which other movements can supply the part you need.
Become a Supporter
Unitas 88
Manual · 17.5‴ · Switzerland · 1940
Dimensions
39.7 mm
Height
3.70mm
Jewels
15
Power reserve
35h
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 | 17.5‴ |
|---|---|
| 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 | 2.00 x 1.15 / 0.27mm |
| Further measures | Mounting Diameter (Dm): 39.1mm Stem height (T): 1.7mm Mounting Height (F): 0.5mm |
Origin & References
| Manufacturer | Unitas |
|---|---|
| Country | Switzerland |
| Launch year | 1940 |
| COSC certified | No |
| Signature | ca. 1940: Swiss, 16 Jewels - 449733
(Unitas 87, open face calibre) |
Notes
Remarks: hunter calibre
varying bridge shapes (cf. other calibres of the family)
Other data: balance staff: U1909 stem: W1818 mainspring / battery: Zf2853, 1.30 x 14.0 x 0.18 x 390mm balance staff ronda: 3263 (16,5-17,75) balance staff ronda: 3264 (16,5-17,75) stem ronda: 928 (16,5-17,75)
varying bridge shapes (cf. other calibres of the family)
Other data: balance staff: U1909 stem: W1818 mainspring / battery: Zf2853, 1.30 x 14.0 x 0.18 x 390mm balance staff ronda: 3263 (16,5-17,75) balance staff ronda: 3264 (16,5-17,75) stem ronda: 928 (16,5-17,75)
Family
Series 83 - 144
83: open face, H= 4.9mm
84 : hunter, H= 4.9mm
85: open face, H= 4.2mm
86: hunter, H= 4.2mm
87: open face, H= 3.7mm
88: hunter, H= 3.7mm
143: open face, H= 6.05mm
144: hunter, H= 6.05mm
84 : hunter, H= 4.9mm
85: open face, H= 4.2mm
86: hunter, H= 4.2mm
87: open face, H= 3.7mm
88: hunter, H= 3.7mm
143: open face, H= 6.05mm
144: hunter, H= 6.05mm
Related calibers
Unitas 143
Unitas 144
Unitas 83
Unitas 84
Unitas 85
Unitas 86
Unitas 87
Unitas 88
Compatible Parts
14 other catalog sources can supply compatible parts for this caliber.
3 compatible parts catalogued · find a donor to harvest a scarce part.
Supporter feature — sign in as a supporter to browse the parts and donor sourcing.