Junghans J24
Description
A Roskopf pocket watch movement – that’s quite unusual for Junghans. The caliber Junghans J24, successor to the Junghans J38 caliber series, was intended to be the robust alternative for those whose hard work made wearing a wristwatch impossible, but who did not want to forgo a modern and accurate timepiece.
base plate
Even though it lacks bearing rubies, the execution of this movement was impeccable.
mainspring barrel with slip clutch
As is typical for Roskopf movements, there is no central minute wheel because the hands are driven by a wheel mounted on the dial side of the mainspring barrel via a slip clutch.
The mainspring barrel itself extends well beyond the center of the movement.
gear train
The mainspring barrel drives the second wheel, followed by third wheel, seconds wheel, and escape wheel. Unlike pure Roskopf movements, this one has four wheels, which is why the seconds wheel (at 6 o’clock) and escape wheel rotate in the usual direction, as is typical for a conventional lever escapement.
Therefore, a standard Swiss pallet fork lever escapement is used.
side view of the gear train
The balance wheel is already shock-protected and beats at a modern rate of 18,000 A/h. It even has a long regulator index with which the effective length of the hairspring can be adjusted.
balance cock and wheel
The balance cock is no longer solid, but stamped, a concession to a somewhat less expensive manufacturing method. However, the balance still features a ruby ellipse.
empty dial side
On the dial side, the drive wheel of the mainspring barrel, into which the minute hand later engages, is clearly visible on the right.
The Junghans shock protection for the balance wheel and the visible, deep red pallet fork make even this rather simple movement appear high-quality.
The clutch winding mechanism is also noteworthy, featuring a simple yet highly effective spring-loaded rocker.
Junghans J24: Dial side
Unlike a true Roskopf movement, only the minute wheel is driven by the mainspring barrel; the hour wheel (removed here) is driven, as in “normal” movements, by an intermediate wheel that is connected to the minute wheel.
In the lab
Timegrapher result
Even though the movement was difficult to regulate in the vertical positions, the results on the timegrapher are quite respectable for a Roskopf movement.| horizontal positions | |||
|---|---|---|---|
| dial up | +-0 s/d | 291° | 0.1ms |
| dial down | +-0 s/d | 284° | 0.1ms |
| vertical positions | |||
| crown right (12 up) | -20 s/d | 257° | 0.1ms |
| crown up (3 up) | -5 s/d | 259° | 0.1ms |
| crown left (6 up) | +1 s/d | 258° | 0.1ms |
| crown down (9 up) | -15 s/d | 257° | 0.1ms |
Technical data
| Manufacturer: | Junghans |
| Caliber: | J24 |
| Size: | 18 1/2''' (measured: 42,1mm) |
| Height: | 5,5mm |
| A/h: | 18000 |
| lift angle: | 48° |
| Number of jewels: | 7 |
| Escapement: | Pallet lever |
| Balance types: | monometallic anular balance (two legs) |
| Shock protection(s): | Junghans |
| Balance bearing / direction hairspring: | Clockwise |
| Moveable stud: | no |
| Adjust mechanism: | Long regulator arm |
| Construction: |
|
| Construction type: | pillar construction |
| Winding mechanism: | yoke winding system |
| Setting lever spring: | 1 hole |
| Attachment of setting lever: | screwed |
| Features: |
|
| Production years: | 1953 - 1958 |
| References: | Flume: K1 1957 - |
| Inventory number: | 24045 |
Usage gallery
Junghans Astra pocket watch