Timekeeping in the former East Germany

UMF Ruhla Caliber 24 Movement

UMF Ruhla 24-33

UMF Ruhla 24-33 – showing second hand sweep wheel – drawing from UMF Ruhla Materials Catalogue 1967

The UMF Ruhla Caliber 24 movement was designed in the early 1960s to ensure that materials for production could be sourced from within the German Democratic Republic or from other socialist nations to fit with the ideals of communism.

Ruhla described this movement, which was the mainstay of their watch production, as a “ruggedly designed mechanical type wristwatch which has been manufactured by the VEB Uhrenwerke Ruhla”. The movements were first produced in 1963.

The UMF Ruhla caliber 24 mainspring will power the watch for approximately 28 hours continuous running. The movement was adapted by the company to be produced in order to provide several different functions. It could be fitted with a sweep second wheel, sweep second wheel and date indicator, eccentric second wheel or a moon phase indicator.

The movement has a yoke type winding mechanism, a pin-pallet escapement with a safety blade and roller. the pallet as well as the balance are located under separate cocks, this providing for easy repairability. The barrel can be easily removed separately. The tension on the spring can be relaxed from the rear of the movement.

Ruhla Calibre 24

Ruhla Calibre 24

The size of the caliber 24 movement gave the Ruhla watch factory the flexibility to use the movement in men’s, women’s and children’s watches. It was also used for pocket watches and small size alarm clocks such as the Sumatic and Midimatic clocks.

From 1973, the factory automated the production of the caliber 24 movement and applied strict quality controls to ensure consistent quality watches.

 

 

Know your Calibre 24!

Escapement: Pin Pallet Escapement with a Safety Blade and Roller
Balance Spring: Temperature Compensating
Accuracy: +240 sec/ – 120 sec/day
Number of Beats per Hour: 18,000
Diameter of movement: 24mm
Height of movement: 6mm

UMF Ruhla Calibre 24-xx Movement  UMF Ruhla Calibre 24-xx (24, 30, 31, 39)

24 – Punktuhr using clear discs with dots to display hour and minutes
30 – no seconds
31 – small seconds
39 – Battery powered alarm clock Sumatic and Midimatic

UMF Ruhla Calibre 24-32 Movement  UMF Ruhla Calibre 24-32

Central second hand

 

 

UMF Ruhla Calibre 24-33 Movement  UMF Ruhla Calibre 24-33

Central second hand and date

 

 

UMF Ruhla Calibre 24-34 Movement  UMF Ruhla Calibre 24-34

Digital display for mens mechanical digital

 

 

UMF Ruhla Calibre 24-35 Movement  UMF Ruhla Calibre 24-35

Chronograph stop mechanism

 

 

UMF Ruhla Calibre 24-36 Movement  UMF Ruhla Calibre 24-36

Digital display for women’s mechanical digital

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7 responses

  1. Dave

    I bought a cute old Ruhla, and knew it’s Cal24 but didn’t know what that is. Now I do. Thank you!

    April 1, 2018 at 7:40 pm

  2. Dennis

    Many thanks for this highly informative website and the time and effort you put in!
    Do you know if the calibre 24-35 housed in the chronograph was waterproofed anyhow, and if so, to which depth?

    February 7, 2018 at 11:21 am

    • Thank you. I am pleased you like the website.

      The calibre 24-35 Chronograf was housed in a “waterproof” case. Both the crown and stop buttons have rubber gaskets as does the case back. The case back often depicts a mermaid for added emphasis! The chronograf was also supplied with a waterproof warranty paper with its instructions in the original packing. However, the waterproof ability would only have been basic as at the time of production in the 1970s many watches were labelled as waterproof but were only actually water resistant. Consumer laws changed in many countries in the 1970s and watches which were previously labelled as waterproof had to be changed to water resistant. Water resistance is the equivalent of about 3 ATM which is splash proof. There are Ruhlas with higher water resistance one of which can be found on my 1970s page. These are labelled on the dial as “100% Wasserdicht”. These watches state on the dial 8TM 80 meters. Having said all that, as these are vintage watches, and as with any vintage watch waterproof properties can no longer be guaranteed and I would not recommend testing them out in water!
      Sekondtime

      February 7, 2018 at 2:11 pm

      • Dennis

        Hi Sekondtime,

        many thanks for your elaboration – i certainly wouldn´t test the watch under water, as i don´t trust rubber gaskets after 40+ years of service 🙂

        February 7, 2018 at 3:30 pm

  3. Konrad

    Dear Sir, thank you very much for your work in creating a very informative site.

    September 22, 2017 at 4:04 pm

    • Thank you! I am pleased you found it interesting.

      Sekondtime

      September 22, 2017 at 6:39 pm

  4. Marie Thérèse Collot

    Superbe site merci.

    June 5, 2017 at 8:21 am

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