1. Servicing a Swiss calendar watch with sweep second hand
Ken Pell
Winter Park Tech
In case we haven’t met, I’m Ken Pell and I have been teaching watch repair at nearby Winter Park Tech for the past 14 years. Three years ago, I entered semi retirement and still teach two evenings each week.
Last year, my presentation addressed the disassemby and reassembly of a basic Swiss movement. Perhaps you were here. Today, we take this to a higher level of complication, with the servicing of a Swiss calendar watch with a date and sweep second hand. Since I am limited to only one hour, I am only going to address the disassembly and reassembly of the movement, not cleaning oiling, and adjusting procedures. Please feel free to ask any questions.

2. Disassembling calendar mechanism
First we disassemble the calendar mechcanism.

3. Pictured here, is the calender movement with the dial and hands removed. It is a caliber from the 1960’s, a Font 96.

4. Carefully remove three screws and bridges
We carefully remove the screws that secure the four bridges as shown. I stress carefully, because it is common for tiny springs and parts to become disengaged prematurely and may fly into never- never land.

5. Observe position of lever and spring
Date ring
With the bridges removed, the date jumper and spring are exposed. Please note the postion of jumper and spring. Carefully release spring tension so that it doesn’t disappear. Placing a flat tool over the spring as this is done, will help.Remove spring, jumper and date ring.
With the bridges removed, the date jumper and spring are exposed. Please note the postion of jumper and spring. Carefully release spring tension so that it doesn’t disappear. Placing a flat tool over the spring as this is done, will help .Remove spring, jumper and date ring.
Observe position of lever and spring

6. Minute wheel Driving wheel Int Wheel Setting wheel Date jumper
With Ring removed, we can see the remaining parts. These parts can now be lifted. Let’s take a better look at how this mechanism functions.
Date jumper

7. Date driving whl Min Whl Interm Whl Set Whl Hour Wheel
With these parts shown outside of watch, we can learn their names and functions, and placement. As the minute wheel is turned by the rotating cannon pinion, it drives the hour wheel which drives an intermediate wheel and eventuallly drives the date driving wheel which turns the date rings. The purpose of the date jumper and spring is to keep from stopping in between numbers. The purpose of the setting wheel is to manually adjust the time and date by turning the crown and stem.
Date Jumper&Spring
Date Ring

8. Disassembly of the train side of the movement.
Now we invert the movement and disassemble the remaining parts.

9. Click
Pictured here is the train side of the movement. With all parts intact. Befpre we proceed, we must release any power from the movement. This is done by turning the crown in a winding motion until the click is extended. The click is held open while the crown is slowly released.

10. Next, we remove the balance bridge screw and carefully extract the balance assembly, storing it in a safe place.

11. Pallet fork and bridge can now be removed.

12. The three barrel bridge screws and ratchet wheel screws are now removed along with the ratchet wheel.

13. Next we slide the mainspring barrel from it’s place.

14. What is left, is the train of wheels
What is left, is the train of wheels. This movement, which has a sweep second hand differs from a basic movement with a second bit, or second hand at the six position. The Structure of the train of wheels is different.

15. Second
wheel
With the train bridge removed, we can see four wheels. The second wheel, which attaches to the sweep second hand, third and center wheel and finally the escape wheel.

16. Center wheel bridge
The center wheel is held in place by a center wheel bridge.

17. All wheels and bridges have been removed except for center wheel which is attached to the cannon pinion.

18. Reassembly of train

19. First, replace center wheel bridge and escape wheel.

20. Replace third and second wheel as shown and train bridge
Replace third and second wheel as shown and train bridge. Note that there are only three wheels which attach to train bridge.

21. Be sure that pivots are shown through jewels before forcing bridge in place and wheels must turn freely.

22. Insert mainspring barrel as shown

23. Attach the barrel bridge and screws and the ratchet wheel.

24. Pallet fork and bridge can now replaced.

25. Finally, the balance assembly can be replaced.

26. Minute wheel Driving wheel Int Wheel Setting wheel Date jumper
Let’s proceed with the reassembly of the calendar mechanism. We can replace the driving wheel first, the intermediate wheel, minute wheel,setting wheel, and date jumper
Date jumper

27. Observe position of spring
Date ring
Replace hour wheel bridge and date jumper spring. Again, guard the spring from flying away while applying tension.
Observe position of spring

28. Four screws and bridges
Replace the four remaining bridges and screws as shown.

29. After replacing the hour wheel, test the movement.