Nivada Chronograph (TDBK Cal. 1369)…
Another interesting chronograph from Nivada, this one is from the mid 1970’s.
(Click pictures to enlarge)
Far from being what you might consider a watchmaking heavyweight, Nivada still had a broad range of watches with interesting calibres. Regular readers will know that I’m a fan of Nivada watches, and this chronograph is one of the most peculiar models I’ve encountered so far.
Just looking at the subdial layout it’s obvious that something out of the ordinary is lurking inside, and opening the caseback reveals a TDBK cal. 1369; a 17 jewel (modular) column wheel chronograph calibre which runs at 21,600bph.
The initials TDBK represent the four companies that were involved in its development; Tenor-Dorly, Dubois-Dépraz, Brac and Kelek. The base calibre, an automatic with date, was developed by Brac and Tenor-Dorly, the chronograph module was subsequently added by chronograph specialists Dubois-Dépraz, and Kelek were responsible for the production.
The calibre was first introduced in 1974 alongside another TDBK calibre, the 1376, which was even more peculiar, a mechanical digital with a 60 minute chronograph module.
With a diameter of just 24.8 cm and a height of 7.6 cm they were the smallest automatic calibres on the market, considerably smaller and thinner than their Heuer cal. 11/12 and Zenith 3019 “El Primero” counterparts.
However, after a production run of just 23,000, time was called on the 1369 and 1376 due to reliability issues, and to be honest I’m not surprised, as it’s not what you’d call robust…. let’s have a closer look. This first picture shows the movement with the winding rotor removed and the automatic mechanism and chronograph module highlighted.
Like the chronograph module in the Heuer Cal. 11/12 the three blued screws can be removed and the entire chronograph module can be lifted from the base calibre underneath. In an ideal world, rather than strip the chronograph module for servicing, it would simply have been replaced with a new one… but I’m not that lucky!
The second picture shows the movement with the chronograph top plate removed.
Under the top plate is the reset hammer for the minute and hour registers and the chronograph actuating lever/hour register brake. One thing to notice about this calibre is the number of click springs used – a click spring is a thin piece of wire used to spring load a lever, or hold a part in position.
Click springs are the enemy of the watchmaker as they are primed and ready to fire off into oblivion at the slightest provocation, so careful consideration has to be given to them during assembly and disassembly. The TDBK 1369 has 10 click springs in total, which has to be some kind of record. In high quality calibres click springs are either screwed down or designed out and replaced with more substantial steel springs, the Valjoux Cal. 72 and Lemania Cal. 2220 are good examples of this.
Going down one more level reveals the heart of the chronograph module…
When the start/stop button is pressed the column wheel is advanced and the actuating lever lowers the driving wheel onto the centre chronograph wheel, and the centre second hands start to rotate. At the same time the actuating lever also releases the brake on the hour register, and being powered directly from the mainspring barrel, it starts right up. The intermediate wheel rotates along with the centre chronograph wheel and the finger advances the minute register.
When the chronograph is stopped and the reset button is pressed, the reset hammer for the centre second moves across returning it to zero, along with the reset hammer for the minute and hour register two levels above.
When the watch arrived, it was running but the chronograph wasn’t working correctly. Thankfully no parts were broken as finding replacements for this one would have been difficult. The problem was that the mechanism had been assembled incorrectly, so after a service and some head scratching to get it all back together again, we were back in business.
The last thing to do was polish the crystal and clean the case. One rescued, 22,999 to go…. 😉
** Many thanks to Daniel Spiegel for letting me feature his watch on the blog. **