In the midst of the quartz crisis, 1977, the Pforzheimer Uhren-Rohwerke once again launched a large (11 1⁄2 ligne diameter) manual wind movement, which thanks to up-to-date manufactury and rational construction should be an alternative to the yet upcoming below-100-DM quartz watches. As known, the success was overdue, any only two years later, 1979, the complete manufactury of mechanical movements ceased.
The PUW 660 shown here is the bast movement of the fifth and final caliber family, which consisted of manual wind movements (calibers 660-664) and of selfwinding movements (calibers 1660-1664). The base construction is still the same as on the caliber family 260, which was launched in 1960.
On the base plate you can see the spave-saving construction with the large mainspring barrel. Interestingly, the slowest turning wheel, the mainspring barrel, is ruby-beared, but not the minute wheel.
The laterally mounted dial securing screws at 9:30 and 3:30 are one of the biggest differences to the predecessor PUW 560, as well, as the date quickset mechanism, for which there’s a recess at 9:15 for a diagonally sitting wheel.
Also on this movement, the minute wheel is directly driven by the mainspring barrel and it sits beyond an own bridge. For 1977, this probably wasn’t state of the art any more, but you still see the relationship to the first caliber family.
The gear train is the same same since 17 years: Mainspring barrel - minute wheel - third wheel - center second wheel - escapement wheel. It’s a very compact construction which wastes lots of space here.
The three-leg anular balance is beared in two shock protections (here Incabloc) and beats rather slow with 21600 A/h. For reference, an ETA 2824, which was launched in 1971, uses 28800 A/h, and in the early 70ies, there were several attempts of launching movements with 36000 A/h. In the age of forthcoming cheap quartz watches, a slow beat movement was conterproductive.
One of the biggest differences to the predecessor family 560 is, that the crown wheel is now located riveted under the winding bridge.
The ratchet remains on the inner side(!) of the gear train bridge, where you can also see the packed construction of the gear train.
On the dial side, there’s not much left from the predecessors. The large recesses are distinctive, they are probably made for the date indication and/or its quickset mechanism.
Unfortunately, the caliber family 660 is so rare, that it wasn’t possible to find a specimen with date mechanism for identification of the uses of the recesses.
In the lab
The specimen shown here came without case and in hardly used condition into the lab and hence did not get a service.
On the timegrapher, it ran fast between +11 and +32 seconds per day with an amplitude between 250 and 290 degrees.
|Number of jewels:||17|
Nickel anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||2 hole(s)|
|Functions:||hour, minute, second|
|Size:||11 1/2''' (measured: 25,6mm)|
|Production period:||1977 - 1979|