When the movement production of the Pforzheimer Uhrenrohwerke in Germany started in the 1930ies, the first ever made movement was a form movement with a size of 8 3⁄4 x 12 lignes, which (at least according to the Flume K1) had not yet an own caliber number. It was later named “PUW 500” and was produced for 25 years.
You can clearly recognize the old-fashioned construction with an escapement wheel cock and a small gear bridge, which houses only three gears.
The screw balance is of course not yet shock protected in the old version, but contains a long regulator arm for adjustment.
On the empty main plate, you see, that the available space is not fully used. There are large areas, which are not hollowed, on top right and bottom left. So many unused space…
On the dial side, there’s nothing viewy. The yoke winding system, with its U-shaped setting lever spring (an indication for the early PUW 500) is clearly visible, as well, as the cap jewel and its long plate of the balance staff bearing (position “8”). At position “2”, there’s the old PUW punch.
|Number of jewels:||15|
Nickel screw balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||3 hole(s)|
|Functions:||hour, minute, decentral second|
|Size:||8 3/4 x 12''' (measured: 19,4 x 24,0mm)|
Flume: 1947 135|