One of the most digilent german manufacturers after WW II was Otero, Otto Epple from the area of Pforzheim. Otero movements were especially in the 1950ies very popular in middle class watches. One of the compareatively rare movements from Otero is the 10 1⁄2 ligne caliber Otero 28 shown here. It’s a well made pallet lever movement, which was cost-efficient constructed.
Looking onto the base plate, you can see, that the ratchet is on the dial side. It is very well made with a true click and at 1 o’clock on the movement side, you can hold the click and untighten the mainspring.
All important bearings, except minute- and mainspring barrel bearing contain rubies and are a little larger, than usual. On the movement bridge, there are even jewels for the minute wheel bearing and a cap jewel for the excapement wheel bearing. In total you get 17 jewels, which is pretty high for a manual wind movement of the 1950ies.
For a pallet lever movement, it’s a bit odd, that the gear bridge also carries the mainspring barrel, so that there are five bearings - the normal value would be three or four. The mainspring barrel can be released separately by its screwed axle. This is normally typical for cost efficient pin lever movement with rocking bar winding mechanisms.
The Otero 28 has got a contemporary gear train with pretty large wheel: The mainspring barrel drives the ceter minute wheel, followed by third wheel, seconds wheel (which carries the decentral second hand on the dial side) and the steel escapement wheel.
You can see, that it builds pretty high despite being a pallet lever movement. And you also see the pin for holding the click mechanism.
The Otero 28 has got a two leg screw balance which beats with 18000 A/h and is beared in two Monorex shock protections. It can be adjusted with a long regulator arm, so, a very well made escapement!
On the dial side you see the rocking bar winding mechanism with its very well made ratchet. At 6 o’clock, there’s the decental seconds axle with its unusally large wheel. The advantage of these large wheel is, that they are not so sensitive against dirt and dust, which will come into the movement sooner or later.
In the lab
Timegrapher resultOf course, on the timegrapher the results are not great for an unserviced specimen, which was used for decades. The beat error is pretty high while the amplitude is a bit low. A revision, maybe with a new balance staff, would improve the rates, but don't expect a chronometer performance from that middle-class movement.
|dial up||0 s/d||237°||5.6ms|
|dial down||0 s/d||285°||4.4ms|
|crown right (12 up)||-74 s/d||227°||6.2ms|
|crown up (3 up)||-99 s/d||227°||6.8ms|
|crown left (6 up)||-143 s/d||200°||6.7ms|
|crown down (9 up)||-126 s/d||223°||5.8ms|
|Number of jewels:||17|
Nickel screw balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||rocking bar winding system|
|Setting lever spring:||1 hole(s)|
|Functions:||hour, minute, decentral second|
|Size:||10 1/2''' (measured: 23,3mm)|
Flume: 1957 35|