The large 12 1/2 ligne pin lever windup movement UMF 54-31 was launched in 1938 as “Thiel Start” and produced until 1961. During that time, it was also available under the names “UMF Start” and “UMF M 54”.
The specimen presented here shows its last but one version from the year 1959, which can be identified by its yellow color, its balance bridge and its missing caliber number engraving.
The base plate shows all characteristics of a simple pin lever movement in pillar construction. There are not bearing rubies and the different heigths of the plate are the result of its punching production.
At one o’clock, you can see the ratchet, which consists of only one geniously constructed part - a pawl with an integrated spring.
We see the classical gear train here, which consists of a directly driven center minute wheel, followed by third wheel, seconds wheel (whose prolonged axle carries the decentral second hand at 6 o’clock on the dial side) and escape wheel.
As most pillar movements, the UMF 54-31 builds pretty high, too. When the gears are not beared on both sides, they tilt.
The screw-less anular balance is beared under a bridge and has got no shock protection. Its frequency is 18000 A/h and it regulates a pin lever escapement.
Like most other pin lever movement, a rocking bar winding system is used here, too.
At 9 o’clock, you can see the height-adjustable bearing for the balance.
|Size:||12 1/2''' (measured: 26,9mm)|
Nickel anular balance|
|Balance bearing / direction hairspring:||Bridge|
|Adjust mechanism:||Long regulator arm|
|Winding mechanism:||rocking bar winding system|
|Setting lever spring:||1 hole(s)|
|Production period:||1938 - 1961|
Flume: 1958 90|