|Diameter:||31 mm (13.75 ligne)|
|Early Cal. 47||Complications:||3-Button Chronograph, Cam Switching Chronograph, Chronograph, Oscillating Pinion Chronograph|
|Hands:||30 Minute Chronograph Hand at 3:00, Central 60 Second Chronograph Hand, Central Hour Hand, Central Minute Hand, Small Seconds Hand at 9:00|
|Distinguishing Technical Characteristics|
Clockwise Balance Cock
|Production: 1937 –|
Cal. 47 was a groundbreaking chronograph movement, the first cam-actuated chronograph on its introduction in 1937. It used three buttons (start, stop, reset in crown) unlike most other movements and was soon replaced by the two-button Cal. 48 family. It was slowly modified into the two-pusher Cal. 48, with many modified parts being added over time.
The axis of the subdials is not perfectly aligned with the crown stem, and the minute counter at 3:00 is slightly (0.05 mm) closer to the center than the running small seconds. This was carried over from previous Landeron chronograph movements and gives them an unusual look. Like all movements in the family it uses Heuer-style oscillating pinion rather than a traditional horizontal clutch to activate the chronograph function.
The basic ebauche was created by Charles Hahn & Cie., part of Ebauches SA, with chronograph components supplied by Dèpraz.Images are taken from official publications and are used here for commentary and educational purposes. Copyright is held by the original owner as noted.