In 1937 Hahn & Cie invented a new series of chronograph movement for Ebauches SA. This movement did away with a column wheel and introduced cams to start stop and reset the chronograph function. This movement would be made at the factory at Le Landeron. The first series was know as calibre 47. The calibre 47 required a third pusher situated by the stem and a special crown that would also work as a pusher. The cam construction was cheaper to manufacture than a column wheel and they saved costs, using wire springs where possible.
The following year the calibre 47 was upgraded to calibre 48 and did away with the third pusher. From the Landeron 47 to the 48 there was a floating transition. Many parts were modified, but except the minute-recorder jumper all are interchangeable. The Landeron 48 opened up the market to a reliable chronograph movement at a lower price point that proved popular with the buying public.
Over the years several variations evolved with their own calibre names, including variants with date complications and moon phase. Between 1937-1975 over 3.5million movements were made.
