column wheel 19 Ligne Cal 1 Cal 18 Cal 2 Cal 20 Cal 22-1928 Cal 22-1947 Cal 22-1949 Cal 22GH Cal 22 heuer Cal 230 Cal 23-1928 Cal 23-1947 Cal 234 Cal 23 heuer Cal 24-1928 Cal 24-1947 Cal 25-1928 Cal 25-1947 Cal 26 Cal 3 Cal 5 Cal 54 Cal 55 Cal 57 Cal 6 Cal 61 Cal 69 Cal 7 Cal 71 Cal 72 Cal 72C Cal 730 Cal 76 Cal 76R Cal 77 Cal 7740 Cal 8-1928 Cal 8-1947 Cal 84 Cal 88 Cal 9-1928 Cal 9-1947 Cal 92 Originallu chronographs used wolfs tooth gears whcih changed to a colum wheel in the late 1800s. The cam/lever design came out int he mid 20th century and because of its lower cost (and neevr mind it was a lot harder to push) it became popular. The column wheels tended to brreak over time the cam lever - not so muych

cam lever Auto Handwind "It’s been estimated that between the end of WWII and the onset of the Quartz Crisis in the 1970s there were as many as 500 different labels offering watches containing outsourced cam-shifting chronograph movements. Between watches housing the Venus 188, the Valjoux 7730, and comparable movements from Landeron and Lemania, millions of cam-shifting chronographs were sold during the post-war decades." - Allen Farmelo