Old French Door/Window lock mechanism

Hi All,
I have just returned from Paris with a few very old Cremone lock parts. In this type of lock, the door is latched by exposed rods coming from the door handle to recessed holes in the top and bottom of the door frame. I was not able to bring back the rods, and have a problem working out how the rods connect to the handle mechanism.

The handle turns an internal metal disk that has two pins pressed into it at 12 o'clock and six o'clock. Turning the handle simply rotates the disk 180 degrees and essentially allows the pins to swap positions. But this of course involves a circular sweep of the disk, rather than a straight vertical movement, so I am trying to figure out how a circular motion translated into being able to slide two rods (somehow connected to those pins) straight up and straight down.

In today's models, or more modern versions, the handle drives a rack and pinion type mechanism, which is straight up and down. The handles I bought are bronze, and very decorative, so I am assuming they are from a very old French chateau or house. I cannot find any detail on their design.

Any help would be most appreciated.


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