Where does “Cam” come from?

I can't write this etymology summary because the chain provided doesn't support the headword "cam." The chain traces only "camera" through Latin, with no connection to "cam" shown. To write an accurate sentence, I would need either a chain showing how "camera" became "cam" in English, or a different chain that actually leads to "cam." If you have the correct etymological chain for "cam," I'd be happy to write the summary.

Cam (English): A turning or sliding piece which imparts motion...

Definitions

  1. A turning or sliding piece which imparts motion...

Ancestry of “Cam”, step by step

Cam traces back through two separate lines of ancestry.

via English camera

StepLanguageWordMeaning
1EnglishcameraA device for taking still or moving pictures or...
2New Latincamera obscuradark chamber
3LatincameraA chamber in its various senses, "including";...
4Ancient GreekκαμάραAnything with an arched cover such as a covered...
5Proto-Iraniankamarā-something curved
6Proto-Iraniankamárati
7Proto-Indo-Iranian*kmárati
8Proto-Indo-Europeankh₂em-to bend, to curve

via Dutch kam

StepLanguageWordMeaning
1DutchkamA comb, utensil to groom hair, fur etc; A ridge,...
2Middle Dutchkamp

Words derived from “Cam

Every word from Proto-Indo-European kh₂em-