On the Vintage Ads LJ group, the awesome Man Writing Slash has rounded up a series of old ads that use mechanical methaphors for the human body.
One of my favorite ad tropes is the Body=Machine/Body=Factory idea, because the imagery is often more detailed and also more hilarious than in most ads. As a kid I used to LOVE any illustrations of the body that depicted tiny workers inside, such as The Human Body, for example. :D This link to a book about Fritz Kahn's Der Mensch als Industriepalast is also fascinating (although not advertisement). Brief video version of that book HERE (well worth 3 minutes of your time.) This series of articles and illustrations in the same vein (XD) appeared in the Berliner Morgenpost in 1931 and is simply breathtaking.