Ok, now I know why your design was familiar. You nearly reinvented (or
repurposed) the Voith-Schneider drive:

http://www.voithturbo.de/file_download.php?file=applications/documents/document_files/659_e_am_vsp_safty_en.pdf

(which uses a cleverer system than gears). There are also wind turbines using
the same principle. The center cam is set by a wind vane.

Peter

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