The document discusses several mechanical mechanisms: an aircraft radial engine used before turbines, a rotary engine that lacks pistons, an inline engine with cylinders lined up side by side, an automatic transmission file mechanism, a universal joint that allows power transfer at different angles and speeds with less friction, the sewing machine invented by Thomas Saint in 1791, a Malta Cross movement used to control clocks, and oval regulation which asks the reader to identify a use. It provides Wikipedia and HowStuffWorks as resources for more information on these mechanical systems.