A herringbone gear, a specific type of double helical gear, is a side-to-side, rather than face-to-face, combination of two helical gears of opposite hands. From the top, each helical groove of this g
This herringbone bevel gear was made by Citroën and installed around 1927 in the small Miřejovice hydropower plant on the River Vltava in the Czech Republic, connecting a Francis turbine to the generator. It worked flawlessly until 2011.