Overhead waterwheel

…There were three types of vertical waterwheels used for power: undershot, which turns the wheel by directing a stream of water under it (also called undershot wheels, similar to water-raising wheels); topshot, which turns the wheel by directing a stream of water on the top of it (topshot wheels); and centershot, which turns the wheel by directing a stream of water on the center of it (Figure 2). Of these, undershot wheels, which can be used immediately with just a certain amount of water flow, began to be widely used from Roman times. …

*Some of the terminology that refers to "overshot waterwheels" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…動力用の垂直型水車には3種類があった。車輪の下に水流をあてて水車を回す下射式(下掛水車ともいい，揚水用水車と似ている)と，水車の頂部に水流をあてて水車を回す上射式(上掛水車)と，水車の中央部に水流をあてて回す中射式(胸掛水車)とである(図2)。このうち，一定量の水流さえあればすぐ使える下射式水車が，ローマ時代から広く利用されはじめた。…

※「上掛水車」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報