Ita bellows

...If you apply force to one end of a long board as a fulcrum and fix the other end as a fulcrum, and the board can be moved up and down at an angle, and both sides of the board are kept airtight with earthen walls or other materials, the result is that the air underneath the board is pushed out strongly. This type of bellows was used in the Tohoku region and the Korean peninsula, starting with the water-powered board bellows used in China. The system in which the center of the board is the fulcrum and the other ends are the fulcrums is also called the stepping bellows or earthen bellows, and was used in Japan for the casting of temple bells. In particular, the balance bellows for tatara ironworks, developed during the Genroku period (1688-1704) to improve the efficiency of air blowing, was designed to connect two stepping bellows with a balance pole, so that both bellows could be operated with one movement, successfully saving labor.

*Some of the terminology that refers to "board bellows" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…長い板の一端を力点として力を加え，他端を支点として固定，その板を斜めに上下できるようにし，板の両側を土壁などで気密に保てば，板の下部にある空気を強く押し出す結果が得られる。中国で使われた水排，すなわち水車駆動による板ふいごをはじめとして，東北，朝鮮半島方面でこの形式のふいごが使用された。また，板の中央を支点，他の両端を力点とする方式は，踏みふいごあるいは土ふいごとも呼ばれ，日本では梵鐘の鋳造などに使われたが，とくに送風の効率化を図るため元禄年間(1688‐1704)に開発されたたたら製鉄用のてんびん(天秤)ふいごは，2個の踏みふいごをてんびんのさおで連結し，1動作で両方のふいごを操作できるよう考案し，省力化に成功している。…

※「板ふいご」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