Tedder (machine) A Molon belt rake/tedder tedding hay. A retired hay tedder. A tedder (also called hay tedder) is a machine used in haymaking. It is used after cutting and before windrowing, and uses moving forks to aerate or wuffle the hay and thus speed up the process of hay-making. The use of a tedder allows the hay to dry (cure) better, which results in improved aroma and color.