Abstract: A stack feeder is described for use in association with a stack mover arranged to advance a haystack in the longitudinal direction of the stack feeder. The feeder includes a base frame and a flail assembly located above the base frame and positioned transversely with respect to said longitudinal direction. Means are provided coupling the flail assembly to the base frame for pivotal movement with respect to the frame about a horizontal axis so that the flail assembly can be moved up and down along an arcuate path above the frame. The flail assembly includes a rotary flail and a hood which extends longitudinally of the flail. The flail is made up of an elongate support rotatable about a horizontal axis, and a plurality of knives carried by the support for action on a haystack in use. Means are provided to move the flail assembly along said arcuate path. The feeder also includes means for rotating the flail at a relatively high speed. Conveyor means are supported on the base frame below the flail assembly.