a drag bucket apparatus for separating pieces of solid material from liquid in a rectangular receiving tank includes driven trolleys that move along the longitudinal tank walls to pull a drag bucket along the tank from a start end to a dump end . if the drag bucket encounters excessive resistance during a pickup run , a pickup level control automatically raises the bucket incrementally to eliminate such excessive resistance ; and when the trolleys near the dump end of the tank the bucket is automatically elevated to a discharge level and when the bucket is at the dump end its load of material is automatically dumped onto a material support out of the liquid . the drag bucket is then lowered and returned to the start end for another pickup run which may begin at once , or which may be delayed depending upon the conditions encountered during the last preceding pickup run . the apparatus is particularly adapted for use with a quenching tank that sits beneath a furnace and has a water seal within and generally parallel to the tank walls .