Abstract: An extraction tower for the counter-current leaching of sugar beets cossettes or crushed sugar cane. The elements which convey the material to be leached through the tower, especially the conveyor screw means and/or the baffle means which are arranged for cooperating with the conveyor screw means are provided with load sensor means, such as strain gauge elements which through control amplifier means control the drive means for the conveying elements to adapt the through-put and thus the conveying to the loads occurring throughout the tower. Even the pump and valve means may be controlled in response to such strain gauge means.