The cooling system consists of standardized cooling block elements, in which water is forced to flow countercurrent to the massecuite. The entire cooling system oscillates vertically by 1 m. This, in conjunction with the symmetric arrangement of the cooling pipes, provides for optimized retention times and massecuite cooling. Two speeds are available for up/down movements of the cooling system. Six hydraulic cylinders, which are symmetrically mounted on the cover of the cooling crystalliser, drive the system. Half of the cooling blocks can be activated or deactivated at a time. With this type of crystalliser, the direction of massecuite flow is always from top to bottom. As it enters the unit, the massecuite is uniformly distributed across the entire crystalliser cross section by a slowly rotating distributor. There are no plain or anti-friction bearings, nor any glands, at the massecuite end throughout the entire crystalliser. The cooling water can be re-cooled in a separate cooling unit or in an air cooler, which is mounted on the lifting system and follows its oscillating movements. In this latter case, the complete secondary cooling water cycle is not required.