(57) Twin roll strip caster comprising parallel casting rolls one of which is mounted on moveable roll supports which allow it to move bodily toward and away from the other roll. A pair of roll biasing units comprising compression act on roll supports to bias the moving roll toward the other roll. Biasing units comprise compression springs acting on roll supports through thrust transmission structures and thrust reaction structures. The positions of thrust reaction structures are set by hydraulic cylinder units operable vary the position of each reaction structure to replicate movements of the respective thrust transmission structure so as to maintain a constant compression of the biasing springs regardless of lateral movements of the roll supports.