In an apparatus for adapting the pressing force of a control roller on a control can in a sheet-processing machine by a torsion spring, the apparatus either changes the effective spring length or the spring stiffness as a function of the rotational speed of the sheet-processing machine. The spring can be a torsion spring rod with an actuator setting the spring force by changing the prestress. A stiffening element can be connected to the torsion spring rod and set the spring force by changing the spring stiffness of the torsion spring rod.