Abstract: The present invention discloses a device for rolling up and unrolling a material web (2) on a shaft (1, 15). The device is distinguished by the fact that a first radial spacing (R1) of the material web (2) from a rotational axis of the shaft (1, 15), which first radial spacing (R1) is assigned to any desired unrolled length (L) of the material web (2), differs from a second radial spacing (R2) of a tensioning cable (3, 16) from the rotational axis of the shaft (1, 15), which second radial spacing (R2) is assigned to said unrolled length (L), with the result that the direction and magnitude of a first torque which is exerted on the shaft (1, 15) via the material web (2) differ from those of a second torque which is exerted on the shaft (1, 15) via the tensioning cables (3, 16), in such a way that, on account of the torque difference between the first torque and the second torque, the shaft (1, 15) is driven by a force (F) which is transmitted by means of the tensioning cables (3, 16).

Abstract: The present invention discloses a device for rolling up and unrolling a material web (2) on a shaft (1, 15). The device is distinguished by the fact that a first radial spacing (R1) of the material web (2) from a rotational axis of the shaft (1, 15), which first radial spacing (R1) is assigned to any desired unrolled length (L) of the material web (2), differs from a second radial spacing (R2) of a tensioning cable (3, 16) from the rotational axis of the shaft (1, 15), which second radial spacing (R2) is assigned to said unrolled length (L), with the result that the direction and magnitude of a first torque which is exerted on the shaft (1, 15) via the material web (2) differ from those of a second torque which is exerted on the shaft (1, 15) via the tensioning cables (3, 16), in such a way that, on account of the torque difference between the first torque and the second torque, the shaft (1, 15) is driven by a force (F) which is transmitted by means of the tensioning cables (3, 16).