In a device or method to change a belt in a machine assembly, a gripper is provided with two flat legs. The legs are held at one end and are free at the other ends. The legs are provided with a respective protective film on side surfaces facing towards one another to protect the belt. A first of the two legs facing towards the machine assembly in an exchange of the belt have a sliding film on its outer surface. The legs are designed such that they exert a gripping force over a width of the belt after sliding onto the belt and grip the belt so that the belt can be slid onto or removed from rollers of at least one of the roller types selected from the group consisting of a drive roller and a deflection roller provided in the machine assembly.