Abstract: A guiding and braking unit for a material web which passes through a processing machine, such as a machine for the manufacture of packing containers. The unit comprises a roller adapted to a guide cylinder for the web. This roller is manufactured from a material with a high coefficient of friction. The roller is adapted so that it can be swivelled via an arm in a direction transverse to that of the material web to thus follow the material web when it is moved sideways, or axially in relation to the guide cylinder. Each sideways movement, however, because of the suspension of the roller, brings about a lifting of the roller which is continuously counteracted by the pressing of the roller against the cylinder. As a result, the roller is returned automatically to a central position and through friction, carries the material web with it to a central position in relation to the guide cylinder.