Friction wheel drive

A friction wheel drive comprising:

• a friction wheel drive having a driving roller capable of being driven in a rotary manner, the driving roller being mounted on a bearing unit so as to be rotatable about an axis of rotation, wherein the bearing unit is displaceably guided transversely to the axis of rotation, and a circumferential surface of the driving roller can be brought into driving engagement with a friction surface;
• the bearing unit being coupled to a first mechanical forced guidance system, by which the driving roller, responding to a driving force acting in a first direction, can be pressed automatically against the friction surface with a contact pressing force that increases as the driving force increases;
• and
• wherein the bearing unit is coupled to a second mechanical forced guidance system, by which the driving roller, responding to a driving force acting in an opposite second direction, can be pressed automatically against the friction surface with a contact pressing force that increases as the driving force increases;
• and
• the first and second mechanical forced guidance systems simultaneously and automatically producing a displacement of the bearing unit in the direction of the friction surface, independently of the direction of drive, upon displacement of the bearing unit parallel to the friction surface.