Mast rollers (support rollers) are a special design of the ball or cylindrical roller bearings with a solid, reinforced outer ring. In contrast to roller bearings, mast rollers are not installed in a housing, but run with their outer ring on a flat or curved track. The strength of the outer ring and the set of rolling elements are decisive for the load-bearing capacity. A good seal against contamination from the outside and loss of grease from the inside of the bearing are of great importance in addition to the high load capacity for the service life.