Abstract: A roller bearing for the shaft of a cement-mixer drum, universally jointed on a stub shaft of a planetary-gear train driving the drum shaft through a gear coupling with arcuate teeth, has an inner race fixed to the drum shaft and an outer race secured to a surrounding transmission housing, this outer race being axially split into two halves each accommodating a set of barrel-shaped rollers. The two sets of rollers are held in respective cages, peripherally offset from each other, and are engaged by toroidal inner surfaces of the two race halves curved about the center of rotation of the universal joint; these race halves extend axially beyond the end faces of the inner race to allow for a swing of more than .+-.3.degree. from a midposition. The outer cage diameter exceeds the smallest diameter of each race half.