Abstract: A device for driving and supporting the drum of a concrete mixer truck comprises a casing fixedly mounted on the truck chassis by stud bolts, and a driving shaft connected in driving relationship with the drum by a universal coupling consisting of a driving member concentrically connected to the driving shaft and rotatably supported through a self-aligning roller bearing by the casing, and a driven member fixed to the drum and in driving engagement with the driving member with a spherical bearing disposed therebetween. All the driven member, self-aligning roller bearing and spherical bushing are concentrically arranged to rotate about a common center of rotation, and the connecting means is arranged on a reference plane in which the center of rotation lies.