An aircraft rotor constant-velocity drive system having a differential mechanism that includes a drive disk configured to be integral in rotation with a mast, an upper member at least partially located above the drive disk, a lower member at least partially located below the drive disk, and at least one link connecting the upper member and the lower member to the drive disk such that the drive disk drives the upper member and the lower member in rotation with the drive disk and that the upper member and the lower member are allowed to rotate differently with respect to the drive disk. The link having opposing end joints and a central joint that pivotally engages the drive disk. The system also having a gimbal device configured to drive a rotor hub and to allow gimbaling of the rotor hub with respect to a mast.