Abstract: A support assembly for coupling of a large-sized universal joint of the cardan type as incorporated in a drive assembly for rolling mills. The assembly supports the coupling on a drive spindle portion to prevent the coupling from hanging. A locking rod fixed to the center of the coupling extends through a hole of large diameter formed in the center of the spider of the universal joint, with a sufficient radial clearance provided between the rod and the inner periphery of the spider. The piston rod of a hydraulic cylinder disposed within an inner bore of the drive spindle portion operates to slidingly move a rod receiving member within the bore, thereby bringing a recess portion of the rod receiving member into engagement with or disengagement from the free end of the locking rod. The coupling is securely supported on the drive spindle portion by the engagement of the rod receiving member with the locking rod.