Abstract: A hydraulic concrete mixer includes a drum (110) having a mixing blade (120) attached to an interior thereof, a frame (130) supporting the drum, an engine (140) mounted on the frame, and a drive train (150) extending through at least a portion of the drum. The drive train includes: a hydraulic motor (210); a first rigid plate (220) between the hydraulic motor and the drum; a second rigid plate (230) inside the drum and coupled to the first rigid plate such that a portion of the drum is held between and in fixed relationship to the first rigid plate and the second rigid plate; a first shaft (240) inside the drum and adjacent to the second rigid plate; a second shaft (250) adjacent to the first shaft; and a mounting plate (260) coupled to the second shaft.