Abstract: The mixer unit of a concrete transport vehicle has a loading hopper constructed in two sections which are connected together at a hinge joint. The one section is attached firmly to the frame of the mixer unit, and this section is located opposite to the opening at the elevated end of the mixer drum. The other section moves about the hinge axis from an extended position to a storage position. When in the extended position, the movable section forms an upward continuation of the fixed section, and the hopper has extended height to facilitate loading concrete mix into the drum. When in the storage position, the movable section is positioned to the rear of the fixed section and is carried entirely below the upper margin of the fixed section. This reduces the height of the mixer unit, enabling the transport vehicle to maneuver in areas where the overhead clearance is relatively low.