Abstract: A photograph materials processing unit having:a motor drive unit comprising,a base member which has an upper surface, anda drive wheel extending from the upper surface which is in operative relationship to a drive motor, the drive motor also being part of the base.The upper surface of the base member also carries a pair of spaced-apart undriven wheels which are rotatable in planes parallel to the plane of rotation of said drive wheel.The motor drive unit is adapted to carry a cylindrical drum for receiving photographic materials including film and liquid processing chemicals. The drum is carried in 3-point contact on the upper surfaces of the wheels whereby when the drive motor is turned on, the drum rotates on the wheels without substantial longitudinal movement of the drum with respect to the motor drive unit so long as the longitudinal center line of the drum is parallel to the axes of rotation of the wheels.