Abstract: A storage and retrieval machine having a base movable in opposite horizontal directions, a mast mounted on the base, and a carriage movable in opposite vertical directions on the mast. A drive is also provided for moving the base and carriage in their respective opposite horizontal directions or opposite vertical directions. A control is connected to the drive for transmitting to the drive for either the base or the carriage, a first signal for a fast acceleration rate in one of the opposite directions of movement, a second signal for a slow acceleration rate in the other of the opposite directions of movement, a third signal for a slow deceleration rate in one of the opposite directions of movement, a fourth signal for a fast deceleration rate in the other of the opposite directions of movement, and a direction signal to move in one of the opposite directions.

Abstract: A wheel assembly for a storage and retrieval machine which is travelable on a rail along a path adjacent overhead storage locations which store objects delivered to and retrieved from the locations by the storage and retrieval machine. The storage and retrieval machine includes a base which is supported on the rail by the wheel assembly. The wheel assembly comprises a wheel engaging the rail and having a horizontal axis of rotation and an upwardly extending axis projecting through the wheel. A wheel support is affixed to the base and includes a bracket on which the wheel is mounted. The bracket has a plate member extending laterally of and around the upwardly extending axis of the wheel. A positioning mechanism is provided for angularly positioning the wheel about the upwardly extending axis and has a plurality of set screws spaced from and in a surrounding relationship to the upwardly extending axis and engaging the plate member of the bracket upon which the wheel is mounted.