The steam used is low pressure downtown-wide steam heating network (from a plant adjacent to the Georgia Viaduct) that powers a miniature steam engine in its base, in turn driving a chain lift. The chain lift moves steel balls upward, where they are unloaded and roll to a descending chain. The weight of the balls on the descending chain drives a conventional pendulum clock escapement, geared to the hands on the four faces. The steam also powers the clock's sound production, with whistles being used instead of bells to produce the Westminster "chime" and to signal the time.