The chime system using wheels with pegs (or pins) of decreasing length was particularly common in Italy. It may be of late medieval origin. The arrangement was occasionally used from the second half of the eighteenth century onward in the mainly wooden clocks made in the Black Forest, where it was known as Surrer. A metal part with a stepped profile is placed on the hours tree. It causes a lateral shift of an axle to which are attached the upright hammer of the bell and a lever extending horizontally toward an internal wheel bearing pegs of decreasing length on its side. When the wheel is allowed to rotate freely, one or more of its pegs meet the lever, depending on their length and its position. As a result, the lever is therefore pressed once or more, producing a corresponding number of strokes. Two springs assist the horizontal axle and the hammer. An analogous system generates the quarter-hour chimes.