The particle size distribution of wood chips, along with the moisture content, are some of the main parameters for defining the quality of most wood fuels. A new experimental rotor, powered by the self-propelled forage harvester Claas Jaguar was developed by the Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (CRA), Agricultural Engineering Research Unit (CRA-ING). The rotor allowed for improved dimensional features of wood chips. The comminution achieved with the CRA–ING drum increased the percentage of 16–45 mm wood chips fraction from 63.69% to 73.29%, and progressively reduced the fraction of chips less than 16 mm from 35.20 to 25.35%. Consequently, the bulk density of the chips decreased by 8.57% in comparison with products obtained by standard devices. The dimensional increments achieved by the rotor and the percentage reduction of the smallest fractions represent two valuable elements affecting the behaviour of the wood chips during storage and handling.