A round baler (12) comprises a baling chamber (16) and a plurality of press means (18) mounted within the baling chamber (16). The round baler (12) is operated by power provided by a primary power source. The round baler (12) is characterized by an auxiliary power source (22) connectable with the press means (18). The auxiliary power source (22) is operable in a power transmitting mode to transmit an auxiliary power to the press means (12). The baler further comprising control means for controlling operation of the auxiliary power source (22). The operation of said auxiliary power source (22) is controlled manually and/or corresponding to at least one of a bale formation cycle parameter.
