The accessory equipment has a hydraulic drive (40,50) that is provided with a drive-fluid inlet (41,51) connected to a pump-fluid outlet (13,23) of the hydraulic pump unit (10,20). A fluid exchange device (60) is provided with a fluid supply line (61) connected to the supply line (S) for a controlled supply of the hydraulic fluid from a hydraulic circuit of the working machine (100) and a fluid discharge line (71) connected to the supply line upstream of the fluid supply line for the controlled discharge of the hydraulic fluid from the supply line into the hydraulic circuit.
