A transmission group (1) for an agricultural mixer connected to the auger (551) to guide the rotary movement thereof.The transmission group (1)comprises an input device (10) suitable to receive rotary motion from a movement system, for example from an engine group of the agricultural mixer or a motor vehicle, and an output device (20) suitable to transmit the rotary motion of the input device (10) to the auger (551).The input device (10) and the output device (20) are mutually operatively connected by a first pair of gears or a second pair of gears, in which the first pair operates on command from a clutch output group (250) and the second pair operates on command from a clutch input group (150).
