The invention relates to a stirring mechanism (90) for a machine for preparing chilled or frozen products comprising one motor, the stirring mechanism (90) comprising an input shaft (94) rotatable by the motor and an output shaft (98) providing the output movement of the stirring mechanism (90) such that depending on the direction of rotation of the input shaft (94), the positioning of the output shaft (98) is different with respect to the input shaft (94). Further, the invention relates to a machine (100) for preparing chilled or frozen products comprising a stirring mechanism (90) as described, the stirring mechanism (90) entraining in rotation stirring means (9) to prepare the product. Even further, the invention relates to a system comprising a machine (100) as the one described and a container (10) comprising the ingredient or ingredients for preparing the product by the rotation of the stirring means (9).