The decanter centrifuge (1) comprises a bowl (2) and a conveyor screw (7) rotatably journalled in the bowl (2) and a reduction gear (22) providing a relative rotation of the screw relative to the bowl. The gear (22) is journalled separately relative to the bowl in separate bearings (25, 26). The housing and the driven shaft of the gear (22) are by means of flexural but torsionally stiff couplings (28, 29) connected with the bowl (2) and the conveyor (7), resp. Said flexural couplings result in that the gear (22) is dynamically insulated from the bowl (2) and does not influence the critical number of revolutions thereof. As a result of this the number of revolutions of the bowl - and thus the maximum allowable number of revolutions of the entire centrifuge - may be increased, thereby offering substantially improved separating properties of the centrifuge as a whole.