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