Abstract: A centrifugal separator, especially a pusher centrifuge is disclosed, wherein at least one rotatable sieve or filter drum is mounted within a housing. Within the sieve or filter drum there is arranged a to-and-fro displaceable pusher or thrust element, for instance in the form of a pusher floor member, which serves for displacing solid materials in the form of a filter cake towards outlet or discharge openings for the treated product. To process thin suspensions with the pusher centrifuge the pusher floor member is arranged for oscillating movement between two turning or deflection points preferably located at the region of an imaginary central line of the sieve or filter drum. A feed or supply pipe for the infeed of the suspension which is to be separated extends substantially coaxially with respect to the sieve or filter drum and its outlet or outflow opening, which extends radially outwardly, is located essentially at the center between the turning or deflection points of the pusher floor member.