publication_number US 4235572 A abstract a rotary displacement pump comprising a casing including a cylindrical in surface defining a stator chamber with an inlet and an outlet connected thereto a cylindrical displacement body is movably mounted within the stator chamber having an outer surface which is movable into close association with the cylindrical inner surface along a line a shaft is provided with an eccentric connected to the displacement body with a bearing to eccentrically move the displacement body within the stator chamber and move the line of close association in a circular path within the stator chamber gas tight spring bodies are connected between the displacement body and the casing for preventing rotation of the displacement body with respect to the casing and the displacement body is provided with first and second slide sealing members for dividing the stator chamber into an inlet base and an outlet base application_number US 96487478 A description referring now to the drawings in particular the invention embodied therein in fig1 and 2 comprise a rotary displacement pump having a casing 1 with an inner cylindrical surface 50 which defines a stator chamber and a cylindrical displacer body 6 6 39 movable therein the pump casing 1 forms a cylindrical stator space and the drive shaft 2 is mounted by means of ball bearings 3 3 39 on either front side thereof the drive shaft carries an eccentric 4 secured thereto and supporting by means of ball bearings 5 5 39 the displacer body of the pump comprising a left hand.