Screw spindle pump

A screw spindle pump, with a housing (2) which surrounds a delivery chamber (5), two spindles (7, 8), namely a drive spindle (7) and an opposed running spindle (8), a housing insert (6) which is arranged in the housing (2) and in which the spindles (7, 8) are accommodated, at least one bearing element (13′, 13″), which is connected to the housing insert (6) and on which bearings (12) of the spindles (7, 8) are arranged, and with at least one housing cover (14′, 14″), closing a housing opening, characterized in that the bearing element (13′, 13″) together with the housing insert (6) and the spindles (7, 8) accommodated therein forms a unit (15) which, after the housing cover (14′, 14″) is taken off, is removable from the housing (2) through the housing opening,

• wherein the screw spindle pump further comprises one removable guide rail arrangement (18) which has at least one guide rail (20, 28) which extends in a longitudinal direction of the screw spindle pump and on which the unit (15) is guided in an axial direction in the housing (2).