A method for operating a progressive cavity pump wherein the stator has at least first and second active stator sections that are at different locations on the stator, comprising inserting a first rotor having a first active rotor section that is aligned with the first active stator section, and rotating the first rotor relative to the first active stator section such that the aligned first active rotor and stator sections generate a pumping force. Subsequently, the first rotor is removed and a second rotor is inserted having a second active rotor section that is aligned with the second active stator section, and rotating the second rotor relative to the second active stator section such that the aligned second active rotor and stator sections generate a pumping force.

The invention relates to a two-spindle screw pump of single-flow construction, comprising a pump housing, which has a pump portion, a bearing portion and a gear portion with a gear chamber, wherein the bearing portion and the pump portion are realized separately from each other characterized in that the gearwheel and the fastening element (and thus the shaft) are mutually rotatable, so that a spacing of the flanks of the feed screws (the flank clearance of the feed screws) is adjustable, that an opening is provided on the gear portion of the pump housing, that the opening is provided with a detachable cover, that the opening is arranged such that the cover is detachable in the mounted state of the screw pump, and that the gear chamber, for the adjustment of the flank clearance of the feed screws, can be reached with the tool necessary for this purpose.

A method and a device for fixing and synchronizing rotary pistons in a rotary piston pump involves introducing the rotary pistons into the pump space of the rotary piston pump. A shaft stub of each rotary piston is then pushed through a pump rear wall onto a driveshaft provided for the respective rotary piston. The rotary pistons are aligned and synchronized in the pump space via a template, the template being fixed detachably to a pump housing. The shaft stubs of the respective rotary piston are connected, after the synchronization, in each case via a clamping device in a friction-locked manner to the respective driveshaft, outside the pump space.