Abstract: A device preferably utilized for pumping oil or other fluid from a drill hole in the ground, said device including a pump lowered into the hole and coupled to a drive motor situated under it. The pump comprises a hydraulic screw pump including a housing in which there is mounted a screw array in the form of a drive screw provided with a shaft coupled to the drive motor, and at least one running screw meshing with the drive screw. The rotational direction of the drive motor is such that the screw array pumps the liquid from an inlet, made radially in the housing and in communication with the liquid in the drill hole, to an outlet arranged at the end of the screw array remote from said shaft.

Abstract: A hydraulic screw machine having a housing employing a screw assembly with a drive screw and cooperating idler screws. The drive screw is sealably connected to a shaft extending beyond the housing on the high pressure side and has associated therewith a balance piston for acting on the screw drive. The drive screw is journalled to the shaft via bearings in the form of a self-adjusting plate surrounding the shaft. The plate is disposed between abutment surfaces connected to the housing for limiting its axial movement. A leakage channel between the piston and the housing is connected to the high pressure side of the machine and is determined by the balance piston.

Abstract: A screw pump includes a screw unit having a drive screw and two impeller screws arranged symmetrically around the drive screw. The screws are enclosed in a housing having mutually intersecting passages for accommodating the screws, and the unit is constructed so that the screws seal against each other and against the housing to form chambers in which liquid is carried from the suction side to the pressure side during rotation of the screws. On the pressure side in the passage accommodating one of the impeller screws there is formed a recess which extends from the pressure side and the length of which is such that each chamber is opened at separate time intervals with respect to the two impeller screws instead of simultaneously.