Abstract: A hydraulic screw machine including a drive screw and at least one running screw co-operating therewith are arranged inside a housing, the drive screw being united with a shaft extending out through the housing at the high pressure side of the machine and being provided with a balancing piston for balancing a part of the axial force acting on the drive screw and also with a collar which together with a wall portion of the housing forms a hydrostatic axial bearing for taking up the remaining axial force acting on the drive screw. The bearing surfaces of the axial bearing are kept separated by a spring means during starting and similar operating conditions. An axially limitedly movable rolling bearing is mounted in association with the hydrostatic axial bearing and takes up axial forces on the drive screw occurring in certain operating conditions.

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: Pump apparatus, for delivering oil to an oil burner which is supplied with oil in excess, the excess oil being collected in a vessel, includes a pump receiving oil partly from an oil tank and partly from the collection vessel, for delivering the oil to the burner. The pump is provided with separate inlets for oil from the tank and vessel. In the inlet for oil from the tank there is mounted a shut-off valve adapted for opening under the action of a sub-pressure on the pump suction side. In the inlet for oil from the collection vessel there is mounted a valve adapted for actuation by the head of liquid in the collection vessel for opening or closing when said head is respectively above or below a given level.