Device and procedure for axial thrust compensation

A method of compensating an axial thrust acting on a shaft of a pump, comprising at least one rotary pump unit and at least one drive unit for the rotary pump unit, in operation of the pump, comprising the steps:

• producing a differential pressure between the pump pressure that is produced in operation and a lower pressure than the pump pressure, wherein communicating the lower pressure or the pump pressure to the compensating piston by an axial bore in the shaft, and
• producing from the differential pressure a force that acts in opposite relationship to the axial thrust at the shaft and at the shaft self-regulatingly reducing the axial thrust occurring in operation of the pump by means of the differential pressure.

A retrofit module for a pump comprising at least one rotary pump unit having at least one impeller wheel driven by at least one drive unit, wherein in operation of the pump an axial thrust corresponding to the pump pressure acts on a shaft of the impeller wheel, the retrofit module comprises:

• an assembly comprising a compensating piston and a compensating cylinder capable of self-regulatingly producing a compensating force which at least partially relieves the load of the axial thrust by means of a pressure difference from the pump pressure and a predetermined lower pressure,
• wherein the compensating piston of the retrofit module is capable of being connected to the shaft of the rotary pump unit in force-locking relationship in the axial direction and in that case is guided movably in the compensating cylinder of the retrofit module, which compensating cylinder can be stationarily fixed to the pump.