A rotating shaft apparatus comprising a thrust regulating mechanism, the apparatus having a rotatable shaft that is subject to an axial displacement caused by an axial thrust, the thrust regulating mechanism being located behind a final impellor stage of the rotating shaft apparatus and comprising: a first segment, being a rotor element, that is longitudinally fixed to and coaxial with the rotatable shaft, and a second segment, being a stator element, that surrounds but is not longitudinally fixed to the rotatable shaft, the first and second segments (400, 402) being configured such that there is a relative rotation therebetween during operation of the apparatus, the second segment being in fluid communication with a high pressure fluid region; a cylindrical male section included on the first segment, and a cylindrical female section included on the second segment, the male section being terminated by a circular leading edge and the female section being terminated at a front edge thereof by a circular opening that is larger in diameter than circular leading edge of the male section, wherein the female section is configured to be filled with fluid that leaks past an impeller, the leading edge of the male section being proximal to the front edge of the female section without entering into the female section, so that a pressure release gap is formed between the leading edge of the male section and the front edge of the female section through which pressurized fluid is able to flow from the second segment, past the first segment, to a low pressure region, while an axial compensating force opposed to said axial thrust is applied to the first segment by the pressurized fluid, said pressure release gap being configured to be reduced in size by said axial displacement, such that the compensating force is increased when the axial thrust and axial displacement are increased, and the size of the pressure release gap is consequently decreased, wherein the rotor element is coaxial with the stator element and of smaller diameter, the difference in diameters defining therebetween said pressure release gap fluidically connected with said intermediate chamber; characterized in that the high pressure fluid region separates the final impeller stage from the thrust regulating mechanism, the high pressure region being connected to an intermediate chamber formed between said rotor element and said stator element by an axial drum gap. a first segment, being a rotor element, that is longitudinally fixed to and coaxial with the rotatable shaft, and a second segment, being a stator element, that surrounds but is not longitudinally fixed to the rotatable shaft, the first and second segments (400, 402) being configured such that there is a relative rotation therebetween during operation of the apparatus, the second segment being in fluid communication with a high pressure fluid region; a cylindrical male section included on the first segment, and a cylindrical female section included on the second segment, the male section being terminated by a circular leading edge and the female section being terminated at a front edge thereof by a circular opening that is larger in diameter than circular leading edge of the male section, wherein the female section is configured to be filled with fluid that leaks past an impeller, the leading edge of the male section being proximal to the front edge of the female section without entering into the female section, so that a pressure release gap is formed between the leading edge of the male section and the front edge of the female section through which pressurized fluid is able to flow from the second segment, past the first segment, to a low pressure region, while an axial compensating force opposed to said axial thrust is applied to the first segment by the pressurized fluid, said pressure release gap being configured to be reduced in size by said axial displacement, such that the compensating force is increased when the axial thrust and axial displacement are increased, and the size of the pressure release gap is consequently decreased, wherein the rotor element is coaxial with the stator element and of smaller diameter, the difference in diameters defining therebetween said pressure release gap fluidically connected with said intermediate chamber;