SM pump is a self-priming pump assembled into a pump body. The pump body and screw are designed to avoid any axial load. The functional pressure creates a definite tolerance between the balanced piston of the main screw and the surrounding body. This creates a balanced fluid power of the screw while lubricating and cooling the sealing components. The torque required to move the transverse screw is transferred hydraulically by the pumping fluid. This means that the screw rotates without mechanical wear.