Abstract: A fluid machine, particularly a hydraulic pump, has a high pressure side and a low pressure side. A rotor or a pair of cooperating gears are mounted for rotation and have spaced end faces extending transversely of their respective axes of rotation. Walls define at each of these end faces at least one fluid compartment which is open to the respective end face and which communicates via a restricted outflow gap with the low pressure side of the machine, and via a conduit with the high pressure side of the machine. In each conduit a throttle is interposed, and the end faces are subjected from the respective compartments to fluid pressures which permanently tend to equalize with one another, and which therefore tend to axially center the rotor or gears in the event of axial displacement thereof.