Characterises the area of hydraulics in which pressurised water (HWBF) is used as the medium. As the water does not have the necessary viscosity or lubrication properties, often special devices and device designs must be used. This statement applies above all to gap seals that produce excessively high leakage losses with pressurised water. For this reason valve plate-controlled pumps must be replaced by valve-controlled pumps and spool valves by seated valves. As a consequence, e.g., a 4-way directional valve must be divided into either four 2/2 directional valves or into two 3/2 directional valves. In addition, in this situation compared tomineral oilcavitation occurs much more easily.
Due to these handicaps water hydraulics have been limited to a few special areas up to now.