The OSPM hydrostatic steering unit, compatible with auxiliary or integrated steering columns, includes a rotary valve and a meter that regulates the oil flow from the pump to cylinder ports based on steering wheel rotation. It switches to manual steering if the pump supply is insufficient. The interaction of spool (1) and sleeve (2), controlled by the steering column, manages the oil flow to the cylinder via rotor sets (3), synchronising with the steering wheel speed. Interruption of the steering movement allows residual oil to position the cylinder, stabilised by the centre spring (4). Pressure relief valve (5) controls the system pressure, with load-sensing versions with a pilot relief valve. Anti-impact valves (6) protect cylinder connections and divert oil as required. In the event of an oil supply failure, the unit acts as a hand pump, facilitated by non-return valves (8, 9) for oil recovery and air prevention. The LAGZ model adjusts the displacement during emergencies and maintains functionality. Overall, the OSPM ensures smooth steering under various conditions and improves vehicle control and safety.