Steering apparatus

A steering apparatus for vehicles, comprising at least:

• a hydraulic steering actuator
• a hydrostatic steering unit hydraulically connected to the steering actuator, and
• a steering shaft,
• wherein the hydrostatic steering unit comprises at least:
• a distributor, and
• a dosing unit,
• wherein the distributor comprises:
• an inlet port for a hydraulic fluid,
• an outlet port for the hydraulic fluid,
• a first connection port hydraulically connectable to the steering actuator,
• a second connection port hydraulically connectable to the steering actuator,
• a first service port hydraulically connectable to the dosing unit,
• a second service port hydraulically connectable to the dosing unit, and
• a movable intercept member, actuatable by the steering shaft, which is adapted to assume a plurality of operating configurations and at least one neutral configuration, wherein it hydraulically connects each of said first and second service ports with a respective one of said first and second connection ports, and wherein the steering apparatus also comprises:
• first valve means selectively actuatable between at least a first operating configuration, wherein they hydraulically separate each of said first and second connection ports from the hydraulic steering actuator, and a second operating configuration, wherein they hydraulically connect the first and second connection ports of the distributor with the hydraulic steering actuator,
• wherein the dosing unit comprises at least two dosing devices (300, 305), both of which can be actuated by the steering shaft, of which:
• a first dosing device hydraulically connected between the first service port and the second service port of the distributor, and
• a second dosing device associated to second valve means which are actuatable between at least a first operating configuration, where-in they hydraulically separate said second dosing device from the first and second service ports of the distributor, and a second operating configuration, wherein they connect said second dosing device between the first service port and the second service port of the distributor, in parallel with the first dosing device.