| 摘要 |
<p>A hydraulic steering system for commercial vehicles includes two operating pistons (4, 5) arranged in parallel and movable in counterphase to drive a common steering control member (12, 13) by means of two independent hydraulic circuits (18, 19). The two circuits include respective pressure-limit valves (24, 28; 25, 30) with different operating thresholds and automatic selector means (32) are provided for simultaneously enabling the limit valve with the higher operating threshold (28, 30) and shutting off the limit valve with the lower operaring threshold (24, 25) in each of the two circuits (18, 19) in tne event of damage to the other circuit.</p> |
