| 摘要 |
A steering circuit system for a moving vehicle in which automatic steering operation as well as manual steering operation can be achieved. Pressurized oil discharged from a hydraulic pump (1) is fed to a steering line (3) and to an auxiliary steering line (10). The pressurized oil of the steering line (3) is fed to an expanding chamber (9a, 90a) and to a contracting chamber (9b, 90b) of a pair of steering cylinders (9, 90) by manual operation steering valve (5). The auxiliary steering line (10) is connected to a third line (12) through a switching valve (11). The third line (12) is connected to a fourth line and to a fifth line (14, 15) through an automatic operation steering valve (13). The fourth line (14) is connected to contracting chamber (9b) and to expanding chamber (90a) of the left and right steering cylinders (9, 90). The fifth line (15) is connected to contracting chamber (90b ) and expanding chamber (9a) of the left and right steering cylinders (9, 90). First and second pilot operation check valves (16, 17) are provided in the fourth and the fifth lines (14, 15), respectively. The first pilot operation check valve is opened in response to pressure in the fifth line (15), and the second pilot operation valve is opened in response to pressure in the fourth line (14).
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