| 摘要 |
PURPOSE:To prevent impossibleness of steering by arranging normally opened shutoff valves to switch a flow and cutoff of operating fluid to respective hydrau lic cylinders as hydraulic control valves. CONSTITUTION:When wheels are steered to the left by a steering wheel, a direction control valve 45 is switched to a position of 45a. Then, pressure oil from a hydraulic pump 39 flows to a pipe line 47 from a pipe line 38, and also flows to a pipe line 36 through a pipe line 48. To the contrary, when the steering wheel is rotated to the right, the direction control valve 45 is switched to a position of 45b. Then the pressure oil from the hydraulic pump 39 flows to the pipe line 48 from the pipe line 38, and also flows to a pipe line 35 through a pipe line 47. Shutoff valves 41 to 44 are normally opened shutoff valves due to spring offset. |
