| 摘要 |
PURPOSE:To enable steering at low speed large steering angles and prevent rear wheels from being steered to large steering angles in the vicinity of the neutral position by providing an operation limiting relief valve between a rear power cylinder and a steering angle reacting shutoff valve, and opening the operation limiting relief valve when the rear wheel steering angle exceeds a specified range so as to relieve the oil pressure of the rear power cylinder through the steering angle reacting shutoff valve. CONSTITUTION:A steering angle reacting shuoff valve 30 drives a spool according to a steering wheel angle and is closed when a steering wheel is steered to a large steering angle. That is, when a rear wheel steering angle exceeds a specified range, an operation limiting relief valve 50 is opened to relieve the oil pressure of a rear power cylinder 22 through the steering angle reacting shutoff valve 30. Accordingly, when the steering wheel angle is within the specified range, the steering angle reacting shutoff valve 30 is opened to relieve the oil pressure of the rear power cylinder 22 by the operation limiting relief valve 50, so that the rear wheel steering angle is limited to a small steering angle. When the steering wheel angle is large, the steering angle reacting shutoff valve 30 is closed to cut off the oil pressure relief of the rear power cylinder 22, so that the rear wheels are steered to large steering angles. |
