| 摘要 |
PURPOSE:To provide an automatic steering device with fail-safe valve which can make the position control and the pressure control conpatible, and can deal with securely and adequately even when a valve driving system of an electric system and the like generates a failure. CONSTITUTION:A hydraulic actuator 33 to hydraulic drive a steering force transmitting member 32; a hydraulic pressure source 20 to feed the hydraulic pressure; change-over valves 35 and 37 provided in the oil passage from the hydraulic pressure source 20 to the hydraulic actuator 33, and having an automatic steering mode and an automatic steering stopping mode; and an automatic steering angle control valve 36 having a left side steering mode, a right side steering mode, a neutral waiting mode, and an automatic steering stop mode; are provided. The automatic steering control valve 36 is composed as a fail-safe valve having a valve body 36A to make in the automatic steering stop at the standard condition, and to realize one side of the left side and the right side steering mode; the neutral waiting mode;' and the other side of the left side and the right side steering mode, a spring 36B to energize the valve body 36A to the standard condition, and an electric control type valve body driving means 36C which can displace the valve body 36A step by step. |
