| 摘要 |
<p>PURPOSE:To improve reliability during a failure in operation, by a method wherein, by means of a hydraulic cylinder, rear wheels are steered in an in-phase or a reverse-phase to front wheel, and when working oil is not fed to the hydraulic cylinder due to a failure in operation of a hydraulic source, rear wheels are maintained in a neutral state. CONSTITUTION:A rear wheel steering device B is provided with a working rod 21 axially displaced by means of first and second supports 22 and 23 rotated by a drive mechanism B1 and rotated through an input shaft 24 and a ball nut 25 in linkage with steering of front wheels, and has both ends to which right and left tie rods to steer rear wheels are coupled. In this case, the drive mechanism B1 is formed with a warm gear 44, a worm shaft 45, and a hydraulic cylinder 46 to drive the worm shaft 45. The hydraulic cylinder 46 displaces a piston rod 46b from a reference position against the force of a spring 54 through the feed of working oil, and engagement of a rack tooth 46b1 with a pinion 45b causes drive of the worm shaft 45.</p> |
