| 摘要 |
PURPOSE:To shift a steering shaft in the axial direction with yet smaller force by prohibiting any energizing force of a centering spring to act on a steering shaft at a time when the steering shaft is shifted in the axial direction to steer each rear wheel. CONSTITUTION:A rear-wheel steering mechanism 171 is provided with a piston 84 being installed in a steering shaft slidably in a cylinder chamber 92 and partitioning off this cylinder chamber 92 into each of first and second cylinder chambers 94, 95, while it feeds pressure oil to either of these cylinder chambers 94, 95 with action of a spool valve mechanism 148, and shifts the steering shaft 80 in the axial direction. In this case, usually, pressure oil out of a hydraulic source 150 is fed to two pressure chambers 115, 102, thereby releasing any contact between spring pressers 124, 125 and ring parts 122, 123 against a centering spring 126, and such a fact that energizing force of the centering spring 126 works on the steering shaft 80 is prohibited, and at time of trouble happening, there is provided a centering mechanism 172 which keeps the steering shaft 80 in a neutral position by means of the centering spring 126. |
