| 摘要 |
PURPOSE:To facilitate a job for transfer operation by making a selector valve so as to be changed over to the manual steering side from the automatic steering side by means of longitudinal differential pressure in a four-way valve at time of operating a steering gear, in a steering system capable of selecting the manual steering and the automatic steering on the basis of operation of a transfer operator. CONSTITUTION:A control valve 18 consisting of a four-way valve is installed in space between both lower side and upper side steering shafts 13a, 13b, while the supply and exhaust ports 18b, 18c are connected to ports 30g1, 30g4 of a 8-port two position hydraulic driving selector valve 30 and a exhaust port 18d to a port 30g3, respectively. Ports 30g6, 30g8 of the selector valve 30 are connected to symmetrical oil chambers 22a, 22b of a power cylinder 22, and a port 30g7 is connected to a reservoir 23. In order to select a valve position of the selector valve 30, two cylinder chambers 30c, 30d are installed, while both symmetrical oil chambers 30d2, 30d1 being partitioned off by a piston 30d3 of a cylinder chamber 30d are connected to a hydraulic pump 21 and the reservoir 23 via a 4-port three-position solenoid driving control valve 26, and this control valve 26 is controlled by an automatic steering control part 24. |
