| 摘要 |
<P>PROBLEM TO BE SOLVED: To accomplish turning of front two-axle vehicle even when an engine driving type main pump MP fails. <P>SOLUTION: The power steering device is provided with the engine driving type main pump MP; a sub-pump SP driven by an axle; a control valve 12 for switching a flow passage from the respective pumps according to operation of a steering wheel; first and second power cylinders 18, 22 for turning front and rear steered wheels 17, 21 of the front two-axle vehicle by a fluid pressure switched by the control valve; and a pump switching valve 10 for connecting the main pump to the control valve and connecting the sub-pump to a tank ST in normal operation and connecting the sub-pump to the control valve in failure of the main pump. A switch valve 24 for power cylinder is provided between the control valve and a rear side power cylinder and in failure of the main pump, the flow passage from the control valve is shut off and both pressure chambers 22L, 22R of a second power cylinder are communicated. <P>COPYRIGHT: (C)2007,JPO&INPIT |
