| 摘要 |
PURPOSE:To prevent an abrupt change in vehicle height and instability of control by setting the fluid pressure of a fluid pressure cylinder to a neutral pressure upon occurrence of an abnormality in an electric instruction transmitting system for a control valve, and by setting the rate of pressure rise to a moderate value upon a pressure rise up to the neutral pressure. CONSTITUTION:When breakage of a signal wire from a control section 30 or the like occurs, pressure fed to hydraulic cylinders 26FL through 26RR is cut off so that pressure accumulated in an accumulator 20 is returned to a tank 40 through a three port selector valve 46 and an operation check valve 47. Accordingly, the pressure on the hydraulic feed side drops to a neutral pressure which is a set pressure of the operation check valve 47. As a result, the operation check valve 47 is closed so that the hydraulic cylinders 26RL through 26RR are held at the neutral pressure. At this time, since the pressure of a pressure chamber L in each hydraulic cylinder is lower than the neutral pressure, the pressure is raised up to the neutral pressure at a rate which is more moderate than that of pressure control sections 22FL through 22RR. Thus, it is possible to prevent an abrupt change in vehicle height and instability of control. |
