| 摘要 |
PURPOSE:To set the fluid-pressure circuit of a control valve back into a safe condition when a tensile spring absorbing extension or a negative feedback cable is involved in breakage by having the fluid-pressure circuit of the control valve set in a safe condition in association with the movement of a detecting member. CONSTITUTION:When a negative feedback cable 50 or a tensile spring 5 is involved in breakage, a bell crank 10 as a detecting member is rotationally moved due to force of a spring 12 in a clockwise direction around a supporting shaft 4 to put a safeguard into operation. Specifically, a normally-closed type open-close valve 39 is set open, which causes oil pressure supplied via a servo control valve (B) into a steering actuator (D) to be released and the steering actuator (D) to be set back into a neutral position by a return spring 45. At the same time the oil pressure of an actuater 55 is released which causes a piston 57 to be pressed down by a spring 56, a rocking member 52 to be engaged with a receiving member 49 and a real wheel 60 to be rocked at a straight-going position. |
