| 摘要 |
PURPOSE:To prevent seizure of a pump or damage of a link by installing a handle shaft revolution detecting part consisting of a luminous element and a light receiving element onto a reduction shaft interlocked with a handle shaft and operating a solenoid valve by the output signal of said detection part and controlling the flow of pressurized liquid. CONSTITUTION:A transmitting and shielding member 7 is installed onto a reduction shaft 6 interlocked with the revolution of a handle shaft 1. A luminous diode 8 and a phototransistor 9 are arranged at the opposite positions each other, having the transmitting and shielding member 7 interposed. Said transmitting and shielding member 7 transmits light only at the limit steering angle of a handle. Said phototransistor 9 is connected to a solenoid valve set onto a piping interposed between an oil tank and a power cylinder. Therefore, when the handle is turned by the limit steering angle, the phototransistor 9 operates to switch the solenoid valve 10. Therefore, the working-oil feed side of the power cylinder communicates to the oil tank, and the pressure is reduced sharply, so excessive force is not applied onto a pump 5 and a link mechanism. |
