| 摘要 |
PURPOSE:To prevent danger of unexpected actions of engine at the startup by providing a circuit by which current to an automatic excavation control circuit is interrupted during the stoppage of engine by the signals of a detection circuit under the operating or stopped condition of engine. CONSTITUTION:A power source switch 37 is connected to a flip-flop 36 and then to a transistor 38. When a relay contact 35 is turned ON and the power source is connected to a control circuit 15, oil-pressure line switch solenoid valves 24, 27, and 30 are automatically switched for automatic control operation. Also, when an engine 23 is stopped during the operation period, the output of an engine rotation detector 43 becomes L, and the output H of an inverter 39 is put in AND circuit 40 to become H which is put in the R input unit of the flop 36. The Q outut of the flop 36 is L-level, and therefore, the coil 34 is demagnetized, the contact 35 is opened, the circuit 15 is broken, and manual condition results. Safety during the restartup period can thus be obtained. |
