Hitachi Excavator Repair
Hitachi excavator suddenly shuts down
According to the analysis, the failure characteristic of this machine is that the engine cannot work with load, so the cause of the failure is likely to be on the host control system. The working principle of this machine's CPU computer control system, load sensing and servo hydraulic control system are shown in the attached drawings.
As can be seen from the figure, the signals of the electro-hydraulic control system come from the engine, hydraulic pumps and main control valves, respectively.
8, 10, 11, 12, 15 and other sensors. These signals are processed by the engine controller EC and the pump valve controller PVC, and then the signals are transmitted to the high-speed on-off solenoid valve (magnet valve) 13, 14 After the internal valve stem is rotated at a high speed, the oil flow of the pilot pump 5 into the servo piston 7 is adjusted, thereby changing the tilt angle of the hydraulic pump swashplate to adjust the displacement of the hydraulic pump; the motor control motor 9 receives input After the signal is changed, the throttle of the engine is changed to ensure that the engine speed matches the load of the hydraulic pump. Excavator maintenance is a comprehensive, systematic and specific introduction to the imported excavator hydraulic system. The structure and working principle of pumps, valves, motors, hydraulic cylinders and auxiliary components in the hydraulic system are introduced in detail, and the disassembly, repair and installation methods of each component are described in detail. In each model, the electronic control system and fault diagnosis and elimination methods are also introduced systematically. The basic content of maintenance excavator includes: equipment maintenance, equipment inspection and equipment repair. The repair work of the excavator is strengthened, and the relevant maintenance personnel must further analyze the damaged condition according to a certain actual condition and quality, and when analyzing the cause, it is usually caused by natural wear and tear, so Targeted research.
After inspection, the engine control motor (motor 9) works normally when the engine is switched to work mode, indicating that it is not the fault. Therefore, judging whether the high-speed on-off solenoid valve (magnet valve) can correctly receive the electrical signal of the pump valve controller PVC and perform the setting action is the key to determining the fault location.
修理挖掘机 。 The high-speed on-off solenoid valve emits a crisp “click, click” sound when the high-speed valve position is switched under normal conditions, but the solenoid valve has no sound when the engine of the machine is running, so it can be determined that the solenoid valve is the faulty part to repair the excavator .
After disassembly, use a multimeter (use: measure voltage, current, and resistance) to measure the resistance between the yellow wire (Y) and the yellow wire (YB) on the high-speed switching solenoid valve 14 to infinity, indicating that the circuit is interrupted; Further inspection revealed that the core wire of this solenoid valve at the wire lead-out terminal 1 was broken. Retry the machine after the repair, and the fault phenomenon is eliminated.