Lifting capacity refers to the smaller of the rated stable lifting capacity or rated hydraulic lifting capacity.
Rated stable lifting capacity: 75% of tipping load.
Rated hydraulic lifting capacity: 87% hydraulic lifting capacity.
Slewing speed.
Slewing speed refers to the average maximum speed that can be achieved by stable slewing when the excavator is unloaded.
This means that the defined slewing speed does not refer to the slewing speed when starting or braking, that is, it is not the slewing speed of accelerating or decelerating. For general excavation work, when this excavator works in the range of 0 ° to 180 °, the slewing horse accelerates or decelerates. When it turns to the range of 270 ° to 360 °, the slewing speed of excavator maintenance reaches a stable level.
Therefore, in the actual excavation work, the slewing speed defined above is impractical, that is, the actual slewing performance required is acceleration / deceleration expressed by slewing torque.
The engine of Hitachi EX200-2 hydraulic excavator was overhauled after 9850h of operation. After the overhaul, the engine operated well during the separate test run, but the following symptoms occurred during the test run after the main engine was installed: the engine emits black smoke when idling, the sound seems that the engine has been loaded, the black smoke emitted when the engine runs at high speed is thicker, and as long as the operating handle on the engine is slightly pulled, the engine will shut down immediately.
The analysis shows that the engine runs well when it is tested separately after overhaul, indicating that the repair quality is guaranteed. Therefore, the excavator repair inspected the hydraulic pump connected to the engine. According to the fault phenomenon that "when the engine is running at high speed, the engine will shut down immediately as long as the operating handle is pulled slightly", we infer that the swashplate or plunger of the hydraulic pump is stuck, So that the flow of the hydraulic pump can not change with the change of external load, resulting in the engine being stalled. Then, we disassembled and inspected the hydraulic pump (after removing the hydraulic pump, start the engine, the engine runs normally, which proves again that the engine itself has no fault). After disassembly and inspection, no abnormal conditions were found, the swashplate and plunger move freely, and the wear condition is within the specified range, Therefore, the fault causes caused by the hydraulic pump are eliminated.
Since there are no abnormal conditions in the engine and hydraulic pump, our excavator repair shop infers that the cause of the fault should be in its control part, and the problem should be in the electrical control part. The electrical system of the machine has main circuit, monitoring circuit and control circuit. The main circuit includes engine starting, battery charging and light operation. The monitoring circuit includes sensors, switches, controllers and monitors, It can transmit all working states of the machine. The operation of the machine controlled on the control circuit is completed by sensors, switches, controllers and actuators. On EX200-2 hydraulic excavator, the whole machine is equipped with 6 microcomputers, which are respectively installed on the monitor controller, EC (engine controller), PVC (pump valve controller), the first switch panel, the second switch panel and engine accessories to monitor the corresponding actions of various parts of the machine.
