Lifting capacity refers to the smaller of the rated stable lifting capacity or the rated hydraulic lifting capacity.
Rated stable lifting capacity: 75% tipping load.
Rated hydraulic lifting capacity: 87% hydraulic lifting capacity.
Swing speed.
Revolving speed refers to the average maximum speed that the excavator can reach when it is rotating stably.
This means that the defined slewing speed does not refer to the slewing speed during starting or braking, that is, the slewing speed is not acceleration or deceleration. For general excavation work, this type of excavator is When working within the range of 0 ° to 180 °, the slewing motor has acceleration or deceleration. When turning to the range of 270 ° to 360 °, the excavator maintenance rotation speed reaches a stable.
Therefore, in actual excavation work, the swing speed defined above is impractical, that is, the actual swing performance required is acceleration / deceleration that can be expressed in swing torque.
Hitachi Ex200-2 hydraulic excavator underwent engine overhaul after working 9850h. After overhaul, the engine worked well when tested alone, but the following symptoms appeared when the engine was put back on the test machine: the engine emits black smoke when idling, and the sound seems to be the engine When the load is applied, the black smoke emitted from the engine at high speed is thicker, and as long as the operating handle on the machine is slightly turned, the engine will immediately stop.
According to the analysis, the engine worked well when tested alone after overhaul, indicating that the repair quality is guaranteed. Therefore, the excavator repair checked the hydraulic pump connected to the engine. According to "the engine needs to be slightly pulled when it is running at high speed. When the engine is operated, the engine immediately shuts down. We infer that the swash plate or plunger of the hydraulic pump is stuck, so that the flow of the hydraulic pump cannot change with the change of the external load, which leads to the engine being stalled. Then, We dismantled the hydraulic pump (after removing the hydraulic pump and starting the engine, the engine was running normally, once again proved that the engine itself was fault-free), no abnormalities were found after dismantling and inspection, the swash plate and plunger are free to move, and the wear conditions are all Within the specified range, the cause of the failure caused by the hydraulic pump is thus eliminated.
Since neither the engine nor the hydraulic pump has any abnormal conditions, our excavator repair plant concluded 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 a main circuit, a monitoring circuit and a control circuit The main circuit includes engine start, battery charging and lighting operations. The monitoring circuit includes sensors, switches, controllers and monitors, which can transmit the full working state of the machine. The operation of the control machine on the control circuit is controlled by sensors, switches, The controller and the actuator are completed. On the Ex200-2 hydraulic excavator, the whole machine is equipped with 6 microcomputers, which are respectively installed in the monitor controller, EC (engine controller), PVC (pump valve controller), The first switch panel, the second switch panel and the engine accessories are used to monitor the corresponding actions of each part of the machine.
