A XCMG 230 excavator has a serious drop in speed, but the engine does not emit black smoke. What is the fault when the speed is turned off?
Hitachi 270-3 ,,,, moving bucket, stick, hold back ,,,, left walking, slewing, what is the reason why the engine speed is very serious?
Colleagues often ask all kinds of questions in this area. We checked the information in this area, and we have organized them as follows to play a role in inspiring others. Take the PC-200-6 model as an example.
Power-plunger pump-main control valve-action effector energy conversion: kinetic energy-pressure potential energy-...-kinetic energy between the pump and power, between man and machine, there are four places Automatic control feedback, some are positive feedback, some are negative feedback, so as to achieve the interactive control of man-machine, power and pump power matching, to meet different working conditions.
1. The speed of the power --- PC-EPC valve ------ PC valve -...- The flow rate of the pump is positive feedback
2. The magnitude of the operator's action-PLS pressure-LS valve-...-the flow rate of the pump This is positive feedback
3. The small external load pressure ... PC valve-the flow rate of the pump is negative feedback 4. The internal automatic speed and oil control of the power, the speed is slow-the oil is large. This is the working condition when the boom is raised by negative feedback. : When the pressure is large, the flow rate is large, the arm and the bucket cylinder are working conditions: the pressure is large, the flow rate is small, and the rotation and walking conditions are: the pressure is small, the flow rate is large. If the output of the pump and power and the main control valve are due to various reasons Failure to meet the above working conditions will cause the vehicle to stall or stall. (Because the speed of human response is much less than the speed of positive and negative feedback adjustment, the machine works normally. Once the machine fails, it will cause the above to slow down or stall). This is a complex feedback adjustment process, which affects several A positive and negative feedback adjustment, so it is difficult to analyze and draw the correct conclusion.
