Problem: The hydraulic directional control valve for oil replenishment/unloading is not powered during normal pumping, and the optimized stroke is found to be closed unexpectedly.
Solution: First, check if there is a signal input from the water tank proximity switch on the display screen. If not, inspect the switch for damage or wiring faults.
If the switch is normal, verify the operation of the pumping pressure sensor. Ensure that the sensor's current output ranges from 4-20mA, corresponding to a pressure display of 0-40MPa. The pump's pumping frequency is calculated based on the pressure difference detected by the pressure sensor.
Problem: The pumping pressure display fluctuates between 0-40MPa.
Solution: Check the normal working current of the pressure sensor, which should range from 4-20mA. Any deviation from this range may indicate a wiring fault or ground short circuit. When inspecting the pressure sensor, refer to the manufacturer's instructions for correct wiring based on the labeling on the sensor.
Problem: The engine speed fluctuates during pumping, despite normal chassis information and engine speed display on the upper unit.
Solution: First, check if there are signals for acceleration/deceleration. If present, investigate if acceleration/deceleration is causing the issue. If not, it may be related to the pumping pressure sensor. A lack of pumping pressure affects constant power parameter adjustment, preventing it from reaching the matched constant power value.
Failure Analysis & Troubleshooting:
1. The solenoid valve for forward pumping may not be powered or may be stuck.
2. The proximity switch of the main cylinder may be damaged or insensitive.
3. Controller program malfunction.
4. The spool valve of the swing cylinder may be stuck or there may be loose blockages internally.
5. Short circuit in the wiring of the cylinder proximity switch causing incorrect feedback of the switching signal to the controller.
1. Check the power supply status of each solenoid valve during forward and reverse pumping. During low pressure, DT1 and DT3 are normally powered, while DT51, DT33, and DT34 alternate. During high pressure, DT1 and DT2 are normally powered, while DT4, DT33, and DT34 alternate.
2. Check from the I0 input point of the controller to ensure that at least one proximity switch of the main cylinder is powered during switching, and after replacing all four proximity switches, if the equipment still does not function properly.
3. Even after refreshing the controller program, the fault persists.
4. Considering the previous occurrence of erratic switching, suspect the spool valve of the swing cylinder may be stuck or there may be blockages in the main valve block. After replacing the spool valve, the fault persists, and no blockages are found.
5. After checking all electrical and hydraulic components responsible for cylinder switching, suspect a problem with the switching signal circuit. Upon rechecking the power supply status of the four proximity switches at input points 10 of the controller, it was discovered that the SQ2 proximity switch is powered during switching of both left and right main cylinders. Suspecting a short circuit in the SQ2 proximity switch circuit with either SQ1 or SQ4, the control line of the SQ2 proximity switch was cut and the main cylinder switching returned to normal. After reconnecting one SQ2 proximity switch signal line to the controller, the equipment resumed normal operation.
In conclusion, addressing these common issues with concrete pump truck components requires thorough troubleshooting and understanding of the hydraulic system and sensor functionality. By following these troubleshooting steps, you can ensure optimal performance and reliability of your concrete pump truck components. For quality concrete pump parts ,is you premier provider of concrete pump components in China and worldwide.
