The main Control Valve was removed for repairs, but after being reinstalled, the machine encountered issues when attempting to lift the boom. There was an obvious lack of coordination between components, making leveling operations nearly impossible. Despite replacing the hydraulic pump, handle assembly, and seals for the main arm cylinder, the problem persisted. Over three months have passed, and the equipment continues to operate under these conditions.
Upon visiting the site for testing, I noticed that the large arm's lifting speed was significantly slower when used independently. Performance tests revealed the large arm took 4.85 seconds to lift. Interestingly, the forearm and bucket functions appeared normal, but combining the large and small arms resulted in the forearm moving faster than usual, while the large arm moved sluggishly or barely moved at all. Only once the forearm had initiated movement would the large arm begin to lift.
Analyzing the fault symptoms, it became clear that the issue arose when the large and small arms were used together, particularly during the lifting action of the large arm. During testing, the pressure readings for pumps 1 and 2 were 4MPa and 30MPa respectively when the boom was raised. This indicated that there was no convergence between the two pumps during the lifting action.
Further investigation into the logic Valves controlling the main arm’s joint operations revealed an incorrect connection between the logic valve oil pipe PB and DR5. Despite this error, there was still no convergence between the pumps when the upper arm was lifted, with pump pressure remaining at 4MPa. A hydraulic gauge connected to the logic valve PB oil pipe showed zero pressure when the upper arm was lifted.
It was hypothesized that the PB oil port of the logic valve lacked pressure when the upper arm was lifted, likely due to a fault in the pilot selection valve or the merging/cutting solenoid valve for the upper arm. Inspection confirmed that the merging/cutting solenoid valve for the upper arm was stuck in the closed position (it should normally be open).
After cleaning and repairing the solenoid valve, it returned to normal function. However, when measuring the pressure at the logic valve PB oil port, it remained at zero. Observing further, it was noted that when the upper arm was lowered, the pressure at the PB oil port was 4MPa. This suggested an incorrect connection of the upper arm’s oil lines.
Upon thorough examination, it was discovered that the high-arm oil line had been incorrectly installed at the shuttle valve block. Correcting this installation restored normal pressure at the logic valve PB oil port. Further measurements showed that the lifting speed of the upper arm was now normal during independent actions. However, during combined movements, the upper arm still moved slowly. Testing revealed zero pressure at the 2px port of the forearm merge valve when the upper arm was lifted, indicating the forearm merge was not properly cut off.
Upon closer inspection of the hydraulic lines, it was determined that the main arm merging solenoid valve had been misconnected during assembly following its disassembly and cleaning. Professional distribution agents were contacted to address this issue. Once the incorrectly installed hydraulic oil line was corrected, the performance test showed the upper arm lifting time reduced to 2.8 seconds. The functionality of the upper arm was fully restored, eliminating the fault entirely.
In conclusion, it is crucial to engage professional distribution agents for such tasks. Additionally, always ensure proper marking and labeling when replacing, disassembling, or overhauling hydraulic components. Incorrect installations can lead to complex failures and avoidable economic losses.
HDPE Water Supply Pipe,water supply hdpe pipe,Underground Drain Hdpe Pipe,Hdpe corrugated pipe
Zhengzhou guan hao yong International Trade Co., , https://www.homepipes.com