Two Methods of Fault Diagnosis of Hydraulic System

by:Join Machinery     2021-04-22
The person in charge of the excavator parts procurement center introduced that the instrument diagnosis of the hydraulic system is in general on-site inspections. Because the detection of flow is more difficult, and the failure of the hydraulic system is often manifested as insufficient pressure, so in the on-site inspection, more The ground is to use the method of detecting system pressure. For example, a 966D loader is found to be unable to walk after 6000h, and the pressure values u200bu200bof the inlet and outlet of the torque converter are detected. The results are all normal; however, when the staff operates the power shift valve , When measuring the directional clutch pressure, the pressure is only 0.5 MPa, that is, the normal pressure cannot be established. After solving the full transmission, it is found that the oil seal in the directional clutch oil passage is damaged, causing hydraulic oil leakage. After replacing the oil seal, the fault is eliminated. Another example, An EX220-5 excavator, after running for 3000 hours, found that the walking deviation was found, and the pressure of the walking system was detected, and the pressure of the walking system was found to be 32MPa on the left and 26MPa on the right. After adjusting the pressure of the right walking safety valve, the fault was eliminated. In the wide application of construction machinery, the person in charge of the excavator parts procurement center said that a single pressure test can no longer meet the needs of on-site testing. Complete, the detection computer has rich data, small size and easy to carry. For example, a Hitachi EX220-2 excavator, the hydraulic system of the working device is weak, when the handle of the excavator is operated, the sound of the engine changes and the smoke is emitted. Use the detection computer to detect It was found that there was no significant change in the flow of the hydraulic pump, and the engine became sound when the pressure increased. After analysis, it was found that the flow of the hydraulic pump was too large and the swash plate could not adjust the flow. The hydraulic pump servo valve was disassembled, and the servo valve and the hydraulic pump flow adjustment swash plate were found The connecting pin is broken, and the fault is eliminated after the pin is replaced.
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