The hydraulic system uses hydraulic oil as the working medium and has a high energy density. There are two types of hydraulic system failures: one is insufficient flow and pressure caused by damage or wear of components; Another type is the malfunction or abnormality of a few mechanisms. It is difficult to diagnose and find the cause and location of hydraulic system faults, but it is easier to locate and remove them. The main manifestations of hydraulic system failures are vibration and noise, crawling, oil contamination, leakage, etc.
The hydraulic system failure of shield tunneling machine drive has the following characteristics:
⑴ Diversity and complexity of faults. For example, when the pressure of the system is unstable, vibration and noise faults often occur together. In addition, the same hydraulic system malfunction may have multiple causes, and the same cause can lead to multiple malfunctions. For example, hydraulic pumps, relief valves, viscosity of hydraulic oil, and system leaks can all cause the pressure of the hydraulic system to fail to meet the requirements; Similarly, when the system inhales air, it can cause the hydraulic pump to be unable to suck up oil in severe cases, and in mild cases, it can cause fluctuations in flow rate and pressure.
⑵ Concealment. The internal structure and working status of hydraulic components cannot be directly observed from the outside, and the pressure oil is located inside the system's pipelines, which is difficult to observe and detect.
⑶ Contingency and inevitability. If the dirt in the oil accidentally blocks the damping hole of the overflow valve or gets stuck in the valve core of the directional valve, causing the system to suddenly lose pressure or fail to change direction; Sometimes it is inevitable, such as system leaks caused by low oil viscosity, large internal clearances in hydraulic pumps, increased internal leakage, and a decrease in pump volumetric efficiency.
(4) The usage conditions are closely related. For example, low ambient temperature increases the viscosity of hydraulic oil, causing difficulty in oil suction for hydraulic pumps. On the contrary, if the ambient temperature is high, the viscosity of hydraulic oil will decrease, which will cause faults such as leakage and insufficient pressure.
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2026-05-24