The operating temperature of the hydraulic system of a shield tunneling machine is usually between 30~55℃. At this temperature range, the viscosity, lubrication, and wear resistance of the oil are at their optimal, resulting in the highest efficiency of the hydraulic system.
When the system temperature exceeds 65°C, the viscosity of the oil decreases significantly, leading to increased system leakage. This can damage the sliding oil film of components such as directional valves, exacerbating the wear and tear on these components, and consequently causing the system temperature to rise even faster.
When the oil temperature reaches above 80℃, the operating state of the components will undergo abnormal changes, and may even experience a "seizure" phenomenon, affecting the normal operation of the system.
The service life of the hydraulic system of a shield machine is not only related to the performance of the hydraulic equipment, but also closely related to the viscosity and cleanliness of the hydraulic oil in the hydraulic equipment. To ensure its functional performance and the normal and reliable operation of the hydraulic system, it is necessary to control the contamination of the hydraulic oil. Here are several key control points:
1. Control the usage temperature: The temperature should be monitored in real-time, and any temperatures exceeding the specified range should be kept under surveillance. The ambient temperature for shield tunneling operations is typically high, and the viscosity of oil and grease decreases with increasing temperature, leading to a significant reduction in mechanical efficiency and performance. Too low a temperature can also have a considerable impact on the suction resistance, resulting in noise. The oil temperature is controlled by regulating the temperature of the circulating cooling water both inside and outside the shield.
2. Ensuring Cleanliness During Use: During the assembly and commissioning of the shield machine, all hydraulic valve blocks and other components must undergo necessary cleaning and pass inspection. After removing contaminants such as dust, iron chips, and welding slag from the oil tank and pipelines, processes such as acid cleaning and polishing should be carried out. During construction, samples should be taken regularly for technical analysis to determine the appropriate treatment plan.
3. Renewal of Oil: During use, it is necessary to replace contaminated oil. This involves sampling and data analysis, visual inspection, and laboratory determination of its indicators. By analyzing a series of data such as viscosity and moisture content, a decision can be made whether to replace the hydraulic oil. Before replacing, the old oil should be drained and the equipment cleaned, after which qualified oil can be added.
4. Real-time monitoring of usage: During the operation process, online particulate matter monitoring is employed, utilizing relevant equipment for surveillance. This allows for the clear detection of oil quality. Through data analysis and processing, when pollution reaches a certain level, the alarm system will sound an alert, prompting replacement if necessary, to ensure that the equipment operates within normal data parameters.
2026 July 4th Week VAFEM Product Recommendation
A linear-motion bearing or linear slide is a bearing designed to provide free motion in one direction. There are many different types of linear motion bearings. Motorized linear slides such as machine slides, X-Y tables, roller tables and some dovetail slides are bearings moved by drive mechanisms. Not all linear slides are motorized, and non-motorized dovetail slides, ball bearing slides and roller slides provide low-friction linear movement for equipment powered by inertia or by hand. All linear slides provide linear motion based on bearings, whether they are ball bearings, dovetail bearings, linear roller bearings, magnetic or fluid bearings. X-Y tables, linear stages, machine slides and other advanced slides use linear motion bearings to provide movement along both X and Y multiple axis.
2026-07-24