Pulsating fatigue testing machines are widely used for pulsating fatigue tests of materials and components such as steel rails, structural members and connectors. Relying on a hydraulic pulsation system to repeatedly apply cyclic loads, they serve as core test equipment in the fields of rail transit and engineering inspection. As a key protective component of the hydraulic pulsation system, the oil circuit filter element directly determines the loading stability, test data accuracy and overall service life of the equipment, and shall be replaced regularly in accordance with specifications.

Under long-term cyclic loading conditions of the pulsating fatigue testing machine, hydraulic oil flows back and forth at high speed continuously. During equipment operation, metal micro-debris generated by friction of pipelines and pistons, rubber particles peeled off from aging seals, residual impurities from assembly and ambient dust will all mix into the hydraulic oil. The core function of the oil circuit filter element is to continuously intercept solid contaminants and maintain the cleanliness of hydraulic oil.

If the filter element is not replaced for a long time, clogging and filter failure will occur. When impurities enter precision components such as pulsators, servo valves and oil cylinders, they are highly likely to cause valve core sticking, pulsating pressure fluctuation and unstable load, which are directly manifested as force value drift and distorted test curves, rendering fatigue test results invalid. Hard particles will continuously scratch the inner wall of oil cylinders, accelerate the wear of seals, and trigger faults such as system oil leakage and insufficient pressure. Once servo valves and core pulsation components are damaged, the maintenance cycle will be long and the cost high, delaying the progress of inspection tasks.

Contaminants also accelerate the oxidation of hydraulic oil and produce sludge, which accumulates inside pipelines and valve assemblies, resulting in poor oil flow, degraded system heat dissipation and abnormal rise of oil temperature, further accelerating the aging and failure of seals. Pulsating fatigue testing machines often require uninterrupted cyclic loading for several hours or even days. They impose much higher requirements on the cleanliness of the hydraulic system than ordinary static testing machines, and risks caused by oil contamination will be amplified.

Key Points for Filter Replacement and System Maintenance

1. Running-in period of new equipment: Complete the first replacement of oil circuit filter element after approximately 200 operating hours of new equipment commissioning to remove residual assembly impurities.
2. Regular replacement cycle: For equipment under continuous fatigue test operation, it is recommended to replace the filter element every 1000 operating hours. For intermittently used equipment, the cycle can be adjusted according to hydraulic oil cleanliness test results.
3. Supporting inspection items: Take oil samples to check the condition of hydraulic oil when replacing the filter element. Replace the hydraulic oil at the same time if the oil turns dark, turbid or has peculiar odor. Inspect pipeline joints for leakage and verify whether pressure gauges and pulsating loading status work normally.
4. Prioritize original factory filter elements: The filtration accuracy and pressure resistance of original supporting filter elements match the hydraulic system of pulsating fatigue testing machines. Inferior filter elements tend to have insufficient filtration accuracy or shell rupture, resulting in secondary contamination of the hydraulic system.

Jinan Lizhi Testing System Co., Ltd. Reminds: Pulsating fatigue testing machines are high-precision cyclic load test equipment. Preventive hydraulic maintenance is critical to reducing equipment failures and ensuring the reliability of fatigue tests. Our company can provide one-stop technical services including on-site inspection of pulsating fatigue testing machines, supply of filter spare parts, hydraulic system cleaning and equipment maintenance & upgrading, to ensure stable implementation of fatigue inspection for various steel rails and structural members.