Maintenance Cycles and Key Points for Fastening Systems
- What is the maintenance cycle of elastic clips? What are the maintenance key points?
Elastic clips on ordinary railways are inspected every 6 months, and those on high-speed railways are inspected every 3 months. Maintenance key points include: checking the appearance of elastic clips for cracks, especially at bends, which can be detected with a magnetic particle flaw detector; measuring the clamping force of elastic clips. The clamping force of elastic clips on ordinary railways should be maintained at 8-12kN, and that on high-speed railways is 10-15kN. Replace them in time if it is lower than the lower limit; clean the dirt and rust on the surface of elastic clips to prevent them from affecting elasticity. A wire brush with rust remover can be used for treatment.
- How to determine the maintenance content and cycle of fishplate bolts?
Fishplate bolts need to be checked for fastening status once a month and comprehensively maintained every 3 months. Maintenance content includes: checking the bolt preload with a torque wrench. The preload of M24 bolts on ordinary railways is 250-300N·m, and that of M27 bolts on high-speed railways is 400-500N·m. Retighten if insufficient; checking whether the bolt threads are damaged, and replace them in time if there is thread slippage; cleaning the debris in the bolt holes to prevent them from hindering bolt installation and affecting the fastening effect.
- What is the maintenance cycle of spikes and the criteria for determining replacement?
Spikes are inspected every six months. The criteria for determining replacement are: if the spike pull-out amount exceeds 5mm, it indicates anchoring failure and needs to be re-anchored; if the spike is obviously deformed, affecting its fixing effect on the rail, it should be replaced; tapping the spike with a small hammer, a dull sound may indicate loose anchoring, requiring further inspection and re-anchoring if necessary.
- What are the maintenance points and replacement cycle of under-rail pads?
Under-rail pads are inspected once a year. Maintenance points are: checking whether the pads are cracked or deformed. If the crack length exceeds 1/3 of the pad width or the deformation exceeds 5mm, they need to be replaced; cleaning the debris on the surface and bottom of the pads to keep them well fitted with the rails and sleepers; for rubber pads, checking their aging condition, such as hardening and cracking, and replacing them in time. Generally, the service life of rubber under-rail pads is 5-8 years, and that of plastic pads is 8-10 years. Whether to replace them when they expire depends on the actual situation.
- What are the differences in maintenance of fastening systems in different seasons?
In spring and autumn, focus on checking the loosening of various components of the fastening system due to temperature changes and fully tighten the bolts; in high-temperature summer, pay attention to the decrease in elasticity of elastic clips due to temperature rise, and appropriately adjust the clamping force; in low-temperature winter, check whether the spike anchoring agent is frozen and cracked, and repair it in time. In the rainy season, strengthen the anti-rust treatment of metal components such as fishplates and bolts, and increase the frequency of applying anti-rust grease; in areas with heavy wind and sand, regularly clean the sand and dust in under-rail pads and fasteners to prevent them from wearing components.