The impact of mixing old and new spring clips on the uniformity of line stress
Q1: Why does mixed installation of new and old clips cause uneven stiffness?
A1: After long-term service, old clips have plastic deformation, elastic attenuation and reduced stiffness; new clips have high stiffness and good elasticity. Mixed installation of the two causes drastic changes in track stiffness within a short distance, resulting in bumps and impacts when vehicles pass.
Q2: What adverse impact does stiffness difference have on gauge retention?
A2: Rail lateral displacement is large in sections with low-stiffness old clips, and gauge is easy to widen; sections with high-stiffness new clips have strong restraint and relatively stable gauge. Gauge fluctuation is obvious in the same section, direction is not smooth, aggravating wheel-rail eccentric wear and shaking.
Q3: Does mixed installation accelerate further failure of old clips?
A3: Yes. New clips bear more loads, and although old clips bear less force, they already have micro-cracks and damage. Cracks continue to propagate under vibration, failure speed is faster than that of single use, and concentrated fracture is easy to occur.
Q4: Why is mixed installation of new and old clips strictly prohibited in joints and curved sections?
A4: These sections have strong impact and complex stress, requiring extremely high stiffness uniformity. Stiffness mutation caused by mixed installation amplifies stress difference, rapidly fatigues clips, bolts and pads, and significantly accelerates disease outbreak speed.
Q5: What clip replacement principles should be followed in on-site maintenance?
A5: Try to uniformly replace new clips in the same span section or the same curve section. Old clips can only be used for temporary emergencies and shall not be mixed for a long time. Uniformly retighten torque after replacement to ensure uniform stress. Establish a clip use ledger to control service life.