Knowledge of Rail Spike Anti-Loosening Performance and Compatible Track Types
What are the main hazards of loose rail spikes?
Loose rail spikes will cause the rail to be improperly fixed, and the rail is prone to transverse displacement during train operation, affecting the line direction. Loose rail spikes cannot effectively transmit loads, leading to stress concentration on other fasteners and accelerating the failure of the overall fastener system. Loose rail spikes will increase track vibration, intensify wear of rails, base plates and sleepers, and shorten service life. In high-speed lines, loose rail spikes may cause sudden changes in track geometric dimensions, seriously threatening driving safety. In electrified lines, loose insulated rail spikes may cause failure of insulation performance and trigger circuit faults.
What are the core structural designs for anti-loosening of rail spikes?
Thread anti-loosening is the most commonly used design, which inhibits loosening by increasing thread friction, such as using fine threads or trapezoidal threads. Anti-loosening washer design uses the elastic deformation of the washer to generate continuous preload to prevent vibration loosening. Cotter pin anti-loosening structure restricts relative rotation by passing a cotter pin through the rail spike and nut, suitable for important sections. Chemical anti-loosening design applies anti-loosening glue to the thread, which forms a fixed connection after curing, with long-lasting anti-loosening effect. Knurled anti-loosening design: the rail spike shank is knurled, which increases friction after being embedded in the installation hole, improving anti-loosening ability.
What are the differences in anti-loosening performance requirements of rail spikes for different track types?
High-speed railways have extremely high requirements for the anti-loosening performance of rail spikes, which must withstand high-frequency vibrations, and the anti-loosening structure must be effective for a long time. Rail spikes in heavy-haul lines need to resist impacts from large axle loads, and the anti-loosening design must balance strength and durability. Conventional speed lines have relatively lower requirements for rail spike anti-loosening, and simple anti-loosening methods can be selected to control costs. Urban rail transit has frequent starts and stops and severe vibrations, so rail spike anti-loosening must have the characteristics of quick installation and long-term stability. Rail spikes in small-radius curve lines are subjected to large lateral forces, and the anti-loosening design must focus on resisting loosening caused by lateral vibration.
How to improve the anti-loosening effect of rail spikes through installation technology?
Ensure that the rail spike is vertically implanted during installation to avoid uneven force caused by inclination and prevent loosening. Strictly control the installation torque and tighten according to the design requirements to ensure sufficient preload. Apply special anti-loosening grease or lubricating oil to the thread part to reduce wear and enhance anti-loosening effect. For pre-embedded sleeve-type rail spikes, ensure that the sleeve is firmly installed and closely matched with the rail spike thread. Perform secondary retightening after installation to eliminate slight loosening caused by initial vibration and improve anti-loosening durability.
What are the testing methods for the anti-loosening performance of rail spikes?
Vibration test detection: detect the loosening degree of rail spikes within a specified period by simulating the train operation vibration environment. Torque decay test: regularly measure the rail spike torque after installation to judge the effectiveness of the anti-loosening structure. On-site long-term tracking detection: regularly check the tightening status of line rail spikes and count the loosening rate. Low-temperature and high-temperature environment tests: verify the stability of the rail spike anti-loosening structure under extreme temperatures. Impact load test: simulate the impact of heavy-haul trains to detect whether the anti-loosening performance of rail spikes meets the standards.