High-Strength Locking and Anti-Loosening Technology for Track Bolts/Spittles
What are the core grade classifications of track bolts and applicable accessory scenarios?
Track bolts are divided into three core grades by strength: 8.8, 10.9 and 12.9 grades, and into ordinary bolts, insulating bolts and high-strength bolts by function, adapting to different accessory locking scenarios. 8.8 grade ordinary bolts are the main model for ordinary railways, suitable for Type Ⅰ elastic strips, ordinary railway pressure plates and fishplates, meeting basic locking needs with economical cost. 10.9 grade insulating bolts are special for high-speed railways, suitable for W2/X3 elastic strips, high-speed railway pressure plates and fishplates, with insulating coating anti-electrocorrosion and higher locking torque. 12.9 grade high-strength bolts are special for industrial and mining heavy-duty, suitable for heavy-duty elastic strips, industrial and mining pressure plates and fishplates, with the strongest tensile strength, impact resistance and anti-loosening. Foreign standard bolts are divided into UIC/BS/AREMA models, used with corresponding foreign standard accessories, strength grade synchronized with international standards, adapting to cross-border projects.
What are the core types of track spikes and key installation and fixing technical points?
Track spikes are divided into four types: screw spikes, embedded spikes, wood sleeper spikes and insulating spikes, screw spikes are the mainstream model, suitable for concrete sleeper rail fixing with convenient installation and stable locking. Screw spikes are made by cold heading process with high thread precision, screwed into sleeper embedded sleeves without sliding wire, screwing depth ≥150mm to ensure fixing strength. Embedded spikes are pre-cast in sleepers, suitable for high-speed railway ballastless track sleepers, more firm fixing without loosening risk, suitable for high-speed driving scenarios. Wood sleeper spikes are pointed design, suitable for wooden sleepers, locked rails after driving, mostly used for old factory tracks. Insulating spikes are with insulating sleeves, suitable for high-speed railway track circuits to avoid spike conduction causing signal faults, insulation resistance ≥5×10^6Ω.
What are the core material requirements and mechanical performance indicators of bolts/spikes?
The core materials of track bolts are 45# high-quality carbon steel and 40Cr alloy steel, spikes are 20MnTiB alloy steel, all are special high-strength materials for tracks with excellent tensile and shear resistance. 8.8 grade bolt material is 45# steel with tensile strength ≥800MPa and yield strength ≥640MPa, meeting the basic locking stress needs of ordinary railway accessories. 10.9/12.9 grade bolt material is 40Cr alloy steel, 10.9 grade tensile ≥1040MPa, 12.9 grade tensile ≥1220MPa, adapting to high-speed railway/heavy-duty high-strength locking. Spike material 20MnTiB alloy steel with tensile strength ≥900MPa, no crack after 15° cold bending, no deformation after screwing and locking, wear resistance and rust resistance. Bolt/spike surface hot-dip galvanized anti-corrosion with coating ≥80μm, salt spray resistance ≥500 hours, no rust and failure in humid environment.
What are the core torque specifications and anti-loosening measures for bolt/spike installation and locking?
Bolt locking torque is strictly implemented according to strength grade, 8.8 grade torque 350-400N·m, 10.9 grade 500-550N·m, 12.9 grade 600-650N·m, torque deviation ≤±5%, uniform force without sliding wire. No torque is required for spike installation, screw spikes are screwed into embedded sleeves until tightened, check no loosening after screwing, wood sleeper spikes are driven until the spike head fits the base plate. The core anti-loosening measures for bolts are installing spring washers and lock nuts, high-speed railway bolts are additionally coated with thread locking glue, industrial and mining bolts are added with anti-loosening gaskets for multiple anti-loosening and anti-vibration loosening. A small amount of lubricating grease is applied to the bolt thread during installation to facilitate locking and later disassembly, avoiding thread corrosion and seizing unable to maintain. Make torque marks after locking, inspect and retest torque monthly, replenish and tighten in time if attenuated to ensure long-term locking effect.
What are the common faults and maintenance treatment measures of bolts/spikes in use?
Common faults of bolts/spikes in use include sliding wire, fracture, rust, loosening and insulation failure, all are major track safety hazards, requiring immediate shutdown treatment. Bolt sliding wire is torque exceeding standard or thread wear, remove sliding wire bolts and replace with new ones of the same specification, repair thread holes, re-lock according to standard torque to avoid sliding wire again. Bolt/spike fracture is overload or material defect, replace with new ones and check line load at the same time, upgrade 12.9 grade bolts for heavy-duty sections and reinforce stress points. Rust is coating falling off and moisture, derust and re-coat anti-rust oil, replace stainless steel bolts/spikes in coastal sections to extend anti-corrosion life. Loosening is torque attenuation or anti-loosening failure, retighten to standard torque, upgrade anti-loosening accessories and increase inspection frequency. High-speed railway bolt insulation failure is coating damage, replace insulating bolts, test insulation resistance up to standard to avoid track circuit failure.