Specifications and dimensions of railway spikes
As a key component of the track structure, the specifications and dimensions of railway spikes directly affect the stability and safety of the track system. Depending on the usage scenario and track type, the size parameters of the spikes are significantly different. The length of common spikes on ordinary railways is between 85mm and 120mm, the diameter is 16mm to 22mm, and it is suitable for rails of 43kg/m to 60kg/m. High-speed railways have higher requirements for spike specifications, with a length generally above 150mm and a diameter of not less than 24mm to cope with the lateral force generated during 350kmh operation. Heavy-duty railway spikes need to withstand loads of more than 30 tons of axle weight. The head is designed as a trapezoidal structure to increase the contact area with the sleeper, and the bottom thread adopts a double-wire design to improve the pull-out resistance.
In terms of material, Q235 carbon structural steel is generally used in China to manufacture spikes, and the yield strength must reach 235MPa. Spikes used in special environments are hot-dip galvanized, and the thickness of the zinc layer is not less than 85um. Road spikes used in high-cold areas need to add nickel elements, and the low-temperature impact energy value must meet the requirement of not less than 27] at -40°C. Road spikes used in coastal salt spray environments use aluminum-magnesium alloy coating technology, and the corrosion resistance cycle can reach 3 times that of ordinary road spikes.
In the international standard system, the European EN13674 standard stipulates that the length tolerance of road spikes is +1.5mm and the diameter tolerance is +0.5mm. The US AREMA standard requires that the head diameter of the road spike shall not be less than 1.5 times the diameter of the nail rod, and the head thickness shall not be less than 12mm. The Japanese JSE1108 standard has special requirements for thread accuracy, and the tolerance band of the middle diameter of the external thread is controlled at 6g level to ensure the matching accuracy with the sleeper nut. The Chinese TB/T2344 standard stipulates that the tensile strength of the road spike shall not be less than 490MPa, the elongation after fracture shall be greater than 15%, and the Vickers hardness shall be controlled in the range of 200-250HV.
The installation process directly affects the performance of the road spike. A torque wrench is required for manual installation, and the tightening torque of ordinary spikes is set in the range of 150-200N·m. A hydraulic impact wrench is used for mechanical installation, and the torque accuracy is controlled within the error range of ±5%. During the construction process, pay attention to the influence of ambient temperature. When the rail temperature exceeds the locking temperature +15℃, stress relief measures must be taken. Daily maintenance requires checking the tightening status of the spikes every quarter, and using a special feeler gauge to measure the gap between the spike head and the rail bottom. If it exceeds 2mm, it needs to be re-tightened immediately.
