There are significant differences in the fastener systems of ballastless track and ballasted track. This difference stems from the differences in the structural characteristics and force modes of the two tracks, and requires targeted adaptation.
Different structural design logic. Ballasted track relies on the ballast gravel to provide elastic buffering, and the fasteners are centered on "rigid fixation + limited adjustment", such as spring bar type I and type II fasteners, which fix the rails to the concrete sleepers with bolts, and set a 10-15mm thick rubber pad under the rail to compensate for the track settlement by using the compressibility of the ballast gravel. The foundation of ballastless track (such as CRTSⅢ type slab) is a rigid concrete slab, and the fasteners need to integrate elastic functions, usually including multi-layer buffer components (such as pre-tightening spring bars, insulating buffer pads, and height adjustment pads). The vertical stiffness can be adjusted by the thickness of the pad layer (range 20-60kN/mm), replacing the elastic effect of the ballast bed.
Different adjustment capacity requirements. Because the ballast track is prone to uneven settlement, the fasteners need to have a large height adjustment (usually ±30mm), and the elevation adjustment is achieved by superimposing the pad under the rail; the ballastless track has a small settlement (design limit ≤15mm), and the fastener height adjustment only needs ±10mm, but requires higher positioning accuracy, the gauge adjustment is controlled within ±2mm, and embedded sleeve bolts are used to avoid water accumulation and rust in the bolt holes.
The material and strength adaptation are different. The bolts of the fasteners of the ballasted track are mostly grade 8.8, and the spring clip pressure is 10-12kN, which is adapted to the characteristics of the ballast bed dispersing load; because the load of the ballastless track is directly transmitted to the foundation, 10.9 grade high-strength bolts are required, and the spring clip pressure is increased to 15-18kN (such as SKL15 type), and the embedded parts connected to the track plate need to use 316 stainless steel to prevent corrosion in the alkaline environment of concrete.
Special function differences. Ballastless track fasteners need to integrate insulation performance, and the gauge baffle is made of glass fiber reinforced plastic (GFRP) to avoid interference with the track circuit; ballasted track focuses on anti-loosening design, and the bolt head is equipped with a stop washer to adapt to the loosening of the bolt caused by the vibration of the track bed. In addition, ballastless track must also meet the temperature adaptability of -40℃ to 60℃ in high-speed rail scenarios, and the low-temperature impact energy of the spring bar is ≥27J, while the temperature resistance range of ballasted track fasteners can be relaxed to -30℃ to 50℃.
It can be seen that the fasteners of the two types of tracks are different in design concepts, performance parameters, and material selection. They need to be accurately selected according to the track type and cannot be universal.
GNEE RAIL is a company specializing in the research and development and production of railway fasteners, mainly providing various types of rail fasteners, spring clip systems and supporting connectors. The factory is equipped with modern production equipment and professional testing laboratories, and strictly implements the ISO quality management system to ensure that the products meet international railway industry standards. With years of technical accumulation, we are able to provide standard products or customized solutions according to customer needs, and have established a complete after-sales service system. We look forward to establishing long-term and stable cooperative relations with more customers.