The selection of rail pads with suitable materials should be combined with the track type, operating conditions and environmental characteristics, and the best cost-effectiveness should be achieved by matching material performance with actual needs. The following are the core selection criteria:
Match the basic material according to the track grade. High-speed railways have extremely high requirements for track stiffness uniformity, so polyurethane pads are preferred. Its dynamic stiffness stability is excellent (the change rate after 3 million fatigue tests is ≤15%), and the model with a Shore hardness of 60±5 can accurately match the impact characteristics of 200-350km/h trains. Conventional railways can use natural rubber pads. The hardness range of 55±5 can balance the buffering performance and cost, and the static stiffness is controlled at 80-100kN/mm to meet the needs.
Heavy-load scenarios focus on material strength. Freight lines with axle weights exceeding 25t need to use fiber-reinforced rubber pads. By adding aramid fibers, the shear strength is increased by 40% to avoid tearing of the pads due to excessive wheel-rail lateral forces. In extreme heavy-load environments such as mining area dedicated lines, rubber-metal composite pads can be selected. The metal skeleton layer can increase the local pressure bearing capacity to more than 150MPa to adapt to frequent heavy-load impacts.
Environmental factors determine the weather resistance of materials. Ordinary rubber pads should be avoided in cold areas (below -30℃), as their low-temperature brittle temperature is only -40℃, which is prone to cracks; hydrogenated nitrile rubber pads should be used instead, with a brittle temperature as low as -55℃ and an elasticity retention rate of over 80% in freeze-thaw cycles. Polyester polyurethane pads are recommended in high-temperature and high-humidity areas (annual average humidity >85%), which have better hydrolysis stability than polyether types and can extend their service life to more than 15 years.
Customized selection for special sections. Small radius curves (R < 600m) require high friction coefficient pads (≥ 0.8), and a 7:3 blend of styrene-butadiene rubber and natural rubber can meet the requirements; flame-retardant pads should be used in poorly ventilated environments such as tunnels, and the oxygen index should be ≥ 32, meeting the fire protection requirements of TB/T 3560. When selecting, the type of fastener system should also be referred to. The thickness deviation of the elastic non-fastener pad must be controlled within ± 0.3mm to ensure assembly accuracy.
By comprehensively evaluating track parameters, load characteristics and environmental conditions, scientific matching of the material of the underrail pad can be achieved, which can avoid cost waste caused by excess performance and prevent early failure caused by insufficient materials.
GNEE RAIL is a professional trading company focusing on the export of railway fasteners, committed to providing reliable rail connection products for global railway construction projects. The main products include a full range of railway fasteners such as various spring clip fastener systems, sleeper bolts, anti-loosening washers and insulating components, which are suitable for various application scenarios such as conventional railways, heavy-duty railways and urban rail transit.