The standardization of rail pad installation directly affects the long-term stability of the rail system, and the following key points need to be focused on:
Environmental adaptation is the basic premise. Before installation, the operating environment temperature needs to be checked. The rubber pad needs to be constructed in the range of -10℃ to 40℃. When it is below 0℃, it needs to be preheated to above 5℃ in advance to avoid brittle fracture of the material; although the polyurethane pad has better temperature resistance, it needs to shorten the exposure time in a high temperature environment (above 60℃) to prevent softening and deformation. When constructing in humid weather, it is necessary to ensure that the rail surface of the sleeper is dry, and the accumulated water or frost must be completely removed. If necessary, a moisture-proof film should be laid to isolate water vapor.
Material matching needs to be strictly controlled. Different track types have clear requirements for pad models: high-speed railways give priority to polyurethane pads with a Shore hardness of 60±5, and conventional railways can use rubber pads with a Shore hardness of 55±5; sections with a curve radius of less than 800 meters must be equipped with chamfered anti-lateral shift pads, and their edge slope should be consistent with the inclination of the rail (usually 1:40). It is strictly forbidden to mix pads of different materials or specifications to avoid uneven force due to differences in stiffness.
Operation specifications are related to installation quality. When placing pads, avoid direct contact with bare hands, and wear clean gloves to prevent oil pollution and affect the fit with the sleeper; special lifting equipment must be used when the rail is in place, and soft pads must be placed at the contact point between the hook and the rail to prevent scratching the bottom of the rail and causing abnormal local force on the pad. When the pad is raised for installation, a thin layer of silicone grease must be applied between each layer to reduce friction, and the bottom layer must be a steel pad to enhance the load-bearing capacity.
Quality inspection cannot be ignored. A second tightening is required within 24 hours after installation. At this time, the fasteners of the pad may loosen due to initial compression, and the tightening torque must be kept consistent with the standard value (300-350N・m). An ultrasonic detector is used to spot check the fit density between the pad and the sleeper. If the hollow area exceeds 5%, it needs to be reinstalled. In long-term operation, the edge of the pad needs to be checked every quarter for warping. If warping of more than 3mm is found, it needs to be replaced in time to prevent rainwater from seeping into and eroding the sleeper.
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.