Anti-slip serration design of the rail bearing plate and its effect on rail lateral restraint
What are the design parameters of the trapezoidal tooth pattern of national standard pressure plates?
The trapezoidal tooth pattern of national standard pressure plates has a depth of 1.0mm, a tooth spacing of 5mm, and a tooth angle of 60°. This parameter is the optimal value verified by friction tests and can maximize friction. The tooth top width of the trapezoidal tooth pattern is 2mm, and the tooth bottom width is 3mm, with a narrow-top and wide-bottom structure, which is not easy to wear and deform, and has a long service life. For pressure plates supporting 60kg/m rails, the tooth pattern must cover the entire pressing surface to ensure that the contact area with the rail bottom surface is ≥90% and enhance the lateral restraint effect. In heavy-haul railways, the tooth pattern depth should be appropriately increased to 1.2mm, and the tooth spacing should be reduced to 4mm to improve friction and adapt to the load requirements of large axle load trains. During construction, it is necessary to check whether the tooth pattern is intact. If there is wear or deformation, the pressure plate must be replaced in a timely manner.
What anti-slip advantages do diamond tooth patterns have over trapezoidal tooth patterns?
The diamond tooth pattern is diamond-shaped, and the contact with the rail bottom surface is point contact, which can generate greater contact stress, and the friction force is increased by more than 20% compared with the trapezoidal tooth pattern, with more significant anti-slip effect. Its tooth pattern depth and spacing can be flexibly adjusted, with a depth range of 0.8-1.5mm and a spacing of 4-6mm, adapting to different rail materials and line working conditions. The diamond tooth pattern has excellent bidirectional anti-slip performance, which can not only resist the leftward displacement of the rail but also prevent the rightward lateral displacement, making it particularly suitable for use in small-radius curve sections. The pressure plate with this tooth pattern design wears evenly, without local excessive wear, and its service life is 15% longer than that of the trapezoidal tooth pattern pressure plate. At the same time, the diamond tooth pattern is easy to clean, and dust and debris on the track are not easy to get stuck in the tooth pattern gaps, facilitating maintenance.
What special requirements are there for the tooth pattern design of pressure plates in small-radius curve sections?
The centrifugal force generated when trains pass through curves in small-radius curve sections is large. The depth of the pressure plate tooth pattern should be increased to 1.5mm, and the tooth spacing should be reduced to 3mm to maximize friction and resist the lateral thrust of the rail. The tooth angle should be adjusted to 75° to increase the meshing degree between the tooth pattern and the rail and prevent rail lateral displacement. The pressing surface of the pressure plate should be carburized, and the surface hardness should be increased to above HRC55 to enhance the wear resistance of the tooth pattern and adapt to the frequent friction in curve sections. The tooth pattern must cover the entire width of the pressure plate, and the contact area with the rail should be ≥95% to avoid pressure plate deformation caused by uneven local stress. In addition, the tooth pattern density of the pressure plate on the outer side of the curve should be higher than that on the inner side, with a tooth spacing of 3mm on the outer side and 4mm on the inner side, to specifically resist the outer centrifugal force.
What is the impact of tooth pattern wear on the lateral restraint capacity of pressure plates?
Tooth pattern wear will increase the contact area between the pressure plate and the rail, changing from point contact or line contact to surface contact, resulting in a significant decrease in friction force and a reduction of more than 50% in lateral restraint capacity. When the tooth pattern depth is worn to less than 0.3mm, the pressure plate cannot effectively prevent rail lateral displacement, and rail lateral displacement is prone to occur when the train passes through curves, causing gauge exceeding the standard. After tooth pattern wear, the meshing degree between the pressure plate and the rail decreases, and slipping is prone to occur when stressed. Under long-term action, the pressure plate will loosen or even fall off. The worn tooth pattern is easy to accumulate dust and debris, further reducing friction and forming a vicious circle. In addition, tooth pattern wear will lead to uneven stress distribution of the pressure plate, accelerate the fatigue damage of the pressure plate, and shorten the service life.
How to detect whether the anti-slip performance of pressure plate tooth patterns meets the standard?
Use a friction coefficient tester to measure the friction coefficient between the pressure plate tooth pattern and the rail bottom surface. A friction coefficient ≥0.6 is up to standard, and the higher the value, the better the anti-slip performance. Conduct a lateral thrust test, apply a lateral load simulating train turning to the pressure plate, observe the lateral displacement of the rail, and a lateral displacement ≤0.5mm is qualified to verify the lateral restraint capacity. Measure the tooth pattern depth through visual inspection, use a depth gauge to measure at different positions of the tooth pattern, and an average depth ≥80% of the design value is qualified. If it is lower than this value, the pressure plate needs to be replaced. Conduct a wear test, simulate the friction working condition of train operation, measure the tooth pattern wear after 100,000 friction cycles, and a wear ≤0.2mm is qualified. In addition, on-site tracking observation can be carried out to count the lateral displacement data of the rail in the curve section and intuitively evaluate the actual performance of the tooth pattern anti-slip performance.