Special-shaped spring: Explain the common faults and countermeasures of special-shaped springs

Special-shaped spring: Explain the common faults and countermeasures of special-shaped springs:
The fifth speed increase of the railway adopts a brand-new operation and maintenance mode, that is, inter-city point-to-point operation that can last up to 20 hours, and the continuous operation speed can reach 160 kilometers per hour. One warehouse inspection operation can meet 5000 kilometers\(one round trip \) No need for maintenance. The adoption of this mode of operation and maintenance puts forward higher requirements on the safety, reliability, maintenance-free performance and stability of the self-monitoring system of passenger cars.
   Therefore, when the speed-up models-25T passenger cars generally enter the A2 repair schedule, “Leapfrog Weekly? Forum” specially invited vehicle manufacturers and vehicle overhaulers to discuss the maintenance countermeasures of 25T passenger cars.
In order to meet the requirements of train running stability and comfort, the SYS series special-shaped spring suspension system has been widely used in the fifth railway speed-up 25T passenger car bogie. After more than one year of testing, the overall application of special-shaped springs is good, It satisfies the operational requirements of our country’s railways, but there are also problems in operational maintenance.
   Special-shaped spring is an inflatable rubber spring that is filled with compressed air in a flexible airtight container and uses the compressibility of the air to achieve elastic action, so it has high requirements for air tightness. There are two types of sealing methods for special-shaped springs: screw fastening and pressure self-sealing. The former uses screws to fasten the metal buckle, the capsule sealing part, and the upper cover together to seal; the latter uses the air pressure inside the capsule Press the sealing surface of the capsule tightly with the cover plate to seal. Because the pressure self-sealing structure has the advantages of small size, light weight and convenient installation, the special-shaped spring of this sealing method is widely used in the 25T passenger car bogie.
  25T type passenger car bogie special-shaped spring system is mainly composed of special-shaped spring, height control valve, differential pressure valve and additional air chamber. The height control valve is an extremely important component in the special-shaped spring system. When the vehicle load changes, the air pressure in the special-shaped spring is automatically adjusted to adapt to it to maintain the height of the vehicle body. The differential pressure valve mainly plays the role of ensuring safety. When the pressure difference between the special-shaped springs on both sides of a bogie is large, or one spring breaks, the differential pressure valve automatically communicates with the special-shaped springs on the left and right sides to prevent the car body from generating excessive pressure. The large tilt prevents derailment to ensure smooth and safe operation of the vehicle.
   Special-shaped spring air leakage In the process of use, due to the influence of weather conditions, line conditions (especially small radius curves), and the quality of special-shaped spring system components and the quality of the special-shaped spring itself, air leakage may occur in the special-shaped spring.
   There is air leakage between the upper cover and the capsule. For the pressure self-sealing special-shaped spring, after using about an A3 repair process, the rubber of the upper cover and the sealing part of the capsule has compression permanent deformation and rubber aging. When suddenly subjected to a large lateral impact, the upper cover and the capsule are sealed The part will be misaligned and air leakage will occur. Especially when the temperature drops in winter, the performance of the rubber material deteriorates further, and it is more prone to air leakage failure. In addition to the factors of the special-shaped spring itself, complex operating conditions, improper operation during use and maintenance are also the main factors that cause air leakage between the upper cover and the capsule.
   The sealing part of the upper cover and lower seat is degummed and leaks air. The sealing part of the upper cover or the lower seat is a layer of vulcanized rubber. In production, when the metal frame of the upper cover is vulcanized with rubber, the vulcanized surface is not clean enough or the adhesive is applied unevenly, which makes the rubber bonding strength poor, and degumming and deformation of the rubber layer occur during a period of use, resulting in air leakage phenomenon.
   Capsules can also cause air leakage due to artificial or accidental damage during use.
   Air leakage caused by defects such as lack of glue, inclusion, damage, etc. in the upper cover, lower seat, and the sealing part of the capsule.
According to the relevant documents of the Ministry of Railways, if there is a slight air leakage in the special-shaped spring system during the operation of the vehicle, it does not affect the braking (the pressure in the main air pipe is ≥550 kPa), and it can run to the end at one time; if the special-shaped spring breaks accidentally , Perforation or severe air leakage, the vehicle must be thrown away at the starting station, and the wind source of the two special-shaped springs of the bogie where the faulty special-shaped spring is located must be cut off at the passing station, and run to the end at a speed below 120 kilometers per hour. When cutting off the wind source, there is no need to cut off the special-shaped spring wind source of the entire car, and there is no need to close the car.
   During the overhaul, if a slight air leak is found between the upper cover and the capsule for the self-sealing special-shaped spring, it is generally not necessary to deal with it, or the air in the special-shaped spring is exhausted and then refilled. The air leakage can generally be eliminated. Special-shaped springs with repeated slight air leakage and severe air leakage should be disassembled and inspected, and the faulty parts or the whole should be replaced if necessary.