In every inch of land where the rail extends, except for the whistling train and the neatly arranged rails, there is a silent but always stick to the post "old man" - anti-corrosion sleeper. It lies quietly under two rails, bearing the rolling of ten thousand tons of trains, transferring the heavy burden of force, and maintaining the safety and stability of railway operation. You may never notice it, but it has served the railway system for hundreds of years and is a true "elder" member.
Say it's an "old man," one is really "old.". Since the birth of railways in the 19th century, wooden sleepers have been an important part of the track structure. At that time, steel was expensive, technology was poor, and wood became the most realistic and accessible support material. Even today, concrete sleepers and steel sleepers have been widely used due to high-speed railway galloping, track upgrading, but anti-corrosion sleepers can still be seen on many branch lines, station yards, turnout areas and even some trunk railways. It has not exited the stage of history, but evolved over time to perpetuate its mission in another way.
Second, it is "old" and strong. The "old" here is not aging, but the "old and prudent" that can stand the test of time. Ordinary wood may be corroded and deformed for several years if it is buried underground or exposed to the wind and rain. However, anti-corrosion sleepers can stably support dozens of years in the harsh environment of sun and rain, freezing and thawing alternation and heavy train pressure. The secret of this "long life" lies in its unique anti-corrosion treatment process.
The first step in the fabrication of corrosion resistant sleepers is material selection. Although there are a variety of wood types, pine is the most widely used wood at present. Pine has a relatively short growth cycle and abundant resources. More importantly, its wood structure is loose and its liquid conductivity is good. Moreover, pine itself has a certain natural resin composition, which has a certain natural resistance to decay fungus, so it can be considered as "good base".
Wood shall be strictly screened and processed after felling. Logs that do not conform to the size, have obvious cracks and excessive knots will be removed. Qualified wood will be sawn into sleeper blanks of standard sizes, typically approximately 2.5 meters long, trapezoidal or rectangular in section, with holes reserved at both ends for fastening. This step focuses on "orderliness", because only the same size can ensure the smoothness and stability of the track.
The next step is the most critical anti-corrosion treatment. This step determines whether the sleepers can change from "ordinary wood" to "soldiers on the railway".
In simple terms, the sleepers are placed in a closed pressure tank, which is vacuumized first and then filled with preservative oil. Under high pressure, the oil is forced to "squeeze" into the fiber gaps and ducts of the wood. This process is not simply immersed, but pushed by pressure to ensure that the preservative oil can penetrate deep.
The sleepers shall be dripped and left standing for a period of time after the oil immersion is completed, so as to allow the excess oil to flow back and prevent the surface from being too oily, and avoid the ballast bed from being polluted during laying.). Finally, a visual inspection shall be carried out to mark the delivery information. Only a genuine anti-corrosion sleeper can be considered as a formal "graduate" and can be transported to the construction site for railway construction.
Don't look at it as a block of wood, it's a little more. Sleeper is the "bearing the upper part and the lower part" in the track structure - the upper part shall hold the steel rail and the lower part shall be connected to the track bed. Impact force, lateral force and longitudinal force during train operation shall be dispersed and transmitted by it. It shall have enough strength to bear the pressure, enough elasticity to buffer vibration and enough stability to prevent track deformation. Preservatively treated pine sleepers provide a good balance between strength, elasticity and durability.
In some special sections, such as bridges, turnouts and curves with small curve radius, the advantage of anti-corrosion sleepers is obvious. Its elasticity is better than that of concrete sleeper, and it can adapt to structural deformation better; It has good insulation property and will not interfere with track circuit like metal; In addition, it is light, easy to install, and more flexible in maintenance and replacement. These characteristics make it still have a place in the modern railway system.
It is like an old railway worker, silent, but always stick to the post. The train runs over it, and it is silent; The rain erodes its body and it does not shrink. It knows that it is part of the track and one of the cornerstones of safety. Even in the future, it will be completely replaced, and its position in the history of China's railway development will not be wiped out.
