Many people think that wooden sleepers, like BPM and Xiao, belong to obsolete antiques and should have been put into the museum.
At the sound of high-speed railway, after all, all the images in our mind are concrete sleepers, ballastless tracks and silvery white bullets. Wood Sleepers? It sounds like the last century.
But the truth is -- it's not going away at all. Not only has it not been demobilized, but also a large number of railway lines, mine special lines and heavy haul freight lines around the world have been solidly carried out. It's not old-fashioned, it's really capable.
You might ask: Is wood not wood? Weathering, sun exposure, rain, insect infestation, not three or five years later rotted into slag?
It is true that the original wood cannot hold it. But who tells you that sleepers are "natural"?
Pine in, iron out
Sleepers are basically pine wood. Pine wood is cheap, easy to find, with straight grain and good processing. It belongs to the "honest people" in the wood world - they can do rough work and do not do anything. But honest people also have weak ribs. Pine wood is afraid of water, insect and decay. It is directly thrown into the field. It will not take long to be "arranged" by the microbial army.
So, before taking the post, the pine must be given a deep "special training".
This is the core process of anti-corrosion sleeper - oil immersion treatment.
The process is not complicated in terms of flow: the sawn and dry pine sleepers are packed into a huge sealed tank, and the air and water in the wood are forced out by vacuum pumping. The preservative oil is then injected and pressurized to allow the oil to penetrate deep into the wood along those emptied channels. The whole process is a little like doing pickled meat - just the wood is pickled, the seasoning is preservative oil, the purpose is not taste, but life.
At the end of this step, the pine wood's temperament changes. If the oil seeps in, the insects are unwilling to gnaw, and the water is not easy to invade, so it is impossible for the fungus to settle down. Oil immersion depth is usually more than 13mm, which seems not much? But for wood, this layer of oil is like wearing a protective suit from the depth of the fiber, and the wind and grass on the outside cannot stir.
Why hasn't it been eliminated yet?
Steel rusts, concrete cracks, wood rots - each material has its own soft ribs. But the advantage of corrosion resistant sleepers is that they are too comprehensive.
Good elasticity. When the train comes over, the wooden sleepers will "yield" slightly, and the soft buffer capacity is not comparable to that of concrete. Especially for heavy haul railways, mountainous curves and other places with complex working conditions, the flexibility of wooden sleepers is the advantage. It is not hard to carry, it unloads the force - this way, all the old man who has practiced Taichi knows.
Convenient for construction. The wood is easy to cut, drill and nail, and it is easy to adjust on site. When arriving at the mine line in the remote mountainous area, the large machinery cannot get in and the sleeper is transported by manpower and mules and horses. At this time, the wooden sleeper with light weight and easy manipulation can save life. You said pulling a truck of concrete sleepers up the hill? Look at the road first.
Strong adaptability. Cold, hot, wet... in many extreme environments, concrete sleepers are subject to freeze-thaw damage or thermal expansion and contraction, while oil-soaked pine sleepers are quite calm in these scenes.g.
Old thing has old thing's gateway
Internet tends to use "eliminated" to describe what "XX is dead" and "XX is abandoned". But the real world is not doing PPT, and the traffic engineering doesn't play the concept hype. Material selection for a railway depends on working conditions, cost, maintenance period and environmental conditions, regardless of feelings.
The anti-corrosion sleeper does not stand under the spotlight, which does not mean it has no stage.
It's just lying quietly on another track that you don't pay much attention to and carrying it when you are passing by on the high-speed rail.
That layer of oil immersed in the bone is its bottom gas.
