Hello, let's talk hard today.
You occasionally ride on a train, crashing and running, and have you looked down at the stuff under your feet -- sleepers? High Probability None. But that doesn't stop it from being a hard character. You think it's built to resist? No, it is no exaggeration to say "torture" about the process that a sleeper goes through from "little fresh meat" in the forest to "iron-bone sound" on the railway.
Take pine for example. Pine, a buddy, has a nice natural condition - fast growing, straight grain and good texture. But there is a deadly weakness: afraid of water, afraid of insects, afraid of decay. You throw it in the wild for less than a few years, termites serving it as a buffet, fungus serving it as a hard-packed room, and rain serving it as a "waterbody" - the end is basically a fight.g.
So, it is impossible to make it carry rails and ten thousand tons of goods without moving any more.
First: air-dried dehydration.
Fresh wood has a very high moisture content, so don't say it's in service. You don't know when you grow mushroom. So the first step is to distribute the excess water.
Generally, natural air drying is used to control the water content below 30% to prepare for subsequent oil immersion treatment.
Second: Cutting nicks.
The excess moisture is removed and the sleepers need to be shaped. The dried wood shall be delivered to the workshop and cut into square rectangles according to the standard size. It is not enough after cutting, and the surface shall be marked with a row of notches. These scratches appear inconspicuous, but are "highways" where preservative oil penetrates the interior of the wood. There is no nick, and the high pressure cannot fill much oil.
Third: oil-immersed corrosion prevention.
Place the treated sleepers in a large sealed tank and fill with preservative oil. This is not done, and the next step is to pressurize the tank-yes, pressurize. Squeeze preservative oil with great pressure into the deep grain of wood.
Under pressure, the oil and grease shall be free from pores and even the capillary pipe at the deepest part of the wood shall not be discharged. The entire immersion depth is often more than 13 mm - what is the concept? The sleepers are all soaked with preservative oil from the skin to the bone, and there is no gap inside and outside.
The entire set of sleepers subjected to "torture" is no longer of the same species as the original clumsy, white and sweet pine.
Think about the service environment of the railway: wind and sunshine, rainstorm and snow, great temperature difference between day and night, and the rail and train weight must be carried on the top. In the past, a freight train was pressed down by thousands of tons, year after year, day after day. Ordinary wood in this environment, has long been the spring mud. But oil impregnated sleepers? It's holding it. The preservative oil penetrates into the wood, forming a dense and air-tight protective layer, so the water cannot penetrate, the insects cannot gnaw, and the fungus does not want to settle down. Even in the wet and rainy southern line, or the northwest gobi where the temperature difference between day and night is great, it can be as stable as an old dog and lie under the rail quietly for more than ten years or even decades.
And there's a hidden buff-throughness in the oil immersion treatment. Preservative oil keeps wood fibers flexible and does not crack like dry wood. When the train comes over, the sleeper can slightly "eat" the impact force and play a role in buffering and shock absorption. This is not easy to do with concrete sleepers.
The sleepers that survive the "torture" are no longer the original pine trees that were slaughtered by people. It solidly nailed to the underside of the rail, silently, solidly and quietly lifted rows of passing trains.
It is unnoticed and requires no attention.
After all, a true hardback never needs spotlights.
