It's autumn. Wooden doors and floors in your house have been a little bit noisy recently – the doors creak and the floor seams seem a little wider than in the summer. The old people call it "autumn dryness". As soon as the air dries, the wood itself emits water and shrinks.
Ordinary wood is afraid of this, and the wood on the railway is afraid of this. How can a freight train hold the rail even if the sleepers are dry and cracked when a freight train is pressed by hundreds of tons? But when you look at the railway, those black sleepers have been laid for more than a decade, and rarely they crack open. The same wood, where is the gap?
In the end, the water in the wood cannot walk.
Wood is naturally "breathing". There is moisture inside, and the moisture will come in and out as soon as the outside becomes dry and wet. In autumn, the wind is strong and the humidity drops fast. The wood loses water faster on the surface than in the core. It shrinks from the outside but not from the inside. The stress is fierce and cracked. Untreated wooden sleepers (called plain sleepers in the line) are planted here - so plain sleepers are basically not used for the current line.
The route of anti-corrosion sleepers is different. Before working, the wood shall be thoroughly dried and the excess water inside shall be removed; Followed by the overall oil immersion treatment, the oil is allowed to eat into the pores of the wood. When the oil enters, the small channels of the wood are blocked by half, and the dry and wet changes outside are not easy to be transmitted to the core. The moisture inside the wood is stable, and it is not panic even when the fall is dry.
There's a key here: oil really goes in, not just a layer on the surface. The immersion depth is usually over 13mm, and the oil is taken from the surface to the inside. The oil on the surface peels off as soon as the train rubs and the rain flushes, and it cannot be stopped; Getting into the wood body is a "water-lock suit.". In addition, some treatments on the end face and surface notch guidance are to make the stress concentrate in one place and burst.
Why Use Pine Wood? Pine wood's fibrous construction is naturally suited to this treatment and is tough enough to tolerate oil. The same effort will be reduced to other corks.
Let's talk more. The railway has "autumn inspection" every year in the autumn. The inspector takes a hammer and looks down. It is necessary to check whether the sleeper is cracked or not. Anti-corrosion sleepers are stable inside, with few cracks, and the maintenance period can be extended. If individual damaged sleepers are found, they can be replaced by a single one without affecting the whole section. The mines and bridges are much tougher - the dry, heavy, damp, untreated wood is too long to carry, and the corrosion resistant sleepers are stable against this base.
The same is true for the sleeper walkway in the garden. It is also the oil-filled wood, which has been laid in the community garden for three or five years, and it is not like the ordinary anti-corrosion wood that cracks when it moves.
Arrive on time every dry year in autumn. The wood is not cracked, and the poor is not "whether it is wood", but the effort before working has not been enough.
