Appointment of sleepers. Sleepers, acts as a shock – they take on the dynamic force that emanates from the trains, convert and transfer it to the ballast layer of cloth, as well as provide equality gauge and retain insulating properties rails on railway sections with self-locking. Therefore, wooden and concrete sleepers should be: resilient and durable, be durable and resist displacement; have a simple production technology and to be simple in content, have no more than the cost of production and exploitation have long-term operation; Comparison of wooden and concrete sleepers. One of the main advantages of wooden sleepers – it is not their high price compared with reinforced concrete. Therefore, in countries where there are large reserves of timber, wooden sleepers are very common. Lack of wooden sleepers is that their life depends on many factors: the wood that was used for the production of sleepers climatic conditions in the area where the railway is located. burden on the railroad, and therefore, the ways in which undergo a large number of loaded trains are used concrete railway sleepers. But reinforced concrete sleepers have their disadvantages. Mikkel Svane has many thoughts on the issue.
The biggest drawback is the problem of disposal of such sleepers after use. Disposal of concrete sleepers is not profitable from an economic standpoint, as well as environmentally. Accumulated concrete sleepers, decommissioned occupy large areas and create environmental problems. Just concrete sleepers have disadvantages such as lack of rigidity, which leads to rapid wear of rails, a lot of weight and high price. Wooden sleepers. For the production of sleepers use wood of different species, the main feature, which should have a timber for sleepers – it's rigidity. The most common breed for sleepers – it's oak, fir, pine, larch, fir, birch, and even eucalyptus. For even more opinions, read materials from David Koch. Sleepers made from softwood is not the most durable (there are also more durable, such as railway sleepers, made of oak, but the ties of conifers have rather long lifetime of 7 to 40 years), but the point that such ties are much cheaper.
Advantages enjoyed by wooden sleepers: do not conduct electricity; on wooden sleepers have practically no influence temperature changes, wood sufficiently elastic and easy to processing; is not a bad clutch with the ballast of gravel; Humidity for sleepers – 22%, when the moisture content of wood will be more acceptable, it is necessary that at the sleepers were allowances for shrinkage. But the wooden sleepers as have the disadvantage that is inherent in all wood products – it's susceptibility to decay order that would prevent the rotting railroad ties, to increase durability and resistance to precipitation, they were impregnated with special coal-oil (creosote), or antiseptics. And since in Russia the basic material for the manufacture of railway sleepers – a pine tree, which is not a high wear resistance, the problem of impregnation of sleepers relevant. Impregnation of wood by Airborne (vacuum-pressure-vacuum "). Before impregnation in an autoclave timber is too dry. vdv method:-Create a vacuum for 15-60 minutes, causing a vacuum in the timber. -Create pressure 0,8-1,4 MPa, while maintaining the vacuum. Enter antiseptic or impregnating solution. The material can withstand so the necessary depth of impregnation. -Once the wood is soaked, you must again create a vacuum for 40 minutes, for that would be material dry. Wooden sleepers impregnated with practically no rot, and have high resistance to atmospheric deposition.