The box bearing unit of the freight car is a complex mechanical system, which is influenced by various factors. Under normal operation, the parameters characterizing the functional state of the components of the axle box should be within the prescribed limits throughout the standard service life. Mathematically, this corresponds to the placement of the axle box elements in the space of admissible states. The railroad model consists of a set of submodules: track and elastic ballast layer. The model allows simulate the microgeometry of the track, the characteristics of the inequalities, and the elasticity of the base under the track. Subsequently, the main parameters characterizing random processes were determined: the magnitude of the mathematical expectation, the variance, as well as the minimum and maximum values of the effort. The results indicate that random processes are distributed according to normal law. According to the results of the research, for each of the random loading processes of the axle boxes, appropriate correlation functions were constructed and the space of “admissible states” for different operating modes was con-structed.
The cars that are operated on the railways of Ukraine are equipped with axle boxes with cylindrical roller bearings. Many years of operating experience has shown that they have insufficient durability. One of the reasons is the uneven distribution of the load between the rollers in the bearings, caused by the design features of the wagon bogies. One of the possible ways to equalize the distribution of loads between the rolling elements can be the creation of a box housing with variable stiffness. The article provides a detailed analysis of existing design solutions. It has been established that the use of aluminum alloys for the manufacture of axle box housings, despite the low specific density of the alloy, is impractical due to their high cost, increased wear of the bearing surfaces, and insufficient service life. The use of rubber as gaskets to create variable stiffness also proved to be impractical. The reason is the inability of rubber to operate at low temperatures in winter. As a result, the destruction of the rubber required additional (unscheduled) axle box repairs. The manufacture of axle box bodies with cavities or grooves of various configurations in order to change the rigidity of the elements of the upper part of the axle box body turned out to be unpromising. The reason was the technological complexity of manufacturing, the difficulty of providing the necessary strength under dynamic loading conditions. The most successful was the design of the box body with two rectangular tides along the edges of the upper part in the roller loading zone. These lugs are located along the entire length of the hull and are the supporting surfaces for transferring the load from the side frame. A promising direction in the 70s of the XX century was the rejection of traditional massive axle boxes and the transition to the use of adapters (half axle boxes). However, this option had to be abandoned at that time due to the impossibility of ensuring reliable sealing of the bearings. At the same time, the modern experience of American railways shows that one of the promising areas for improving the design of roller axle boxes is the use of adapters in freight bogies of wheelsets equipped with cassette bearings. The adapter redistributes the load from the bogie to the cassette bearing, acts as a supporting part of a conventional axle box and limits the longitudinal, transverse and angular shifts of the wheel set relative to the bogie frame. In addition, the adapter allows you to reduce the tare weight of the car. However, the use of adapters is possible only if the bearings themselves are reliably sealed. Also, a promising direction can be considered the creation of a box body with variable stiffness, including the use of rubber-metal elements. Keywords: freight car, axle box, housing, bearing, adapter, support surface, actuation.
The article is devoted to the analysis of the level of safety on Ukrainian railways. The reliability of wagons plays an important role in ensuring safety. Uncoupling of wagons along the route due to failures of wagon structural elements causes transport incidents and can lead to an emergency. The most common reason for uncoupling a wagon from a train is axle box failures. The conducted studies show that the absolute number of uncouplings of wagons along the route has decreased compared to 1995. But the number of uncouplings caused by roller axle box failures remains at a high level with certain fluctuations. Functional dependences characterizing the change in the number of cuts over time are determined. For a more complete description of the change in the level of traffic safety on the railways, the performance indicators were considered depending on the overall performance of the railway transport. In particular, the number of working park was taken into account. It has been established that over the past decade, in relation to the working fleet, the number of wagon failures due to the fault of roller axle boxes remains practically at the same level. An analysis of the causes of failures shows that the main one is damage to cylindrical roller bearings. This is followed by end mount failures. Attention is drawn to the sharp increase in the number of failures caused by non-compliance with the technology of installation work. This indicates insufficient qualification of the service personnel. Lubricants for bearings have insufficient reliability. Also, a number of failures are caused by damage to the axle boxes. The lack of reliable methods for diagnosing axle boxes failures at an early stage in operation leads to the occurrence of fractures of the axle journals. One of the possible ways to increase the reliability of axle box units is the use of cassette bearings, which have a number of significant advantages.
Розглянуто роботу залізобетонних шпал марок Ш-1-1 і СБ-3-0 в умовах магістральних залізниць і колій незагального користування. Визначено основні експлуатаційні фактори, які впливають на їх роботу в колії. На основі даних обстеження залізобетонних шпал марки Ш-1-1 встановлено залежності їх виходу в непридатні. Запропоновано загальний підхід до прогнозування надійності роботи залізобетонних шпал марки СБ 3-0 на основі даних виходу шпал марки Ш-1-1. Отримано прогнозні залежності імовірності безвідмовної роботи шпал СБ 3-0 з використанням універсального двопараметричного розподілу Вейбулла. Визначено очікувані терміни служби шпал СБ 3-0 в різних експлуатаційних умовах. Ключові слова: колія, шпала, робота, надійність, відмови, напруження. Рассмотрена работа железобетонных шпал марок Ш-1-1 и СБ-3-0 в условиях магистральных железных дорог и путей необщего пользования. Определены основные эксплуатационные факторы, влияющие на их работу в пути. На основе данных Збірник наукових праць Українського державного університету залізничного транспорту Збірник наукових праць УкрДУЗТ, 2018, вип. 175 48 обследования железобетонных шпал марки Ш-1-1 установлены зависимости их выхода в дефектные. Предложено общий подход к прогнозированию надежности работы железобетонных шпал марки СБ-3-0 на основе данных выхода в дефектные шпал марки Ш-1-1 в условиях путей необщего пользования. Предложены прогнозные зависимости вероятности безотказной работы шпал СБ-3-0 с использованием универсального двухпараметрического распределения Вейбулла. Определены прогнозные сроки службы шпал СБ 3-0 в различных эксплуатационных условиях.
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