THE STRUCTURAL ANALYSIS OF THE HOUSING OF THE FREIGHT CAR AXLE BOX

Abstract

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.