The running gear of railway trains includesits design is a lot of elements, but the key one is the wheel pair. There are different versions of this component, and they differ not only in size and shape, but also ability to withstand various loads. In many ways, this characteristic is the determining factor for the working resource of the running gear. Manufacturers initially endow its elements with high operational potential, but, of course, this does not guarantee the complete elimination of breakages and malfunctions. Regardless of the purpose and characteristics of the use of transport, wheel pairs of wagons require maintenance of a healthy condition. By the way, elementary wear is a normal phenomenon - it's another matter that maintenance personnel need timely detection of sites close to breakage and the performance of appropriate repair operations.
Causes of malfunctions
Despite the use of a reliable design withhigh-strength metal alloys, strong dynamic and static loads can lead not only to wear, but also to deformation. To the greatest extent such phenomena are affected wheel pairs of freight cars, as during the movement of the train there is an increased voltage in the contact area of the rail and wheels. Therefore, in order to minimize the negative consequences from this interaction, technologists include carbon in the alloy in large proportions. Either way, loads can increase if the crew follows the terrain with a crooked roadway - this creates additional stress as a result of centrifugal forces.
In this case, do not think that the pairs forpassenger trains have significant advantages in the form of low loads. In part, of course, the risks in this case are lower, but all impacts and jolts in the process of movement are also transmitted to the running gear, resulting in the wheel pair of the passenger car gradually deteriorating. It is worth noting and other factors affecting the condition of the wheels. Among them are braking forces, skid effect, undesirable axis contacts with the drive part, arrows, etc. Now you can get acquainted with the most common types of malfunctions.
Wear of solid wheel pairs of wheels
There are several groups of similar wear.First of all, this is the formation of a uniform rolling, to which wheel pairs of wagons are subjected even in the normal operation mode. The appearance of such a deformation is due to the fact that when contacting the rails and brake pads, a strong stress is created, which entails rolling on the surface of the wheels.
An uneven rolling is also common.It is characterized by the appearance of deformation zones not over the entire area of the contact zone, but only in certain axes. This indicates that the wheelsets of the wagons were manufactured with an uneven distribution of properties over the entire mass of the alloy. That is, the appearance of such a rolling testifies, first of all, to marriage in the pairs themselves. Next, it is worth noting a circular influx. It can be observed outside the contact rim of the wheel, when the mass drifts along the sides of the chamfer.
Wear of rolling surfaces
Deformation of this kind also occurs on the squarecontact zone. The peculiarity of wear is that it occurs when moving by a yuz. Therefore, the deformation of rolling surfaces is often associated with disruptions in the work of brake pads. Visually, such wheel pair faults appear as a slider - a flat area on a white metal surface. Despite the fact that in the process of exploitation such defects do not cause serious problems, they can already go into trouble of a different kind.
The fact is that in the places of the slider almost alwaysThere is an increased formation of heat, which is transmitted deep into the rim of the wheel. As a result, so-called scrapes are formed, attracting a specific coloring in the place of rolling. Over time, the wheel pair begins to respond sensitively to any unevenness of the "canvas", which results in the appearance of impacts in the running gear. Therefore, if the sliders are detected more than 1 mm, then the speed of the train is seriously constrained. By the way, the wheel pair of a diesel locomotive and a freight car are most susceptible to such deformation. It is noteworthy that the intensity of the formation of the slider depends on the season - for example, in winter and early spring the risks of its formation are higher.
Malfunction of the axis
Malfunctions in necks and pre-precessional partsare expressed in the form of low dimensionality of the axes. There may be several reasons for this. First of all, the deformation arises because of insufficiently strong connection and in those cases when the metal surfaces were cleaned from the rust formations incorrectly. Also, the axis of the wheel pair is often fractured and cracks in places with the highest loads. Similar processes occur due to cyclic stress, the presence of sections with transition cross sections and the discontinuity of the metal itself. Of course, the usual breakdowns in the form of insufficiently strong fastenings of bolts and nuts are not excluded.
Navar Metal
This is a thermomechanical damage,which affects wheel pairs of cars in the surfaces of skating. During inspections, such deformations fix the shear zones of material with a U-shaped shape. In essence, this is a kind of plastic deformation processes. The maximum shift occurs on the central part of the contact strip. In turn, the minimum shift can be detected at the edges. The cause of such damage is the distribution of loads with pressure on the contact area.
General measures for wheel maintenance
Preventive measures contribute to the extension ofwheel operation. Maintenance involves examinations, surveys, indications for repair operations, etc. If we talk about technical measures, the main one will be the correct turning of wheel sets with a minimum layer of metal removal. The number of turning points is reduced due to special measures aimed at increasing the reliability of wheel sets and eliminating the existing weak points of the running gear. In particular, specialists are trying to eliminate the force factors that occur in the process of exploitation and appear due to previously arising defects. For example, problems in the springs and springs, which affect the performance of the running gear, are eliminated.
Repair and recovery operations
Repair operations are carried out in a specialmechanical zone after the elements have been thoroughly washed. In a special department, wheels are changed, turning or welding operations are carried out. If it is planned to repair the wheel sets with the purpose of changing the profile of the elements, the work is carried out using special templates. It should be noted that the permissible deviation in the parameters of the wheels from the template is 1 mm at the ridge height, and along the inner faces and the skiing area - 0.5 mm. As already mentioned, electric welding operations can be used in repair. Such equipment is used to cut the axial thread and surfacing the center holes.
Conclusion
There are special regulations in whichfaulty wheel pairs, as well as methods and technologies for their elimination and prevention. It is important to note that on the chassis, in general, there are many factors of mechanical properties. As a result, the working capacity and resource of a wheel pair depend not only on the quality of the tracks, but also on the braking system, the spring-spring unit, the mode of the crew's movement and even the time of the year.
