Currently, the railway connection is quite developed. Passenger traffic, the delivery of goods or mail - these are industries that are used constantly and everywhere. However, in order for everything to work like a clock, it is necessary to monitor the condition of each car and its components.
Device
The axle box unit is one of the elements of the carriage chassis. The purpose of this part is to transfer the gross load from the car to the axle neck. At the same time, this unit is designed to accommodate the lubricating devices and the grease itself. Also, this part serves as a connecting element between the wheelset and the frame of the trolley, the unit protects the necks from pollution or damage. And the last function that the nodes perform is to limit the longitudinal or lateral displacement of the pair relative to the trolley.
It is also important to note that the node is unsprung and therefore will be quite rigidly perceiving any dynamic fluctuations emanating from the path, which will unambiguously arise as a result of transport movement.
Bearing Assembly
Currently, there are many different types of axle boxes. There are elements with bearings that can be divided into two groups precisely for these details. There are nodes with cylindrical and spherical roller. Currently, these two types of axle boxes with these types of bearings are used throughout the CIS.
It is worth noting that the production of these components with spherical has not been carried out since 1964, and currently there are only about 5% of trains whose wagons have nodes with this type of device. In addition, if these parts fail, they are replaced not with similar ones, but with units with a cylindrical type of bearing, therefore this small percentage is constantly reduced.
At present, the main type of axle box assembly is one that has a cylindrical roller type of bearing on a hot suspension.
Roller bearings
Today, all types of passenger and freight cars are equipped with roller bearings. Also, all old passenger cars and almost all (about 80%) freight cars were transferred from old models to roller ones. In addition, since 1982, all released axlebox units of the car are equipped with a roller type. This decision is justified by the fact that the quality and reliability of operation of this type of part is higher than that of plain bearings. This is clearly noticeable if we take into account such an indicator as the delay or disengagement of cars due to the heating of this part. Practice has shown that roller elements heat up about half as much as their previous counterparts. Another of the advantages of a wheel axle equipped with roller bearings is that they reduce the resistivity of the entire car by about 7-10 units at a time when the train is moving. And the fuel or electricity consumed by the train will be reduced by 10%.
Passenger car assembly
At present, a typical axle box assembly for a passenger carriage is also used, in which the bearings are mounted by means of a washer. In order to constructively correctly perform the arrangement of the axle box of a freight car or passenger, it is necessary to follow the scheme of supporting the frame of the trolley to a specific node. It is also worth noting that the case for this part can be made in different ways. Production can be carried out with support brackets, as well as a continuous labyrinth part or with several grooves for the jaws, and the labyrinth part will be pressed in.
Node installation
In order to carry out the installation of the axle box with a roller bearing, it is necessary to perform some preliminary operations. Such operations include the search for a suitable labyrinth ring, as well as the bearings themselves. The main characteristic by which the ring is selected is an interference fit, that is, it is the difference in the positive direction between the difference between the diameter of the inner landing part and the diameter of the pre-approach part of this axis. This indicator should be in the range from 0.08 mm to 0.15 mm. The choice of roller bearings should also be carried out by interference, but here the diameter of the inner ring is important. The parameter must be between 0.04 mm and 0.065 mm. It is also important to take into account the axial clearance and the radial difference, the index of which should be equal to 0.2 mm.
The assembly process begins with the fact that it is necessary to heat the labyrinth ring to a temperature of 125-150 degrees Celsius. The installation of the ring is carried out on the pre-approachable part of the axis. Next, it is necessary to wait for complete cooling and, using a piece square, check the perpendicularity of the installation. It is also necessary to use a feeler gauge to make sure the ring is tight. After that, they proceed to the installation of a guide cup screwed onto the axis thread and designed to protect it from damage that may be caused by further mounting of the bearing inner rings.
Cassette bearings
At present, if we turn to the countries of Europe, then in their high-speed trains axle boxes with double-row tapered roller bearings are installed. The speed of these vehicles ranges from 200 to 350 km / h. The wide distribution of cassette bearings has become possible due to the fact that they have several of the following advantages:
- Adapted to high level combined loads. In turn, this ensures greater mileage that the train can pass, and also guarantees 100% operation of the train during the entire warranty period, if the axle box assembly is inspected in a timely manner.
- This type of bearings in geometric terms fully complies with the conditions that are required to achieve high speeds of movement of the composition.
- The design of this node model is more compact.
Pair of wheels
In order to guarantee safety, it is necessary to periodically check the serviceability of the axle boxes and their pairs. It is important to know that at the first inspection of the pair and when it becomes necessary to grind it, this can be done without removing the axle box. If, after carrying out this operation, the next inspection will again show defects that need to be eliminated by turning the pair, then it is impossible to do without removing the axle box.
After the repair is completed or the process of complete inspection of the wheelset is completed, it is painted black. It is also worth noting that the junction of the hubs with the axle axles is also painted, but with bleaching paint. Staining is done around the entire circumference of the joint.
Bearing landing
Currently, there are three known methods of landing bearings on the axis - this is hot, sleeve, extruded. However, in the axlebox units of the modern type, only two of the three methods are used - this is hot and pressing.
It is also important to know that after the completion of the complete assembly process, the unit is filled with grease. If we talk about the lubricant that is used for roller bearings, then since the beginning of 1973 it is LZ-TsNII. The main purpose of this mixture include such functions as: to provide resistance to wear, corrosion, to ensure the absence of scoring phenomena that occur during operation of the bearing.