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What are the railway bearings?

What are the railway bearings?


Axle box bearing

Locomotive wheel through the axle box connected to the locomotive car-body, springs and bogie frame, axle box bearing locomotive bearing spring directly under the gravity of the wheel and rail of the radial, axial impact, in addition, also passed the traction and produce some of the additional load, and enough so axle box bearing to have the larger bearing capacity, can impact resistance vibration, And has a higher life, safety and reliability, smaller size and quality; It is easy to check and maintain. Therefore, locomotive bearings often use non-standard series of bearings and special bearing technical conditions, commonly used in rolling bearings for locomotives have the following three categories.

Cylindrical roller bearings

Cylindrical roller bearings are used in most axle boxes of locomotives and electric locomotives. There are mainly the following two kinds of bearings:

Four rows of cylindrical roller bearings

China's locomotive axle box bearing is the earliest use of the largest number of loaded four rows of cylindrical roller bearings (972832). The bearing has a high bearing capacity and long life, and its rated dynamic load is 1445KN. Because it can only bear the radial load, can not bear the axial load, so it must be set in the axle box to bear the axial force of another device.

Double row cylindrical roller bearings

China's Dongfanghong 2, 3, 5, 21 type locomotive axle box and Beijing type locomotive axle box adopts double-row cylindrical roller bearing 982832T, the bearing bears radial force, and the angular contact ball bearing (146132T type) bears the axial load.

Although the application of the above two kinds of bearings is satisfactory, due to the need for a thrust bearing and buffer device, so the overall component mass is larger, the price is higher, the structure is complex, and the failure rate is relatively high. In fact, the axle axial force is not very large, and the action time is short, the cumulative action time is generally only 3% of the total running time; In addition, the axle box is air-cooled in operation, and the temperature rise of the bearing is not too high. Therefore, many foreign locomotives use two sets of single row cylindrical roller bearings with an inner ring and retaining ring. Axle boxes (including passenger car axle boxes) produced by locomotive manufacturing enterprises in China have gradually adopted this kind of bearings. On the six-axle locomotive, bearing 552732QT type is installed on the inner side of axle box of 1, 3, 4, and 6 positions, and 752732QT type is installed on the outer side of axle box.2. 552732QT is installed on the inside of the 5-bit axle box and 652732QT on the outside. In order to ensure its strength and sufficient service life, this kind of bearing is made of vacuum degassed steel or electro slag remelting steel, and some strengthening measures are taken in the structural design, such as ring flange with bevel, roller with the spherical end face, roller with a crown (logarithm roller), increase the diameter of the roller, improve the cage and so on.

Self-aligning roller bearings

The advantage of using self-aligning roller bearing is that there can be no tilting compensation device between the axle box and the bogie frame. The axle box bearing of the ND2 diesel locomotive imported from Romania is C type of self-aligning roller bearing produced by the SKF bearing company. Its model is equivalent to domestic bearing 3G4053736KT. The roller of this kind of bearing is of symmetrical shape, the inner ring has no outer baffle, and the middle flat baffle ring can be separated. The roller and the outer ring are in linear contact. The effective working length of the roller is longer, and the service life is slightly longer than that of the asymmetric self-aligning roller bearing with the same outer contour size.

Tapered roller bearings

This type of bearing used in locomotive axle boxes is a double row tapered roller bearing. The AP type bearing produced by Timken is used in ND5 diesel locomotive in the United States. This kind of bearing is in inch size, usually used bearing B, C,

D, E, F, and G grades are used for different grades of axles.

Traction motor bearing

Armature bearing for traction motor

The traction motor is the main equipment in the transmission system of electric locomotive and electric drive diesel locomotive, and its armature bearing is one of its main parts. The armature bearing load is large, and the size of the traction motor is limited by wheel diameter, an inner distance of two wheels and the lower limit of the locomotive, therefore, this kind of bearing must meet the requirements of small size and higher limit speed as far as possible.

Single side drive bearing

The armature is usually supported by a double fulcrum, the output end of the mounting gear is the walking support, and the commutator end is the positioning support. The position of the output end bearing is close to the gear, the maximum force is the key bearing in the armature two bearings. In order to reduce the load, NU cylindrical roller bearings with no edges are generally used. The rectifier end is generally used in the NUP type cylindrical roller bearings with a single inner ring and a flat retaining ring, and there are also cylindrical roller bearings with a single inner ring and an inclined retaining ring abroad.

Double drive bearings

When the motor power is large if the single-side drive is still used, the bearing load of the gear end is too large, and it is difficult to choose the bearing whose rated dynamic load and limit speed can meet the requirements. Therefore, the two-side drive mode is used when the motor design allows. The advantage of bilateral transmission is that the helical gear can be used so that the helical Angle of the two gears is equal, the direction of rotation is opposite, so as to obtain a more stable transmission quality, and do not produce axial load. The bearings suitable for this purpose are NU-type cylindrical roller bearings with no flange on the inner ring. If straight tooth cylindrical gears are still used for bilateral transmission, bearings that can withstand a certain axial force should be selected. NJ-type cylindrical roller bearings with a single flange on the inner ring are generally used.

Axle bearing for traction motor

The shaft-suspension traction motor is usually supported on the bogie by adjusting the rod on one side and supported on the axle by holding the shaft bearing on the other side. Bearing with sliding support is relatively simple, but its lubrication and inspection are not very convenient, so from the 1950s began to use rolling bearings. Up to now, cylindrical roller bearings, self-aligning roller bearings, and tapered roller bearings are still used.

The cylindrical roller bearing is suitable for high-speed locomotives. It has a long grease filling cycle and is easy to install and maintain, especially when the whole shell is used. This advantage can be fully displayed. Tapered roller bearing has good installation stiffness, which is beneficial to ensure the meshing accuracy of gear, but it is difficult to assemble and disassemble and adjust the axial clearance. The installation of two sets of self-aligning roller bearings, especially when dismantling, is more difficult than tapered roller bearings, but it can adapt to the bending of the shaft. China's electric locomotives traction motor axle bearing with self-aligning roller bearings, its model is 3G3053148T.

Traction generator bearing

The block of traction generator of modern electric diesel locomotive is usually installed on the block face of the output end of diesel engine.No matter in this way or in other ways, the input end of the armature is rarely installed with bearings, generally through the elastic coupling will support the armature on the crankshaft or output shaft of the diesel engine, in order to shorten the longitudinal size of the generator.

The outer end of the electric pivot is generally cylindrical roller bearings. Sometimes, in order to facilitate the alignment with the diesel engine, self-aligning roller bearings are also used.

Bearings for hydraulic transmission system of diesel locomotive

Diesel locomotive hydraulic transmission system generally includes hydraulic transmission box, universal shaft, axle gearbox three parts. A shunting locomotive sometimes also includes a working gearbox, which is fitted with a considerable number of rolling bearings.

Hydraulic transmission box bearing

The working mode of the hydraulic transmission box is to convert the power of the diesel engine into the power of the locomotive through the hydraulic torsion converter when pulling the train. During power braking, the hydraulic brake is used to absorb the kinetic energy of the locomotive wheels. A plurality of shafting systems are arranged in the hydraulic transmission box, and the support of each shaft is fully supported by rolling bearings.

Intermediate gearbox bearing

The main parts of the intermediate gearbox are the input shaft and the output shaft with two gears. The gear on one shaft is a shift gear. The shaft and the gear have a clutch mechanism, which can make one of the gears connect with the shaft and transfer power. The other gear is just idling in this case. Shift gears and clutches are often arranged on the input shaft, because the input torque is small, which is conducive to reducing the size of spline clutch and bearing size.

Diesel engine crankshaft bearing

Diesel engine crankshaft bearing is only used for high-speed diesel engine rolling bearings, its main advantages are small friction loss, high mechanical efficiency, reliable work, long service life; Easy lubrication, the small size of oil radiator, etc. The main disadvantages of using sliding bearings are high price, large-quality, high technical requirements for assembling bearings and crankshafts, inconvenient maintenance and replacement, and large noise.

For single cylinder and double cylinder small diesel engine crankshaft, multi-purpose 0 levels rolling bearing; For high-speed high power diesel engine crankshaft, because of its large load, generally only use cylindrical roller bearing.

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