JP2008232224A - Radial roller bearing with cage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a structure that can cope with a capacity of load required in the using environment at a reduced cost as well as flexibly. <P>SOLUTION: Only an appropriate number of rollers 2d, 2d for the capacity of load required in the using environment are retained in pockets 9d, 9d formed in the cage 3d. Part of the pockets 9d, 9d in the cage 3d without the rollers 2d, 2d retained therein are located equally in the circumference. It is thus possible to solve the problem. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in a radial roller bearing incorporated in a rotation support portion of an automobile transmission or various mechanical devices. The term “roller” in the present specification and claims includes needles having a large ratio of length to outer diameter (aspect ratio).

  A radial roller bearing is incorporated in a portion to which a large radial load is applied in a rotation support portion of an automobile transmission or various mechanical devices. For example, Patent Document 1 discloses a structure of a radial roller bearing incorporated in a planetary gear type transmission that constitutes an automatic transmission of an automobile. As shown in FIG. 7, this radial roller bearing 1 holds a plurality of rollers 2, 2 by a cage 3, which is a radial roller bearing cage, so that it can roll, and an outer peripheral surface of an intermediate portion of a support shaft 4. Is a cylindrical inner ring raceway 5, the inner peripheral surface of the planetary gear 13 disposed around the support shaft 4 is a cylindrical outer ring raceway 6, and the rolling surfaces of the rollers 2 and 2 are the inner ring raceways. 5 and the outer ring raceway 6 in rolling contact.

  The retainer 3 includes a pair of rims arranged in an axial direction (left-right direction in FIGS. 8 to 9) spaced apart from each other and each having a ring shape, as shown in detail in FIGS. Parts 7 and 7 and a plurality of pillars 8 and 8. These column portions 8 and 8 are intermittently arranged in the circumferential direction, and both end portions thereof are made to be continuous with the outer diameter portions of the inner side surfaces of the rim portions 7 and 7 facing each other. . Moreover, each said pillar part 8 and 8 has the shape where the axial direction intermediate part bent in the trapezoid shape toward radial inside. And the space part surrounded by the circumferential direction both sides edge of these pillar parts 8 and 8 adjacent to the circumference direction and the inner side surface where both the above-mentioned rim parts 7 and 7 mutually oppose is made into pockets 9 and 9, respectively. The rollers 2 and 2 are held in the pockets 9 and 9 so as to roll freely.

The cage 3 configured in this manner is formed by rolling a strip-shaped metal plate (generally a steel plate or a stainless steel plate) into a cylindrical shape as described in Patent Document 2 and the like, as is well known. That is, although not shown in the drawing, a first stage intermediate material having a basic cross-sectional shape as a cage is formed by pressing a band-shaped metal plate, and then the first stage intermediate material is sheared. By applying, the above-mentioned pockets 9 and 9 for holding the rollers 2 and 2 in a freely rollable manner are punched and formed to be a second stage intermediate material. Further, the intermediate material of the second stage is cut into a predetermined length to obtain the intermediate material 10 of the third stage as shown in FIG.
Then, the intermediate material 10 in the third stage is rounded into a cylindrical shape, and both end portions in the circumferential direction are butt welded to form the cage 3 as shown in FIG.
The cage 3 can also be made by subjecting a metal plate as a material to punching, cutting, plastic deformation, or the like using a press. In the case of such a method, the degree of freedom of processing is large. However, there are problems such as an increase in cost and a decrease in mass productivity.

  Since the radial roller bearing 1 having the above-described structure is continuously used in an environment where a large radial load is applied, a structure having a large load capacity, excellent durability, and high-speed rotation has been conventionally considered. Yes. For example, Patent Document 3 describes a structure that can improve the flowability of the lubricating oil and achieve excellent durability and high-speed rotation by devising the structure of the cage constituting the radial roller bearing. Yes.

Although not described in Patent Document 3, when it is desired to increase the load capacity of the radial roller bearing, the number of pockets can be reduced by reducing the width of each column portion between the pockets of the cage constituting the radial roller bearing. It is possible to increase the number of rollers and increase the number of rollers to be held. However, if the width of each column portion is too small, it is difficult to ensure the strength of the cage.
On the other hand, when the load capacity of the radial roller bearing has an excessive margin with respect to the load capacity required in the usage environment of the radial roller bearing, the width of each column portion is increased (the pockets are It is conceivable to reduce the number of these pockets and the number of the rollers held in each of these pockets by widening the arrangement interval.

This will be specifically described with reference to FIGS.
A radial roller bearing 1 a shown in FIG. 11 is cylindrical and has an outer ring 11 having an outer ring raceway 6 a on the inner circumferential surface, and an inner ring arranged in a concentric manner with the outer ring 11 having an inner ring raceway 5 a on the outer circumferential surface. 12, a total of twelve rollers 2a, 2a provided between the outer ring raceway 6a and the inner ring raceway 5a so as to be freely rollable, and provided between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring. And a retainer 3a for holding these rollers 2a, 2a.
Of these, the retainer 3a is formed by welding and joining both ends in the circumferential direction of a metal plate rounded into a cylindrical shape, provided in parallel with each other at both ends in the axial direction, respectively, A pair of rim portions 7 and 7 (see FIG. 8) each having an annular shape are provided in parallel with each other in a state of being spanned between the rim portions 7 and 7 and at a uniform interval in the circumferential direction. A plurality of pillar portions 8a, 8a, and the portions surrounded by the four circumferences by the respective pillar portions 8a, 8a adjacent to each other in the circumferential direction and the rim portions 7, 7 are respectively provided with the rollers 2a, 2a. Are pockets 9a and 9a for holding them freely.
When such a radial roller bearing 1a is used, if the load capacity required in the usage environment can be sufficiently ensured by only six rollers 2a and 2a, the radial roller bearing 1a is shown in FIG. When used in the configuration as shown in FIG. 11, 12−6 = 6 rollers 2a and 2a become excessive. Therefore, like the radial roller bearing 1b shown in FIG. 12, the width of the column portions 8b and 8b of the cage 3b is made larger than that of the column portions 8a and 8a of the radial roller bearing 1a shown in FIG. It is generally considered that the number of pockets 9b, 9b formed in the retainer 3b is reduced to 6, and the total number of rollers 2b, 2b used is also reduced to 6. In the case of the configuration as shown in FIG. 12, excessive rollers 2a, 2a (2b, 2b) can be saved and cost waste can be eliminated. Also, the dynamic torque (rotational loss) can be reduced by reducing the rolling resistance.

  However, the ratio of the total volume of each of the pockets 9b and 9b to the total volume of the third stage intermediate material 10 (see FIG. 10) when producing the cage 3b constituting the radial roller bearing 1b is small. If it is too high (the ratio of the total volume of each of the column parts 8b and 8b is too large), an excessive stress is generated in the welded part of the cage 3b, and the strength of the welded part is reduced. That is, when the circumferential width of each of the pillar portions 8b and 8b is increased, a large force is required to bend the intermediate material 10 in the third stage shown in FIG. Each column portion 8b, 8b is difficult to bend into an arc shape), and a large force is easily applied to the welded portion by a spring back or the like. Due to this, the cage 3b may be damaged or deformed during use, or the roundness of the outer diameter of the cage 3b after welding may be deteriorated. For this reason, the number of pockets 9b, 9b formed in the intermediate material 10 in the third stage is limited.

In addition to the method described above, as a method of reducing the excessive load capacity of the radial roller bearing 1a, a method of reducing the diameters of the rollers 2a and 2a is conceivable. However, reducing the diameters of the rollers 2a and 2a increases the number of the pockets 9a and 9a formed in the cage 3a and the number of rollers 2a and 2a held in the pockets 9a and 9a. This will increase costs. Furthermore, since at least one of the inner diameter and the outer diameter of the radial roller bearing changes, it is necessary to change the configuration of peripheral members such as a pinion shaft and a pinion gear, which also increases the cost.
In view of the above, it is desired to realize a radial roller bearing that can cope with a low cost and a light weight with respect to a load capacity required in a use environment.

JP 2005-351475 A JP-A-8-270658 Japanese Patent Laid-Open No. 11-108065

  In view of the circumstances as described above, the present invention was invented to realize a radial roller bearing having a load capacity suitable for use conditions with a structure having low cost and excellent durability.

Radial roller bearings that are the subject of the present invention are inner ring raceways and outer ring raceways that are arranged concentrically with each other, and a plurality of rolls provided between these inner ring raceways and outer ring raceways. And a cage.
Of these, the cage is formed by joining the circumferential ends of a metal plate rounded into a cylindrical shape by welding. In addition, a pair of rim portions each having an annular shape are provided parallel to and concentric with each other at both axial end portions. In addition, a plurality of pillar portions provided in parallel with each other and at a uniform interval in the circumferential direction in a state of being spanned between the two rim portions are provided. A portion surrounded by the four circumferences by each of the column portions adjacent to each other in the circumferential direction and the rim portions serves as a pocket for holding the rollers in a rollable manner.

  In particular, in the radial roller bearing of the present invention, the rollers are held only in some of the pockets. Further, the pockets that do not hold the rollers inside are arranged at substantially uniform intervals in the circumferential direction. Note that the arrangement at substantially uniform intervals means, of course, that each roller is arranged at equal intervals in the circumferential direction, as well as a plurality of rollers (each equal number for each set). It also includes a state in which the set (set) is arranged at equal intervals in the circumferential direction.

According to the radial roller bearing of the present invention configured as described above, the diameter of the radial roller bearing is considerably larger than the diameter required to ensure the load capacity required in the usage environment. In addition, if the number of pockets formed in a cage that has a diameter corresponding to this diameter cannot be reduced due to restrictions in the manufacture of the cage, a lightweight radial with a load capacity suitable for the usage environment is ensured. Roller bearings can be realized at low cost.
This can be achieved by holding only as many rollers as needed in the usage environment in only some of the pockets formed in the cage.

In addition, since the pockets that do not hold the roller among the pockets formed in the cage are arranged at substantially uniform intervals in the circumferential direction, in the usage environment that rotates at high speed, It is possible to effectively prevent a load that is biased from being applied to the radial roller bearing and a malfunction such as generation of abnormal noise.
Of the pockets formed in the cage, a pocket that does not hold the roller serves as a lubricating oil passage and improves oil permeability in the radial roller bearing. By this. It is possible to effectively prevent the occurrence of damage such as smearing, seizure, wear, and peeling. Furthermore, by improving the oil permeability, it is possible to suppress the temperature rise inside the radial roller bearing, and it is possible to prevent a decrease in the viscosity of the lubricating oil existing inside the radial roller bearing. Thereby, the oil film formation property of the lubricating oil to each rolling contact part can fully be ensured.
Also, by reducing the rollers for the excessive load capacity, the total contact area between the surfaces of all the rollers and the raceway surface is reduced. For this reason, it is possible to reduce the torque of the radial roller bearing.

[First example of embodiment]
1 and 2 are sectional views of radial roller bearings 1c and 1d for explaining a first example of the embodiment of the present invention, and FIG. 2 shows a first example of the embodiment of the present invention. . In FIGS. 1 to 6 for explaining the embodiment of the present invention, a black roller represents a roller that is actually incorporated, and a roller represented by a virtual line represents a roller that is not actually incorporated. Yes.
The feature of this example is that the state of incorporation of a plurality of rollers that are rotatably held in a plurality of pockets formed in a cage constituting the radial roller bearing is devised. The structure and operation other than this characteristic portion are the same as those of the conventionally known radial roller bearings including the radial roller bearings shown in FIGS. For this reason, the overlapping description will be omitted or simplified, and the following description will focus on the features of this example.

First, a radial roller bearing 1c as a comparative example shown in FIG. 1 has 20 pockets 9c, 9c formed at uniform intervals in the circumferential direction of the cage 3c, and all these pockets 9c, 9c holds the rollers 2c and 2c, respectively. Here, it is assumed that the number of the pockets 9c, 9c that can be formed in the cage 3c cannot be less than 20 due to manufacturing restrictions of the cage 3c.
When the load capacity of the radial roller bearing 1c is sufficiently larger than the load capacity required in the use environment of the radial roller bearing 1c (for example, the load capacity required by the use environment is the above-described roller 2c, If the load roller capacity can be secured by 16 pieces), if the configuration of the radial roller bearing 1c is used, 20−16 = four pieces of rollers 2c and 2c become excessive.

In such a case, the configuration of the radial roller bearing 1d of this example as shown in FIG. 2 is adopted. The retainer 3d constituting the radial roller bearing 1d is formed by rounding the intermediate material 10 (see FIG. 10) into a cylindrical shape, and then joining both circumferential edges of the intermediate material 10 by welding. The rollers 2d and 2d are held only in some of the 20 pockets 9d and 9d formed at uniform intervals in the circumferential direction of the cage 3d. . Of these pockets 9d and 9d, pockets 9d and 9d that do not hold the rollers 2d and 2d are arranged at a uniform interval in the circumferential direction (at a central angle pitch of every 90 degrees).
Specifically, every four pockets 9d and 9d holding the rollers 2d and 2d are arranged, and one pocket 9d and 9d that does not hold the rollers 2d and 2d is arranged. A total of five pockets 9d, 9d are set as a set, and four sets are arranged in the circumferential direction. That is, each of the four rollers 2d and 2d is set as a set, and each set is arranged every 90 degrees with a central angle pitch.

In the case of this example, the radial roller bearing 1d having a load capacity suitable for the environment to be used is realized at low cost and light weight without using excessive rollers 2d, 2d (2c, 2c). it can.
Further, the volume of the pockets 9d, 9d as a whole with respect to the entire intermediate material 10 in the third stage can be sufficiently secured. In other words, by reducing the width of the column portion that has a large resistance to rounding the intermediate material 10 into a cylindrical shape, and deforming the portion other than the column portion into an arc shape, a cylindrical shape with no practical problem Can be obtained. For this reason, the problem that excessive stress arises in the welding part of the retainer 3d as mentioned above can be prevented.
Further, since the pockets 9d and 9d that do not hold the rollers 2d and 2d are arranged at a uniform interval in the circumferential direction, a load that is biased toward the radial roller bearing 1d when used at high speed rotation or the like. It is possible to effectively prevent the occurrence of troubles such as the generation of noise and the generation of abnormal noise.
The pockets 9d and 9d that do not hold the rollers 2d and 2d serve as a lubricating oil passage. For this reason, the oil permeability inside the radial roller bearing 1d is improved. And, smearing, seizure, wear, peeling, temperature rise, etc. are effectively prevented. Furthermore, when the oil permeability is improved, it is possible to prevent a decrease in the viscosity of the lubricating oil. Thereby, oil film formation property can fully be ensured.

[Second Example of Embodiment]
FIG. 3 is a cross-sectional view of a radial roller bearing 1e showing a second example of the embodiment of the present invention.
In the radial roller bearing 1e of this example, when the radial roller bearing 1c of the comparative example shown in FIG. 1 is used as it is, ten rollers 2c, 2c are used with respect to the load capacity required in the use environment. This is a configuration corresponding to a case in which the number becomes excessive.
The cage 3e constituting the radial roller bearing 1e of the present example is only in a part (ten places) of the 20 pockets 9e, 9e formed at a uniform interval in the circumferential direction. The rollers 2e and 2e are held. Of these pockets 9e, 9e, pockets 9e, 9e that do not hold these rollers 2e, 2e are arranged at uniform intervals in the circumferential direction.
Specifically, the pockets 9e and 9e holding the rollers 2e and 2e and the pockets 9e and 9e not holding the rollers 2e and 2e are alternately arranged. Adjacent to the circumferential direction, 10 sets of pockets 9e holding the rollers 2e and non-holding pockets 9e are arranged as 10 sets at equal intervals in the circumferential direction.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, redundant description is omitted.

[Third example of embodiment]
FIG. 4 is a cross-sectional view of a radial roller bearing 1f showing a third example of the embodiment of the present invention.
In the radial roller bearing 1f of the present example, when the radial roller bearing 1c of the comparative example shown in FIG. 1 is used as it is, the 12 rollers are excessive with respect to the load capacity required in the use environment. This is a configuration corresponding to the case.
The cage 3f constituting the radial roller bearing 1f of the present example is provided only in some (eight) pockets 9f, 9f of the 20 pockets 9f, 9f formed at a uniform interval in the circumferential direction. The rollers 2f and 2f are held. Of these pockets 9f and 9f, pockets 9f and 9f that do not hold these rollers 2f and 2f are arranged at uniform intervals in the circumferential direction.
Specifically, every two pockets 9f and 9f holding the rollers 2f and 2f are arranged, and three pockets 9f and 9f that do not hold the rollers 2f and 2f are arranged. Four sets of these five pockets 9f, 9f are arranged at equal intervals in the circumferential direction.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, redundant description is omitted.

[Fourth Example of Embodiment]
FIG. 5 is a cross-sectional view of a radial roller bearing 1g showing a fourth example of the embodiment of the present invention.
In the radial roller bearing 1g of this example, when the radial roller bearing 1c of the comparative example shown in FIG. 1 is used as it is, 15 rollers are excessive with respect to the load capacity required in the use environment. This is a configuration corresponding to the case.
The cage 3g constituting the radial roller bearing 1g of the present example has only a part (five places) of the pockets 9g, 9g of the 20 pockets 9g, 9g formed at a uniform interval in the circumferential direction. The rollers 2g and 2g are held. Of these pockets 9g and 9g, pockets 9g and 9g that do not hold these rollers 2g and 2g are arranged at a uniform interval in the circumferential direction.
Specifically, every other pocket 9g, 9g holding the rollers 2g, 2g is arranged, and three pockets 9g, 9g not holding these rollers 2g, 2g are arranged. That is, these rollers 2g and 2g are arranged at equal intervals in the circumferential direction at a central angle pitch of 72 degrees.
Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, redundant description is omitted.

Table 1 shows the results of a life test assuming a lean amount of lubricating oil in order to confirm the durability of the structures of the first to fourth examples of the above-described embodiment. As a comparative example, a radial roller bearing 1c having the configuration shown in FIG. 1 was used. The configuration and test conditions of the radial roller bearing used for the test are shown below. The cages used in the first to fourth examples of the embodiment and the comparative example all have the same structure. In addition, this test is for confirming how the number of rollers and the lubrication state affect the durability. For this reason, as in the first to fourth examples of the embodiment, the circumferential edges of the third stage intermediate material 10 (see FIG. 10) rounded into a cylindrical shape are welded together to join the cage. For convenience, an object manufactured by a method of cutting a metal material as a material was used.
The test is carried out by incorporating a radial roller bearing into the rotation support portion of the planetary gear as shown in FIG. The time until time was defined as the rolling fatigue life of the radial roller bearing. In addition, the rolling fatigue life (measured value life in Table 1) and the calculated value life of the radial roller bearings 1d to 1g of the first to fourth examples of the above embodiment are the rolling fatigue life and the calculated value life of the comparative example. Each ratio is expressed as a ratio of 1. In addition, it is considered that the influence of the lubrication state is large, and since it becomes a peeling start point, the presence / absence of smearing, which has an important effect on the durability, was confirmed, and the results are also shown in Table 1.
[Configuration of radial roller bearing]
Cage outer diameter: 22.8 mm
Cage width: 27.15mm
Cage material: JIS standard SCM415 carbonitrided.
Roller diameter: 2.5mm
Roller length: 24.8mm
Roller material: Carbonitriding treatment of 2 types of high carbon chromium bearing steel (SUJ2).
Number of pockets: 20 (pieces)
Pinion shaft diameter: 18mm
Pinion shaft length: 50mm
Pinion shaft material: Carbonitriding treatment of two types of high carbon chromium bearing steel.
Pinion gear hole diameter: 23mm
Pinion gear material: Carbonitriding treatment of two types of high carbon chromium bearing steel.
[Endurance test conditions]
Testing machine: Planetary needle testing machine manufactured by NSK Ltd. Load: 500 (N)
Pinion rotation speed: 10000 min ^-1
DmN: 285,000 Lubricating oil: ATF
Lubricating oil amount: 30cc / min
Oil temperature: 120 ° C

As is apparent from Table 1 above, which shows the results of the tests conducted under the conditions described above, in the first example structure of the embodiment, the measured value life is nearly twice the measured value life of the comparative example. (1.96 times). In all the structures of the embodiments, the ratio of measured value life / calculated value life> 1, and it can be seen that reducing the number of rollers during light load operation leads to improved durability. Further, the comparative example generates smearing, whereas the structures of all the embodiments do not generate smearing.
From the above results, it can be seen that the oil permeability and the heat generation suppression effect of the radial roller bearing are largely attributed to the improvement of the durability of the radial roller bearing operated in a light load state. It can also be seen that the configuration of the radial roller bearing of the present invention can provide excellent oil permeability and heat generation suppressing effect, and can ensure sufficient durability.

In each of the embodiments described above, the total number of pockets formed in the cage is 20, but this number is not limited. For example, a case where the total number of pockets 9h, 9h formed in the cage 3h is 21 as in the radial roller bearing 1h shown in FIG.
In the case of the example shown in FIG. 6, the cage 3h constituting the radial roller bearing 1h is a part (seven locations) of 21 pockets 9h, 9h formed at uniform intervals in the circumferential direction. The rollers 2h and 2h are held only in the pockets 9h and 9h. In addition, a pair of pockets 9h, 9h that do not hold these rollers 2h, 2h among these pockets 9h, 9h are arranged at uniform intervals in the circumferential direction.
Specifically, every other pocket 9h, 9h holding the rollers 2h, 2h is arranged, and two pockets 9h, 9h not holding these rollers 2h, 2h are arranged. These three pockets 9h, 9h are set as a set, and seven sets are arranged at equal intervals in the circumferential direction. Of course, the number of pockets 9h, 9h holding the rollers 2h, 2h and the number of pockets 9h, 9h not held may be reversed depending on the required load capacity.
The present invention satisfies the restrictions on the manufacture of the cage (restriction on the total number of pockets that can be formed in the cage), and holds the rollers only in some of the pockets formed in the cage. And all the radial roller bearings which can arrange | position the pocket which does not hold | maintain these each roller of these each pocket at a uniform space | interval regarding the circumferential direction are object.

Sectional drawing of the radial roller bearing which shows the comparative example regarding this invention. Sectional drawing of the radial roller bearing which shows the 1st example of embodiment of this invention. Sectional drawing of the radial roller bearing which shows the 2nd example. Sectional drawing of the radial roller bearing which shows the 3rd example. Sectional drawing of the radial roller bearing which shows the 4th example. Sectional drawing of the radial roller bearing which shows another example of embodiment of this invention. Sectional drawing of the planetary gear rotation support part incorporating the radial roller bearing which shows an example of the conventional structure. The perspective view of the radial roller bearing retainer which shows an example of the conventional structure. AA sectional drawing of FIG. The figure which looked from the side used as an outer peripheral surface when the intermediate material of the 3rd step before forming in a cylindrical shape is made into a cylindrical shape. Sectional drawing of the radial roller bearing before correspondence for demonstrating the correspondence method when the load capacity with which a radial roller bearing is equipped has a margin. Similarly, sectional view after correspondence.

Explanation of symbols

1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h Radial roller bearings 2, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h rollers 3, 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h Cage 4 Support shaft 5, 5a Inner ring raceway 6, 6a Outer ring raceway 7 Rim part 8, 8a, 8b Pillar part 9, 9a, 9b, 9c, 9d, 9e, 9f, 9g, 9h Pocket 10 First Three-stage intermediate material 11 Outer ring 12 Inner ring 13 Planetary gear

Claims (1)

The inner ring raceway and the outer ring raceway, which are arranged concentrically with each other, and a plurality of rollers provided between the inner ring raceway and the outer ring raceway so as to roll freely, and each of these rollers can roll freely. And a retainer
Of these, the cage is formed by welding both ends in the circumferential direction of a metal plate rounded into a cylindrical shape by welding, and is provided in parallel with each other at both ends in the axial direction. A pair of rim portions that are annular, and a plurality of column portions that are provided in parallel with each other in a state of being spanned between the two rim portions and at a uniform interval with respect to the circumferential direction. In a radial roller bearing with a cage, the portions surrounded by the four circumferences by these pillar portions adjacent to each other and the rim portions are pockets for holding the rollers in a freely rolling manner.
The rollers are held only in some of the pockets, and the pockets that do not hold the rollers are arranged substantially uniformly in the circumferential direction. Radial roller bearing with cage.

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