JP2009036348A - Tandem type double-row angular contact ball bearing and bearing device for pinion shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tandem type double-row angular contact ball bearing that prevents damage of a retainer while avoiding an increase in dimension. <P>SOLUTION: The tandem type double-row angular contact ball bearing 1 is composed of a single outer ring 2 having a large-diameter outer-ring raceway surface 2a and a small-diameter outer-ring raceway surface 2b, a single inner ring 3 having a large-diameter inner-ring raceway surface 3a radially facing the large-diameter outer-ring raceway surface 2a and a small-diameter inner-ring raceway surface 3b radially facing the small-diameter outer-ring raceway surface 2b, a large-diameter-side ball group stored between the large-diameter outer-ring raceway surface 2a and the large-diameter inner-ring raceway surface 3a, and a small-diameter-side ball group stored between the small-diameter outer-ring raceway surface 2b and the small-diameter inner-ring raceway surface 3b, and retainers 8, 9 for retaining balls 5, 6, respectively constituting each ball group, at circumferentially equally arranged positions. A diameter D<SB>L</SB>of each ball 5 constituting the large-diameter ball group is set larger than a diameter D<SB>S</SB>of each ball 6 constituting the small-diameter ball group. A difference between the revolution number of the large-diameter ball group and that of the small-diameter ball group is set so as to be ≤10% of the revolution number of the large-diameter ball group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tandem double-row angular contact ball bearing suitable for supporting a pinion shaft of, for example, an automobile differential device or transfer device.

  2. Description of the Related Art Conventionally, in an automobile transfer device, a pinion shaft provided at one end with a pinion gear meshing with a ring gear of a differential transmission mechanism is rotatably supported by a pinion gear side bearing and an anti-pinion gear side bearing. Conventionally, as a bearing device for a pinion shaft used in this type of transfer device, both the bearing on the pinion gear side and the bearing on the anti-pinion gear side are constituted by tapered roller bearings, both the bearings are arranged back to back, and the preload is applied. Some are housed in a housing in an added state. Since a relatively large thrust load acts on the bearing on the pinion gear side, a tapered roller bearing larger in size than the bearing on the anti-pinion gear side is used.

  The conventional pinion shaft bearing device has a disadvantage that a large frictional resistance is applied to the tapered roller bearing on the pinion gear side, resulting in a large rotational torque, and hence a reduction in efficiency of the transfer device. Thus, conventionally, a pinion shaft bearing device using tandem double-row angular ball bearings for both the pinion gear side and the anti-pinion gear side bearings has been proposed (for example, see Patent Document 1). The basic structure of a tandem type double row angular contact ball bearing is described in Japanese Patent No. 181547.

  The tandem double-row angular contact ball bearing has two rows of raceways on the outer ring and the inner race, and a plurality of balls having different pitch circle diameters in each row are arranged between the raceways facing each other. The contact angles formed between the two rows of raceway surfaces and the balls are all in the same direction. The balls in each track array are held at circumferential intervals by a cage. In the tandem double-row angular contact ball bearing on the pinion gear side, the raceway surface on the pinion gear side has a large diameter, and the raceway surface on the anti-pinion gear side has a small diameter. On the other hand, in the tandem double-row angular contact ball bearing on the anti-pinion gear side, the raceway surface on the pinion gear side has a small diameter, and the raceway surface on the anti-pinion gear side has a large diameter.

Tandem double-row angular contact ball bearings have a structure in which the inner ring, ball and cage assembly can be separated from the outer ring, and the assembly is as good as tapered roller bearings, but the load capacity is the same as that of tapered roller bearings. If the rigidity is to be ensured, the size tends to be larger than that of the tapered roller bearing.
JP 2002-523710A Patent No. 181547

  The tandem double-row angular contact ball bearing used for the pinion shaft of the transfer device rotates when the pinion shaft rotates at a maximum speed of about 7000 rpm. There is a risk of the containers coming into contact with each other and being damaged. In addition, when the two rows of cages have an integral structure, the cages and balls may be damaged.

  Accordingly, an object of the present invention is to provide a tandem double-row angular contact ball bearing that can prevent the cage from being damaged while avoiding an increase in size.

  In order to solve the above problems, a tandem double-row angular contact ball bearing of the invention of claim 1 includes an outer ring having a double-row raceway surface formed on an inner periphery, and a double-row raceway facing the double-row raceway surface. The inner ring having a surface formed on the outer periphery and the raceways facing each other between the inner ring and the outer ring are formed with different pitch circle diameters, and the contact angles that contact the raceways of each row are in the same direction. In the tandem double-row angular contact ball bearing comprising a plurality of ball rows facing each other and a plurality of cages that respectively hold the ball groups between the raceways of the double rows, the plurality of ball groups include the outer ring and When the inner ring rotates relatively, the difference in revolution speed between the ball group having the maximum revolution speed and the ball group having the smallest revolution speed is 10% or less of the maximum revolution speed. It is characterized by having been comprised.

  According to the above configuration, the revolution speed of the double row ball group is configured such that the difference between the maximum revolution speed and the minimum revolution speed is 10% or less of the maximum revolution speed. Even if a relative slip of the ball group occurs on a predetermined track surface of the track surfaces, the change from the revolution speed of the ball group on the other track surface can be reduced. Therefore, since the revolution speed of the cage, which is substantially the same as the revolution speed of the ball group, is less changed due to the relative slip of the ball group, the revolution speed of the cage is greatly changed. The inconvenience of the cages coming into contact with each other and damaging the cage can be prevented.

The tandem double-row angular contact ball bearing according to claim 2 is the tandem double-row angular contact ball bearing according to claim 1, wherein the double-row raceway surface formed on the inner ring and the outer ring is a large-diameter raceway surface. And the small-diameter raceway surface, and the double-row ball group includes a large-diameter ball group interposed with a large pitch circle diameter between the large-diameter raceway surfaces of the inner ring and the outer ring, and the inner ring And a small-diameter ball group interposed between the small-diameter raceway surfaces of the outer ring and the small-diameter raceway. The diameter D _{L of} the balls constituting the large-diameter ball group and the diameter D _{S of} the balls constituting the small-diameter ball group However, it satisfies the relationship of D _L > D _S.

According to the above embodiment, inner and outer rings are provided with raceways two rows, and the diameter D _L of balls constituting a large径玉group interposed one raceway surface, interposed the other raceway surface diameter The diameter D _{S of} the balls constituting the ball group satisfies the relationship of D _L > D _S , so that the large diameter ball group and the small diameter ball group are composed of balls of the same diameter, so that the tandem double row angular ball bearing Can be reduced.

  The tandem double-row angular contact ball bearing according to claim 3 is the tandem double-row angular contact ball bearing according to claim 1, wherein the plurality of cages are connected to each other so that relative movement in the circumferential direction is impossible. It has been done.

  According to the above embodiment, even if slip occurs in a ball group held by a predetermined cage among a plurality of cages connected to each other, the revolution speed of the ball group in which the slip has occurred and other ball groups Since the difference with the revolution speed of the ball is small, damage to the cage and balls can be reduced.

  The tandem double-row angular contact ball bearing according to claim 4 is the tandem double-row angular contact ball bearing according to claim 1, wherein the outer ring and the inner ring are separated by a plurality of outer ring portions and a plurality of outer ring portions separated for each raceway surface. A plurality of single-row angular contact ball bearing portions formed in an inner ring portion and configured in parallel with the outer ring portion, the inner ring portion, and a ball group interposed between raceways facing the outer ring portion and the inner ring portion are arranged in parallel. Is configured.

  According to the above embodiment, a plurality of single-row angular contact ball bearing portions are arranged in parallel, i.e., tandem double-row angular contact ball bearings configured so that the contact angles face each other in the same direction. It is possible to reduce the damage to the cage and balls caused by the relative sliding that occurs. Further, by changing the combination of the single-row angular ball bearing portions, it is possible to cope with various load conditions and to obtain versatility, so that the cost of the tandem type double-row angular ball bearing can be reduced.

  According to a fifth aspect of the present invention, there is provided a pinion shaft bearing device comprising: a pair of bearings rotatably supporting a pinion shaft having a pinion gear provided at one end on a pinion side close to the pinion gear and an anti-pinion side far from the pinion gear. A pinion shaft bearing device comprising: an outer ring having a double row raceway surface formed on an inner periphery thereof; and a double row raceway surface facing the double row raceway surface on an outer periphery. A double row in which the formed inner ring and the inner race and the outer race facing each other are arranged with different pitch circle diameters, and the contact angles of the rows in contact with the race surfaces are in the same direction. And a plurality of cages each holding a ball group between the double-row raceway surfaces, and a double-row ball of the tandem double-row angular ball bearing. The group consists of the outer ring and the inner ring. The relative revolution speed of the ball group having the maximum revolution speed and the ball group having the smallest revolution speed is 10% or less of the maximum revolution speed. It is characterized by being configured.

  According to the above configuration, the pinion-side bearing of the pinion shaft bearing device receives a larger load than the anti-pinion-side bearing due to the rotation of the pinion gear and operates at a high rotational speed, but is used for the pinion-side bearing. The tandem double row angular contact ball bearing is configured so that the difference between the maximum revolution speed and the minimum revolution speed is 10% or less of the maximum revolution speed in the double row ball group. Even if relative slip occurs in a ball group on a predetermined raceway surface, a change in revolution speed of the ball group on another raceway surface can be reduced. Therefore, the change in the revolution speed of the cage can be reduced, and damage due to contact between the cage holding the ball group in which the relative slip has occurred and another cage can be prevented. As a result, the high-speed rotation pinion shaft can be stably supported by the tandem double-row angular ball bearing, and as a result, a highly durable pinion shaft bearing device can be obtained.

  According to the present invention, even if relative slip occurs in a ball group on a predetermined raceway surface in a double row raceway surface, it is possible to reduce a change in the revolution speed of the ball group and the cage, and damage the cage and the ball. Therefore, it is possible to obtain a highly durable tandem double-row angular ball bearing that enables high-speed rotation of the rotating member over a long period of time. Thereby, energy saving is possible, and a highly durable pinion shaft bearing device and transfer device can be realized.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a tandem double-row angular contact ball bearing as a first embodiment of the present invention.

  The tandem double-row angular contact ball bearing 1 of this embodiment includes a single outer ring 2 having a large-diameter outer ring raceway surface 2a and a small-diameter outer ring raceway surface 2b, and a large-diameter inner ring that faces the large-diameter outer ring raceway surface 2a in the radial direction. A single inner ring 3 having a small-diameter inner ring raceway surface 3b that is radially opposed to the raceway surface 3a and the small-diameter outer ring raceway surface 2b, and a large housing accommodated between the large-diameter outer ring raceway surface 2a and the large-diameter inner ring raceway surface 3a. The diameter-side ball group, the small-diameter side ball group accommodated between the small-diameter outer ring raceway surface 2b and the small-diameter inner ring raceway surface 3b, and the balls 5 and 6 constituting each ball group are held at equal positions in the circumferential direction. It consists of cages 8 and 9.

The diameter D _L of the balls 5 constituting the large-diameter side ball group is formed larger than the diameter D _{S of the} balls 6 constituting the small-diameter side ball group, and satisfies the relationship D _L > D _S. That is, a ball group having a large pitch circle diameter is constituted by the balls 5 having a large diameter D _L , while a ball group having a small pitch circle diameter is constituted by the balls 6 having a small diameter D _S.

And the diameter D _L of the ball 5 having a large diameter, the diameter D _S of the small diameter side of the ball 6, the pitch circle diameter d _L of the larger-diameter ball group, the pitch circle diameter d _S of the smaller-diameter-side ball group, larger diameter balls It is set based on the contact angle α _L of the group, the contact angle α _S of the small-diameter side ball group, and the outer ring rotation speed n _E or the inner ring rotation speed n _I. As a result, the difference between the revolution speed of the large-diameter side ball group and the revolution speed of the small-diameter side ball group is set to the larger of the revolution speed of the large-diameter side ball group and the revolution speed of the small-diameter side ball group. 10% or less. Specifically, the revolution speed n _CL of the large-diameter side ball group and the revolution speed n _CS of the small-diameter side ball group are obtained by the following equations (1) and (2) using the above parameters.

Here, the contact angle α _L of the large-diameter side ball group and the contact angle α _S of the small-diameter side ball group are set according to the magnitude and ratio of the thrust load and the radial load received by the tandem double-row angular ball bearing 1. Is done. Further, the inner ring rotation speed n _I and the outer ring rotation speed n _E are set by the rotation speed of the rotation member supported by the rotation side member depending on which of the outer ring 2 and the inner ring 3 is the rotation side member. Using these values as conditions, the revolution speed n _CL of the large-diameter side ball group and the revolution speed n _CS of the small-diameter side ball group are obtained from the above equations (1) and (2). In this case, the difference of the revolution speed n _CS of the revolution speed n _CL and the smaller-diameter-side ball group of the large-diameter ball group, the revolution speed n of the revolution speed n _CL and the smaller-diameter-side ball group of the large-diameter side ball group The pitch circle diameter d _L of the large-diameter side ball group, the pitch circle diameter d _S of the small-diameter side ball group, and the diameter D _L of the large-diameter side ball 5 so that the larger one of _CS is 10% or less determining the diameter D _S of the ball 6 of small diameter side. Thus, while setting the pitch circle diameter d _L of the large-diameter side ball group and the pitch circle diameter d _S of the small-diameter side ball group to appropriate values, avoiding an increase in size of the tandem double-row angular ball bearing 1, The difference between the revolution speed n _CL of the ball group and the revolution speed n _CS of the small-diameter side ball group can be reduced.

The ball 5 on the large diameter side and the ball 6 on the small diameter side are points where the balls 5 and 6 are in contact with the large diameter outer ring raceway surface 2a and the small diameter outer ring raceway surface 2b in the cross section passing through the axis L of the tandem double row angular contact ball bearing. A line L _E connecting the balls 5 and 6 with a line L _I connecting the points where the balls 5 and 6 are in contact with the large diameter inner ring raceway surface 3a and the small diameter inner ring raceway surface 3b intersect at a point P on the axis L _C on the front side of the inner ring. It is formed to do.

The cages 8 and 9 are formed so as to hold the balls 5 and 6 of each ball group at equal intervals in the circumferential direction, and are separated so as to be relatively movable in the circumferential direction. The rotation speeds of the cages 8 and 9 are substantially the same as the revolution speed n _CL of the large diameter side ball group and the revolution speed n _CS of the small diameter side ball group, respectively.

  The outer ring 2 and the inner ring 3 are made of high carbon chromium bearing steel (SUJ2). The surface of the raceway surfaces 2a, 2b of the outer ring 2 and the surface of the raceway surfaces 3a, 3b of the inner ring 3 are provided with a hardened layer by induction quenching or the like, or subjected to continuous quenching, so that the surface hardness is 60 to 64 HRC. Yes.

  In the operation of the tandem double-row angular ball bearing 1, a thrust load and a radial load are applied to either the outer ring 2 or the inner ring 3 that is the rotation side member from the rotating member. The load is applied from one of the large-diameter outer ring raceway surface 2a and the small-diameter outer ring raceway surface 2b of the outer ring 2 and the large-diameter inner ring raceway surface 3a and the small-diameter inner ring raceway surface 3b of the inner ring 3 via the balls in each row. Acts on the other. Thus, the rotational load acting on one of the outer ring 2 and the inner ring 3 is supported on the large and small diameter raceway surfaces provided on the other of the outer ring 2 and the inner ring 3.

  In the tandem double-row angular ball bearing 1, relative sliding of the balls 5, 6 may occur on the raceway surfaces 2a, 2b, 3a, 3b on the large diameter side or the small diameter side. Here, the difference between the revolution speeds of the large-diameter side and the small-diameter side of the ball group is 10% or less of the larger revolution speed. The change in the revolution speed with respect to the ball group can be reduced. Therefore, since the change in the revolution speed of the cages 8 and 9 that is substantially the same as the revolution speed of the ball group can be reduced, the cages 8 and 9 come into contact with each other and are damaged due to relative slip. Can be prevented.

  FIG. 2 is a cross-sectional view showing a pinion shaft bearing device as a second embodiment of the present invention. This pinion shaft bearing device is used in an automobile transfer device, and includes the tandem double-row angular ball bearing 1 of the first embodiment. In the second embodiment, the same components as those in the first embodiment are referred to by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the transfer device accommodates a pinion shaft 13 having a pinion gear 12 at the tip in a front case 10 constituting a differential case. A tandem type double-row angular contact ball bearing 1 that rotatably supports the pinion side of the pinion shaft 13 and a single-row angular contact ball bearing 15 that rotatably supports the anti-pinion side of the pinion shaft 13. Is configured. The pinion gear 12 is meshed with a ring gear of a differential transmission mechanism (not shown). The pinion shaft 13 is formed in a step shape so as to have a larger diameter toward the pinion gear side.

  Two annular walls 10a and 10b for mounting bearings are formed on the inner surface of the front case 10, and the tandem double-row angular ball bearing 1 is accommodated in the annular wall 10a on the pinion gear side, while the anti-pinion gear. A single-row angular ball bearing 15 is accommodated in the annular wall 10b on the side. The pinion shaft 13 is fitted to the inner peripheral surface of the inner ring 3 of the tandem double-row angular ball bearing 1 and the inner peripheral surface of the inner ring 53 of the single-row angular ball bearing 15. The tandem double-row angular contact ball bearing 1 is formed such that the diameter of the balls 5 constituting the large-diameter side ball group is larger than the diameter of the balls 6 constituting the small-diameter side ball group, and the difference in revolution speed between the two ball groups. However, it is formed so that it may become 10% or less of the larger revolution speed.

  A cylindrical spacer 16 is interposed between the front side end face of the inner ring 3 of the tandem double row angular ball bearing 1 and the front side end face of the single row angular ball bearing 15. On the back side of the single row angular ball bearing 15, a cylindrical companion sleeve 17 that is fitted on the pinion shaft 13 is disposed. A single-row angular ball bearing 15, a spacer 16, and a tandem double-row angular ball bearing 1 are sandwiched between an end face of the companion sleeve 17 and an end face 12 a of the shoulder of the pinion gear 12. A preload introduced from the companion sleeve 17 is applied to the single-row angular ball bearing 15 and the tandem double-row angular ball bearing 1 through the spacer 16.

  The pinion shaft bearing device configured as described above uses a tandem double-row angular ball bearing 1 having a low frictional resistance as a pinion gear side bearing on which a larger load is applied than on the anti-pinion gear side. Thereby, compared with the conventionally used tapered roller bearing, a rotational torque becomes small and the efficiency of a transfer apparatus can be improved. Further, by using the double row ball bearing, the load capacity can be increased as compared with the single row ball bearing, and sufficient support rigidity can be obtained.

  Further, as the tandem double-row angular ball bearing 1, the pinion gear side on which the larger load is applied by increasing the pitch circle diameter of the large-diameter side ball group on the pinion gear side compared to the pitch circle diameter of the small-diameter side ball group. The number of balls 5 on the large-diameter side can be increased, and a large load can be withstood.

  In the tandem double-row angular contact ball bearing 1, the difference in revolution speed between the large-diameter side ball group and the small-diameter side ball group is 10% or less of the larger revolution speed. Therefore, even if relative slip occurs in any of the ball groups, the change in the revolution speed with respect to the other ball group can be reduced. Therefore, even under operating conditions in which the pinion shaft reaches a maximum rotational speed of about 7000 rpm, the change in the revolution speed of the ball group and the cages 8 and 9 can be reduced, so that the balls 5 and 6 and the holding caused by the relative slip can be reduced. The damage to the devices 8 and 9 can be effectively prevented. Thereby, the performance of the tandem double-row angular contact ball bearing 1 can be stably maintained. As a result, a highly efficient transfer device having stable performance can be obtained.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention. For example, in the above embodiment, the outer ring 2 and the inner ring 3 are provided with two rows of raceway surfaces, but three or more rows of raceway surfaces may be provided. The diameter and pitch circle of each ball group is such that the difference between the maximum revolution speed and the minimum revolution speed is 10% or less of the maximum revolution speed for the ball groups interposed between these double-row raceway surfaces. What is necessary is just to set a diameter.

  Moreover, you may comprise the holder | retainers 8 and 9 as a monolithic structure connected mutually, and the relative movement improper. Even when holding a double row ball group with an integrated structure cage, the difference between the maximum revolution speed and the minimum revolution speed between the ball groups in each row is 10% or less of the maximum revolution speed. Damage to balls and cages can be prevented.

  In the above embodiment, the single outer ring 2 is provided with the double-row raceway surfaces 2a and 2b, and the single inner ring 3 is provided with the double-row raceway surfaces 3a and 3b. A plurality of outer ring portions having a single raceway surface may be arranged in parallel to form an outer ring, and a plurality of inner ring portions having a single raceway surface may be arranged in parallel to constitute an inner ring. . That is, a plurality of single-row angular contact ball bearings composed of an outer ring part, an inner ring part, and a ball group interposed between raceways facing the outer ring part and the inner ring part are arranged in parallel to form a tandem type compound bearing. You may comprise a row angular contact ball bearing. In this case, by changing the combination of the single-row angular ball bearings, it is possible to cope with various load conditions and obtain versatility, so that the cost of the tandem double-row angular ball bearing can be reduced. .

  Further, in the pinion shaft bearing device of the above embodiment, the single row angular contact ball bearing is used as the bearing on the anti-pinion gear side, but the pitch circle diameter of the ball group on the anti-pinion gear side is larger than the pitch circle diameter of the ball group on the pinion gear side. You may use the taper roller bearing which comprises a back combination bearing with the tandem type double-row angular contact ball bearing set large or the double-row ball bearing on the pinion gear side.

  The tandem double-row angular contact ball bearing and pinion shaft bearing device of the present invention are not limited to automobile transfer devices, and can be applied to power transmission devices of various industrial machines.

It is sectional drawing which shows the tandem type | mold double row angular contact ball bearing of embodiment of this invention. It is sectional drawing which shows the pinion shaft bearing apparatus of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tandem type double row angular contact ball bearing 2 Outer ring 2a Large diameter outer ring raceway surface 2b Small diameter outer ring raceway surface 3 Inner ring 3a Large diameter inner ring raceway surface 3b Small diameter inner ring raceway surface 5 Large diameter side ball 6 Small diameter side ball

Claims (5)

An outer ring having a double-row raceway surface formed on the inner periphery, an inner ring having a double-row raceway surface facing the double-row raceway surface, and each raceway surface facing the inner ring and the outer ring. , Each having a pitch circle diameter different from each other and holding a double row ball group in which the contact angles contacting the raceway surfaces of each row are in the same direction and a ball group between the double row raceway surfaces, respectively. In a tandem double-row angular contact ball bearing with a plurality of cages,
When the outer ring and the inner ring rotate relative to each other, the plurality of ball groups has a maximum difference in revolution speed between the ball group having the maximum revolution speed and the ball group having the smallest revolution speed. A tandem double-row angular contact ball bearing, characterized in that it is configured to be 10% or less of the revolution speed. In the tandem double-row angular contact ball bearing according to claim 1,
The double-row raceway surface formed on each of the inner ring and the outer ring is a two-row raceway surface of a large-diameter raceway surface and a small-diameter raceway surface,
The double row ball group has a small pitch circle diameter between a large diameter ball group interposed between the large diameter raceway surfaces of the inner ring and the outer ring and a small diameter raceway surface of the inner ring and the outer ring. Small diameter ball group intervening,
A tandem type double row angular contact ball bearing characterized in that a diameter D _{L of} the balls constituting the large-diameter ball group and a diameter D _{S of} the balls constituting the small-diameter ball group satisfy a relationship of D _L > D _S . In the tandem double-row angular contact ball bearing according to claim 1,
The tandem double-row angular contact ball bearing characterized in that the plurality of cages are connected to each other and cannot be moved relative to each other in the circumferential direction. In the tandem double-row angular contact ball bearing according to claim 1,
The outer ring and the inner ring are formed of a plurality of outer ring portions and a plurality of inner ring portions separated for each raceway surface,
A plurality of single-row angular contact ball bearing portions constituted by the outer ring portion, the inner ring portion, and a ball group interposed between the raceways facing the outer ring portion and the inner ring portion are arranged in parallel. Tandem type double row angular contact ball bearing characterized by A pinion shaft bearing device comprising a pair of bearings that rotatably support a pinion shaft provided with a pinion gear at one end close to the pinion gear and an anti-pinion side far from the pinion gear,
The pinion-side bearing includes an outer ring having a double-row raceway surface formed on an inner periphery, an inner ring having a double-row raceway surface facing the double-row raceway surface, and an inner ring and an outer ring. A double-row ball group in which the contact angles contacting the raceway surfaces in each row are in the same direction, and the double-row raceway surfaces are interposed between the opposing raceway surfaces with different pitch circle diameters. A tandem double-row angular contact ball bearing with a plurality of cages for holding a group of balls,
When the outer ring and the inner ring rotate relative to each other, the double-row ball group of the tandem double-row angular contact ball bearing is between a ball group having the highest revolution speed and a ball group having the lowest revolution speed. The pinion shaft bearing device is characterized in that the difference in revolution speed is 10% or less of the maximum revolution speed.

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