The present invention relates to the self-aligning clutch release bearing. More particularly, the present invention relates to the self-aligning clutch release bearing wherein said clutch release bearing have both self-aligning and self-centering feature in a single mechanism.

BACKGROUND OF THE INVENTION:

Majority of automotive vehicles are equipped with manual or automatic manual transmission system for providing control of speed and torque to the vehicle for different driving conditions. Said control of speed and torque is achieved by altering the gear of transmission. This alteration of gear changes the speed and torque of the vehicle but the engine output remains unchanged. To compensate this change of speed and torque between engine and vehicle a clutch is used to facilitate smooth alteration of gear in transmission systems. Depending on the type of the vehicle, said clutch can be of following types:

• Friction Clutch

• Centrifugal Clutch

• Hydraulic Clutch

• Dog Clutch

Centrifugal clutch mostly used in moped or mini-bike, Hydraulic clutch used in vehicle which is equipped with automatic transmission and dog clutches are very old type of clutch which is obsoleted because of its low life and wearing problem.

When passenger vehicles and goods careers are considered, the type of clutch used is Friction Clutch. There were two types of friction clutch i) Push type and ii) Pull type. The main difference between these two types of clutch is direction of clutch release force. Selection of push and pull type is according clutch design and its packaging dimension. Present invention is related to push type of friction clutch. An illustrative line diagram of typical push type of friction clutch assembly is shown in Fig. 1.

As shown in Fig. 1, typical push type of friction clutch assembly 100 comprises of flywheel 60, engine output shaft 70, clutch 40, clutch bearing 20, fork 30 and driven shaft 50. Said flywheel 60 is rigidly connected to engine output shaft 70 to store the energy of engine in terms of inertia. Said clutch 40 is concentrically mounted on the flywheel 60, to provide disengagement and engagement of output shaft 70 and driven shaft 50 for smooth gear shifting. Said driven shaft 50 is placed concentric with clutch 40. Said clutch bearing 20 is placed between clutch 40 and fork 30 and is concentrically and slide-ably mounted on driven shaft 50.

Said clutch 40 comprises of preloaded diaphragm spring 41 or spring loaded levers (not shown), clutch cover 42, clutch plate 43 and pressure plate 44. Said preloaded spring 41 is connected with clutch cover 42 through pivot point 45, holding said pressure plate 44 through point 46. Said pressure plate 44 is frictionally in contact with clutch plate 43, which is further frictionally in contact with flywheel 60. Said clutch plate 43 is connected with the driven shaft 50 by means of spline 51. Said spline 51 allows relative axial movement of clutch plate

43 and driven shaft 50.

Fig. 1 shows engage condition of engine output shaft 70 and driven shaft 50 wherein the preloaded diaphragm spring 41 applies force on clutch plate 43 by pushing the pressure plate

44 against it. During gear shifting it is require to disengage the driven shaft 50 from output shaft 70 which is done by releasing pressure from clutch plate 43. To release said pressure from clutch plate 43, some axial force must be applied on diaphragm spring 41. The axial force required for releasing clutch plate 43 is known as clutch release force. Applying force on diaphragm spring deflects it from pivot point 45 as shown in Fig. 1 and pull the pressure plate 44 through point 46 to release the clutch plate 43, thereby disengaging driven shaft 50 from engine output shaft 70.

Said disengaging process of driven shaft 50 from engine output shaft 70 is achieved by clutch bearing 20 and fork 30 or hydraulically operated actuation mechanism (not shown). Said fork 30 is actuated by slave cylinder (not shown) or mechanical linkages which further operated by pedal effort to apply clutch release force on clutch bearing 20 which further transfer the axial force to the clutch finger 41 in order to disengage clutch plate 43 from flywheel 60, thereby disengaging the driven shaft 50 from engine output shaft 70 and providing smooth gear shifting. Said typical clutch 40 suffers from geometrical inaccuracy as result of manufacturing tolerance of its components. Because of manufacturing tolerance there is eccentricity between clutch rotation axis 47 and driven shaft axis 52. To compensate this eccentricity self- centering feature is provided in conventional clutch bearing 20. To provide this self-centering feature static ring 212 of bearing is preloaded by spring 23 and there is a gap c between static ring 212 and sleeve 22 of clutch bearing 20 as shown in Fig. 2. Because of this gap c bearing 21 has tendency to shift under application of radial forces and get in centered with clutch axis 47.

Furthermore, there are two more geometrical inaccuracies in clutch assembly 100,

i. One of the geometrical inaccuracy run-out r of clutch finger 41 is shown in Fig. l and Fig. 2. This inaccuracy caused by inaccurate fitment of diaphragm spring 41 with clutch cover 42 and cumulative tolerance of all components which are connected with it. ii. Also because of mounting inaccuracy of clutch 40 and flywheel 60 there is misalignment Θ between clutch rotation axis 47 and driven shaft axis 52 as shown in Fig. 1 and Fig. 2.

As mentioned above the clutch bearing 20 suffers from total three geometrical inaccuracies,

1. Eccentricity of rotational axis of clutch and driven shaft 47,57

2. Run-out r of spring 41

3. Misalignment Θ of rotational axis of clutch and driven shaft

from which the inaccuracy of eccentricity is compensated in conventional clutch bearing 20 by self-centering feature. Because of remaining two inaccuracies, clutch bearing 20 suffers from unbalanced forces of diaphragm spring 41. Said unbalanced forces create vibrations in clutch bearing, which transferred to the clutch pedal by fork and its actuation mechanism. Said vibration reduces the driver comfort while clutching. Furthermore, said unbalanced forces create noise, wearing of rotating ring and wearing of rolling elements, which results in excessive temperature rise and premature failure of clutch bearing 20.

PRIOR ARTS AND ITS DISADVANTAGES:

To compensate said misalignment Θ and run-out r many attempts has been carried out, like: • German patent DE 102009055659A1 describes a method of manufacturing clutch release bearing which has both self-centering and self-aligning feature in single mechanism by providing spherical face on ring and on support structure. However, this device requires a modified bearing ring which includes extra material and complex machining, thereby increases packaging size d, cost and weight of Clutch release bearing 20.

• German patent DE 102007053180A1 describes a method of manufacturing clutch release bearing which has self-aligning feature by providing spherical rings. However this device comprises of loose spherical ring which leads to noise, vibration and wear of bearing ring.

Therefore, an available prior art teaches about the clutch release bearing that suffers from the disadvantages of loose parts, extra material and extra machining.

OBJECTS OF THE PRESENT INVENTION:

The main object of present invention is to provide a self-aligning clutch release bearing; which compensate the inaccuracy of run-out of diaphragm spring and misalignment of driven shaft in clutch assembly by self-aligning feature.

Another object of present invention is to provide a self-aligning clutch release bearing; which has both self-centering and self-aligning feature in single mechanism.

Another object of present invention is to provide a self-aligning clutch release bearing; wherein said clutch release bearing has more life and temperature rise of which is less, as there were no wearing of its components.

Another object of present invention is to provide a self-aligning clutch release bearing; wherein present self-aligning clutch bearing has same packaging size as conventional clutch bearing.

Another object of present invention is to provide a self-aligning clutch release bearing; wherein present self-aligning clutch bearing do not tilt the sleeve, as a result of which harsh sliding of clutch bearing on driven shaft is eliminated, which reduces the clutch pedal effort and wearing of bearing sleeve.

Another object of present invention is to provide a self-aligning clutch release bearing; wherein present self-aligning clutch bearing absorbs the vibrations caused by the unbalanced forces of diaphragm spring and increases the comfort of driver while clutching

Another object of present invention is to provide a self-aligning clutch release bearing; which does not have any loose parts, thereby reducing wear and vibration of bearing.

Still another object of present invention is to provide a self-aligning clutch release bearing; wherein no major modification required in bearing rings, thereby reduces requirement of extra material and the complexity of machining.

Yet the object of the present invention is to provide a self-aligning clutch release bearing; which has self-aligning and self-centering feature, without providing any major modification in bearing ring, thereby eliminating wear and premature failure bearing.

SUMMARY OF THE INVENTION

Aspects of the present disclosure relate to a self-aligning bearing for clutch release bearing application in a clutch, which adjusts its position to compensate the inaccuracy of run-out of clutch fingers/ diaphragm spring, as well as misalignment of driven shaft in clutch assembly.

In an aspect, the disclosed self-aligning bearing comprises a rotating ring, a static ring and a spherical cup.

In an aspect, the rotating ring has a face that engages with fingers of the clutch to transfer axial force to disengage clutch plate from flywheel.

In an aspect, the static ring is in engagement with the rotating ring through a plurality of balls positioned between the rotating ring and the static ring, for a frictionless rotation of the rotating ring relative to the static ring about a rotational axis of the bearing.

In an aspect, the spherical cup is sized to accommodate the static ring within an inner cavity of the spherical cup. In an aspect, the spherical cup incorporates an inner spherical surface such that the static ring engages with the spherical cup through the spherical surface on the spherical cup.

In an aspect, the spherical surface on the spherical cup has a radius whose center coincides with a center point, which is defined by intersection of the rotational axis of the bearing and a plane defined by the face of the rotating ring that engages with fingers of the clutch.

In an aspect, engagement of the static ring with the spherical cup enables the static ring, along with the rotating ring and the plurality of balls positioned between the rotating ring and the static ring, to tilt about the center point to accommodate any angular misalignment between the fingers of the clutch and the rotating ring.

In an aspect, the static ring, in the region that is in engagement with the spherical surface on the spherical cup, incorporates a radius that is equal or less than the radius of the spherical surface on the spherical cup.

In an aspect, the self-aligning bearing further comprises a spherical ring located within an inner diameter of the static ring. The spherical ring incorporates a spherical end face on its outer diameter, and the static ring incorporates a spherical end face on its inner diameter. The two spherical end faces on the static ring and the spherical ring have same radius with their centers coinciding with the center point.

In an aspect, the spherical ring is preloaded against the spherical end face of the static ring by a spring.

In an aspect, the spring is positioned between a stopper on a sleeve on which the bearing is mounted, and the spherical ring.

In an aspect, the two spherical end faces on the static ring and the spherical ring are configured such that engagement of the spherical ring with the static ring through the respective spherical end faces, coupled with the preloading of the spherical ring by the spring retains the bearing with the sleeve against axial displacement. In an aspect, the inner diameters of the spherical ring and the spherical cup larger than outer diameter of the sleeve resulting in a clearance for the spherical ring and the spherical cup to shift radially inward, thereby allowing the bearing to self-center with reference to the clutch.

In an aspect, the spherical ring is heat treated.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 shows a sectional view of a clutch assembly with conventional clutch release bearing.

Fig. 2 shows an enlarged sectional view of conventional clutch release bearing with inaccuracies of run-out and misalignment.

Fig. 3 shows a sectional view of the proposed self-aligning clutch release bearing, which compensates inaccuracies of run-out and misalignment.

Fig. 4 shows an enlarged sectional view of the proposed self-aligning clutch release bearing showing its self-aligning feature.

Fig. 5 discloses a sectional view of second embodiment of the proposed self-aligning clutch release bearing showing setup to convert conventional clutch release bearing into a self- aligning clutch release bearing in accordance with the present disclosure.

Fig. 6 discloses a sectional view of third embodiment of the proposed self-aligning clutch release bearing showing setup to convert conventional clutch bearing of hydraulically operated actuation mechanism into a self-aligning clutch bearing in accordance with the present disclosure.

Reference numerals used for various parts of the invention:

1 Present self-aligning clutch release bearing

1A Second embodiment of self-aligning clutch release bearing

IB Third embodiment self-aligning clutch release bearing

100 Clutch assembly Center point of bearing

Bearing

A Bearing for second embodimentB Bearing for third embodiment1 Rotation axis of Bearing

2 Static ring of Bearing

3 Spherical face of Static ring

4 Rotating ring of bearing

5 Rolling element of bearing'

6 Inner spherical face of static ring

Sleeve

A Sleeve of second embodimentB Sleeve of third embodiment

1 Bush of sleeve

2 Bracket support

3 Bracket

4 Spring stopper

Spherical cup

1 Spherical face of cup

Spherical ring

1 Spherical face of ring

Spring

Cover

1 Outer spherical face of cover2 Inner spherical face of cover

Cover for third embodiment

1 Spherical face of cover

Conventional clutch bearing

Conventional bearing

1 Rotation axis of Conventional bearing2 Static ring of conventional bearing

Conventional sleeve

Spring of conventional clutch bearing 30 Fork

40 : Clutch

41 Diaphragm spring

42 Clutch cover

43 Clutch plate

44 Pressure plate

45 Pivot point on cover

46 Pivot point on pressure plate

47 Rotation axis of clutch

50 Driven shaft

51 Spline of driven shaft

52 Rotation axis of driven shaft

60 Flywheel

70 Engine output shaft

DETAILED DESCRIPTION OF THE PRESENT INVENTION:

The present invention provides a self-aligning clutch release bearing 1, wherein said self- aligning clutch release bearing further provides both self-centering and self-aligning feature in single mechanism.

Referring to Fig. 3, 4 and 5; which show main embodiment of the present invention, wherein said self-aligning clutch release bearing 1 mainly comprises:

• Bearing 11

• Sleeve 12

• Spherical cup 13

• Spherical ring 14

• Spring 15

Said bearing 11 comprises a rotating ring 114 and a static ring 112, between the tracks of which a plurality of balls 115 are accommodated and allowed to roll between them 114 and 112. Rotating ring 114 and static ring 112 are preferably made from bearing steel and are hardened. Said sleeve 12 is placed between actuating fork 30 or piston of hydraulic actuation mechanism (not shown) and bearing 11 to provide seating face for fork 30 or piston of hydraulic actuation mechanism.

Said static ring 112 incorporates a spherical end face 113 (also referred to simply as face and the two terms used interchangeably hereinafter) at its inner diameter, unlike of prior art without any spherical face. Said spherical ring 14 is heat treated. Further, said spherical ring 14 incorporates a spherical end face 141 (also referred to simply as face and the two terms used interchangeably hereinafter) on its outer diameter, the spherical face 141 matches with spherical end face 113 of the static ring 112. Both the spherical faces 113 and 141 have same spherical radius R2 to allow the tilting of bearing 11 on action of unbalanced forces due to misalignment. The center point 10 of said spherical radii is defined by intersection of the rotational axis 111 of the bearing 11 and a plane defined by the face of the rotating ring that engages with fingers of the clutch as shown in Fig. 4. Said spring 15 is placed between stopper 124 of sleeve 12 and spherical ring 14 and is in preloaded condition, thereby applying force on spherical ring 14. As shown in Fig. 4 and 5 there is gap c between spherical ring 13 and bush 121 to provide means of self-centering while working.

Said bearing 11 is placed in spherical cup 13, which is placed on said sleeve 12. The spherical cup 13 incorporates an inner spherical surface 131 with radius of Rl. Said spherical cup 13 is heat treated. This spherical surface 131 also has the same center point 10 as spherical face 141 of spherical ring 14.

As shown in Fig. 4, the static ring 112, in the region that is in engagement with the spherical surface 131 on the spherical cup 13, incorporates a radius that is less than the radius of the spherical surface 131 on the spherical cup 13. This ensures smooth engagement between the static ring 112 and the spherical cup 13 by minimizing contact surface between the two.

There were three components:

i) spherical ring 14,

ii) static ring 112 and

iii) spherical cup 13 are preloaded by means of spring 15 against the sleeve 12, which retains the bearing 1 along with the spherical cup 13 with the sleeve 12, yet providing self-centering functionality by allowing the bearing 11 to shift as shown in Fig. 5.

Further, these three components have spherical faces 113, 131 and 141 with same center point 10, which allows bearing 11 to tilt about center point 10 by an angle of a. As shown in Fig. 3 this mechanism compensate the run-out r of diaphragm spring 41 and misalignment Θ of shaft 50 and matches the rotation axis (47 and 111) of clutch 40 and clutch bearing 1, as shown in Fig. 3, on action of unbalanced forces, yet equally distribute the forces on bearing 11, thereby reduces the wearing of ring, vibrations, noise and premature failure of clutch release bearing 1.

As shown in Fig. 3 said bearing 11 gets tilted by an angle β, which is cumulative of run-out r and misalignment Θ on application of unbalanced forces. This tilting match the clutch rotation axis 47 and bearing rotation axis 111, which aligns the bearing 11 with diaphragm spring 41 and equally distribute the release force on bearing 11.

As shown in Fig. 4 said bearing 11 is allowed to tilt by an angle a as result of self-aligning feature constituted by preloaded spring 15, bearing 11 and spherical cup 13. Said bearing 11 is tilted by unbalanced forces from diaphragm spring as a result of geometrical in accuracies of run-out r and misalignment Θ. Tilting of bearing 11 equally distributes release force on bearing ring which helps to reduce wear and rise in temperature.

Further, said bearing 11 is allowed to shift radially on sleeve 12 to an extent of gap c shown in Fig. 4. This shifting requires some amount of radial force on bearing ring 114 as bearing 11 is preloaded under spring 15. The amount of required radial force on bearing ring 114 to shift the bearing 11 is called shifting force. Said shifting force comes from diaphragm spring 41 as a result of geometrical inaccuracy of eccentricity.

OTHER EMBODIMENTS OF PRESENT INVENTION:

i) Second embodiment of present invention:

Second embodiment of the present invention provides present self-aligning clutch release bearing 1A as an improvement of the conventional bearing 11 A. As shown in Fig. 5, said improvement comprises of cover 16. Said bearing 11A is press fitted in cover 16. Said cover 16 comprises of outer spherical face 161 and inner spherical face 162. Said spherical face 161 has radius of Rl which is same as radius of spherical cup 13. Further said spherical face 162 has radius of R2 which is same as radius of spherical ring 14. Said cover 16 is preloaded between spherical cup 13 and spherical ring 14 by spring 15. The center points of said spherical faces are at the same position on point 10. In this embodiment the cover 16 and bearing 11A can tilt about point 10 and compensate the run-out r and misalignment Θ. Hence present invention allows one to convert conventional clutch bearing in present Self-aligning clutch bearing 1. ii) Third embodiment of present invention:

Third embodiment of the present invention provides present self-aligning clutch release bearing IB as an improvement of the conventional bearing 11B of hydraulic actuation mechanism.

As shown in Fig. 6 bearing 11B comprises a static ring 112 with spherical face 113. The cover 17 for this embodiment is as shown in Fig. 5 comprises of a spherical face 171. Said cover 17 is preloaded between spring 15 and spherical ring 14. The center points of said spherical faces 171, 113, 116 and 141 are at the same position on point 10. In this embodiment the bearing 11B can tilt about point 10 and compensate inaccuracies of run-out r and misalignment Θ. Hence present invention allows one to convert conventional clutch bearing in present Self- aligning clutch bearing.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

WORKING OF INVENTION:

1. With the starting of automotive vehicle, the output shaft 70 of engine starts to rotate, which further rotates the flywheel 60 as it is rigidly connected with output shaft 70. The clutch 40 also rotates at same speed of flywheel as they are connected rigidly and concentrically by clutch cover 42. The driven shaft 50 is connected with clutch plate 43 by means of spline 51, which implies that driven shaft also rotates. Further the rotating ring 114 of clutch bearing 1 is in contact with the diaphragm spring 41 of clutch 40 with some preload. Here the rotating ring 114 rotates, while static ring 112 remains stationary as there were balls 115 rolling between them. Said static ring 112 makes the sleeve 12 of clutch bearing 1 to remain stationary as sleeve 12 is connected with static ring 112 by means of preloaded spring 15. The fork 30 is placed on sleeve 12 and is connected with slave cylinder (not shown). So, here fork 30, sleeve 12 and static ring 112 are stationary.

2. At the time of starting of vehicle, the gears are in neutral condition so that gears are not connected with output shaft and vehicle speed is zero. To achieve some speed of vehicle it is requires to change the gears condition from neutral. The driven shaft 50 is connected to the gears.

3. Said assembly of friction clutch 100 has inaccuracies of eccentricity, run-out r and misalignment Θ. Because of this inaccuracies said rotating ring 114 of clutch bearing 1 suffers from unbalanced forces from diaphragm spring 41.

4. Applying release force on clutch bearing 1 by fork 30, which is operated by slave cylinder or mechanical linkages (not shown), said diaphragm spring 41 deflects and release clutch plate 43 from flywheel 60.

5. In starting condition of vehicle, clutch 40 and clutch bearing 1 are rotating at speed of engine. So when there is inaccuracy of eccentricity, the clutch 40 applies radial load on rotating ring 114. Through the rotating ring 114, force transmits to the static ring 112 via balls 15. As static ring 112 get the required shifting force, it slides frictionally on sleeve 12 as it is preloaded by spring 115. As the bearing 11 slides on sleeve 12, the rotation axis of bearing and clutch becomes same.

To run the vehicle at some speed, driver applies some effort on clutch pedal which is converted to clutch release force by slave cylinder (not shown). Said slave cylinder actuates fork 30 which applies force on clutch release bearing 1. As amount of force increases on clutch bearing 1, the bearing 11 experiences more unbalanced forces as a result of geometrical inaccuracies of run-out r and misalignment Θ. Said unbalances forces tilt the bearing 11 about center point 10 as contact faces 131, 113 and 141 has spherical faces.

After tilting, the release force equally distributes on bearing ring which reduces noise, vibration, and wear. Further as there were no wear of bearing ring temperature rise is less.

COMPARATIVE TABLE:

Conventional/

Feature Present Invention

Prior Art

Present invention have self- Conventional clutch bearing aligning feature, which do not have self-aligning

Self-aligning equally distributes the feature, because of which

unbalanced forces of bearing suffers from

diaphragm spring. unbalances forces

Because of equal distribution As conventional bearing

of forces present clutch suffers from unbalanced

Life

bearing has 25-30% more forces, its life is short

life than conventional

Because of self-aligning Conventional clutch bearing feature, present clutch do not absorbs vibration

Clutching bearing absorbs the vibration caused by unbalanced

Comfort caused by unbalanced forces forces, which reduces

and increases clutching clutching comfort.

comfort Because of equal distribution As conventional bearing of forces, wearing of bearing suffers from unbalanced

Wear and ring reduces as a result of forces, wearing of bearing

Temperature which rise in temperature is ring is more as result of

less by 10-15%. which rise in temperature is

higher.

Present self-aligning clutch Packaging size d is more in bearing has same packaging case of prior art, as there

Packaging Size

size d as of the conventional. were extra material required

for self-aligning feature.

Very slight and reliable Extra material, extra

modification required to machining or loose parts

convert conventional clutch required to provide self-

Complexity bearing into present aligning feature as described

invention. in prior arts, which

increases complexity of

manufacturing.

From the table and description it is seen that by providing spherical faces to the static ring 121, spherical cup 13 and spherical ring 14, said bearing 11 is allowed to tilt by the center point 10. Said tilting equally distributes unbalanced forces of diaphragm spring 41, which increases life of bearing 11 and reduces wearing of bearing rings. Further, as there were no wear of bearing rings, the rise in temperature is less than conventional bearing 20. Furthermore, because of self-aligning feature present bearing 1 absorbs vibration of diaphragm spring 41, which improves the clutching comfort of driver. Further, comparing with the prior art present invention do not include any extra material or complex machining, instead it require very slight modification in conventional bearing 20. Furthermore, present invention has same packaging size d as of the conventional bearing 20, unlike the prior art having larger packaging size of bearing. So that present invention describes the best way to provide self-aligning and self-centering feature to the clutch bearing, which is very reliable and because of which the life and clutching comfort of driver increases. ADVANTAGES OF THE INVENTION:

The present invention imparts various advantages over the prior art. Said advantages are listed herein below:

Present invention provides self-aligning clutch release bearing; wherein both feature of self-centering and self-aligning feature is provided in single mechanism.

Present invention compensates the inaccuracies of run-out r and misalignment Θ, which implies that bearing do not suffer from unbalanced forces. That is why there is no risk of premature failure.

Present invention reduces the harsh sliding of clutch bearing on driven shaft 50, thereby reduces the pedal effort.

Further, present invention absorbs unbalanced forces from diaphragm spring, which increases the clutching comfort of driver.

Because of self-aligning feature bearing life increases by 25-30% and rise in temperature is reduced by 10-15%. vi. Present invention provides self-aligning clutch release bearing; which does not have any loose parts. vii. It reduces noise and vibration in bearing