JP4819147B2 - Underwater bearing - Google Patents

Description

  The present invention relates to an underwater bearing for supporting a main shaft of a pump.

  It is known to diagnose wear and breakage of a submerged bearing by supplying compressed air to a gap between the submerged bearing and the main shaft of the pump and letting it flow into the pump casing. For example, Patent Document 1 discloses diagnosing wear of a submerged bearing based on a supplied air flow rate and a differential pressure between an air supply pressure and a pump discharge pressure. Patent Document 2 discloses that air in a pressure tank is supplied to a gap between the underwater bearing and the main shaft, and the wear of the underwater bearing is diagnosed from the time required for pressure drop in the pressure tank. Furthermore, Non-Patent Document 1 discloses that an orifice is provided upstream of the gap between the underwater bearing to which air is supplied and the main shaft, and the wear of the underwater bearing is diagnosed using the principle of an air micrometer. .

  When the underwater bearing is a resin bearing or the like, a plurality of grooves penetrating from one end to the other end in the axial direction are provided at intervals in the circumferential direction on the hole peripheral wall of the bearing hole. The purpose of these grooves is to reduce the friction with the main shaft and to prevent the seizure caused by the bearing temperature rise during the air operation of the pump. However, the diagnostic compressed air supplied to the gap between the resin bearing and the main shaft escapes through the plurality of grooves penetrating in the axial direction, and the portion (land portion) where the groove is not provided in the hole peripheral wall and the main shaft This causes a phenomenon in which the flow rate of compressed air passing between the outer peripheral surface and the outer peripheral surface of the steel sheet is remarkably reduced (blow-through phenomenon). Because of this blow-through phenomenon, in the case of an underwater bearing with a groove in the peripheral wall of the bearing hole, such as a resin bearing, wear and breakage can be diagnosed with high accuracy by airing the gap between the main shaft of the pump. Have difficulty.

Japanese Patent No. 3933586 JP 2009-074530 A

Kanemori, 1 outside, “Development of pump underwater bearing external diagnostic device”, Torishima Review, Takashima Seisakusho Co., Ltd., March 10, 2009, Vol. 22

  The present invention provides an underwater bearing capable of diagnosing wear and breakage with high accuracy by supplying compressed air to a gap between the main shaft of the pump while preventing an increase in bearing temperature during an air operation of the pump. The issue is to provide.

  The present invention is an underwater bearing that is disposed in a casing of a pump and supports a main shaft of the pump, the bearing body including a bearing hole that penetrates the main shaft, the bearing body being held in the casing, and the bearing A holding body having a supply port for supplying diagnostic air to a clearance between the hole peripheral wall of the bearing hole of the body and the main shaft, and the hole peripheral wall of the bearing hole includes the bearing A plurality of first grooves that are partially formed in the axial direction of the main shaft of the hole and that are spaced apart from each other in the circumferential direction of the main shaft, and the first grooves are adjacent to the first grooves. A plurality of second grooves that are partially formed in the axial direction of the main shaft of the bearing hole and are spaced apart from each other in the circumferential direction of the main shaft are formed, and the first groove and the second groove If the rotation angle position of the groove around the axis of the main shaft is different, Are not communicate with each other Te, it provides water bearing.

  Both the first and second grooves are partially formed in the axial direction of the main shaft of the bearing hole. Further, the first and second grooves are not in communication with each other at different rotational angle positions around the axis of the main shaft. Therefore, the compressed air for diagnosis escapes from the supply port formed in the holding body through the first and second grooves, and the portion where the first groove and the second groove of the hole peripheral wall are not provided (the land portion). ) And the outer peripheral surface of the main shaft does not cause a phenomenon that the flow rate of compressed air significantly decreases (blow-through phenomenon). By preventing this blow-through phenomenon, it is possible to diagnose the wear and breakage of the bearing body of the underwater bearing with high accuracy. Further, by providing the first and second grooves in the hole peripheral wall of the bearing body, it is possible to prevent the bearing temperature from increasing during the air operation of the pump and the seizure due to the friction reduction with the main shaft.

  Specifically, the bearing body includes a first member in which the first groove is formed in the peripheral wall of the hole, and a second member in which the second groove is formed in the peripheral wall of the hole.

  In this case, the first member is located on the outer side of the holding body in the axial direction of the main shaft than the second member, and the first member has higher wear resistance than the second member. It is preferable that the second member is made of a material that has better sliding characteristics than the first member.

  With this configuration, good characteristics can be obtained with respect to good wear resistance and sliding characteristics of the bearing body.

  As an alternative, the bearing body comprises a single member in which the first and second grooves are formed.

  You may further provide the cyclic | annular part arrange | positioned at the at least one edge part of the said bearing body.

  With this configuration, the blow-through phenomenon can be prevented more effectively.

  The underwater bearing according to the present invention includes a first and a second part that are partially formed in the axial direction of the main shaft on the hole peripheral wall of the bearing hole of the bearing body, and that are not in communication with each other at different rotational angle positions around the main shaft. Since the second groove is provided, wear or breakage can be diagnosed with high accuracy by supplying compressed air to the gap between the main shaft of the pump while preventing an increase in bearing temperature during the air operation of the pump.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a preceding standby vertical shaft pump provided with an underwater bearing according to an embodiment of the present invention. FIG. 2 is a schematic partial enlarged view of a part II in FIG. 1. Sectional drawing of the underwater bearing of 1st Embodiment of this invention. The figure which looked at the shell and sliding body of the underwater bearing of a 1st embodiment of the present invention from the direction of an axis (above). Sectional drawing in the VV line | wire of FIG. The figure for demonstrating arrangement | positioning of the groove | channel in a bearing body. Sectional drawing of the underwater bearing of 2nd Embodiment of this invention. Sectional drawing of the underwater bearing of 3rd Embodiment of this invention.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 shows a pre-standby vertical pump (hereinafter simply referred to as a vertical pump) 2 that is provided with a non-poured submersible bearing (hereinafter simply referred to as a submersible bearing) according to an embodiment of the present invention.

  The vertical shaft pump 2 is for draining water such as rainwater flowing into the water absorption tank 3 of the drainage pump station from an inflow side pipe (not shown) to the downstream side, and includes a casing 4 extending in the vertical direction. The casing 4 is connected to the straight tubular pumping pipes 4a and 4b, the impeller casings 4c and 4d connected to the lower end of the pumping pipe 4b, the suction bell 4e connected to the lower end of the impeller casing 4d, and the upper end of the pumping pipe 4a. A discharge casing 4f curved from the vertical direction to the horizontal direction is provided. A discharge pipe 6 provided with a gate valve 5 is connected to the discharge casing 4f. An impeller 7 is disposed in the impeller casing 4d.

  The main shaft 8 on which the impeller 7 is fixed to the lower end extends in the vertical direction and protrudes outside the casing 4. 9 is a thrust bearing of the main shaft 8, and 10 is a shaft seal device. The upper end side of the main shaft 8 is connected to a pump drive mechanism (not shown) including a motor, an internal combustion engine, a speed reduction mechanism, or the like.

  In FIG. 1, 13 </ b> A, 13 </ b> B, and 13 </ b> C are submerged bearings that are disposed in the casing 4 of the pump 2 and function as radial bearings for the main shaft 8. One end of each of the air injection pipes 102A, 102B, and 102C of the diagnostic apparatus 101 is connected to each of the underwater bearings 13A to 13C. The diagnostic apparatus 101 is connected to the other end of the air injection pipes 102A, 102B, and 102C from the compressor 103 via an air tank 104, a regulator 105, a pressure gauge 106 that measures the supply pressure of compressed air, an orifice 107, a flow meter 108, and the like. A connected supply pipe 109 is provided. A branch pipe 110 branched from the supply pipe 109 is connected to the discharge casing 4f. The branch line 110 is provided with a differential pressure gauge 111.

  The control device 112 included in the diagnostic device 101 includes submerged bearings 13A to 13C (which will be described later in detail) through compressed air generated by the compressor 103 and stored in the air tank 104 from the supply pipe 109 through the air injection pipes 102A to 102C. 41A, 41B) and the outer peripheral surface of the main shaft 8 are supplied to diagnose the wear and breakage of the underwater bearings 13A to 13C (bearing bodies 41A, 41B). For example, the control device 111 can diagnose wear of the underwater bearings 13A to 13C by the following method. First, as described in Patent Document 1, the flow rate of compressed air (measured by the flow meter 108) supplied to the gap between the underwater bearings 13A to 13C and the main shaft 8, the supply pressure of the compressed air, and the pump 2 The wear of the underwater bearings 13A to 13C can be diagnosed based on the differential pressure (measured by the differential pressure gauge 111) with respect to the discharge pressure. Further, as described in Patent Document 2, the compressed air in the air tank 104 is supplied to the gaps between the underwater bearings 13A to 13C and the main shaft 8, and the time required for the pressure drop in the air tank 104 to reduce the pressure of the underwater bearings 13A to 13C. Diagnose wear and the like. Furthermore, as described in Non-Patent Document 1, by supplying compressed air in the air tank 104 to the gap between the underwater bearings 13A to 13C and the main shaft 8, and measuring the pressure of the compressed air before and after the orifice 107, Wear of the underwater bearings 13A to 13C can be diagnosed using the principle of the air micrometer.

  Since the three underwater bearings 13A to 13C have the same structure, the underwater bearing 13A will be described below. 2 to 5, the bearing 13 </ b> A includes a cylindrical bearing holder 31 that is open at both ends. A flange portion 31 a that protrudes outward is provided at the upper end of the bearing holder 31. The flange portion 31a is fixed by a bolt 33 to a rib 32 protruding from the inner surface of the casing 4 (pump 4b). A holding member 34 having openings at both ends is fixed to the upper end of the bearing holder 31 with bolts 35. A shell 36 having openings at both ends is accommodated in the bearing holder 31. The shell 36 is fixed to the bearing holder 31 by bolts 37. A pair of upper and lower step portions 36 a and 36 b are formed on the outer surface of the shell 36. A cushion ring 38 and a packing 39 disposed on these step portions 36a and 36 are interposed between the shell 36, the bearing holder 31, and the pressing member 34, respectively. The bearing holder 31 and the shell 36 are provided with supply ports 31b and 36c each having a through hole. These supply ports 31b and 36c are provided to face each other and communicate with each other. One end of the air supply pipe 102 </ b> A is connected to the supply port 31 b of the bearing holder 31. The bearing holder 31, the lid member 34, and the shell 36 constitute a holding body in the present invention.

  In the shell 36, two bearing bodies 41A and 41B arranged in the vertical direction are accommodated. In the shell 36, an air supply space 42 is provided between the two bearing bodies 41A and 41B. The air supply space 42 communicates with the supply port 36c.

  Except for the fact that the lower bearing body 41B is upside down. It has the same structure as the upper bearing body 41A. Hereinafter, the upper bearing body 41A will be described in detail. The bearing body 41A includes an inner bearing part (second part) 43A and an outer bearing part (first part) 43B, both of which are integrally structured cylindrical bodies having openings at both ends. The inner bearing part 43A is disposed on the inner side (air supply space 42 side) in the axis L direction of the main shaft 8 in the shell 36, and the outer bearing part 43B is disposed on the outer side (opening of the shell 36) in the axis L direction of the main shaft 8 in the shell 36. Side). The upper end surface of the inner bearing part 43A and the lower end surface of the outer bearing part 43B are in close contact with each other. The through-holes of the inner bearing part 43 </ b> A and the outer bearing part 43 </ b> B are arranged coaxially and constitute a bearing hole 44.

  The material of the inner bearing part 43A and the outer bearing part 43B is preferably a resin such as PBI (polybenzimidazole) or PEEK (polyetheretherketone), but rubber or the like as long as necessary slidability and wear resistance can be secured. Other materials may be used.

  On the inner peripheral wall surface of the inner bearing part 43A (the hole peripheral wall of the bearing hole 44), a plurality of grooves 45 having a constant width that penetrates in the direction of the axis L of the main shaft 8 are formed at regular intervals in the circumferential direction. That is, on the inner peripheral wall surface of the inner bearing part 43A, the grooves 45 and the portions without the grooves 45 (land portions 46) are alternately arranged. In the groove 45 of the inner bearing part 43, the inner end of the main shaft 8 in the axis L direction communicates with the air supply space 42, and the outer end of the main shaft 8 in the axis L direction reaches the lower end surface of the outer bearing part 43. ing. When viewed as a whole of the bearing body 41A, the plurality of grooves 45 are grooves of the same length provided partially from the upper end toward the inside in the axis L direction of the main shaft 8 in the drawing of the hole peripheral wall 44 of the bearing body 41A. is there.

  Similarly, a plurality of grooves 45 ′ penetrating in the direction of the axis L of the main shaft 8 are formed at regular intervals in the circumferential direction on the inner circumferential wall surface of the outer bearing part 43 </ b> B (hole circumferential wall of the bearing hole 44). . That is, portions (land portions 46 ′) without the grooves 45 ′ and the grooves 45 ′ are alternately arranged on the inner peripheral wall surface of the outer bearing part 43 </ b> B. In the groove 45 ′ of the outer bearing part 43 B, the inner end of the main shaft 8 in the axis L direction reaches the upper end surface of the inner bearing part 43 A, and the outer end of the main shaft 8 in the axis L direction opens to the outside of the shell 36. is doing. The width of the groove 45 'of the outer bearing part 43B is substantially constant, but the outermost part of the main shaft 8 in the direction of the axis L is formed in an arc shape. When viewed as a whole of the bearing body 41A, the plurality of grooves 45 ′ are grooves of the same length partially provided from the lower end toward the inside in the axis L direction of the main shaft 8 in the drawing of the hole peripheral wall 44 of the bearing body 41A. is there.

  As described above, the upper end surface of the inner bearing part 43A and the lower end surface of the outer bearing part 43B are in close contact with each other, and the groove 45 of the inner bearing part 43A and the groove 45 ′ of the outer bearing part 43B are in the direction of the axis L of the main shaft 8. Are adjacent to each other. However, as shown most clearly in FIG. 6, the groove 45 of the inner bearing part 43A and the groove 45 ′ of the outer bearing part 43B are arranged in a staggered manner with the rotational angle positions around the axis L of the main shaft 8 being different. Therefore, they are not in communication with each other. Specifically, it is not the groove 45 of the outer bearing part 43B but the land part 45 'that faces one groove 45 of the inner bearing part 43A in the direction of the axis L of the main shaft 8. Further, it is not the groove 45 of the inner bearing part 43A but the land part 46 that is opposed to the single groove 45 'of the outer bearing part 43B in the direction of the axis L of the main shaft 8. In FIG. 6, the grooves 45 and 45 'are hatched for easy understanding.

  As shown in FIG. 2, the main shaft 8 passes through the bearing holes 44 of the bearing bodies 41A and 41B of the shell 36, and the portion where the sleeve 47 of the main shaft 8 is attached is the hole peripheral wall of the bearing holes 44 of the bearing bodies 41A and 41B. With a gap 30 therebetween. Further, a dustproof cover 51 for preventing dust and the like from entering the gap 30 between the main shaft 8 and the peripheral wall of the bearing hole 44 of the bearing bodies 41A and 41B is disposed above the lid member 34. The dust cover 51 is fixed to the main shaft 8 and rotates together with the main shaft 8.

  During normal pumping operation of the pump 2, the inside of the casing 4, the clearance 30 between the bearing hole 44 of the bearing body 41 </ b> A, 41 </ b> B of the underwater bearing 13 </ b> A and the main shaft 8, and the inside of the dust cover 47 are filled with water. ing. During this normal pumping operation, the diagnostic device 101 supplies compressed air from the air supply pipe 102A. The compressed air from the air supply pipe 102A enters the air supply space 42 in the shell 36 via the supply ports 31b and 36c, and from the air supply space 42 the bearing holes 44 of the upper and lower bearing bodies 41A and 41B. It flows out into the casing 4 through the gap 30 between the hole peripheral wall and the main shaft 8 (see the arrow in FIG. 2). At this time, the grooves 45 and 45 ′ of the inner bearing part 43A and the outer bearing part 43B are not in communication with each other with the rotational angle positions around the axis L of the main shaft 8 being different from each other in both the bearing bodies 41A and 41B. Instead of flowing linearly along the direction of the axis L of 8, the flow flows while meandering and branching as indicated by an arrow A in FIG. As a result, the compressed air for diagnosis escapes through the grooves 45 and 45 ′, and the flow rate of the compressed air passing between the land portions 46 and 46 ′ and the outer peripheral surface of the main shaft 8 is remarkably reduced (blow-through phenomenon). ) Does not occur. By preventing this blow-through phenomenon, the wear and breakage of the bearing bodies 41A and 41B of the underwater bearing 13A can be diagnosed with high accuracy.

  Further, in both the bearing bodies 41A and 41B, the grooves 45 and 45 'are provided in the hole peripheral walls of the inner bearing part 43A and the outer bearing part 43B, so that the friction with the main shaft 8 is reduced and the pump 2 is operated in the air. The temperature rise of the underwater bearing 13A can be prevented and seizure can be prevented.

  The materials of the inner bearing part 43A and the outer bearing part 43B of the bearing bodies 41A and 41B need not be the same. Since the outer bearing part 43B has a greater influence on the wearability of the bearing bodies 41A and 41B than the inner bearing part 43A, the outer bearing part 43B is preferably made of a material having higher wear resistance than the inner bearing part 43A. On the contrary, since the inner sliding part 43A has a greater influence on the slidability of the bearing bodies 41A and 41B than the outer bearing part 43B, the inner bearing part 43B is made of a material having better slidability than the outer bearing part 43B. It is preferable to become. When the inner bearing part 43A and the outer bearing part 43B are made of a resin such as PBI or PEEK, the inner bearing part 43A has good slidability by adjusting the amount of additives such as carbon graphite and boron. However, the outer bearing part 43B can be made of a material having high wear resistance but relatively poor sliding properties.

  Referring to FIG. 4, the hole diameters of the supply ports 31b and 36c of the bearing holder 31 and the shell 36 are preferably set so that the peripheral wall of the bearing hole 44 of the inner bearing part 43A can be observed through the endoscope. . The initial depth S of the groove 45 is known as the machining dimension. When the hole peripheral wall of the bearing hole 44 of the inner bearing part 43A is worn by friction with the outer peripheral surface of the main shaft 8, the depth S decreases. Therefore, by measuring the depth S of the groove 45 using an endoscope, the distance C of the gap 30 between the hole peripheral wall of the bearing hole 44 and the outer peripheral surface of the main shaft 8 can be indirectly measured.

(Second Embodiment)
In the second embodiment of the present invention shown in FIG. 7, each of the bearing bodies 41A and 41B is a single-piece cylindrical body having a single opening at both ends. A plurality of grooves 45 are formed in the circumferential wall of the bearing hole 44 of the bearing bodies 41 </ b> A and 41 </ b> B at intervals in the circumferential direction at positions inside the shell 36 in the axis L direction of the main shaft 8. A land portion 46 exists between the adjacent grooves 45. In addition, a plurality of grooves 45 ′ are formed at intervals in the circumferential direction adjacent to the positions outside the shell 36 in the direction of the axis L of the grooves 45 and the main shaft 8. There is a land portion 46 'between adjacent grooves 45'. The inner groove 45 and the outer groove 45 ′ are arranged in a staggered manner with different rotational angle positions around the axis L of the main shaft 8, so that they are not in communication with each other.

  During the normal pumping operation of the pump 2, the compressed air supplied by the diagnostic device 101 and entering the air supply space 42 from the supply port 36 c is formed between the peripheral walls of the bearing holes 44 of the upper and lower bearing bodies 41 A and 41 B and the main shaft 8. It flows out into the casing 4 through the gap 30. At this time, since the grooves 45 and 45 ′ of the bearing bodies 41A and 41B are not in communication with each other with the rotational angle positions around the axis L of the main shaft 8 being different from each other, the diagnostic compressed air is not communicated with the grooves 45 and 45 ′. There is no blowout phenomenon in which the flow rate of the compressed air passing through between the land portions 46, 46 ′ and the outer peripheral surface of the main shaft 8 is remarkably reduced. By preventing the blow-through phenomenon, the wear and breakage of the bearing bodies 41A and 41B can be diagnosed with high accuracy. Further, by providing the grooves 45 and 45 ′ on the peripheral walls of the bearing bodies 41A and 41B, the temperature of the underwater bearing 13A during the air operation of the pump 2 and the seizure prevention caused by the friction with the main shaft 8 are reduced. it can.

  Since other configurations and operations of the second embodiment are the same as those of the first embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

(Third embodiment)
In the third embodiment of the present invention shown in FIG. 8, the annular plates 48A and 48B are arranged on the outer side of the outer bearing part 43B (both ends of the shell 36) in both of the bearing bodies 41A and 41B. The annular plates 48A and 48B are fixed to the shell 36 with bolts 49. The inner diameter D1 of the annular plates 48A, 48B is set to be the same as the hole diameter D2 of the bearing hole 44 of the outer bearing part 43B at the land portion 46 '(the portion without the groove 45'). These annular portions 48A and 48B provide fluid resistance when compressed air flows out of the bearing bodies 41A and 41B from the outer grooves 45 ′. That is, the annular portions 48 </ b> A and 48 </ b> B have a function of extending the residence time of the compressed air in the gap 30 between the hole peripheral wall of the bearing hole 44 of the bearing bodies 41 </ b> A and 41 </ b> B and the main shaft 8. Therefore, by providing the annular portions 48A and 48B, the blow-through phenomenon can be prevented more reliably. Even if only one of the annular plates 48A and 48B is provided, the effect of extending the stay time of the compressed air can be obtained to some extent. Even when the inner and outer grooves 45, 45 ′ are communicated with each other without being arranged in a staggered manner, the effect of preventing the blow-through phenomenon can be obtained to some extent by providing the annular portions 48A, 48B.

  Since other configurations and operations of the third embodiment are the same as those of the first embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

  Although the present invention has been described by taking the submersible bearing of the stand-by type vertical shaft pump as an example, the present invention can also be applied to submersible bearings of other types of pumps including a horizontal shaft pump.

DESCRIPTION OF SYMBOLS 2 Prior standby type vertical shaft pump 3 Water absorption tank 4 Casing 4a, 4b Pumping pipe 4c, 4d Impeller casing 4e Suction bell 4f Discharge casing 5 Gate valve 6 Discharge pipe 7 Impeller 8 Main shaft 9 Thrust bearing 10 Shaft seal device 13A, 13B, 13C Bearing 30 Clearance 31 Bearing holder 31a Flange part 31b Supply port 32 Rib 33 Bolt 34 Holding member 35 Bolt 36 Shell 36a, 36b Step part 36c Supply port 37 Bolt 38 Cushion ring 39 Packing 41A, 41B Bearing body 42 Air supply space 43A Inner bearing Parts 43B Outer bearing parts 44 Bearing holes 45, 45 'Groove 46, 46' Land part 47 Sleeve 48A, 48B Annular plate 101 Diagnostic device 102A, 102B, 102C Air supply pipe 103 Compressor 104 Atanku 105 regulator 106 pressure gauge 107 orifice 108 flow meter 109 supply pipe 110 branched passage 111 differential pressure gauge 112 controller

Claims (5)

A submerged bearing disposed in the casing of the pump and supporting the main shaft of the pump,
A bearing body including a bearing hole penetrating the main shaft;
And holding the bearing body in the casing, and a holding body formed with a supply port for supplying diagnostic air to a gap between a peripheral wall of the bearing hole of the bearing body and the main shaft. ,
In the hole peripheral wall of the bearing hole,
A plurality of first grooves that are partially formed in the axial direction of the main shaft of the bearing hole and that are spaced apart from each other in the circumferential direction of the main shaft;
A plurality of second grooves that are partially formed in the axial direction of the main shaft of the bearing hole so as to be adjacent to the plurality of first grooves, and are spaced apart from each other in the circumferential direction of the main shaft; Formed,
The underwater bearing in which the first groove and the second groove are not in communication with each other at different rotational angle positions around the axis of the main shaft.   The said bearing body is provided with the 1st member by which the said 1st groove | channel was formed in the said hole surrounding wall, and the 2nd member by which the said 2nd groove | channel was formed by the said hole surrounding wall. Underwater bearing. The first member is located on the outer side of the holding body in the axial direction of the main shaft than the second member,
The first member is made of a material having higher wear resistance than the second member, and the second member is made of a material having a sliding property better than that of the first member. Underwater bearing.   The underwater bearing according to claim 1, wherein the bearing body is made of a single member in which the first and second grooves are formed.   The underwater bearing according to claim 1, further comprising an annular portion disposed at at least one end portion of the bearing body.

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