Test evaluation system and method for axial bearing capacity of knuckle bearing under gradient load

Abstract

The invention provides a test evaluation system and method for the axial bearing capacity of a knuckle bearing under gradient loads. By combining gradient axial load, abrasion loss or radial clearance with deformation, powerful support is provided for application of the knuckle bearing, the axial bearing capacity test model comprises a loading shaft, a tested bearing, a tool and a test device, and the axial bearing capacity test model is particularly suitable for a self-lubricating knuckle bearing with the inner diameter smaller than phi 15 mm or with the small spherical surface wrapping angle and the large size. According to the invention, organic combination of the abrasion loss or the radial clearance of the self-lubricating material and the gradient axial load can be realized, so that the assessment result has higher engineering practicability.

Description

Technical Field

[0001] The present invention belongs to the field of bearings, and in particular, relates to a system and method for testing and evaluating the axial load-bearing capacity of spherical plain bearings under gradient loads. Background Art

[0002] At present, the assessment method of the axial load-bearing capacity of self-lubricating spherical plain bearings is becoming less and less compatible with the actual production environment, and it is difficult to fully meet various actual production needs.

[0003] For example, the current standards such as GJB10850-2022 "Specifications for Low-speed Swinging Self-lubricating Radial Spherical Plain Bearings" only stipulate the determination method for the axial load-bearing capacity assessment of self-lubricating spherical plain bearings under the factory initial state and axial rated static load.

[0004] For example, patent document CN118780002A discloses a method and system for calculating the axial load-bearing capacity of spherical joint bearings. Based on the characteristics of spherical contact of spherical joint bearings, a plane strain problem solving method is used to solve the spherical load-bearing capacity of the bearings, and the bearing load-bearing capacity is combined with the metal matrix material parameters and the bearing structure size parameters.

[0005] However, during the use of spherical joint bearings, as the bearings wear, their axial load-bearing capacity will change, especially for spherical joint bearings with an inner diameter less than Φ15mm or a small spherical bread angle or large size, this change is more significant.

[0006] Therefore, the axial load capacity assessment carried out according to the existing standard method has limited guiding role in the actual application of spherical plain bearings and cannot effectively reflect the axial load capacity status of the bearings after use. Summary of the Invention

[0007] In view of the defects in the prior art, the purpose of the present invention is to provide a system and method for testing and evaluating the axial load-bearing capacity of spherical plain bearings under gradient loads.

[0008] According to the present invention, a system for testing and evaluating the axial load capacity of a spherical plain bearing under a gradient load is provided, wherein the gradient load comprises: a preload F 预 , axial static load rating F 额定 , the preload F 预 The size of the gradient load value is 5% to 10%, the axial static load rating F 额定 The maximum axial load that the spherical bearing can withstand under static working conditions. The axial load-bearing capacity test evaluation system includes an axial load-bearing capacity test model. The axial load-bearing capacity test model is sequentially installed with a loading shaft, a test bearing, a tooling, and a test device.

[0009] The tooling is the main load-bearing part of the axial load-bearing capacity test model, the loading shaft is located at the upper part of the axial load-bearing capacity test model, the test bearing is located in the middle part of the axial load-bearing capacity test model, and the testing device is located at the lower part of the axial load-bearing capacity test model. The gradient load passes through the loading shaft at the upper part of the axial load-bearing capacity test model and evenly applies the load to the test bearing in the middle part of the axial load-bearing capacity test model in a cycle. At the same time, the testing device at the lower part of the axial load-bearing capacity test model can continuously monitor the applied load.

[0010] The tested bearing includes a spherical joint bearing, which includes a self-lubricating spherical joint bearing. The self-lubricating spherical joint bearing includes: a bearing outer ring, a bearing inner ring, and a self-lubricating material. The bearing outer ring, the self-lubricating material, and the bearing inner ring are arranged in sequence from the outside to the inside.

[0011] The inner surface of the bearing outer ring and the outer surface of the bearing inner ring are both spherical surfaces. The surface treatment of the spherical surface includes: carbide plating, hard chromium plating, diamond-like carbon plating or ceramic plating. The self-lubricating material is bonded to the inner spherical surface of the bearing outer ring. The self-lubricating material includes: polytetrafluoroethylene composite liner, copper mesh liner, carbon fiber composite liner or molded liner; the material of the outer surface of the bearing outer ring 1 and the inner surface of the bearing inner ring 2 includes: stainless steel, alloy steel or titanium alloy.

[0012] The testing device includes a testing instrument, which can continuously monitor the deformation and status of the tested bearing.

[0013] The deformation and state of the tested bearing include: factory state and wear state. The wear state is the wear amount or radial clearance H of the tested bearing. The test instrument records the initial load of the gradient load as F1, the gradient increment of the gradient load as ΔF, and the permanent deformation of the tested bearing under each gradient load as δ 永 .

[0014] According to the present invention, a system for testing and evaluating the axial load capacity of a spherical plain bearing under gradient load is provided, comprising:

[0015] Module M1: Apply a preload F to the axially loaded test bearing for a fixed time. 预 ;

[0016] Module M2: Zero the test instrument in the test device;

[0017] Module M3: at the preload F 预 On the basis of the above, let the loading shaft increase the load to the test bearing by F per unit time. i The load, where F i =n%×F 额, n is a real number. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the size of the tested bearing by F in unit time. i until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永1 ;

[0018] Module M4: Applying load F i Based on the above, the loading shaft is required to increase the gradient load F to the test bearing in unit time. j , where F j =F i +ΔF, ΔF is the gradient increment of the gradient load. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the load to the test bearing by F per unit time. j until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永2 ;

[0019] Module M5: When the permanent deformation of the tested bearing does not exceed the judgment value of deformation δ 判定 Or if the bearing does not axially disengage, readjust the value of ΔF. After the adjustment is completed, apply the adjusted gradient load F to the loading axis. j , and continue to pressurize for a certain period of time, then reduce the load on the loading axis within a unit time until the test instrument detects that the current load size drops to the preload F 预 , the test instrument records the permanent deformation of the current tested bearing;

[0020] Module M6: When the permanent deformation of the tested bearing exceeds the judgment value of deformation δ 判定 Or when the bearing is axially dislocated, the test is terminated and the corresponding visual view and evaluation results are generated according to the permanent deformation data recorded by the test instrument. Otherwise, the module M5 is triggered to continue execution.

[0021] According to the present invention, a method for testing and evaluating the axial load capacity of a spherical plain bearing under a gradient load is provided, comprising:

[0022] Step S1: Apply a preload F to the axially loaded bearing for a fixed time. 预 ;

[0023] Step S2: zeroing the test instrument in the test device;

[0024] Step S3: At the preload F 预 On the basis of the above, let the loading shaft increase the load to the test bearing by F per unit time. iThe load, where F i =n%×F 额 , n is a real number. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the size of the tested bearing by F in unit time. i until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永1 ;

[0025] Step S4: Apply the load F i Based on the above, the loading shaft is required to increase the gradient load F to the test bearing in unit time. j , where F j =F i +ΔF, ΔF is the gradient increment of the gradient load. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the load to the test bearing by F per unit time. j until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永2 ;

[0026] Step S5: When the permanent deformation of the tested bearing does not exceed the judgment value of deformation δ 判定 If the bearing does not axially disengage, the test is terminated. Otherwise, the value of ΔF is readjusted. After the adjustment is completed, the adjusted gradient load F is applied to the loading shaft. j , and continue to pressurize for a certain period of time, then reduce the load on the loading axis within a unit time until the test instrument detects that the current load size drops to the preload F 预 , the test instrument records the permanent deformation of the current tested bearing;

[0027] Step S6: When the permanent deformation of the tested bearing exceeds the judgment value δ of the deformation 判定 Or when the bearing is axially dislocated, the test is terminated, and a corresponding visual view and evaluation results are generated according to the permanent deformation data recorded by the test instrument. Otherwise, step S5 is triggered to continue execution.

[0028] According to the axial load-bearing capacity testing device of a spherical joint bearing provided by the present invention, the axial load-bearing capacity of the spherical joint bearing is assessed by the axial load-bearing capacity testing device of the spherical joint bearing.

[0029] According to the present invention, a spherical plain bearing axial load-bearing capacity testing system is provided to evaluate the axial load-bearing capacity of the spherical plain bearing after use and wear.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention can combine the axial load-bearing capacity of a bearing with the gradient axial load and the bearing wear (or radial clearance), and is a set of evaluation methods and systems with greater engineering practicality.

[0032] 2. The present invention conducts a dynamic cyclic assessment of the axial load-bearing capacity of spherical plain bearing components, and organically combines the wear amount (or radial clearance) of the self-lubricating material and the axial load-bearing capacity of the spherical plain bearing during the assessment process.

[0033] 3. The present invention can assess the bearing load-bearing capacity by applying a gradient axial load and exploring the changing patterns of the gradient axial load, wear or radial clearance, and deformation, thereby providing support for the application of spherical bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0035] Figure 1 It is a structural diagram of a self-lubricating spherical plain bearing;

[0036] Figure 2 This is a schematic diagram of the axial load capacity test model of the spherical plain bearing;

[0037] Figure 3 This is a schematic diagram of the process for evaluating the axial load capacity of bearings under gradient loads;

[0038] Figure 4 Schematic diagram of GE12 bearing structure, dimensions and tolerances;

[0039] Figure 5 This is a schematic diagram of the change of permanent deformation of bearings in factory condition with load;

[0040] Figure 6 Schematic diagram of the change of bearing permanent deformation with load when the wear amount is 0.1mm;

[0041] Figure 7 Schematic diagram of the change of bearing permanent deformation with load when the wear amount is 0.2mm;

[0042] Figure 5 In the figure, 1#, 2#, and 3# represent multiple part numbers of the bearings shipped from the factory.

[0043] Figure 6 In the figure, 4#, 5#, and 6# represent multiple part numbers of bearings with a wear loss of 0.1mm;

[0044] Figure 7 In the figure, 7#, 8#, and 9# represent multiple part numbers of bearings with a wear amount of 0.2mm;

[0045] The figure shows:

[0046] DETAILED DESCRIPTION

[0047] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0048] The present invention provides a system for testing and evaluating the axial load capacity of spherical plain bearings under gradient loads, wherein the gradient loads include: preload F 预 , axial static load rating F 额定 , the size of the preload is 5% to 10% of the gradient load value, the axial static load rating F 额定 The maximum axial load that the spherical bearing can withstand under static working conditions. The axial load-bearing capacity test evaluation system includes an axial load-bearing capacity test model. The axial load-bearing capacity test model is sequentially installed with a loading shaft, a test bearing, a tooling, and a test device.

[0049] The tooling is the main load-bearing part of the axial load-bearing capacity test model, the loading shaft is located at the upper part of the axial load-bearing capacity test model, the test bearing is located in the middle part of the axial load-bearing capacity test model, and the testing device is located at the lower part of the axial load-bearing capacity test model. The gradient load passes through the loading shaft at the upper part of the axial load-bearing capacity test model and evenly applies the load to the test bearing in the middle part of the axial load-bearing capacity test model in a cycle. At the same time, the testing device at the lower part of the axial load-bearing capacity test model can continuously monitor the applied load.

[0050] The tested bearing includes a spherical plain bearing, and the spherical plain bearing includes a self-lubricating spherical plain bearing; the self-lubricating spherical plain bearing includes: a bearing outer ring, a bearing inner ring, and a self-lubricating material;

[0051] The bearing outer ring, self-lubricating material and bearing inner ring are arranged in sequence from outside to inside;

[0052] The inner surface of the bearing outer ring and the outer surface of the bearing inner ring are both spherical surfaces, and the surface treatment of the spherical surfaces includes: hard alloy plating, hard chrome plating, diamond-like carbon plating or ceramic plating;

[0053] The self-lubricating material is bonded to the inner spherical surface of the bearing outer ring; the self-lubricating material includes: a polytetrafluoroethylene composite liner, a copper mesh liner, a carbon fiber composite liner or a molded liner;

[0054] The materials of the outer surface of the bearing outer ring and the inner surface of the bearing inner ring include: stainless steel, alloy steel or titanium alloy.

[0055] The testing device includes a testing instrument, which can continuously monitor the deformation and state of the tested bearing. The deformation and state of the tested bearing include: factory state and wear state. The wear state is the wear amount or radial clearance H of the tested bearing. The testing instrument records the initial load of the gradient load as F1, the gradient increment of the gradient load as ΔF, and the permanent deformation of the tested bearing under each gradient load as δ 永 .

[0056] The present invention provides a system for testing and evaluating the axial load capacity of a spherical plain bearing under gradient load, comprising:

[0057] Module M1: Apply a preload F to the axially loaded test bearing for a fixed time. 预 ;

[0058] Module M2: Zero the test instrument in the test device;

[0059] Module M3: at the preload F 预 On the basis of the above, let the loading shaft increase the load to the test bearing by F per unit time. i The load, where F i =n%×F 额 , n is a real number. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the size of the tested bearing by F in unit time. i until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永1 ;

[0060] Module M4: Applying load F i Based on the above, the loading shaft is required to increase the gradient load F to the test bearing in unit time. j , where F j =F i +ΔF, ΔF is the gradient increment of the gradient load. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the load to the test bearing by F per unit time. j until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永2 ;

[0061] Module M5: When the permanent deformation of the tested bearing does not exceed the judgment value of deformation δ 判定Or if the bearing does not axially disengage, readjust the value of ΔF. After the adjustment is completed, apply the adjusted gradient load F to the loading axis. j , and continue to pressurize for a certain period of time, then reduce the load on the loading axis within a unit time until the test instrument detects that the current load size drops to the preload F 预 , the test instrument records the permanent deformation of the current tested bearing;

[0062] Module M6: When the permanent deformation of the tested bearing exceeds the judgment value δ 判定 Or when the bearing is axially dislocated, the test is terminated and the corresponding visual view and evaluation results are generated according to the permanent deformation data recorded by the test instrument. Otherwise, the module M5 is triggered to continue execution.

[0063] The present invention also provides a method for testing and evaluating the axial load-bearing capacity of a spherical joint bearing under gradient load. The method can be implemented by executing a module of the system for testing and evaluating the axial load-bearing capacity of a spherical joint bearing under gradient load.

[0064] Preferably, according to the test and evaluation method for the axial load capacity of a spherical plain bearing under a gradient load provided by the present invention, the test bearing is a self-lubricating spherical plain bearing GE12, as shown in the attached Figure 4 As shown, the self-lubricating spherical plain bearing GE12 includes: a bearing outer ring, a bearing inner ring, and a self-lubricating material. The bearing outer ring and the bearing inner ring are made of stainless steel, and the self-lubricating material is made of a polytetrafluoroethylene composite liner.

[0065] First, set the axial static load rating F of the self-lubricating spherical plain bearing GE12 额定 The gradient load F is 1kN. j The value is 1kN, and the test is terminated when the permanent deformation is greater than 1.3mm;

[0066] Then, the permanent deformation of the bearing under each gradient load was recorded;

[0067] Finally, based on the self-lubricating spherical plain bearing GE12 in the states of wear of 0.1mm and 0.2mm, the corresponding visualization diagram is generated according to the variation law of its permanent deformation with gradient load, as shown in the attached figure. Figure 5 , Attachment Figure 6 , Attachment Figure 7 shown.

[0068] Based on the above visualization, the following situations can be clearly presented:

[0069] When the wear amount of the self-lubricating spherical plain bearing GE12 is at 0.1 mm, its axial displacement value will experience two rapid growth processes as the load increases. The first stage is the elastic deformation process of the liner extrusion, and the second stage is the liner extrusion deformation and outer ring elastic deformation process.

[0070] When the wear reaches 0.2 mm, the axial displacement only shows a rapid growth stage with the increase of load. This stage is mainly the process of liner extrusion deformation. Under small load conditions, the axial displacement does not show a rapid growth stage. This is mainly because the liner has been worn and the extrusion deformation effect is no longer significant.

[0071] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A system for testing and evaluating the axial load capacity of spherical plain bearings under gradient loads, characterized in that: The gradient load includes: preload F 预 , axial static load rating F 额定 , the size of the preload is 5% to 10% of the gradient load value, the axial static load rating F 额定 The maximum axial load that the spherical bearing can withstand under static working conditions. The axial load-bearing capacity test evaluation system includes an axial load-bearing capacity test model. The axial load-bearing capacity test model is sequentially installed with a loading shaft, a test bearing, a tooling, and a test device.

2. The axial load capacity test and evaluation system for spherical plain bearings under gradient load according to claim 1, characterized in that: The tooling is the main load-bearing part of the axial load-bearing capacity test model, the loading shaft is located at the upper part of the axial load-bearing capacity test model, the test bearing is located in the middle part of the axial load-bearing capacity test model, and the testing device is located at the lower part of the axial load-bearing capacity test model. The gradient load passes through the loading shaft at the upper part of the axial load-bearing capacity test model and evenly applies the load to the test bearing in the middle part of the axial load-bearing capacity test model in a cycle. At the same time, the testing device at the lower part of the axial load-bearing capacity test model can continuously monitor the applied load.

3. The axial load capacity test and evaluation system for spherical plain bearings under gradient load according to claim 1, characterized in that: The tested bearing includes a spherical joint bearing, the spherical joint bearing includes a self-lubricating spherical joint bearing, and the self-lubricating spherical joint bearing includes: a bearing outer ring (1), a bearing inner ring (2), and a self-lubricating material (3), wherein the bearing outer ring (1), the self-lubricating material (3), and the bearing inner ring (2) are arranged in sequence from the outside to the inside.

4. The axial load capacity test and evaluation system for spherical plain bearings under gradient loads according to claim 3, characterized in that: The inner surface of the bearing outer ring (1) and the outer surface of the bearing inner ring (2) are both spherical surfaces, and the surface treatment of the spherical surfaces includes: carbide plating treatment, hard chrome plating treatment, diamond-like plating treatment or ceramic plating treatment. The self-lubricating material (3) is bonded to the inner spherical surface of the bearing outer ring (1), and the self-lubricating material (3) includes: polytetrafluoroethylene composite liner, copper mesh liner, carbon fiber composite liner or molded liner; the material of the outer surface of the bearing outer ring (1) and the inner surface of the bearing inner ring (2) includes: stainless steel, alloy steel or titanium alloy.

5. The axial load capacity test and evaluation system for spherical plain bearings under gradient loads according to claim 1, characterized in that: The testing device includes a testing instrument, which can continuously monitor the deformation and status of the tested bearing.

6. The axial load capacity test and evaluation system for spherical plain bearings under gradient loads according to claim 1, characterized in that: The deformation and state of the tested bearing include: factory state and wear state. The wear state is the wear amount or radial clearance H of the tested bearing. The test instrument records the initial load of the gradient load as F1, the gradient increment of the gradient load as ΔF, and the permanent deformation of the tested bearing under each gradient load as δ 永 .

7. The axial load capacity test and evaluation system for spherical plain bearings under gradient loads according to claim 1, characterized in that: include: Module M1: Apply a preload F to the axially loaded test bearing for a fixed time. 预 ; Module M2: Zero the test instrument in the test device; Module M3: at the preload F 预 On the basis of the above, let the loading shaft increase the load to the test bearing by F per unit time. i The load, where F i =n%×F 额 , n is a real number. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the size of the tested bearing by F in unit time. i until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永1 ; Module M4: Applying load F i Based on the above, the loading shaft is required to increase the gradient load F to the test bearing in unit time. j , where F j =F i +ΔF, ΔF is the gradient increment of the gradient load. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the load to the test bearing by F per unit time. j until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永2 ; Module M5: When the permanent deformation of the tested bearing does not exceed the judgment value of deformation δ 判定 Or if the bearing does not axially disengage, readjust the value of ΔF. After the adjustment is completed, apply the adjusted gradient load F to the loading axis. j , and continue to pressurize for a certain period of time, then reduce the load on the loading axis within a unit time until the test instrument detects that the current load size drops to the preload F 预 , the test instrument records the permanent deformation of the current tested bearing; Module M6: When the permanent deformation of the tested bearing exceeds the judgment value of deformation δ 判定 Or when the bearing is axially dislocated, the test is terminated and the corresponding visual view and evaluation results are generated according to the permanent deformation data recorded by the test instrument. Otherwise, the module M5 is triggered to continue execution.

8. A method for testing and evaluating the axial load capacity of spherical plain bearings under gradient loads, characterized in that: include: Step S1: Apply a preload F to the axially loaded bearing for a fixed time. 预 ; Step S2: zeroing the test instrument in the test device; Step S3: At the preload F 预 On the basis of the above, let the loading shaft increase the load to the test bearing by F per unit time. i The load, where F i =n%×F 额 , n is a real number. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the size of the tested bearing by F in unit time. i until the test instrument detects that the current load size is reduced to the preload F 预 The test instrument records the permanent deformation of the current test bearing as δ 永1 ; Step S4: Apply the load F i Based on the above, the loading shaft is required to increase the gradient load F to the test bearing in unit time. j , where F j =F i +ΔF, ΔF is the gradient increment of the gradient load. When the loading shaft continues to pressurize for a certain period of time, the loading shaft is required to reduce the load to the test bearing by F per unit time. j until the test instrument detects that the current load size is reduced to the preload F 预 The tester records the permanent deformation of the current test bearing as δ 永2 ; Step S5: When the permanent deformation of the tested bearing does not exceed the judgment value of deformation δ 判定 If the bearing does not axially disengage, the test is terminated. Otherwise, the value of ΔF is readjusted. After the adjustment is completed, the adjusted gradient load F is applied to the loading shaft. j , and continue to pressurize for a certain period of time, then reduce the load on the loading axis within a unit time until the test instrument detects that the current load size drops to the preload F 预 , the test instrument records the permanent deformation of the current tested bearing; Step S6: When the permanent deformation of the tested bearing exceeds the judgment value δ of the deformation 判定 Or when the bearing is axially dislocated, the test is terminated, and a corresponding visual view and evaluation results are generated according to the permanent deformation data recorded by the test instrument. Otherwise, step S5 is triggered to continue execution.

9. A spherical plain bearing axial load capacity test device, characterized in that: The axial load-bearing capacity of a spherical plain bearing under gradient load test and evaluation system according to any one of claims 1 to 7 is used to assess the axial load-bearing capacity of the spherical plain bearing.

10. A spherical plain bearing axial load capacity test system, characterized in that: The axial load-bearing capacity test and evaluation system of a spherical plain bearing under gradient load according to any one of claims 1 to 7 is used to evaluate the axial load-bearing capacity of a spherical plain bearing after use and wear.

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