Preliminary Requirements

Procedure

1. SUBTASK 70-29-01-290-010 Equipment and Material

   1. Consumable materials.

      CoMat 01-224 FLEXIBLE GREASE PROOFPAPER	Flexible greaseproof paper
      CoMat 01-233 BARRIER MATERIAL	Barrier material
      CoMat 02-069 DISPOSABLE CLEANING TISSUES	Disposable cleaning tissues
      CoMat 02-093 BARRIER MATERIAL	Barrier material
      CoMat 02-095 POLYETHYLENE PREFORMEDBAGS	Polyethylene bag
      CoMat 02-099 LINT-FREE CLOTH	Lint free cloth
      CoMat 06-085 CORD, Nonwicking	Cord
      CoMat 06-086 TIES	Ties
      CoMat 10-039 ENGINE OIL	Lubricant (engine oil)
      CoMat 10-040 LUBRICANT (ENGINE OIL)	Lubricant (engine oil)
      CoMat 10-061 STODDARD SOLVENT	Stoddard solvent
      CoMat 10-125 LUBRICATING AND PRESERVATION OIL	Lubricating and preservation oil
      CoMat 12-027C CORROSION PREVENTIVE COMPOUND	Corrosion preventive compound
      NOTE To identify the consumable materials refer to the PCI.

   2. Special tools.

      IAE 2J12621 Plug gage	Inspection plug gage	1 off
      NOTE Special tools are identified in the procedure by the tool primary number.

2. SUBTASK 70-29-01-290-011 General

   1. The data in this General is applicable to most bearings. If there is a difference in the data for a specified bearing type, the applicable data must be used.

   2. Bearing components.

      The names given to the bearing components, shown in Figure have been agreed with the Anti-friction Bearing Manufacturers Association (AFBMA). Always use these names in all inspection reports.

   3. Inspection reports.

      1. Inspection reports must be started at disassembly so that conditions of operation of the bearings and related parts can be monitored. Entries of unsatisfactory conditions and bearing failure must be included in the report.

      2. The total time must be marked on the bearing, with an approved procedure, on the face that shows the part number and the serial number. Put a line through any time that was marked before and remove any high metal with a stone.

   4. Handling precautions.

      1. Obey all the precautions that follow:

         1. 

            CAUTION

            DO NOT MIX THE PARTS OF DIFFERENT BEARINGS.

            Each bearing must be put in a different container on removal from the engine.

         2. Always wear synthetic rubber gloves or nylon mesh gloves with polyethylene palms and fingers. If these are not available wear clean cotton gloves and change them regularly so they do not become soaked with sweat.

         3. Do not spin dirty bearings. Turn them slowly while you clean the surfaces.

         4. Do not spin bearings with pressurized air.

         5. Clean the bearings before inspection to prevent damage during inspection.

         6. Be very careful when handling bearings. If you hear metallic clicks it is possible that not sufficient care is being taken.

         7. Do not work on the internal load carrying surfaces.

         8. The polishing of mating surfaces as a Rework procedure must be kept to a minimum. No change in dimension is permitted, unless specified. Refer to the Table of Limits in the Engine Manual.

         9. Do not move bearings on electrically propelled trucks.

         10. Only use CoMat 02-099 LINT-FREE CLOTH or CoMat 02-069 DISPOSABLE CLEANING TISSUES to remove unwanted oil from bearings. Do not vapor degrease.

   5. Unpacking new bearings.

      NOTE

      Do not remove the bands that hold the bearing together.

      New bearings need not be fully depreserved for an initial inspection of the ID and OD fits only. Preservative can be wiped from the ID and OD and applied again after inspection.

      1. Unpack new bearings from the shipping container and remove the preservative as follows:

         1. Ball bearings must not be disassembled.

         2. The removable ring must be carefully disassembled from the roller bearings, which are received assembled.

         3. 

            CAUTION

            YOU MUST WEAR CLEAN COTTON GLOVES WHEN YOU TOUCH BEARINGS.

            If the bearing has preservative grease on it, pressure flush the bearings with CoMat 10-125 LUBRICATING AND PRESERVATION OIL. The oil temperature must be 150 to 170 deg F (66 to 77 deg C) at a pressure of 15 to 25 psi (104 to 173 kPa). Continue to flush until all the preservative is removed. Replace the mineral oil when it is contaminated.

         4. 

            CAUTION

            DO NOT USE PETROLEUM BASED OIL ON A BEARING WHICH WILL BE USED IN AN ENGINE THAT USES SYNTHETIC OIL IN THE LUBRICATING SYSTEM. THIS WILL PREVENT SLUDGE AND CONTAMINATION OF THE ENGINE OIL.

            Remove the lubricating and preservation oil with CoMat 10-061 STODDARD SOLVENT. If pressure flush is available, use 25 to 35 psi (173 to 242 kPa) for a minimum of one minute, then, immediately preserve the bearing. Refer to Step.

   6. Inspection area.

      1. A visual inspection must be made in diffused light and inspectors must have good or corrected close range vision.

      2. Dirt and dust are abrasive so keep tools clean and the work area clean. If possible examine bearings in an air conditioned room. If this is not possible a specified area must be kept clean and dust free all the time.

   7. Examine the bearings at a magnification of 2X to 4X. Make sure all inspection departments use the same magnification.

   8. When the use of a ball-end or radius-tip scriber is necessary lightly hold the scriber perpendicular to the base of the area. Only the weight of the scriber must be used on the surface.

      Standard scribers can be made with AISI-01 or AISI-W1 (Grade 4) steel. The tolerance on the highly polished nose radii must be plus or minus 0.001in. (0.025 mm). The hardness must be Rockwell C55 to 60. Scriber kits can be purchased from some bearing suppliers.

   9. Functional and non-functional surfaces.

      1. Functional surfaces - Balls, rollers and raceways. Roller corners are functional if eccentricity or run-out is specified, otherwise they are non-functional.

      2. NOTE

         Radii or chamfers that connect functional and non-functional surfaces are non-functional.

         Non-functional - All surfaces not defined as functional.

3. SUBTASK 70-29-01-290-001 Properties and Causes of Defects

   1. There are differences between the damage caused by material fatigue, wear, corrosion, plastic deformation, service conditions, incorrect installation or bad maintenance. Damage can be caused when anti-friction bearings do not turn freely. Damage can also be caused by unwanted materials, material defects and manufacturing defects. But these differences are not always clear.

   2. A bearing with the correct load applied and correctly lubricated can become defective after a given time, because of material fatigue. A bearing with too much load applied will also become defective, but in a lesser time. The same theory also applies to wear. Some wear is usual and can be accepted for most bearings. Too much wear, which frequently occurs as a result of unwanted material in the bearing area, must be carefully monitored to prevent more damage.

   3. Damage can be caused by incorrectly installed bearings. Corrosion caused by body sweat when bearings are touched by bare hands, can also cause damage. These causes of damage can be prevented.

4. SUBTASK 70-29-01-290-002 Material Fatigue

   1. Material fatigue is not unusual and can occur in all anti-friction bearings. All bearings that turn, with a load applied, have a specified life. This life is related to the number of turns and the load applied. A bearing becomes unserviceable when its raceways and/or parts that turn become damaged, because of material fatigue. Fatigue damage usually starts as small cracks below the surface. As the load increases the cracks become larger until they get to the surface where the material becomes peeled.

   2. Damage to the material continues as the peeled particles get into the bearing raceways which then becomes very hot. The condition of the bearing then becomes worse, it runs rough and makes a noise. If the bearing continues to run, all the components will become badly damaged. Raceways can then become ruptured because there is no internal radial clearance.

5. SUBTASK 70-29-01-290-003 Wear

   1. Wear usually occurs when particles of unwanted material get into the bearing. Abrasive particles such as dust, sand or broken pieces of a seal can make the roller surfaces rough and give them a matt silver effect. When there is too much wear, the clearances become larger and the shape of the raceways change.

6. SUBTASK 70-29-01-290-004 Corrosion Damage

   1. When roller surfaces have corrosion damage, the bearing runs rough and makes a noise. The corrosion that comes off the roller parts is abrasive and causes wear. Corrosion not only starts when water, acid or alkaline solution gets in to the bearing, but also when acid lubricants are used. Condensation because of high humidity can also cause corrosion.

   2. Condensation can also cause damage to bearings before they are installed. Because of this, bearings with no preservation must be stored in an area where the humidity must not be more than 55 percent, with a temperature of 64 to 68 deg F (18 to 20 deg C).

7. SUBTASK 70-29-01-290-005 Plastic Deformation

   1. The raceways of anti-friction bearings can be found to have small irregular contours which usually look almost the same as the adjacent area. Usually they are only seen because of the light reflections caused by changes to the surface. Bearings with such damage usually run rough and make a noise. In general, there are two possible causes for such damage.

      1. Deformation can be caused by high static loads or impact loads because of bad handling (This is true brinelling).

      2. Almost the same damage can be caused when static bearings get exposed to vibration (This is false brinelling).

8. SUBTASK 70-29-01-290-006 Visual Inspection and Identification of Defects to Anti-Friction Bearings

   1. 
      CAUTION
      ALWAYS MAKE SURE THAT THE SYMPTOMS ARE CORRECT BECAUSE FATIGUE AND PITTED SYMPTOMS ARE ALMOST THE SAME. INITIAL FATIGUE SYMPTOMS HAVE AN IRREGULAR SHAPE, WHILE PITTED SYMPTOMS USUALLY HAVE A CIRCULAR SHAPE.

      Fatigue break-up (or spalling), refer to Figure.

      1. Definition and description - Failure of the rolling surfaces that touch. Usually irregular, sharp edged, deep holes with edge conditions that show the hole will get larger.

      2. Cause - Fatigue of the rolling surfaces that touch. This condition can also be caused by inclusions (not metal) below the surface.

      3. Overhaul limits - Reject.

   2. Skidding, refer to Figure.

      1. Definition and description - Too much slipping between balls or rollers and raceways. Skidding is seen on rollers as a burnished or frosted ring around the rollers and/or raceways. On ball bearings it is seen as a speckled pattern or a burnished or frosted ring on the balls and as burnished, irregular frosted or smeared areas on the inner race. Heavy cage pocket wear is frequently a symptom of skidding.

      2. Cause - Incorrect lubrication and/or light or no load between the balls or rollers and the raceway.

      3. Overhaul limits - Reject.

   3. True Brinelling, refer to Figure.

      1. Definition and description - Smooth shallow dents on balls, rollers or raceways that usually look shiny at the bottom of the dent. The contour of the dent in the raceway is the same as the ball or roller radius.

      2. Cause - Heavy shock load or too much static loads which makes impressions of the balls or rollers in the bearing race. True brinelling occurs when there is no movement of the bearing.

      3. Overhaul limits - True brinelling is acceptable if it can not be felt with the specified scriber for the applicable diameter bearing. If it can be felt it must not be more than the limits given in Figure.

   4. False Brinelling, refer to Figure.

      1. Definition and description - Surface marks on balls, rollers or raceways that usually look polished or have a satin finish. These marks will be seen as lines on the raceway at each roller position or as dots at each ball position. Because false brinelling is a type of fretting corrosion, red iron oxide can be found where false brinelling has occurred.

      2. Cause - Continuous vibrations when the bearing is topped which make ball or roller marks on the raceway surfaces. False brinelling only occurs when the engine is stopped and frequently results from vibration when the engine is being moved.

      3. Overhaul limits - False brinelling is acceptable on functional and non-functional surfaces.

   5. Cracked, refer to Figure.

      1. Definition and description - A linear opening which can cause the material to break.

      2. Cause - Too much stress because of sudden loads that are too large, extension of a nick or scratch or from too much heat.

      3. Overhaul limits - Reject.

   6. Scuffing, refer to Figure.

      1. Definition and description - A sequence of small light scratches usually found on the ball, roller or raceway surfaces.

      2. Cause - The surfaces that touch, slide with unwanted material between them or a local failure of the lubricant film.

      3. Overhaul limits - Scuffing on balls, rollers and raceway surfaces is acceptable if it can not be felt with the specified scriber for the applicable diameter bearing, refer to Step Table 1.

   7. Heavy electrical discharge, refer to Figure.

      1. Definition and description - Roller bearings: A line of dots on rollers and raceway with signs of material transfer and local heat discoloration. Ball bearings: A dot on the ball and the raceway where they touch with signs of material transfer and local heat discoloration.

      2. Cause - Heavy electrical discharge through the parts of a bearing.

      3. Overahul limits - Reject.

   8. High temperature color change, Refer to Figure.

      1. Definition and description - Color change of bearing surfaces that range from light straw (low temperature) to purple (high temperature). Bearings from the hot section of the engine will usually show some color change.

      2. Cause - Bearing surfaces that are in a hot air environment, that do not have sufficient lubrication, are a tight fit or have heat transferred from other components.

      3. Overhaul limits - Heat color change is acceptable unless the surfaces show unsatisfactory colors (dark blue to purple). If it is possible that the bearing hardness is not correct a hardness check must be done on non-functional surfaces. Use a Rockwell A tester so you do not go into the hardened surface.

   9. Worn roller ends and guide faces, refer to Figure.

      1. Definition and description - Wear on the roller ends and guide faces that range from circles of light scratches to very bad scoring and galling.

      2. Cause - The inner or outer raceway is not square or not correctly aligned, rollers not balanced or cage pockets too large. It can also be caused by axial loads on the bearing.

      3. Overhaul limits - Wear is acceptable unless there is a step of 0.0005in. (0.0127 mm) or more, rough sharp edges or eccentric burnishing of the roller end faces.

   10. Pitted, refer to Figure.

       1. Definition and description - Small holes, of irregular shape, in a surface from which material has been removed.

       2. Cause - Corrosion, chemical or electrolytic damage, oxidation and/or mechanical damage such as chipping or grain breakout or removal of imbedded particles.

       3. Overhaul limits.

       4. Functional surfaces - Pits are acceptable if they can not be felt with the specified scriber for the applicable diameter bearing or are not more than the maximum dimension given in Figure. Groups of pits are acceptable if three or more pits in a given circular area can not be felt with the specified scriber for the applicable diameter bearing. If it can be felt it must not be more than the maximum dimension given in Figure.

       5. Non-functional surfaces (not corner radii or chamfers that connect two non-functional surfaces) -.

          1. Bearings with bores of 5.9055in. (150 mm) or smaller:

             1. Pits are acceptable if they do not extend on to a functional surface and are not larger than 0.062in. (1.588 mm) across the largest dimension.

             2. Groups of pits are acceptable if three or more pits are in a 0.250in. (6.35 mm) diameter circle and each is no larger than 0.031in. (0.794 mm) across the largest dimension.

          2. Bearings with bores of more than 5.9055in. (150 mm):

             1. Pits are acceptable if they do not extend on to a functional surface and are not larger than 0.125in. (3.175 mm) across the largest dimension.

             2. Groups of pits are acceptable if three or more pits are in a 0.50 in. (1.27 mm) diameter circle and each is no larger than 0.062 in. (1.588 mm) across the largest dimension.

       6. Corner radii and chamfers that connect non-functional surfaces -.

          1. Bearings with bores of 5.9055in. (150 mm) or smaller:

             1. Pits are acceptable if they do not extend onto a functional surface and are no larger than 0.062 in. (1.588 mm) across the largest dimension or if there are no more than seven which are from 0.062 in. (1.588 mm) to 0.125 in. (3.175 mm) across the largest dimension.

             2. Groups of pits are acceptable if three or more pits are in a 0.250 in. (6.35 mm) diameter circle and each is no larger than 0.031 in. (0.794 mm) across the largest dimension.

          2. Bearings with bores of more than 5.9055 in. (150 mm):

             1. Pits are acceptable if they do not extend onto a functional surface and are no larger than 0.125 in. (3.175 mm) across the largest dimension or if there are no more than seven which are from 0.125 in. (3.175 mm) to 0.187 in. (4.763 mm) across the largest dimension.

             2. Groups of pits are acceptable if three or more pits are in a 0.50 in. (12.7 mm) diameter circle and each is no larger than 0.062 in. (1.588 mm) across the largest dimension.

   11. Marks caused by unwanted materials, refer to Figure.

       1. Definition and description - Small irregular dents in the raceways, balls or rollers that can possibly be seen as a pattern.

       2. Cause - Unwanted material such as sand, metal chips or abrasive media in the bearing. The unwanted material can be the result of bad maintenance or a problem in the engine which causes loose material to get in to the bearing.

       3. Overhaul limits - The damage caused by unwanted material is acceptable if the marks can not be felt by the specified scriber for the applicable diameter bearing. If it can be felt it must not be more than the maximum dimension given in Figure.

   12. Scratches, refer to Figure.

       1. Definition and description - Narrow, shallow abrasions in the surface of bearing components.

       2. Cause - Movement of a sharp object or particle across a surface.

       3. Overhaul limits.

       4. Functional surfaces.

          1. Scratches on balls are acceptable if they cannot be felt with the specified scriber for the applicable diameter bearing or, if felt, single scratches do not extend more than halfway around the surface, or if multiple scratches do not cross or extend more than one quarter way around the surface or the maximum scratch width is not more than 0.010in. (0.254 mm).

          2. Scratches on rollers are acceptable if they cannot be felt with the specified scriber for the applicable diameter bearing or, if felt, single scratches do not extend more than halfway around the circumference, or if multiple scratches do not cross or extend more than one quarter way around the circumference or the maximum scratch width is not more than 0.010in. (0.254 mm).

          3. Scratches on ball or roller raceways are acceptable if they can not be felt with the specified scriber for the applicable diameter bearing or, if felt, the maximum length of each circumferential scratch is less than 0.50in. (12.7 mm) and each transverse scratch is less than one half the width of the raceway, the maximum scratch width is 0.010in. (0.254 mm) or the scratches do not cross.

       5. Scratches on non-functional surfaces are acceptable if not more than 2.00in. (50.8 mm) in length and/or 0.016in. (0.406 mm) in width.

   13. Scored, refer to Figure.

       1. Definition and description - Deep scratches found on the ball, roller and raceway surfaces. Scores can also occur on bearing ID and OD surfaces. It will frequently be seen as parallel or concentric scratches on these surfaces.

       2. Cause - Unwanted material between the surfaces that touch, continued movement of balls or rollers on a surface with sharp edges or incorrect installation.

       3. Overhaul limits.

       4. Functional surfaces: Scores are acceptable if they can not be felt with the specified scriber for the applicable diameter bearing, refer to Step Table 1.

       5. Non-functional surfaces: Scores are acceptable unless a dimensional change has occurred.

   14. Nicks and dents, refer to Figure and Figure.

       1. Definition and description - Dents: shallow smooth indentations. Nicks: sharp, clearly defined cuts. On functional surfaces there will frequently be a shiny area around the indentation. On non-functional surfaces there will be an edge of lifted material.

       2. Cause - Unwanted material has got between the balls or rollers. Or they have been hit by a hard, sharp object.

       3. Overhaul limits.

       4. Functional surfaces: Nicks and dents are acceptable if they can not be felt with the specified scriber for the applicable bearing diameter. If they can be felt they must not be more than the dimension given in Figure.

       5. Non-functional surfaces: Nicks and dents are acceptable if they do not extend on to a functional surface or are not more than the maximums given in Figure. The high material around nicks or dents can be stoned level with the surface.

   15. Corrosion, refer to Figure.

       1. Definition and description - The surface area is broken, pitted or discolored with groups of shallow small pits. The surface will usually show an orange peel effect.

       2. Cause - Bad bearing protection during handling or storage or failure of lubrication which causes chemical action or, in humid conditions, condensation.

       3. Overhaul limits.

       4. Corrosion on functional surfaces is acceptable if it can not be felt with the specified scriber for the applicable bearing diameter, refer to Step Table 1.

       5. Corrosion on non-functional surfaces is acceptable.

   16. Fretting, refer to Figure.

       1. Definition and description - Surface oxidation between parts that are a close fit, more frequently on bearing raceways and mounting surfaces. It can range from black to a shiny effect.

       2. Cause - Small related movement between surfaces.

       3. Overhaul limits - Fretting of non-functional surfaces is acceptable. Fretting can be removed by light polishing.

   17. Galling, refer to Figure.

       1. Definition and description - A more severe type of fretting where material moves between surfaces.

       2. Cause - Relative movement between two surfaces that are not lubricated and have a load on them.

       3. Overhaul limits.

       4. Galling of functional surfaces is cause for rejection.

       5. Galling of non-functional surfaces is acceptable unless a dimensional change has occurred.

   18. Stains, varnishing and carbon particles, refer to Figure and Figure.

       1. Definition and description - A surface discoloration, that is not dangerous, that ranges from light brown to black which can occur as stripes or patches. The surface will be smooth and not broken.

       2. Cause - Corrosive attack or failure of the lubricant because of high temperature.

       3. Overhaul limits - Staining or varnishing is acceptable on all surfaces.

   19. Peeling, refer to Figure.

       1. Definition and description - Peeled particles of the surface layer in thin irregular pieces.

       2. Cause - Very high temperatures or loads, lubrication is not sufficient or defects below the surface of the material.

       3. Overhaul limits - Peeling on functional surfaces is cause for rejection.

   20. Load path indications.

       1. Definition and description.

       2. Ball bearings.

          1. The load path witness mark for the inner race will usually be on one side and not near the shoulder. There will usually be no well defined load path on the half of the inner race that has no load. The load path witness mark for the outer race will be near the center in the direction of the applied load. Inner and outer paths must be a constant distance from the shoulder through 360 degrees.

       3. Non or Lightly Loaded Roller bearings.

          1. NOTE

             The center of the bedding band must not wander from side to side (i.e. axially) around the track.

             On the outer race the bedding band (load path) witness mark will usually be a constant circumferential path and not on either edge. The path must be a constant distance from the shoulder through 360 degrees. The inner race will show a light bedding band (load path) which may be indistinct.

       4. Loaded roller bearings.

          1. The bedding band (load path) on the outer race will not necessarily be constant, but may vary in width and intensity around the track. But, intensity of the bedding band (load path) must be constant across its width.

          2. The inner race bedding band (load path) will be the same as for a non or lightly loaded roller bearing but more distinct.

          3. Cause - The continuous movement of the balls or rollers, that have a load on them, on the raceway surface.

       5. Overhaul limits - The load path indications that follow are cause for rejection:

          1. Ball bearings that show a well defined wear path on the split, on the edge of the shoulder or which extends into the inner race oil holes.

          2. Roller bearings where the axial position of the bedding band (load path) wanders from side to side around the track. Axial changes in the bedding band (load path) can be a result of the shaft and housing not being aligned.

          3. Roller bearings where the bedding band (load path) is distinctly one sided (i.e. significantly more intense to one side of the roller path (bedding band)).

   21. Cage defects - flaking, peeling and blistering.

       1. Definition and description - The separation of plate, seen as pieces (flaking), strips (peeling) or lifted areas (blistering) from a plated surface.

       2. Cause - Unsatisfactory bond or no bond between the plate material and the base material.

       3. Overhaul limits.

       4. Flaking, peeling or blistering of lead plate is acceptable.

       5. Flaking, peeling or blistering of silver plate is cause for rejection.

   22. Cage defects - Rubbing and local wear.

       1. Definition and description - Seen as different wear patterns, refer to paragraph W.

       2. Cause - Movement of the cages on the land-riding area.

       3. Overhaul limits - Any rub pattern which extends across an arc of more than 30 degrees is acceptable, if the edge cannot be felt with a 0.030 in. (0.762 mm) radius scriber.

   23. Cage defects - Damage and wear.

       1. Definitions and description - Cage defects , see (1) thru (7).

       2. Cause - The bearing is not aligned, the cage is not correctly balanced or there is not sufficient lubrication. Nicks and dents can occur from bad handling.

       3. Overhaul limits - Damage or wear as given is cause for rejection.

       4. Wear through the lead and silver plate in to the base metal in the cage pockets in a line more than 0.125 in. (3.175 mm) wide.

       5. Wear on the land-riding surface through the lead and silver plate in to the base metal.

       6. Cage pocket wear which permits balls or rollers to drop free of a cage which does not come apart.

       7. The cage becomes too hot, seen as local melting of the lead plate.

       8. Broken or cracked cages.

       9. Out-of-round or bent cages.

       10. Nicks or dents more than 0.125 in. (3.175 mm) long, in to the base material in pockets or riding surfaces.

       11. Nicks or dents in other areas more than 0.250 in. (6.35 mm) long, in to the base material.

9. SUBTASK 70-29-01-290-007 Feel Test

   1. The feel test is a supplement to other inspections, specially for bearings that do not come apart.

      1. This test must only be done by approved persons.

   2. Clean the bearing before inspection, refer to the SPM TASK 70-11-22-300-503 or TASK 70-11-17-300-503.

   3. Always demagnetize the bearing before the feel test.

   4. As an aid, use a new bearing and examine the bearing for end play, radial play and rock.

   5. 

      CAUTION

      DO NOT SPIN THE BEARING WITHOUT A LOAD APPLIED. THIS CAN CAUSE THE BALLS OR ROLLERS TO GROUP TOGETHER AND NOT MOVE FREELY IN THE CAGE. THIS WILL GIVE AN INCORRECT INDICATION OF ROUGH RUNNING.

      Make sure the bearing is clean and lubricated. Apply a light axial force to the outer race and turn it slowly by hand, while you hold the inner race to make sure the raceway and the balls or rollers touch. Turn the bearing the opposite way up and do the inspection again. Any rough bearings must be cleaned and examined again. Reject the bearing if it still feels rough after inspection.

10. SUBTASK 70-29-01-290-008 Dimensional Checks

    1. All bearing components must be at the same temperature during dimensional inspection. Do not warm bearings by too much handling.

    2. Measure the radial clearance, refer to Figure.

       1. The internal radial clearance is the movement of one race in relation to the other.

       2. NOTE

          This check is also applicable to both details of a duplex bearing.

          Measure the radial clearance as follows:

          1. Attach the inner ring of the assembled bearing to a horizontal flat surface. Put a distance piece between the inner ring and the flat surface.

          2. Install a dial gage in the center of the bearing outer diameter, on the raceway centerline.

          3. Push the outer race against and away from the dial gage. The total movement of the dial gage is the internal radial clearance. To make allowances for eccentricity of the inner ring this check must be done at more than one radial location and take an average result. This procedure is accurate to 0.0005 in. (0.0127 mm) and must be considered before you reject a bearing.

    3. Ball bearing contact angle.

       1. The contact angle is the angle between a position perpendicular to the bearing axis and the load line.

       2. The contact angle is a function of the internal radial clearance and will change as the internal radial clearance changes.

       3. NOTE

          The direction of the inner ring thrust loading can be determined from the Table of Bearing Limits. The rear ring of a forward loaded bearing is the loaded ring.

          Measure the contact angle of a single-row ball bearing with a split inner ring, as follows:

          1. Apply a thin layer of CoMat 10-125 LUBRICATING AND PRESERVATION OIL to the load bearing elements of the bearing. See Figure.

          2. Remove unloaded half of inner ring of bearing. Place bearing on surface plate with loaded half of inner ring up and X or H marks on inner and outer races aligned within five degrees.

          3. Place graduated adapter ring (determined from Table of Bearing Limits) over outer ring of bearing as shown in Figure.

          4. Use any one of the approved temporary marking methods and combination square with center head to scribe a line on rear face of ball cage opposite zero mark on graduate ring. See Figure. Refer to the SPM TASK 70-09-01-400-501 for temporary marking of parts.

          5. Align zero degree position on graduated ring with scribe mark on cage.

          6. Place gage (Figure) over inner ring of bearing. Align gage pointer with zero degree position on graduated ring and scribe mark on cage.

          7. Place weight (Figure) on top of gage.

          8. Rotate load clockwise five revolutions to seat the load bearing surfaces correctly. Return gage pointer to initial positions on ring and cage by rotating load counterclockwise five revolutions.

          9. Aligning pointer of gage with zero mark of graduated ring and previously applied mark on cage, rotate weight clockwise exactly ten revolutions. See Figure.

          10. Read contact angle on scale of graduated ring opposite mark on cage.

          11. To check reading, rotated load counterclockwise exactly ten revolutions. Pointer, previous mark on cage and ring zero mark should be aligned. If they are not, do the procedure again.

    4. Measure the diameter below the rollers, refer to Figure.

       1. The diameter below the rollers is only measured on roller bearings with no inner race; for example, where the inner race is part of a gearshaft.

       2. To measure the diameter below the rollers, the rollers are pushed against the outer raceway.

          1. Install the correct bearing IAE 2J12621 Plug gage inspection plug gage on to the holding plate.

          2. 

             CAUTION

             DO NOT APPLY PRESSURE TO THE BEARING. ONLY THE WEIGHT OF THE BEARING IS USED.

             Carefully lower the bearing on to the plug gage and turn it.

          3. The bearing must stop in the 'GO' area.

          4. A bearing which stops below the lowest mark must not be accepted.

    5. NOTE

       When the outer diameter 'D' is examined for differences in dimensions and shape, the reject limits do not apply for distances of less than 2r (When r is the corner radius), from the side faces of the race.

       Measure the outer diameter, refer to Figure, Detail A.

       1. Use approved equipment to measure the minimum and maximum outer diameters, then calculate the average of the two results.

          1. For example: D avg = (D min + D max)/2.

       2. If distortion of the outer diameter is found, when the bearings are measured with their axes horizontal, they must be measured again; with their axes vertical.

    6. Measure the inner race outer diameter of roller bearings that come apart, refer to Figure, Detail B.

       1. The inner race outer diameter is measured the same as that specified in step D.

    7. NOTE

       When the bore diameter 'd' is examined for differences in dimensions and shape, the reject limits do not apply for distances of less than 2r (Where r is the corner radius), from the side faces of the race.

       Measure the bore diameter (ID), refer to Figure, Detail C.

       1. Use approved equipment to measure the minimum and maximum bore diameters, then calculate the average of the two results.

          1. For example: d avg = (d min + d max)/2.

       2. If distortion of the bore diameter is found, when the bearings are measured with their axes horizontal, they must be measured again; with their axes vertical.

    8. Measure the cage guide clearance, refer to Figure, Detail A.

       1. The cage guide clearance is the distance between the cage and the cage guide shoulder. For bearings with an inner guide shoulder, the inner race is used to measure. For bearings with an outer guide shoulder, the outer race is used to measure. Measure the cage guide clearance, as follows:

          1. Put the bearing on to a slope and use light pressure to push the cage down.

          2. Use a feeler gage to measure the cage guide clearance between the cage guide shoulder and the cage inner or outer diameter.

    9. Measure the axial free movement, refer to Figure, Detail B.

       1. The axial free movement of a ball bearing is the axial movement of the outer race, in relation to the inner race. Measure the axial free movement as follows:

          1. Install the outer race of an assembled bearing in a fixture.

          2. Apply the specified force. Move the inner race up and down. Measure the movement with a dial gage.

       2. 
          CAUTION
          THE FOLLOWING LIMITS APPLY IF FITS WITH THE MATING SHAFTS OR HOUSINGS ARE NOT EXCEEDED. ANY INDICATION OF A SPUN RACE OR INDICATIONS OF HOT RUNNING WOULD NEGATE THESE LIMITS.

          These service limits are for main bearing inspection at the overhaul level and are beyond the basic limits shown in the Table of Limits in the Engine Manual.

          1. Bearing Bore: Plus or minus 0.0001 in. (0.0025 mm) beyond limit.

          2. Bearing OD: Plus or minus 0.0001 in. (0.0025 mm) beyond limit.

          3. Contact Angle: Plus or minus 0.5 degree beyond limit.

          4. Internal Radial Clearance: Plus or minus 0.0003 in. (0.0076 mm) beyond limit.

       3. 
          CAUTION
          THE FOLLOWING LIMITS APPLY IF FITS WITH THE MATING SHAFTS OR HOUSINGS ARE NOT EXCEEDED. ANY INDICATION OF A SPUN RACE OR INDICATIONS OF HOT RUNNING WOULD NEGATE THESE LIMITS.

          These service limits are for accessory bearing inspection at the overhaul level and are beyond the basic limits shown in the Table of Limits in the Engine Manual.

          1. Bearing Bore: Plus or minus 0.0003 in. (0.0076 mm) beyond limit.

          2. Bearing OD: Plus or minus 0.0003 in. (0.0076 mm) beyond limit.

          3. Internal Radial Clearance: Plus or minus 0.0003 in. (0.0076 mm) beyond limit.

11. SUBTASK 70-29-01-290-009 Bearing Corrosion Protection and Preparation for Storage After Cleaning or Inspection

    1. For preservation of bearing after cleaning or inspection refer to TASK 70-53-01-620-501, SUBTASK 70-53-01-620-002.

12. SUBTASK 70-29-01-220-001 Table 1 Overhaul Limits

    Scratches, scuffs, scores and corrosion.
    Ball or roller diameter	Scriber Radius
    0.500in. (12.70 mm) or less	0.040in. (1.016 mm)
    Over 0.500in. (12.70 mm) thru 1.00in (25.40 mm)	0.080in. (2.032 mm)
    Over 1.000in (25.40 mm)	0.120in. (3.048 mm)

Figure: The names of the bearing components

The names of the bearing components



Figure: Examples of fatigue break-up (Spalled)

Examples of fatigue break-up (Spalled)



Figure: Examples of skidding

Examples of skidding



Figure: True brinelling

True brinelling



Figure: False brinelling

False brinelling



Figure: Examples of cracks

Examples of cracks



Figure: Examples of scuffing marks

Examples of scuffing marks



Figure: Examples of heavy electrical discharges

Examples of heavy electrical discharges



Figure: Examples of high temperature color changes

Examples of high temperature color changes



Figure: Examples of worn roller ends and guide faces

Examples of worn roller ends and guide faces



Figure: Examples of pitted surfaces

Examples of pitted surfaces



Figure: Examples of marks caused by unwanted materials

Examples of marks caused by unwanted materials



Figure: Examples of scratches

Examples of scratches



Figure: Examples of scores

Examples of scores



Figure: Examples of nicked surfaces

Examples of nicked surfaces



Figure: Examples of dented surfaces

Examples of dented surfaces



Figure: Examples of corroded surfaces

Examples of corroded surfaces



Figure: Examples of galled surfaces

Examples of galled surfaces



Figure: Examples of stains

Examples of stains



Figure: Examples of carbon particles

Examples of carbon particles



Figure: Examples of peeled surfaces

Examples of peeled surfaces



Figure: Measure the internal radial clearance

Measure the internal radial clearance



Figure: Lubricating the bearing

Lubricating the bearing



Figure: Installing Graduated Ring

Installing Graduated Ring



Figure: Marking Ball Cage

Marking Ball Cage



Figure: Bearing and Contact Angle Measurement Equipment

Bearing and Contact Angle Measurement Equipment



Figure: Rotating the Load

Rotating the Load



Figure: Measure the diameter below the rollers

Measure the diameter below the rollers



Figure: Bearing dimension checks

Bearing dimension checks



Figure: Bearing dimension checks

Bearing dimension checks



Figure: Overhaul limits

Overhaul limits



Figure: Overhaul limits

Overhaul limits



Figure: Overhaul limits

Overhaul limits



Figure: Overhaul limits

Overhaul limits



Figure: Overhaul limits

Overhaul limits



Figure: Overhaul limits Deleted see SUBTASK 70-29-01-220-001

Overhaul limits Deleted see SUBTASK 70-29-01-220-001



Figure: Measure the contact angle

Measure the contact angle