Bearing

BEARINGWhen there is relative rotating motion between two machine parts. One of which supports the other, the supporting member is called BEARING. Bearing is very importent element in any machine.

FUNCTIONS OF BEARING1. It bears load. 2. It locates rotating part in correct position. 3. It provides free motion to the rotating part by reducing friction.

Bearing bears the load in machinery. The term 'load' refers to the force of weight that is placed on the bearing. A bearing must be able to support a load placed on it. Locating the rotating parts in correct position means hold the rotating part in predetermined place. Bearings are required to resist motion in one or more directions while allowing motion to occur in other directions. Bearings must be able to reduce friction to provide free motion to a rotating part. Friction is the resistance to motion that exists between two surfaces that are in contact with each other. Too much friction can prevent movement of machine parts, and equipment may be damaged.

CLASSIFICATION OF BEARINGBEARING

SLIDING CONTECT OR FRICRIONAL BEARING

ROLLING CONTECT OR ANTI FRICTIONAL BEARING

SLIDING CONTACT BEARING OR FRICTIONAL BEARING

Bearings in which the contact surfaces either make sliding contact separated by a film of lubricant. It operates on the basis of sliding friction.

Advantages of Sliding contact bearing:1. Easy to manufacture, 2. Cost manufacture is low, 3. Quieter in operation particularly after a suitable running- in period, 4. It has unlimited life, 5. High load carrying capacity. 6. Less sensitive to injury, 7. Less radial space required,

Disadvantages of Sliding Contact Bearing:

1. There required higher starting torque, 2. Continuous or more lubricant is needed for lubrication, 3. Loss of lubricant is more, 4. More power is needed for driving, 5. More axial space is required.

ROLLING CONTACT BEARING OR ANTIFRICCTIONAL BEARING.Bearings which have rolling contact between surfaces. It operates on the basis of rolling friction..

Advantages of R.C. bearings:1. Lower axial space required, 2. Operates on minimum friction, 3. Lower Power consumption, 4. Low starting torque, 5. Less lubricant is needed for lubrications, 6. Easy maintenance, 7. More axial rigidity in this case.

Disadvantages of R.C. bearings:1) 2) 3) Manufacturing Process is complex innature,

Cost of manufacturing is higher, It has limited life in term s of millions of revolutions, 4) More sensitive to foreign bodies & injury's

PARTS OF ROLLING CONTACT BEARINGS Outer race

Rolling element

Shield

Retainer or Cage Inner race

Rolling contact Bearing consists of the following main parts.1. Outer ring OR outer race. 2. Inner ring OR Inner race 3. Retainer or Cage 4. Rolling elements.

Bearings can be classified according to type of load carried by the bearing.1. Bearings for radial load (Radial bearings). 2. Bearings for axial load (Thrust bearings). 3. Bearings for combined load (It takes both radial and axial load).

Redial loadCombine load

Axial load

BEARINGS FOR RADIAL LOADDifferent types of R. C. bearings which can be used for radial loads are, 1. Single or double row deep groove ball bearings. 2. Double row self-aligning ball bearing. 3. Cylindrical roller bearings. 4. Single or double row self-aligning ball bearings.

BEARINGS FOR COMBINED LOADThe following bearings are suitable when loads are made up of one component perpendicular to the axis of the rotation and other parallel to the axis of rotation. 1. Angular contact ball bearings either of the single row type (to be fitted in opposite pairs) or of the double row type. 2. Spherical roller thrust bearings. 3. Taper roller bearings single or paired (for axial load in either one or both directions respectively.)

BEARINGS FOR THRUST LOAD Different types of R. C. bearings which can be used for thrust loads are :

1. Single or double thrust ball bearings (for thrust load in either one or both directions respectively). 2. Cylindrical roller thrust bearings

Bearings can be classified according to type of rolling element used. They are:Ball Bearing. Roller Bearing

Difference between Ball and Roller bearings.1. Can carry lighter load. 1. Can generally carry heavier load. 2. Can run at higher speed. 2. Can run at lower speed 3. Maximum friction that may occur is 0.0015. 0.003

BALL BEARINGSSingle row deep groove ball bearings.This is the most common type of ball bearings in general engineering. This type has the following advantages. 1. It can withstand considerable amount of thrust load in addition to radial load 2. It can function successfully at very high speed. 3. As there is no flexibility is provided in this type, alignment of the shaft and housing should be as correct as possible. Bearings of this type are available with side shields, seals and snap rings.

Single row deep groove ball bearings.

Double row deep groove ball Bearings.These are the same as single row bearings but are wider to allow a double row of ball with the object of increasing the load capacity.

Single row angular contact ball bearings.

These are designated to take a combination of thrust and radial load. These should be used in pairs in opposite direction and their axial adjustment must be made very carefully. High supporting shoulders on both inner and outer rings affect the thrust load and axial rigidity.

Double row angular contact ball bearing

This is rigid bearing whose raceway is so designated that the direction of load through the balls is oblique to the axis. The angle of contact is 30 deg. And is made with filling slots. These bearings are used where the thrust load is equal to or greater than radial load. These bearings can be substituted by two bearings of single row angular contact either face to face or back to back and also two bearings in tandem.

Self aligning ball bearing.

This is a double ball bearing with spherical raceway in the outer ring thus permitting it to swivel. It is particularly suitable where there is possibility of miss-alignment of shafts.

Single row thrust ball bearings.

This type comprises a row of balls running between two flat grooved washers with ball track designated to absorb thrust load in one direction. This does not with stand and any radial load also, this is not suitable for high speeds.

Double row thrust ball bearings.These comprise two rows of balls, one for each direction of thrust. It is only used to absorb thrust loads in either direction at low moderate speed. These cannot withstand any radial load. These are occasionally mounted on spherical seating for self aligning purpose.

Roller Bearings:

Single row cylindrical roller bearings.This bearing is a rigid bearing comprising a single row of cylindrical rollers and raceway. The open form bearings can be withdrawn in both directions. Those of the half-closed form can be withdrawn in one direction only. Whilst the close forms type serves to locate the shaft axially.

Double row cylindrical roller bearings.These are twice as wide as the single row type. These are also called Duplex bearings and can sustain extremely heavy loads. These are a available in either separable in either separable inner or outer races.

Spherical roller bearings.The race of the outer ring is ensuring correct operation when the axes of the two rings are inclined to each other. These bearings are therefore suitable for use with independent support housings and wherever there is possibility of a lack of alignment. They are designed to carry medium or heavy radial or combined load.

Taper roller bearingsThese bearings consist of two parts; the inner ring, complete with the row of rollers, is retained by a pressed steel cage, forming an integral sub-assembly (cone) and outer ring (cup). These bearings carry heavy radial and thrust loads at moderate Speeds. These should always be mounted in pairs with opposed taper because in each bearing the radial load. produces a axial component which needs counter balance. The assembly of paired bearings is available in various styles.

1. Cylindrical roller thrust bearings. These have tow flat washers without any grooves. The specially designed cage retains the rollers in position. These can take heavy thrust loads at moderate speeds. These cannot take radial loads.

Spherical Roller thrust Bearings.

The roller of these bearings is controlled by a lip on the ring which is secured to the shaft. The axis of rollers with meets at one point one the bearing axis. The track on the inner ring mostly fitted one the housing in spherical and thus allows self-alignment of the bearing. The special feature of this bearing is its capacity to carry a light radial load.

Needle roller bearings.

This is another form of cylindrical roller bearing with the rollers, having a very small diameter in comparison with their length. This diameter varies from 1.5mm to 5mm. these bearings are made in various types and their application or their mounting also varies. These are used with inner race and outer race, only inner race with roller and cage or only outer race with roller and cage. Owing to very small diameter size the spacing cage is generally omitted. These bearings are used in places where the speed is low or where oscillation takes place as in wrist pin, rocker arm, and universal Joint, etc.

BEARING COMPONENTS AND MATERIALS 1. The rings and rolling elements of rolling bearings are generally made form through hardened high grade carbon chromium steel having a high degree of cleanliness. Or special applications case hardened or even stainless steel may be used. 2. Each individual bearing receives optimum heat treatment, resulting in hardness normally between 59 and 65 HRC. Pressed steel, or brass cages are normally used for small and medium sized bearings.

3. Injection molded plastic cages are, however, used more and more as Standard or small and medium size bearings. 4. Large bearings generally have machined cages which are usually made of brass, but even steel; spherical graphite cast iron and light alloys are used for machined cages.5. Shields are made of steel sheet only and form a narrow gap with the inner ring. Seals protect bearings better than shields do, but the heat resulting from the friction between seal lip and the inner ring will Reduce the limiting speed by one third

INTERNAL CLEARANCEThe bearing internal clearance is defined as the total distance through with one bearing ring can be made relative to the other under zero measuring loads. 1. Movement in the radial direction called radial internal clearance; 2. Movement in the Axial direction called Axial internal clearance; The internal clearance will vary from bearing type to bearing type. The most common clearance is NORMAL (with no suffix). Internal clearance smaller than normal are designated by suffixes C1 and C2 while internal clearances larger than normal are designated by C3, C4 and C5.

Internal Clearance

Suffix internal ClearanceC1 C2 Normal C3 C4 Greater than normal Greater than C3 Smaller than C2 Smaller than normal

C5

C5 Greater than C4

Example: 6210/C3 - Bearing with increased clearance.

Reasons for providing internal clearance:1 In order to fit a bearing tightly on a shaft, it is necessary that the shaft is slightly Larger than the bore of inner ring. When the bearing is mounted, the inner ring will expand and consequently the space available for the rolling elements will be reduced. (Sometimes the housing seatings are made slightly smaller than the outside diameter of the outer ring resulting in compression of the outer ring and hence further reduction of available space for rolling elements.) The reduction in space available for rolling elements when the bearing mounted is accommodated by the internal clearance. 2. Steel will expand with increased temperature. In operation the temperature of the various parts of a bearing will not remain uniform and resulting in varying degrees of expansion which is compensated by the internal clearance.

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CODE FOR BEARING TYPEThe first digit (or letter) designates the type of bearing. Following are the codes for bearing type: CODE DESCRIPTION3code for Bearing Type Example: 3 = Taper roller Bearing

0Code for Wide (or Height) Series Example: Width Series = 0

2Code for Diameter Series Example: Diameter Series = 2

06Code for Bore Diameter Example: Code = 3 i.e. Bore Dia. = 30mm

0-

Double row angular contact ball bearings.

1-

Self-aligning ball bearings.

2-

Spherical roller bearings and spherical rollerthrust bearings.

345-

Taper roller bearings Double row deep groove ball bearings. Thrust ball bearings.

6 - Single row deep groove ball bearings.Bearing with bore dia. Less than 10 mm aredesignated by three figures where the last figure

represents the bore dia in mm.

78-

Single row angular contact ball bearings. Cylindrical roller thrust bearings.

N - Cylindrical roller bearings. The symbol "N" which indicates the type of bearings may be supplemented by one or two letters to indicate different guide flange combinations. QJ - 4-point contact ball bearings. T - Taper roller bearings. The prefix T is followed by 3 symbols designated the bearing series and a 3digit code indicating the bore dia, in mm.

CODE FOR BORE DIAMETER1. The two digits indicate the diameter of bore between 20 to 490 mm. The bore Diameter is obtained by multiplying last two digits by 5. 2. For bearings with bore diameter greater than 490 mm, the bore diameter is directly Indicated after an oblique (e.g. 511/500). 3. Special coding applies for the bearings with bore diameter less than 20mm. 00 -- -- 10 mm 01 -- -- 12 mm 02 -- -- 15 mm 03 -- -- 17 mm 4. For the bore diameter less than 10 mm, the bore diameter is indicated by a single Digit which gives the value of bore diameter directly.

SUPPLEMENTARY DESIGNATIONSCode letters additional to the basic designation are used to distinguish bearings which differ from standard or have modified components where several code letters are required they are added to the bearing designation in the order given below. Some of the most commonly used supplementary designations are given below:

PREFIXESBEARING COMPONENTS L Removable ring (inner or outer) of a separable bearing. e.g; LNU 207 Inner ring of cylindrical roller bearing NU207. L30307 Outer ring of taper roller bearing 30207. R Separable bearing less removable ring (inner or outer). e.g: RNU207 outer ring and roller cage assembly of taper roller bearing 30207. R30207 Inner and roller and cage assembly or taper roller bearing 30207.

SUFFIXES INTERNAL DESIGNModified internal design of bearing. e.g. 7205 D Single row angular contact ball bearing with a contact angle of 40 degree.

A Contact angle 30 degree. B Contact angle 40 degree. C Contact angle 15 degree. D Contact angle 45 degree.

SUFFIXESEXTERNAL DESIGNX Boundary dimensions altered to conform to ISO standards. RS Synthetic rubber seal fitted at one side of the bearing. 2LS Synthetic rubber seal fitted on both side of the bearing. Z Shield fitted t one side of the bearing. ZZ Shield fitted at both sides of the bearing. K Tapered bore, taper 1:12 on diameter. K30 Tapered bore, taper 1:12 on diameter. N Snap ring groove on outer ring. NR Snap ring groove in outer ring with a snap ring. ZN Shield at one side and snap ring groove at other. ZNR As for ZN including snap ring. N2 Two diametrically opposed slots at one outside corner of outer ring.

N2 Two diametrically opposed slots at one outside corner of outer ring. G Single row angular contact ball bearing with ring faces adjusted so that any two bearings can be mounted in pairs, either in tandem, back to back, or face to face.

CAGEJ Pressed steel cage, unhardened.

Y Pressed brass cage. F Machined steel or C.I cage L Machined light alloy cage. M Machined brass cage. P Polyamide 6-6 cage reinforced with 25% glass fiber. T Cage of fabric reinforced phenolic resin. TH Fabric reinforced phenolic resin cage with snap type pockers. TN9 Reinforced plastic cage.

MOUNTING OF BEARINGSIn order to ensure proper mounting of bearings, proper tools must be used, Especially when a large number of bearings are to be frequently mounted and Submitted. Bearings can be fitted by the following methods depending on the size and fit of the bearings.

1. By HammeringBearings can be mounted by tapping gently with a copper or lead faced hammer on a suitable blind tube having its open end against the bearing race to the pressed into the seat. Pressure should not be used on outer race to press fit the inner race or vice versa. Two separate tubes should be used for pressing two races. Cage should be protected against any shock or pressure. If a bearing has to be mounted simultaneously on the shaft and housing, the mounting sleeve should bear in both the outer and inner races. If a suitable mounting sleeve is used, bearings with a cylindrical bore of 70 mm maximum can be mounted in this way.

2. Pressing by hydraulic pressWhen a quite a number of small bearings are to be fitted, the use of hydraulic press may be advantageous. The advantages of this method is that it helps in ascertaining the maximum and minimum pressure load to be applied for a particular mounting.

3. Mounting by heating Larger bearings and those which demand greater interference are usually mounted after heating. The method of bearings may be either in oil bath or by induction heating.

While hearting the bearing in oil bath, the following points are to be noted:a) Use suitable medium for heating, such as clean transfer oil. b) Do not allow the bath temperature to exceed 90C. c) Use false bottom at the bath so that bearings do not comes in contact with the bottom or sides. d) Bearings should be handle by means of tongs. A spring attached to the lifting gear will be an added advantage for correctly centering the bearing.

DISMOUNTING OF BEARINGS1. Dis mounting by pulling ,The method of removing bearings depends upon the design of the bearing installation. If the seatings are not too tight, withdrawal appliance usual in the trade will be found sufficient for dismantling from the shaft or the housing. It is important to ensure that the force required for withdrawal is not transmitted through the rolling elements.

2.

In the case of adapter sleeve bearings, after the nut of the adapter sleeve has been loosened, the later must be knocked out of the bearing bore by means of a tubular bushing. Bearings with withdrawal sleeve are dismantled by screwing a withdrawal nut on the thread of the withdrawal sleeve so far that the withdrawal but bears upon the face of the inner ring and then draws the sleeve not of the bearing bore.

For large beating with specially tight seatings, an oil pressure method is used. The journals are provided with ducts and grooves to allow the oil injection method for dismounting the bearings. The method provides a supply of high pressure oil to the interference surface, thereby reducing the friction between the inner ring and journal and keeping the mounting force to the minimum. Hydraulic nuts can also be used for loosening the withdrawal sleeve. The nut is screwed on the threads of the withdrawal sleeve like normal withdrawal nuts and then pressurized to dismount the bearings as stated earlier. . `

Electrical induction heaters are also used for withdrawing the inner rings of the cylindrical roller bearings. This needs only 20 or 30 seconds for removing the inner race. The greatest advantage of this method is that seating remains undamaged even after any number of repeated fittings.

LUBRICATION OF BEARINGS

The purpose of lubrication is: 1. To reduce friction between the rolling members. 2. To protect bearing from corrosion. 3. To prevent the intrusion of drift into the bearing.

4. To reduce the running noise.5. To dissipate heat.

1. Before being packed, the bearings are coated with preservative grease which prevent corrosion. Bearings, therefore, should be left in their original packing until just before they are fitted.2. Never wash out bearings which are available in the suppliers packing. 3. If due to any reason the bearings become dirty, they should be cleaned in fresh petrol and re lubricated immediately. 4. Avoid using compressed air for cleaning bearings as compressed air very often carries water and dust.

Oil Lubrication is confined to certain cases:1. Bearing running at very high temperatures. Oil should be fed through them continuously for cooling purposes. (The oil should be sucked through the bearing and never forced through.)2. Bearings fitted on the vertical shafts where it is difficult to seal in the grease, so that drip-lubrication with oil is preferable. 3. Bearing installed in machines which are already lubricated with oil and in which it is difficult to separate the lubrication of bearings from that of the other components of the machine. 4. Self-aligning thrust roller bearings which are almost always lubricated with oil.

ROLLING BEARING DAMAGE AND ITS CAUSESThe life of ball or roller bearing depends upon the total number of stress cycles and loads incurred by rolling elements and raceways. Normal fatigue manifests itself by flaking or Spalling of the rolling surfaces. If the bearing continues in service an increased localized stress may result in catastrophic ring fracture. If the bearing fails earlier than predicted by the fatigue life, it should be checked for overloading. With this failure cause excluded, thought should be given to the possibility of poor installation or maintenance or to operational wear.

Why does a bearing fail?Faulty MountingAn usual pattern of the running track suggest internal nipping which may be caused by exceedingly tight fits, excessive axial adjustment, malformation of the bearing seats of the shaft or the housing, misalignment, or when the axial freedom of the floating bearing is lost. Localized damage to the raceway such as nicks, score marks, or indentations suggest faulty mounting. This type of damage occurs if, for instance, the inner ring of a cylindrical roller bearing is pushed into the outer ring in a tilted position or if the mounting pressure is transmitted through the rolling elements.

Faults in DesignRolling bearing ring should be fully supported on the shaft and in the housing. A groove in the seating area will cause localized stress concentrations and subsequent raceway destruction. Similar damage occurs when a set screw is used to clamp the ring or when grooves or bores are ground into the bearing after its completion in manufacture.

CorrosionCorrosion is caused by inadequate sealing against moisture, Acid fumes, lubricant containing acids, condensation, unsuitable storage.

Entrance of DirtEntrance of dirt may be due to unclean parts, sand in housing (castings), inadequate seals, contaminated lubricants, Metallic abrasion from gears brought into the bearing by the lubricant.

BrinellingBrinelling is caused by static overloading, shock and vibration on stationary bearing (e.g. during transportation), passage of electric current through the bearing.

Deep groove ball bearing. Inner ring, outer ring, and balls are flaked. The cause is excessive load.

Outer ring of angular contact ball bearing Flaking of raceway surface spacing equal to distances between balls. The cause is improper handling.

Inner ring of deep groove ball bearing Flaking on one side of the raceway surface The cause is an excessive axial load.

* Inner ring of spherical roller bearing. * Flaking only on one side of the raceway surface. * The cause is an excessive axial load.

Tapered roller bearing Flaking on 1/4 circumference of inner ring raceway with outer ring and rollers discolored light brown. The cause is excessive pre-load.

Outer ring of double row angular contact ball bearing. Flaking on 1/4 circumference of outer ring raceway. The cause is poor installation.

Thrust ball bearing Flaking on inner ring raceway (bearing ring fastened to shaft) and balls. The cause is poor lubrication.

Outer ring raceway of double row tapered roller bearing (RCT bearing) Flaking originated from electric pitting on the raceway surface (refer to Section 5.13 Electrical Pitting)

Rollers of spherical roller bearing Peeling on rolling contact surfaces The cause is poor lubrication.

Tapered roller bearing Development of peelling to flaking on inner ring and rollers The cause is poor lubrication.

Inner ring of cylindrical roller bearing Spalling on rib The cause is excessive load.

Inner ring of cylindrical roller bearing Spallling on raceway surface and cone back face rib The cause is poor lubrication.

Rollers of tapered roller bearing Cycloidal spallling on the end faces (Scuffing) The cause is poor lubrication.

Roller of cyllindrical roller bearing Score in axial direction on rolling contact surface caused during mounting. The cause is poor mounting practice.

Inner ring of cylindrical roller bearing Smearing on raceway suface The cause is slippage of rollers due to foreign objects trapped within.

Roller of same bearing as that of the inner ring shown in Photo D-1 Smearing on rolling contact surface The cause is slippage of rollers due to foreign objects trapped within.

Rollers of spherical thrust roller bearings Smearing at middle of rolling contact surfaces The cause is slippage of rollers due to foreign objectstrapped within.

Inner ring of double row tapered roller bearing (RCTbearing) Smearing on raceway surface

Inner ring of double row tapered roller bearing (RCT bearing) Raceway surface is speckled The cause is electric pitting.

Ball of deep groove ball bearing Speckled all over The cause is foreign objects and poor lubrication.

Inner ring (cut off piece) of self-aligning roller bearing Dents on one side of the raceway The cause is trapping of solid foreign objects.

Rollers of spherical roller bearing Dents on rolling contact surfaces The cause is trapping of solid foreign objects.

Rollers of tapered roller bearings Dents all over rolling contact surfaces. (Temper color attwo ends.) The cause is foreign objects carried by lubricating oil.

Inner ring of tapered roller bearing Dents on raceway surface The cause is trapping of foreign objects.

Cylindrical roller bearing Chipping of guide ribs of inner and outer rings The cause is excessive impact load.

Inner ring of spherical roller bearing Rib chipped The cause is excessive impact load.

Outer ring of four-row cylindrical roller bearing Split of raceway surface in the circumferential direction originated from large flaking. The cause is large flaking.

Inner ring of spherical roller bearing Split of raceway surface in the axial direction The cause is excessive interference fit.

Inner ring of tapered roller bearing Rusting on raceway surface spacing equivalent to the distance between rollers. The cause is water in lubricant.

Outer ring of tapered roller bearing Rusting on raceway surface spacing equivalent to the distances between rollers. The cause is water in lubricant. Some points are corroded.

Inner ring (split type) of selfaligning roller bearing Rust and corrosion of the raceway surface The cause is ingress of water.

Inner ring of double row tapered roller bearing Seizing-up discolors and softens inner ring producing stepped wear at spacing equal to distances between the rollers. The cause is poor lubrication.

Inner ring of cylindrical roller bearing Raceway surface is corrugated by electric pitting

Rollers of tapered roller bearings Electric pitting at middle of rolling contact surfaces

Retainer of angular contact ball bearing Breakage of machined high tension brass retainer L1 The cause is poor lubrication.

Retainer of spherical roller bearing Breakage of partitions between pockets of pressed steel retainer

Retainer of tapered roller bearing Breakage of pockets of pressed steel retainer

Retainer of cylindrical roller bearing Breakage of partitions between pockets of machined high tension brass casting retainer L1.

Rolling Contact Bearing Trouble ShootingSome common bearing troubles are listed here along with their possible causes and effects on typical machinery . Performance of bearing : Noisy running Possible Cause : Damage tracks and rolling elements. Examples Automobiles : Increasing shake in wheels. Vibration in steering links and associated components. Fans : Increasing vibration. Saw Frames : Increasing shocks and fluctuation in spindle speed. I.C. Engines : Increasing vibration in crank shaft.

Performance of bearing : Diminishing accuracy in operation. Possible cause : Wear and tear resulting from the presence of foreign bodies, dirt, filings, chips, of inadequate lubrication. Damaged Track and rolling elements. Examples: Lathes : Gradual appearance of chatter marks on work piece. Grinders : Undulating surface on ground section. Cold rolling Mills : Surface imperfection on folled material, appearing mostly spasmodically, such as undulation, shades, etc.

Performance of bearing : Extraordinary running noise. High pitch scream or whistle. Possible cause : Insufficient running clearance. Performance of bearing : Rattling or noise of varying intensity. Possible cause : Excessive running clearance. Damaged race tracks. Foreign matter. Unsuitable lubricant (too heavy in consistency.) Examples : Electric motor gears. (It is very difficult to defect bearing noise in gears due to the performance of gear whine and noise emanating from the gears themselves).

Performance of bearing : Gradual change in running noise .

Possible cause : Vibration in running clearance due to influence of temperature. Damaged race tracks due, for example, too contaminated lubricant or fatigue. Performance of bearing : Excessive temperature Higher temperature than usual with identical working conditions. Possible cause : At medium and high speeds. Insufficient running clearance. Unsuitable and excessive lubrication. Faculty shafts seals or packing. Rubbing seals with excessively tight fits. Labyrinth seals rubbing against bearing. Example : In the case of machines and equipment manufactured in large quantity such faults are generally detected on test and certified by suitable action as refitting adjustment, etc.

Performance of bearing : Sudden rise in temperature without any change in working conditions. Possible cause : Insufficient or faulty lubrication commencement of flanking. Examples : Such faults in generally are detected in the course of maintenance. Performance of bearing : Sluggish running. Uniform high resistance in rotation. Possible cause : Bearings mounted out tune. Miss-alignment. Excessive tight seals or packing. Excessive amount of lubricant or heavy consistency of lubricant. Examples : The excessive frictional resistance may in general be ascertained when turning the bearing by hand.

DO'S & DON'TS FOR HANDLING ROLLER BEARINGS DO'S 1. Work with clean tools, in clean surroundings. 2. Remove all outside dirt from housing before exposing bearings. 3. Handle with clean dry hands. 4. Treat a used bearing as carefully as the new one. 5. Use clean solvents and flushing oils. 6. Lay bearings out on clean paper . 7. Protect disassemble bearing s from dirt & moisture. 8. Use clean lint-free cloths if bearings are wiped. 9. Keep bearings wrapped in oil-proof paper when not in use. 10. Clean inside of housing before replacing bearings. 11. Install new bearings as removed from packages, without washing. 12. Keep bearing lubricants clean when applying and cover containers when not in use.

DON'TS1. Don't work in dirty surroundings. 2. Don't use wood mallets or work on rough or dirty bench tops. 3. Don't use dirty, brittle, or chipped tools. 4. Don't handle bearings with dirty moist hands. 5. Don't spin unclean bearings. 6. Don't spin any bearings with compressed air. 7. Don't use same container for cleaning and final rinsing of bearings 8. Don't use cotton waste or dirty cloths to wipe bearings 9. Don't expose bearing to dirt or moisture at any time 10. Don't scratch or nick bearing surfaces. 11. Don't remove grease or oil from new bearings 12. Don't use incorrect kind or amount of lubricant

BEARINGS CONDITION MONITORINGBearing accounts for the largest number of rotating components in an industry and its healthy running can ensure the productivity of the plant. Most of the machine problems are accounted due to an ingenuity developed in the bearings. There are several methods for monitoring bearing condition such as : 1. Vibration analysis. 2. Temperature 3. Sound, etc.

Shocks Pulse AnalyzerShocks Pulse Analyzer is used to monitor 1. The mechanical condition of rolling contact bearings (bearing damage development) 2. The lubrication condition of rolling bearings. (lubricant film il1 the rolling interface)