Bearing Tester User Guide
Contents
1. there can be a number of different causes for bad bearing condition other than damage Evaluation requires only normal care and common sense Use the probe transducer and the headphone and also use your senses look touch listen By being thorough you can avoid raising false alarms or missing damaged bearings Initial readings and changes There are only two situations where an evaluation is necessary The first is when you start with bearing monitoring Always evaluate the first readings on new measuring points and newly installed bearings The purpose is to establish a reliable base for routine measurements You want to be quite sure that you are measuring shock pulses from the bearing and that the reading itself is correct If you find that bearing condi tion is good you do not have to evaluate the following readings on that measuring point as long as there is no significant change The other situation is when you notice a change in the readings or get high readings from the start E nvestigate any significant increase or decrease of the shock pulse level Again you want to be quite sure that you are measur ing shock pulses from the bearing and that the reading Itself is correct If you find that bearing condition is not good you have to distinguish between bad installation poor lubrica tion overload and damage in order to decide what kind of maintenance work is needed If you are getting an interferenc2. E 9 u gt t 9 T e NO c u TIMKEN TIMKEN Where You Turn Bearings Steel Precision Components Lubrication Seals Remanufacture and Repair Industrial Services www timken com Timken is a registered trademark of The Timken Company 2008 The Timken Company Printed in U S A 000 00 00 00 Order No 00000
3. Unit for diameter Back Return Select inch or mm Accessories 15288T 15287T 15286T Accessories 7 TRA7AT 15286T 152571 15288T EAR12 External transducer with probe Transducer with quick connector for adapters Belt holder tor external probe transducer Belt case for accessories Protective cover with wrist strap Headphones with ear defenders TRA73T Shock Pulse Measurement 1004 dBsv 90 80 70 60 50 40 30 20 2 seconds o The Shock Pulse Method The bearing tester is based on the Shock Pulse Method Measurements with the shock pulse method give an indirect measure of impact velocity i e the difference in velocity between two bodies at the moment of impact At the point of impact a mechanical compression wave a shock pulse arises instantly in each body The peak value of the shock pulse is determined by the impact velocity and is not influenced by the mass or the shape of the colliding bodies Shock pulses in rotating ball and roller bearings are caused by impacts between raceways and rolling elements From the points of impact the shock pulses travel through the bearing and the bearing housing Extensive experience proves that there is a simple relationship between the bearing s operating condition and the value of the shock pulses A transducer detects the shock pulses in the bearing The transducer signals are processed in the bearing detector
4. countersunk mounting holes on the bearing housings Glue on adapters are available To attach the transducer with quick connector press It against the adapter and twist clockwise Twist counter clockwise to remove It Adapter surfaces must be clean and plane Use an adapter cap to protect them Check that installed transducers and adapters are prop erly mounted and good condition You cannot expect a useful signal by attaching the quick connect transduc er to a rusty lump of metal or from a transducer that is rolling on the floor on the other side of a partition Permanently installed transducers and measuring terminal A permanently installed transducer and a measuring terminal BNC or TNC connector are used when the bearing cannot be reached directly Use a measuring cable to connect instrument and terminal Use dust caps to protect the connector Check that installed transducers and adapters are prop erly mounted and in good condition You cannot expect a useful signal by attaching the quick connect transduc er to a rusty lump of metal or from a transducer that is rolling on the floor on the other side of a partition 18 TRA74T Standard adapter Push and twist Pd Standard transducer Installed transducer Measuring terminal Bearing Measurement Input data For a reading of bearing condition with bearing tester you need the initial value dBi If you do not know the bearing s
5. 10 to 185 14 to 365 F 1 C 1 F Thermopile Sensor TPS 334 3161 built in contact free IR sensor 8 level amplification Bearing tester External transducer with probe Transducer with quick connector for adapters Belt holder for external probe transducer Belt case for accessories Protective cover with wrist strap Headphones with ear defenders Maintenance and calibration An instrument calibration e g for the purpose of compliance with ISO quality standard requirements is recom mended once a year Please contact your Timken representative for service upgrading the software or calibration EU Directive on waste electrical and electronic equipment WEEE is EU Directive 2002 96 EC of the European Parliament and of the Council on waste electrical and electronic equipment The purpose of this directive is as a first priority the prevention of waste electrical and electronic equipment WEEE and in addition the reuse recycling and other forms of recovery of such wastes so as to reduce the disposal of waste wW This product must be disposed of as electronic waste and is marked with a crossed out wheeled bin symbol in order to prevent it being discarded with household waste O c p
6. Settings menu press the LEFT arrow key To return to the Main display use LEFT RIGHT arrow keys to highlight the Return icon then press the UP arrow key Unit for temperature measurement Temperature can be displayed in either Celsius or Fahrenheit To choose your unit of measurement use the DOWN arrow key in the Main display to enter the General Settings mode Use the LEFT RIGHT arrow keys to highlight the Temperature icon then press the UP arrow key Use the UP DOWN arrow keys to set the measurement unit of your choice To save and return to the General Settings menu press the LEFT arrow key To return to the Main display use the LEFT arrow key to highlight the Return icon then press the UP arrow key Unit for bearing diameter setting Bearing diameter can be displayed in either mm or inch To choose your unit of measurement use the DOWN arrow key in the Main display to enter the General Settings mode Use the LEFT RIGHT arrow keys to highlight the Measurement icon then press the UP arrow key Use the UP DOWN arrow keys to set the measurement unit of your choice To save and return to the General Settings menu press the LEFT arrow key To return to the Main display use the LEFT arrow key to highlight the Return icon then press the UP arrow key 6 Main display v General settings a S EN A Battery type E A Unit for temperature Back Return Select F or C fum A
7. key then position the cursor as required to set the dBi Press the measuring key to return to Bearing mode The dBi value whether calculated by the instrument or manually input is shown in the lower right part of the Bearing display shaft diameter o Bearing measurement 5S HA Enter shaft diameter amp Mes A D o oll lo Enter dBi value Shock pulse measurement For shock pulse measurement press the UP arrow key in the Main display to enter the Bearing display Make sure the shaft diameter and rotational speed of the bearing or its dBi have been entered see chapter Input data or the reading will be incorrect From the Bearing display press the transducer to the measuring point Measurement starts automatically taking a few seconds during which the blue measuring LED is lit up The two measuring results are the maximum value dBm and the carpet value dBc Depending on the dBm value the green yellow or red light LED to the left of the display will light up When an external transducer is used the instrument will display a TLT warning sign if the transducer line test result is unsatisfactory For further information about TLI please see chapter Transducer Line Test When measurement is finished the LED indicators show the bearing condition and an evaluation code is displayed The code refers to the Evaluation Flow Chart on page 32 33 whi
8. s microprocessor and the measured shock pulse values are shown on the display An headphone can be connected to the instrument for listening to the shock pulse pattern Please note that this instrument cannot be used for plain bearings Shock pulses are short duration pressure pulses which are generated by mechanical impacts Mechanical impacts occur in all rotating rolling bearings because of irregularities in the surfaces of the raceways and the rolling elements The magnitude of the shock pulses depends on the impact velocity 8 dBi z Initial value of a bearing dBc z Carpet value weak pulses dBm z Maximum value strong pulses dBn z Unit for normalized shock level dBsv z Unit for absolute shock level The initial value dBi depends on rpm and shaft diameter d Carpet value dBc Surface roughness small irregularities will cause a rapid sequence of minor shock pulses which together constitute the shock carpet of the bearing The magnitude of the shock carpet is expressed by the carpet value dBc decibel carpet value The carpet value is affected by the oil film between rolling elements and raceways When the film thickness Is normal the bearing s carpet value is low Poor alignment and installation as well as insufficient lubrication will reduce the thickness of the oil film in the whole or parts of the bearing This causes the carpet value dBc to rise above normal Maximum value dBm Bearing damage i e relat
9. to force evaluated measurement results on transducers with TLT below 15 e g when measuring via coupling trans formers In the TLT menu press the RIGHT arrow key to turn the test off The TLT test is automatically turned back on by entering the TLT menu again and when the instrument is automatically or manually turned off Storing measurement results This function is useful for easy comparison of measurement results for a particular measuring point It can also be used to store measurement results temporarily until they can be recorded on paper for trending and follow up On the last page of the User Guide is a follow up form which can be copied and used for this purpose Current memory place Bearing measurement 5 Transducer Line Test 14 TLT THU TLT I TETI 2 Measure TLT TLT off mm 191 amp TLT l TET Bearing measurement 2117 4 dBi 22 4 TR TLT 5 save LY Select place Latest reading Stored reading SSS The bearing tester can store up to ten measuring results In the Bearing display use LEFT RIGHT arrow keys to highlight the Memory icon then press the UP arrow key to enter Memory mode Select memory place 1 10 by using the UP DOWN arrow keys Press the RIGHT arrow key to store the reading This action will overwrite any previously stored value in the memory place selected To return to the Bearing d
10. 116 PALATE Back Ret pnt Measure From the Main display press the LEFT arrow key to enter Temperature mode Hold the probe tip against the sur face you wish to measure and press the measuring key to get a temperature reading For most accurate results take two consecutive readings a few seconds apart Measurement will continue as long as the measurement key or the probe tip is being pressed To return to the Main menu press the LEFT arrow key NOTE If you are using an optional transducer for shock pulse measurement measure temperature manually see instructions in paragraph above Machine surface temperature is also measured automatically when an shock pulse measurement is made see the temperature reading after an shock pulse measurement use LEFT RIGHT arrow keys to activate the Return icon in the Bearing display then press the UP arrow key to enter the Main display Press the LEFT arrow key to enter Temperature mode and see the reading The value presented is always the latest reading whether automatically or manually see above measured To return to the Main display press the LEFT arrow key Using the Stethoscope Function The stethoscope function is useful for detecting machine sound irregularities such as load shocks and scraping Connect your headphones to the output connector 7 From the Main display use the RIGHT arrow button to enter the Stethoscope mode Hold the probe tip against the o
11. Load or pressure shocks in the machine s operation causing mechanical shocks in the bearing e Individual gear tooth damage e Bearing damage No signal or only a very low value can be obtained Probable causes e Bearing damage Measure shorter in tervals follow the progress of the damage e Foreign particles in the lubricant Can also be caused by disturbance from loose bearing cap protecting cover or similar items If possible isolate the source of disturbance and test again Probable causes axial shocks load shocks defective If possible lubricate the bearing and check the reading at the same time When lubricating check that the lubricant penetrates into the bearing shaft coupling gear tooth damage cross talk from other defective bearings Probable causes No e Insufficient lubrication possibly in combination with minor bearing damage e Cavitation in pumps e Mechanical rubbing e Gear tooth damage Probable causes e Incorrect bearing installation e Insufficient lubrication possibly Yes in combination with minor bearing damage e Cavitation in pumps e Mechanical rubbing e Gear tooth damage Is the instrument and the transducer working ok Is the measuring point correct Is the adapter or the trans ducer correctly installed Is the machine in operation If possible lubricate the bearing and check the reading
12. Where You Turn Bearing lester User Guide Contents Instrument Overview Instrument parts General description Displays and icons Start up Batteries settings Battery type Unit for temperature measurement Unit for bearing diameter setting Accessories Shock Pulse Measurement The Shock Pulse Method Carpet value dBc Maximum value dBm dBm dBc Normalized shock pulse values with dBi Unnormalized readings The dBm dBc technique Rules for measuring points Measuring points examples Measuring range Creating acceptable measuring conditions Measuring intervals Shock pulse transducers Bearing Measurement Input data Entering shaft diameter and rpm for dBi calculation Entering dBi manually Shock pulse measurement Transducer Line Test Storing measurement results Listening to the shock pulse pattern Evaluating the Bearing Condition Identifying the shock pulse source Shock pulse patterns condition codes Typical shock pulse patterns from rolling bearings Confirming bearing damage Readings on gear boxes Evaluation flow chart Temperature Measurement Using the Stethoscope Function Technical Specifications Maintenance and calibration Document Outline This User Guide contains useful information about the bearing tester beginning with general information about instrument parts user interface batteries and settings A chapter explaining the theories of shock pulse measurement follows It is advisable th
13. also be used connected to the transducer input 8 The dBi value is programmed into the instrument and the measurement is started with key 6 The actual condition reading is displayed on the graphical display 4 as a carpet value dBc and a maximum value The condition indicators 3 indicate the evaluated bearing condition in green yellow red Headphones for listening to the shock pulse pattern can be connected to the output 7 The Bearing tester can also be used for measuring surface temperature via the IR sensor 2 and for detecting machine sound irregularities via headphones using the stethoscope function Internal or external probes can be used for listening Displays and icons Main display Bearing measurement Temperature Stethoscope measurement function General settings Bearing measurement xi TLT Sl i CES Back Return Measurement Input dBi TLT test Input data 14 122i am 2 TLTI TET TOERE fella iS 4 Back Return Back Return vj Measure or press the probe tip Volume 1 8 General settings Temperature F m t l Start up Pressing the measuring key 6 switches on the instrument oet up and measuring modes are selected with the arrow keys 5 Measuring is started automatically whenever the internal probe is pressed in When using external probes measuring Is started manually by pressing the measuring ke
14. at the same time When lubricating check that the lubri cant penetrates into the bearing If possible lubricate the bearing and check the reading at the same time When lubricating check that the lubri cant penetrates into the bearing Have normal values been previous ob served NOTE Be suspicious when sudden drastic changes readings Occur The reading drops but increases again within a few hours Cause bearing damage Shorten measuring intervals to follow the progress of the damage The reading drops to normal level and does not increase again Cause foreign particles in the bearing which have been removed by the new lubricant The reading does not drop Probable causes disturbances from loose bearing cap pro tecting cover or similar items Can also be caused by Large bearing damage The reading drops but the max value increases again within a few hours Probable causes insufficient lubrication which probably has caused minor bearing damage The reading drops to normal level and does not increase again Cause insufficient lubrication The reading does not drop Probably causes e Cavitation in pumps e Mechanical rubbing e Gear tooth damage The reading drops but the dBm increases again within a few hours Probable causes insufficient lubrication which probably has caused minor bearing damage The reading drops to normal level and does not increase again Cau
15. at you read this as it is valuable in order to understand measurement results and to evaluate them correctly The shock pulse theories chapter is followed by chapters describing the hands on use of the instrument and how to confirm and evaluate measurement results References to icons displays and modes in the instrument are in bold text References to instrument keys are in capital letters Instrument Overview Instrument parts Measuring probe Temperature IR sensor Condition indicators Graphical display Navigation keys Measuring key and power on Output for headphones Transducer input cO ON O A C N Measuring LED Battery compartment Serial number label General description The bearing tester is a shock pulse meter based on the well proven shock pulse method for quick and easy identification of bearing faults The instrument has a built in microprocessor programmed to analyze shock pulse patterns from all types of ball and roller bearings and display evaluated information on the operating condition of the bearing Bearing tester is battery powered and designed for use in harsh industrial environments The graphic display 4 gives the condition readings and the LED indicators 3 give an immediate evaluated bearing condition in green yellow red The shock pulse transducer 1 of probe type is built in All types of SPM shock pulse transducers for adapters and permanent installation can
16. ation in green yellow red does not apply See also chapters Normalized shock pulse values with dBi and Input data 2 Work out the direction of possible cross talk You know that the stronger source can mask the signal of the weaker source In this case cross talk must go from bearing to bearing B 3 Subtract the dBi values from the dBsv values In the example you get 26 aB for bearing A 40 dB for bearing B You can now draw two conclusions The reading for bearing A coming from the stronger source is prob ably accurate Ihe bearing condition is reduced 26 dB yellow zone but not seriously so The reading from bearing B is either true or false It true It Indicates bad bearing condition 40 dB red zone but you cannot confirm that with the instrument before condition gets worse and bearing B becomes the stronger shock pulse source Your solution is to take frequent readings and compare the results from both bearings 53 dBsv 47 dBsv 1 Readings with dBi z reveal the stronger source 2 Cross talk must go from the stronger to the weaker source 53 dBsv 47 dBsv 27 dBi 7 dBi 26 40 dBn 3 The reading from the stronger source is normally accurate The reading from the weaker source cannot be confirmed Evaluation flow chart 60 53 dBn Where do you get the highest reading Where do you get the highest reading Where do you get the hig
17. bject Use UP DOWN arrow keys to adjust the volume 1 9 NOTE Setting the volume to the maximum level may harm your hearing To return to the Main display press the LEFT arrow key Back Return K v Volume 1 8 Technical Specifications Casing cover Size Weight Keypad Display Bearing condition indication Measurement indication Power supply Battery life Operating temperature Input connector Output connector General functions Shock pulse measurement Measurement technique Transducer type Temperature measurement Temperature range Resolution Transducer type Stethoscope Headphone mode Article no BI2100 Accessories 7 TRA7AT 15286T 152671 15288T EAR12 36 ABS PC IP54 158 x 62 x 30 mm 6 2 x 2 4 x 1 2 in 185 g 6 5 ounces including battery oealed membrane silicone rubber Graphic monochrome 64 x 128 pixels LED backlight Green yellow and red light LEDs Blue light LED 2x 1 5V AA batteries alkaline or rechargeable 20 hrs of normal use O to 50 C 32 to 122 F L emo coaxial for external shock pulse transducers probe or quick connector 3 5 mm stereo mini plug for headphones Battery status display transducer line test metric or Imperial units of measurement language independent menus with symbols storage of up to 10 measurement values dBm dBc measuring range 9 to 90 dBsy 3 dBsv Built in probe transducer
18. ch must be used to further evaluate the bearing condition When you get high readings yellow and red zone you should immediately verify their nature and probable cause Do not give the verdict bearing damage be fore making a further investigation As a first measure use the headphones to identify the shock pulse pattern measure on and outside of the bearing housing to identify the shock pulse source Surface temperature is measured automatically when a shock pulse measurement is made see the temperature reading use LEFT RIGHT arrow keys to activate the Return icon in the Bearing display then press the UP arrow key to enter the Main display Press the LEFT arrow key to enter Temperature mode and see the reading To return to the Main display press the LEFT arrow key 20 Check Shaft diameter and rpm dBi setting Measuring point in the load zone Probe pointed straight at the bearing Adapter transducer properly mounted Adapter surface clean undamaged Quick connect transducer firmly attached Bearing measurement 4 4 0 B 9 dBi 22 O dei or press the Evaluation probe tip code dEi 22 dB dBi Condition indicators red bad 235 yellow caution 21 34 green good lt 20 TLT warning Transducer Line Test When measuring shock pulses with external transduc ers a transducer line test TLT will a
19. dBi bearing tester will calculate and display the dBi given the rotational speed rpm and the shaft diameter Neglecting to enter this information will produce incorrect measurement results Entering shaft diameter and rpm for dBi calculation From the Main display press the UP arrow key to enter Bearing mode Use LEFT RIGHT arrow keys to high light the Input Data icon then press the UP arrow key Use the LEFT RIGHT arrow keys to position the cursor and the UP DOWN arrow keys to increase or decrease the rpm value respectively To enter the shaft diameter first press the measuring key then use the arrow keys to set the diameter value the same way rpm was set Press the measuring key to return to Bearing mode Entering dBi manually Changing the dBi directly is faster when you know it from your records From the Main display press the UP arrow key to enter Bearing mode Use LEFT RIGHT arrow keys to highlight the dBi icon then press the UP arrow key First position the cursor using the LEFT RIGHT arrow keys then use the UP DOWN arrow keys to increase or decrease the dBi value respectively The highest dBi value that can be entered is 60 the lowest 9 Any attempt to enter values below this results in dBi and an unnormalized shock pulse reading see also chapters Normalized shock pulse values with dBi and Readings on gearboxes set the dBi value back from to or 7 press the UP arrow
20. e indicate poor lubrication or dry running This is sufficient for maintenance purposes dBm and dBc are measured in a fixed time window and automatically displayed The headphone is used to listen to the shock pulse pat tern in case of suspect or high readings This and the possibility to search for shock pulse sources with the probe transducer are means to verify the measuring result and its cause Rules for measuring points The rules for the selection of shock pulse measuring points have a very practical purpose We are trying to capture low energy signals which are getting weaker the farther they travel and the more they are bounced about inside a piece of metal We know that they lose strength when they cross over from one piece of metal to another We cannot know for all bearing applica tions how much of the strength of the signal emitted by the bearing will reach the measuring point How ever by necessity we try to apply general evaluation rules i e treat all measured signals as if they were of the same quality The rules for shock pulse measuring points try to as sure that most of them are within tolerance and that the green yellow red condition zones are valid 1 The signal path between bearing and measuring point shall be as short and straight as possible 2 he signal path must contain only one mechanical interface that between bearing and bearing housing 3 The measuring point shall be located in the l
21. e of other poorly maintained parts or badly adjusted operating parameters Therefore do not accept interference try to remove the cause Coping with interference If the source of interference cannot be removed there are several possibilities fitis intermittent measure while there is no interference If interference is persistent measure its shock pulse level with the same dBi setting as the bearing and compare it with the condition zones finterference masks the green zone you can get true bearing condition readings in the yellow and red zone f interference masks the yellow zone you can get true bearing condition readings in the red zone i e find a damaged bearing If the interference level is persistently higher than the shock level that would be caused by bad bearing condition 35 to 40 dB above the dBi do not try to monitor the bearing Measuring intervals measure often Measuring personnel should know about e lubricant type e maximum quantity e lubricating intervals 1 3 months several days one week Unpredicted very rapid damage development is rare Normally surface damage develops slowly over a period of many months These are the general guidelines for selecting the interval between periodic readings The bearings should be checked at least once every three months he bearings in critical machinery and heavily preloaded bearings e g spindle bearings should be meas
22. e signal it is probably caused by machine faults which have to be reported and repaired Identifying the shock pulse source Play scrapin Excessive ping Cavitation Gear tooth damage Shock pulses are strongest close to the source They spread through the material of all machine parts but are dampened loss of signal with distance and when passing through interfaces in the material Measure on and near the bearing housing to find the strongest shock pulse source Listen for unusual noises Sources of interference Any kind of metallic clatter hard impacts or scraping produces shock pulses which may interfere with the measurement on the bearings Some of the more common sources of interference are Shocks between poorly fastened machine feet and foundation Rubbing between shafts and other machine parts Loose parts striking the machine frame or the bearing housing Excessive play and misalignment of couplings Vibration in connection with loose parts and excessive bearing play vibration alone does not affect the reading Cavitation in pumps Gear tooth damage Load and pressure shocks arising during the normal operation of certain machines 24 Shock pulse patterns condition codes The headphone is a means to verify and trace shock pulse sources The signal from a bearing should be highest on the bearing housing If you get a higher signal outside of the bearing h
23. eadphone volume use the RIGHT arrow key NOTE Setting the volume to the maximum level may harm your hearing To return to the Bearing display press the LEFT arrow key Headphones 10 Adjustment of Bearing measurement dBi 22 4e B3 amplitude level v Headphone volume Adjust gt Back volume Lv Evaluating the Bearing Condition Cross talk from Interference from mechanical shocks Interference other bearings High maximum value Operating condition not good Machine alignment Bearing lubrication Bearing installation Bearing damage Qo Reading correct Check Measuring point Installation Correct dBi dBm Look feel check data Shock pulse source Search Bearing Interference Signal pattern Loose parts Look listen Use probe transducer headphone e Bearing fault Analyze Lubrication Alignment Installation Bearing damage Identify shock pulse pattern Check trend Test lubrication A reading taken with an incorrect dBi value causes an incorrect evaluation of the bearing condition Always check that the correct dBi for the bearing in question has been entered Evaluation simply means that you make sure that the information you pass on to the maintenance personnel IS as correct as possible and as detailed as necessary Always remember that some machines can contain many types of shock pulse sources other than the bearing and
24. failure in a transducer installation or a serious bearing fault Check the instrument by measuring on some other bearing In case of an installed transducer try to get a reading by tapping on the bearing housing If your reading is correct it is possible that one of the bearing races is slipping either on the shaft or in the housing In case of a heavily loaded bearing with previous read ings in the red zone suspect cage failure 6 60 53 dBn M 50 ZZRIL F TSS matea A Confirming bearing damage On receiving the typical bearing damage signal high dBm large difference between dBm and dBc random peaks strongest signal on the bearing housing you must confirm one of the following causes for the reading tapping of loose parts against the bearing housing excessive bearing play in combination with vibration E particles in the lubricant bearing damage Interference can usually be detected by a careful Inspection Lubrication test A lubrication test is the best means to reach a conclusive verdict Make sure that the lubricant is clean and not contaminated Lubricate the bearing and repeat the measurement Measure immediately after lubricating and again a few hours later Make sure that the lubricant reaches the bearing Typically you will get the following results A he shock pulse level remains constant The signal is caused by interference or cross talk from a
25. he setup menu shows the pres ent battery voltage The battery status icon will show when the batteries are low and have to be replaced or recharged The battery life depends on how the instrument is used Full power is only consumed while a reading is in progress from pressing the measuring key until a measured value is displayed Before long time storage of the instrument keep in mind to remove the batteries Battery check For exact battery voltage go to the battery setup menu From the Main display press the DOWN arrow key to enter the General Settings folder Use LEFT RIGHT arrow keys to highlight the battery icon then press the UP arrow key to enter battery type setup The present battery voltage is shown in the upper left corner To return to the General Settings menu press the LEFT arrow key Main display Back Return Settings Battery type Alkaline or rechargeable batteries can be used In bearing tester The battery type has no influence on in strument functionality or operation but should be set for the battery status icon to correctly show battery level From the Main display press DOWN arrow key to enter the General Settings folder Use LEFT RIGHT arrow keys to highlight the Battery icon then press the UP arrow key to enter battery type setup Use UP DOWN arrow keys to set the battery type of your choice 1 2 V for rechargeable 1 5 V for alkaline batteries To save and return to the General
26. hest reading Adjacent to the bearing housing On the bearing housing Adjacent to the bearing housing On the bearing housing Adjacent to the bearing housing On the bearing housing Good bearing condition installation and lubrication Locate the signal source The reading can be caused by cross talk from other defective bearings or disturbances from other mechanical shocks If possible isolate the source of disturbance and test again Check the value of adjacent bearings Are the signals from these bearings similar to the tested bearing Locate the signal source The reading can be caused by interference from other defective bearings cavitation in pumps or mechanical rubbing If possible isolate the source of disturbance and test again Newly installed bearing Locate the signal source If possible isolate the source of disturbance and test again Probable causes The shaft rubs against the bearing housing or the end of the shaft rubs against the bearing cap Gear tooth damage Other mechanical rubbing Where do you get the highest reading 50 32 Adjacent to the bearing housing On the bearing housing Locate the signal source Probable causes e Load or pressure shocks from equipment installed on the machine frame e Other mechanical shocks from the machine s operation If possible isolate the source of disturbance and test again Probable causes e
27. iameter and a dBi of 40 The upper part of the table contains examples of possible combinations of shaft diameter and rom giving a maximum dBi of 40 The lower part of the table exemplifies combinations that give dBi 0 The instrument calculates the dBi up to 40 However it is possible to manually set the dBi to max 60 A reason for setting dbi 40 is when measuring on e g turbo chargers high speed gear boxes etc oO GO OO O O O Low speed bearings he lowest acceptable dBi is 9 dB However it is nearly impossible to get a meaningful reading from bearings in the extremely low speed ranges he practical limit are bearings with a dBi around O dB see lower half of the table Adapters required A heavy load with a well defined direction and a low in terference level make it easier to get readings from low speed bearings Successful measurements has been carried out on bearings with dBi 3 54 rom shaft diameter 260 mm Note that the dynamic measuring range decreases when dBi values get below For example a bearing with dBi 3 showed very heavy damages at dBn 40 x ziz DANSIN M ER MD Y S or ARS S I IES SS BH SNES Covered housing Installed adapters required The installation of adapt ers 15 strongly recommended for all systematic shock pulse monitoring In some cases it is a requirement on bearings with dBi below 5 on heavily vibrat
28. ing bearing housings on covered bearing housings Heavy vibration Low speed Do not use a handheld probe on low speed bearings As a rule the measurement should cover at least 10 full revolutions of the shaft single damaged part in the raceway will cause a strong pulse only when hit by a rolling element while passing through the load zone It can take several revolutions before that event occurs or is repeated 14 Creating acceptable measuring conditions Scraping alignment NS Alignment MANN A B Quels Cavitation gt Gear tooth damage 60 50 40 30 20 10 0 No interference Low level interference High level interference The clicking of valves high pressure steam flow mechanical rubbing damaged or badly adjusted gears and load shocks from machine operation can cause a general high shock level on the machine frame This interference can mask the bearing signal in cases where he shock level measured outside of the bearing housings is as high or higher than the shock level on the bearing housings Remove sources of interference In most cases interference is the result of bad machine condition For example cavitation in a pump is due to flow conditions for which the pump was not designed Cavitation does more than interfere with bearing monitor ing it slowly erodes the material of the pump Monitoring the bearings is pointless if the machine breaks down or requires frequent repairs becaus
29. ing pair at measuring point 1 can be reached with a long adapter through a clearance hole in the bracket The hole must be large enough to allow bearing adjustment and still prevent metallic contact between bracket and adapter Measuring point 2 placed below and opposite to the pump outlet load direction can be reached with a long adapter through an opening in the pump shield Multiple bearings in one housing If there are several bearings in the same housing they are normally treated as a single bearing Figure D shows the bearing arrangement for a vertical pump It Is not possible to distinguish between the shock pulses from the paired bearings in point 1 There is also a risk for cross talk between point 1 and point 2 which means that the shock pulses from the bearing in worst condition are picked up at both points Check signal strength with the probe Use one measur ing point only if readings are identical in both points This point x can be placed halfway between points 1 and 2 12 On large electric motors the bearings are often mounted in housings which are welded or bolted to the motor shields Because of the damping in the interface between the bushing and the shield the measuring point should be on the bushing The bearing housing at the drive end A is usually within reach A long adapter is installed at an angle to the shield so that there is enough space for connect ing the transd
30. isplay press the LEFT arrow key Listening to the shock pulse pattern The stream of shock pulses from a rotating bearing is continuous They vary in strength depending on the relative positions of rolling elements and raceways The headphone is a means to verify and trace shock pulse sources The headphones allow you to listen to the shock pulse pattern In the headphone the noise carpet is represented by a continuous tone The dBc level is approximately where you can start to distin guish between an even sound and individual pulses Typical for bearing signals is a random sequence of strong pulses with no discernible rhythm best heard a few dB below the dBm level A spot of surface damage causing a strong shock pulse will only register if a roller hits it during the measuring interval Especially at low rotational speeds the instru ment can miss the strongest pulse simply because it does not occur during the measuring interval To listen to the shock pulse pattern after taking a read ing connect your headphones to the output connector 7 From the Main display press the UP arrow key to enter Bearing mode Use the LEFT RIGHT arrow keys to highlight the Listening icon then press the UP arrow key to enter listening mode where the dBm value of the latest reading is displayed Use the UP DOWN arrow keys to adjust the amplitude level at which you wish to listen anything below this value will be filtered out To adjust the h
31. ively large irregularities in the surfaces will cause single shock pulses with higher magnitudes at random intervals The highest shock pulse value measured on a bearing is called its maximum value dBm decibel maximum value The maximum value dBm is used to determine the operating condition of the bearing The carpet value dBc helps to analyze the cause of reduced or bad operating condition Normalized and unnormalized readings The bearing tester measures impact velocity over a large dynamic range In order to simplify readout and evaluation a logarithmic measuring unit is used decibel shock value dBsv dBsv is the general measuring unit for shock pulses By measuring the shock pulses from a bearing in dBsv a value for their magnitude is obtained for instance 42 dBsv However this value is only part of the information needed to judge the operating condition of the bearing We also need a standard of comparison i e a norm value for identical or similar bearings Such norm values have been obtained empirically by measuring the shock pulses from a large number of new perfect ball and roller bearings They are called initial values dBi decibel initial The dBi value can be set manually or calculated by the instrument after input of rpm and shaft diameter see chapter Input data The highest dBi value that can be entered is 60 the lowest 9 Any attempt to enter values below this will result in dBi and an unnor
32. lse pattern caused by a cavitating pump or by persistent rubbing is identical with that from a dry running bearing You have an interference signal when the shock pulse level is highest outside of the bearing housing and is not affected by lubricating the bearing If you cannot remove the cause of interference you have a blind spot up to a certain level the interfer ence signal will mask the signal from one or more bear ings However you may still be able to detect bearing damage When the dBm rises above the interference level it must be caused by something else probably bad bearing condition In that case lubricating the bear ing should cause the value to drop at least temporarily 28 Cavita dBn Poor lubrica tion 4 Periodic bursts Periodic bursts are a typical interference signal caused by rubbing between machine parts e g shaft against bearing housing or seal The burst occurs at an rpm related frequency 5 Rhythmical peaks single rhythmical peaks can be caused by load and pressure shocks which occur during the machine s normal operation Other possible causes are clicking valves or loose parts knocking regularly against the machine frame If the signal is strongest on the bearing housing you can suspect a cracked inner ring 6 Large drop in the readings If the shock pulse level drops after a sequence of normal readings you have either a malfunction of the instrument a
33. malized shock pulse reading see below By subtracting the dBi from the dBsv value we obtain the normalized shock pulse value or dBn decibel normalized of the bearing for example 42 dBsv 10 dBi 32 dBn The normalized shock pulse value dBn is the measuring unit for the operating condition of bearings A maximum value of 32 dBn means 32 dB above normal which implies reduced operating condition for the measured bearing By programming the bearing tester with the dBi before taking a reading the bearing condition will be indicated directly on the condition display in green yellow red for good reduced or bad operating condition for the measured bearing Bad operating condition can be synonymous with bearing damage but the term also includes a number of other bearing faults which can be detected by shock pulse measurement The initial value dBi of a bearing is directly related to its rotational speed and shaft diameter The absolute shock pulse level of a bearing measured in dBsv decibel shock value is both a function of roll ing velocity and of bearing condition The dBi value of the bearing must be entered in order to neutralize the effect of rolling velocity on the measured value The bearing tester takes a sample count of the shock pulses occurring over a period of time and displays the maximum value dBm for the small number of strong shock pulses the carpet value dBc for the large number of
34. nother bearing B The shock pulse level drops immediately after lubri cating and remains low Foreign particles in the bearing were removed by the fresh lubricant C The shock pulse level drops immediately after lubricating but rises again within a few hours The bearing is damaged Note that metal particles in the lubricant can originate from the bearing itself Measure the bearing again over the next few days and make sure that the values stay low 30 Readings on gear boxes Shock pulses can sometimes spread through a ma chine housing without significant damping This means that the shock pulses from the bearing with the highest shock pulse level can under unfavorable circumstanc es interfere with the readings on all the other bearings The problem is aggravated when the bearings are of different sizes and rotating at different speeds as in a gear box A bearing with high rotational speed has a high dBi value and generates relatively strong pulses even when its operating condition is good The same shock pulse level measured on a bearing with a low dBi may indicate bad bearing condition In such cases you must proceed as follows 11 1 a reading with dBi set to on all bearings This will reveal the strongest shock pulse source on the machine In the example in the figure you get a reading of 53 dBsv for bearing A and 47 dBsv for bearing B When taking readings with dBi set to the evalu
35. oad zone of the bearing Short means up to 75 mm 3 in but that depends also on how straight the path is bends cause re and deflections whose effects are hard to judge The load zone is the load carrying half of the bearing housing normally the lower one Allow for the pull of belts or other forces which can shift the load to one side Use the probe to find the spot yielding the strongest signal When a measuring point cannot conform to the rules because an ideal spot cannot be reached make allow ance for a weaker signal 1 Straight and short path 2 No interface S S TMS 3 In the load zone of the bearing K Measuring point Measuring points examples The following two pages show measuring points and possible adapter or transducer installations 727 2 4 j Fr MN a Through hole for long adapter Figure A shows how a measuring point beneath a fan cover can be reached with a long adapter through a hole in the cover Adapter with lock nut In figure B the fan cover is fastened directly to the motor shield which is also the bearing housing One of the cover s holding screws can be replaced by an adapter with lock nut Bearing housings beneath brackets Consult machine drawings and identify the bearing housing before selecting a measuring point In figure C showing a pump the bearings are placed in two separate housings inside the bearing bracket The bear
36. ousing across an interface in the material you are most likely measur ing shock pulses from another bearing or some other source Typical for bearing signals is that the stronger shock pulses best heard a few dB below the peak level appear at random intervals The codes refer to the Evaluation Guide or the Flow Chart on page 32 33 which must be used to further evaluate the bearing condition If instrument displays 2 3 or 4 5 use the head phones to determine the condition code 1 For a good bearing the dBm is within the green zone dBm and dBc are close together 2 he shock pulse pattern from a damaged bearing contains strong pulses in the red zone a random sequence and a large difference between dBm and dBc When you lubricate the bearing the values should drop but rise again 3 A dry running bearing has a high carpet value very close to the dBm When you lubricate the bearing the values should drop and stay low A similar pattern is caused by pump cavitation in which case readings on the pump housing are stronger than those taken on the bearing housing and are not influenced by lubricating the bearing 4 Aregular pattern containing bursts of strong pulses in a rhythmic sequence is caused by e g scraping parts 5 Individual pulses in a regular sequence are cause by clicking valves knocking parts regular load shocks 6 A sudden drop in the shock pulse level is suspicious Check your measu
37. ring equipment If the reading is correct you may have a slipping bearing ring Typical shock pulse patterns from rolling bearings A shock pulse pattern is a sequence of either random or rhythmical strong pulses dBm level above a carpet of very rapid weaker pulses dBc level You have to be aware of the dBm value the difference between dBm and dBc the rhythm of the strongest pulses The rhythm of the strongest pulses is best discerned by listening with the headphone at a setting a few dB below the dBm level Typical for bearing signals is a random sequence of strong pulses no discernible rhythm Rhythmical shocks can come from a bearing but are more often a sign of interference Typical patterns are described on the next pages The bearing tester recognizes the pattern of the read ing taken and determines which of the six patterns below is a match The matching number is displayed in the upper left corner of the Bearing display when the measurement is completed This number corresponds to the pattern numbers below There may be times when the instrument displays a combination of the numbers 2 3 or 4 5 in which case the instrument can not distinguish between the two codes Use the headphones and listen to the pat tern to determine condition code 1 Pattern from a good bearing A bearing in good condition should have a dBm value below 20 and a dBc value approximately 5 to 10 dB lower Once you have
38. rn is caused by contaminations in the lubricant metal or dirt The particles either originate from parts of the bearing itself for instance from a damaged cage or they are transported by the lubricant into the undamaged bearing Test bearing and lubricant according to the description Confirming bearing damage in this manual Cracked inner ring A clean crack in the inner ring of a bearing is difficult to detect especially at a low rpm You may get low read ings through most of the bearings rotation then one or two peaks while the crack is in the load zone Signal strength can differ considerably as the crack opens or closes depending on bearing temperature In time the surface tends to spall along the crack leaving sharp edges and metal particles which cause high shock values until they are rolled out Irregular measuring results Large variations between consecutive readings are a danger sign Damaged bearings do not improve with time although their shock values may temporarily drop Make sure the measuring interval is established accord ing the variations in production load e g air compressors Always measure under the same production conditions Wide variations in the readings taken at different times can occur on heavily loaded roller bearings with surface damage The high readings are caused by metal par ticles breaking off the surfaces and by the sharp edges of new spallings When particles and edges are rolled o
39. se insufficient lubrication The reading does not drop Probably causes e Incorrect bearing installation e Cavitation in pumps e Mechanical rubbing Probably causes e he bearings inner ring is slipping on the shaft e The bearings outer ring is slipping in the housing The reading has been taken just after lubricating a Temperature Measurement Temperature measurement is carried out with a con tact free infrared sensor IR The sensor is placed on top of the instrument next to the probe transducer The window of the sensor is covered with a filter for infrared radiation If the window is covered or smudged with some other material e g water the sensor will not be able to detect the correct amount of radiation and the instrument will therefore give an incorrect reading A polished metal surface emits less radiation than a painted surface If you want to measure on a polished metal surface you may have to attach a paper label or paint the surface to get a correct reading Also bear in mind that a blank surface may reflect heat radiation from surrounding objects Emissivity of some common materials Pain vanish ummmfo O The viewing angle of the sensor is 60 degrees giving a measuring area of 36 mm diameter at the distance of the probe tip and 115 mm at a 10 cm distance To measure temperature Measurement area Measurement indicator Temperature measurement c
40. the probe tip against the measuring point until the rubber sleeve is in contact with the surface Hold the probe steady to avoid rubbing between probe tip and surface The probe is directionally sensitive It has to be pointed straight at the bearing The centre of the probe tip should touch the surface Avoid pressing the probe tip against cavities and fillets which are smaller than the probe tip Shock pulse transducer with handheld probe The handheld probe can be used to reach measuring points in narrow spaces and has the same construction and method of operation as the built in transducer see above The only part likely to wear out is the rubber sleeve for the probe tip It is made of chloroprene rubber neoprene and tolerates 110 C 230 F Spare sleeves have part number 13108 Rubber sleeve in contact With the surface Point at the bearing Hold steady Avoid small cavities and fillets Transducer with probe TRA73T Transducer with quick connector All types of shock pulse transducers are connected to the transducer input 8 The choice of transducer type depends on how the measuring point is prepared For systematic shock pulse monitoring Timken recommends the use of permanently installed adapters and quick connect transducer wherever possible Adapters are solid metal bolts of different length and thread sizes tuned for correct signal transmission They are installed in threaded
41. ucer Installed transducer The bearing at the fan end B requires a permanent transducer installation The transducer is installed in the bushing The coaxial cable is run through a slit in the fan cover to a measuring terminal on the stator frame Check installed equipment Incorrectly installed adapters or transducers can cause a significant damping of the shock pulse signal Check all installations Make sure that mounting holes are correctly countersunk and that the seat surfaces of adapters have good contact with the material of the bearing housings Any metallic machine part knocking or rubbing against the adapter will produce a disturbance This must be avoided by making large clearance holes and using soft elastic sealing material Use high temperature cables and moisture proof equipment where required and protect installations against damage Adapters should be fitted with protective caps Mark the measuring points Measuring points for the probe transducer should be clearly marked get comparable readings one must always use the same measuring point A drive end Measuring range The measuring range of the bearing tester is large and covers most bearing applications but there are a few cases where shock pulse monitoring should only be attempted with installed measuring equipment or not at all Shaft mm rpm High speed bearings bearing tester accepts max 19999 rpm 1999 mm shaft d
42. ured more often than other bearings The bearings should be measured more frequently when their condition is unstable rising or irregular readings Damaged bearings should be closely watched until they can be replaced This implies that one has to allow time for extra checks on bearings in dubious or bad condition Check stand by equipment Vibration and corrosion can damage the bearings in stand by machines Check bearing condition each time such machines are being tested or used Synchronize with lubrication It may be necessary to synchronize regreasing and measuring intervals Grease lubricated bearings should not be measured until they have run for approximately one hour after regreasing except when doing a lubrication test Keep in mind that bad bearing condition is often connected with lubrication problems For grease lubricated bearings a lubrication test usually provides the final proof of bearing damage Make sure that the right type and quantity of grease Is used 16 shock pulse transducers Built in transducer with probe Measuring points for the built in probe should be clearly marked Always measure in the same spot In addition the probe is used to measure elsewhere on the machine in case it is necessary to search for other shock pulse sources such as pump cavitation or rubbing parts The probe tip is spring loaded and moves within a sleeve of hard rubber To maintain a steady pressure on the tip press
43. ut the readings will drop again 60 50 30 20 dBn 3 Patterns from poorly lubricated bearings A high carpet value very close to the maximum value Is typical for dry running bearings The dBm does not always reach the red zone typical for poor lubrication is that the gap between dBm and dBc is very small If the signal is strongest on the bearing housing it can have several causes insufficient lubricant supply to the bearing poor oil flow old caked or cold grease very low or very high bearing speed preventing the build up of an oil film separation between the loaded rolling elements and the raceway installation fault excessive preload or out of round bearing housing misalignment or bent shaft If possible lubricate the bearing or increase the oil flow Measure immediately afterwards and again a few hours later If the problem was insufficient lubricant supply the shock pulse level should drop and stay low In the case of very low or very high bearing speed one can try lubricants of a different viscosity or use addi tives to prevent metal to metal contact between the bearing surfaces In cases of installation faults unround housings and misalignment the shock pulse level may drop after lubrication but will soon rise again Misalignment nor mally affects the bearings on both sides of the coupling or at both ends of the shaft Cavitation and similar interference The shock pu
44. utomatically be made to check the quality of the signal transmission between transducer and instrument to see the TLT val ue enter the TLT mode see below Part of your signal will be lost in a poor transducer line so your measuring results will be lower than they should be If an shock pulse measurement is made with a poor transducer line the instrument will display a TLT warning sign To perform a transducer line test TLT manually connect the external transducer to the instrument From the Main display press the UP arrow key to enter the Bearing folder then use LEFT RIGHT arrow keys to highlight the TLT icon Press the UP arrow key to enter the TLT menu Press the measuring key briefly The blue measuring LED lights up and the reading is shown in the display The TLT test window also displays transducer type IPR internal probe EPR external probe TRA 40000 type or TMU 42000 type TRA is also displayed in case of a cable breakdown The TLT value then depends on the distance to the breakage point 1 2 dB meter In case of a short circuit TMU and the value normally Is displayed At TLT values from 15 upward there is normally no signal loss due to poor transmission between trans ducer and instrument If the value is below 15 or if it is deteriorating from a previously higher value you need to check cables connectors and transducers for poor connections and moisture The TLT test can be temporarily turned off
45. verified the reading there is no need for any further evaluation The maximum value can be lower than 0 However be suspicious when the measured value is very low The cause is often a bad measuring point or an incorrectly installed adapter or transducer If the reading is very low check the installation Measure on other parts of the bearing housing and try to pick up a stronger signal Another possible reason for a very low reading is that there is no load on the bearing This can happen with well balanced fans and similar rotating machines 26 A Maximum value dBm B Difference between dBm and dBc C Rhythm of the strongest pulses Evaluation code 3 90 B s z CE Bi 2 Signal from a damaged bearing The pattern shown is typical for damaged bearing surfaces a dBm above 35 dB a large gap between dBm and dBc and a random pattern of strong pulses The strength of the maximum value dBm indicates the degree of damage 35 40 Slight damage 40 45 Severe damage gt 45 dB High breakdown risk First signs of damage dBm values between 20 and 35 dB in the yellow zone and a moderate increase of the carpet value are a sign of stress in the bearing surfaces or minor damage Note that the gap between dBm and dBc gets larger Bearings with dBm values in the yellow zone should be measured more frequently to determine if their condi tion Is stable or deteriorating A similar patte
46. weaker shock pulses E ali up LED on the condition scale for normalized readings only green for dBn up to 20 dBn good condition yellow for 21 34 dBn caution red for 35 dBn and more bad condition The maximum value dBm defines the bearing s position on the condition scale The difference between dBm and dBc is used for a finer analysis of the causes for reduced or bad condition Unnormalized readings For unnormalized readings set the dBi value to see chapter Input data You will then measure In dBsv absolute shock values and get no condition indication as the condition scale is graded In normalized shock values dBn This method is used for comparative readings on different bearings and or other shock pulse sources The dBm dBc technique dBy 60 40 20 The dBm dBc technique has been successfully applied for more than 35 years and continues to be widely used It is well suited for industrial condition monitor ing because it works with few easy to understand in and output data Even on a logarithmic scale there is normally a large distinct difference between the maximum values from good and bad bearings Thus minor inaccuracies in the input data rpm and shaft diameter have little effect on the evaluated measuring result Lubrication condition is indicated by the delta value i e the difference between dBm and dBc High readings 10 100 Life time and a small delta valu
47. y 6 while in the Bearing mode The blue measuring LED 9 stops blinking when a measuring cycle is completed The green yellow and red LEDs 4 beside the display indicate the bearing condition after an shock pulse measurement If not used the instrument will automatically shut off after 2 minutes It can also be shut off by simultane ously pressing the LEFT and RIGHT arrow keys When switched back on the instrument will resume its last mode Serial number and software version To check which software version is in your instrument and find out the instrument serial number go to the Main display Press the DOWN arrow key to enter the General Settings mode Use LEFT RIGHT arrow keys to highlight the Information icon i then press the UP ar row key to see the software version and serial number To return to the General Settings mode press the LEFT arrow key To return to the Main display use LEFT RIGHT arrow keys to highlight the Return icon then press the UP arrow key Main display Software version and serial number TIMKEN do KJ Back Return Batteries The instrument is powered by two batteries type MN 1500 L R6 Alkaline AA or rechargeable batteries can be used Please note that rechargeable batteries must be removed from the instrument before recharging The battery compartment is located at the back Press and push the lid to open the compartment The battery test on t
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