Office of Research and 

Development 

Washington, D.C. 20590

Federal 

Railroad 

Administration 

U.S. 

Department 

This document is available to the 

U.S. public through the National 

Technical Information Service 

Springfield, Virginia 22161

August 2003 

Final Report

DOT/FRA/ORD-00/06.II

ACOUSTIC DETECTION OF 

ROLLER BEARING DEFECTS: 

PHASE II, FIELD TEST 
Notice:

This document is disseminated under the sponsorship of the Department of Transportation in 

the interest of information exchange. The United States Government assumes no liability for 

the contents or use thereof. 

 

Notice: 

The United States Government does not endorse products or manufacturers. Trade or 

manufacturers' names appear herein solely because they are considered essential to the 

object of this report 
i 

2.2 

REPORT DOCUMENTATION PAGE Form approved 

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, 

searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send 

comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to 

Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 

22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0702-0288), Washington, D.C. 20503 

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

August 2003 FRA, Nov.-Dec. 1996 

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS 

Acoustic Detection of Railcar Roller Bearing Defects: 

Phase II, Field Test Report 

6. AUTHOR(S) 

Gerald B. Anderson, James E. Cline, Transportation Technology 

Center, Inc. and Richard L. Smith, North-South-East-West (NSEW)

DTFR53-93-C-00001, Task Order 111

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION 

 REPORT NUMBERS

Transportation Technology Center, Inc. 

P.O. Box 11130 

Pueblo, CO 81001

9. SPONSORING/MONITORING AGENGY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING 

AGENCY REPORT NUMBER 

U.S. Department of Transportation Federal Railroad Administration 

Office of Research and Development 

1120 Vermont Avenue, NW 

Washington, D.C. 20590

DOT/FRA/ORD-00/06.II 

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

This document is available through National Technical Information 

Service, Springfield, VA 22161

13. ABSTRACT

The Transportation Technology Center, Inc. (TTCI), a subsidiary of the Association of American Railroads 

(AAR) Research and Test Department, conducted a series of simulated revenue service tests with a train of 

eight cars containing wheel sets with specific roller bearing defects and wheel sets with good bearings. 

Testing was completed to record acoustic emissions of the bearings as they passed an array of microphones 

mounted along the track. Tests were conducted at the Transportation Technology Center in November and 

December 1996. Data collected was processed, filtered only to improve data quality, and distributed on 

compact disks to all program participants. The database was established to encourage development of 

advanced roller bearing inspection systems for railroad implementation. Participants included several 

potential developers of detector systems. The bearing defect types tested include raceway spalls (inner and 

outer ring, single or in multiples), roller defects, water etching, and loose inner rings (spun cones). This 

report describes the test methodology, instrumentation, and operation, as well as providing a description of 

the database content.

14. SUBJECT TERMS 15. NUMBER OF 

PAGES

50 

16. PRICE CODE

Acoustic railroad bearing detection, tapered railroad roller bearings, railroad bearing 

defects, spalls, water etching, loose inner rings, roller defects

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 

OF THIS PAGE 

19. SECURITY CLASSIFICATION 

OF ABSTRACT 

20. LIMITATION OF 

ABSTRACT 

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED SAR 

NSN 7540-01-280-5500 Standard Form 298 (Rec. 2-89) 

Prescribed by ANSI/NISO Std. 

239.18 

298-102

iii 

Acknowledgements 

Those who contributed to making the field test a success are gratefully appreciated and 

acknowledged. First of all, we thank those TTCI staffers who assembled the bearings and put 

the test train together: Allen Armstrong, John Peachee, Ray Martin, and Joe Chamberlin. A 

special thanks to the train crew and test controller: Dean Holcomb, Bob Thuyns, and Gordon 

Columber. From the TTCI instrumentation crew, a special thanks to Richard Graff, Dave 

Williams, and Carl Bachhuber. And thanks to the engineering and computer support provided by 

Jim Bilodeau. 

In addition to those directly involved in the test, the authors offer special thanks to the Federal 

Railroad Administration for making this program a reality, including Gerard Deily, Contracting 

Officers Technical Representative, and Monique Stewart, Task Order Technical Monitor. 
iv 

(blank page) 
v 

EXECUTIVE SUMMARY 

This research project solicited participation by industry and academia to stimulate the 

development of improved wayside defective railroad roller bearing detection techniques. A 

series of laboratory and field tests were conducted using defective and good railroad roller 

bearings to generate practical bearing acoustic emission databases. These databases will be 

available for the development of analytical techniques to "recognize" bearing defects from 

wayside sensor systems, and to produce working detector systems based on specific acoustic 

emissions. 

This report describes the field tests of the Improved Freight Car Roller Bearing Wayside 

Inspection Program conducted by Transportation Technology Center, Inc. (TTCI), a subsidiary 

of the Association of American Railroads (AAR) at the Federal Railroad Administration's (FRA) 

Transportation Technology Center (TTC) in Pueblo, Colorado. The program is funded by the 

FRA under Task Order No. 111, Contract DTFR53-93-C-00001, with in-kind support from the 

AAR. This report also provides a brief synopsis of the data collected. A thorough description of 

the acoustic instrumentation used to collect the data is provided along with the minimal filtering 

and processing performed on the data prior to distribution. The data was carefully checked 

before testing ended to ensure that all defective bearing conditions were represented in the 

database without error to the best knowledge of the authors. The database was distributed to the 

participants in binary format on two compact disks (CDs). 

Objectives of the field test included: (1) determine if acoustic techniques can be reliably used in 

a wayside operation to identify the same specific bearing defects that were used in the laboratory 

test, (2) identify improvements in acoustic signal processing techniques, and (3) identify 

improvements in current wayside acoustic sensor arrays and/or improved array designs to 

enhance system performance. These objectives were accomplished by distributing the field test 

data of defective bearing acoustic emissions to program participants who will work with this data 

to develop improved wayside detector systems. 
vi 

(blank page) 
vii 

Table of Contents 

1.0 INTRODUCTION.................................................................................................. 1 

 1.1 Objectives..................................................................................................... 1 

 1.2 Background .................................................................................................. 2 

2.0 TEST SPECIMENS .............................................................................................. 3 

 2.1 Test Train Makeup........................................................................................ 3 

 2.2 Test Site ....................................................................................................... 5 

3.0 INSTRUMENTATION AND DATA COLLECTION ................................................ 6 

 3.1 Data Sensors................................................................................................ 6 

 3.2 Data Collection System ................................................................................ 7 

4.0 TEST PROCEDURES .......................................................................................... 9 

 4.1 General Procedures ..................................................................................... 9 

5.0 TEST RESULTS................................................................................................. 10 

6.0 DISCUSSION ..................................................................................................... 14 

 6.1 Acoustic Data ............................................................................................. 14 

7.0 CONCLUSIONS ................................................................................................. 24 

8.0 RECOMMENDATIONS ...................................................................................... 25 

Appendix A: List of Participants...................................................................................A-1 

Appendix B: Defective Bearing Tables & Photographs ...............................................B-1 
viii 

List of Figures 

Figure 1. Test Train ..................................................................................................... 3 

Figure 2. Wayside Test Site ........................................................................................ 6 

Figure 3. Microphone Array ......................................................................................... 6 

Figure 4. Wayside Instrumentation Setup.................................................................... 8 

Figure 5. Typical Test Run Data Plot......................................................................... 13 

Figure 6. Exaggerated Illustration of Bow Wave Effect.............................................. 13 

Figure 7. Large Cup Defect in Bearing on Axle 4 of Run 24...................................... 15 

Figure 8. Large Cone Defect in Bearing from Axle 19 of Test Run 24....................... 16 

Figure 9. Raw Acoustic Microphone Output from "Run 24AP1N30.001"................... 16 

Figure 10. First Derivative of Acoustic Microphone Output from "Run 24AP1N30.001" 

with Wheel Gate Signatures attached below.............................................. 16 

Figure 11. CD Data File 24AP1N30.001 after Envelope Detection Processing is 

Applied ....................................................................................................... 17 

Figure 12. Expanded CD Data File 24AP1N30.001 Signature from the up Defective 

Bearing on Axle 4 of Car 1 ......................................................................... 18 

Figure 13. Spectrum of Above Enlarged Trace from Cup Defective Bearing on 

Axle 4 ......................................................................................................... 18 

Figure 14. Expanded CD Data File 24AP1N30 Signature from the Cone Defective 

Bearing on Axle 19 of Car 5 ....................................................................... 19 

Figure 15. Spectrum of above Enlarged Trace from 

Cone Defective Bearing on Axle 19............................................................ 19 

Figure 16. Spectral Plots from 12 Microphone Matrix Signatures for 3 Bearings ........ 21 

Figure 17. Spectral Plots from 12 Microphone Matrix Signatures for 3 Bearings ........ 22 

List of Tables 

Table 1. Car Numbers and Weights ........................................................................... 4 

Table 2. Defective Bearing Location & Onboard Instrumentation............................... 4 

Table 3. Defective Bearing Location and Onboard Instrumentation ........................... 5 

Table 4 Test Run Information—First half................................................................. 10 

Table 5. Test Run Information—Second half............................................................ 11 

Table 6. Test Run Data Included in CDs .................................................................. 12 

Table 7. Typical Statistical Table—Lab Data (volts) ................................................. 12 

Table 8. CD File Sizes and Names .......................................................................... 14 
1 

1.0 INTRODUCTION 

This report documents Phase II, the field test for wayside acoustic bearing development of the 

Improved Freight Car Roller Bearing Wayside Inspection Program conducted by Transportation 

Technology Center, Inc. (TTCI), a subsidiary of the Association of American Railroads (AAR). 

The program was funded by the Federal Railroad Administration (FRA) under Task Order No. 

111, with in-kind support from the AAR. 

1.1 Objectives 

Based upon the current understanding of the capabilities of present wayside acoustic roller 

bearing inspection technology, the following research objectives were determined for the field 

testing phase of the program. 

Building on the success of the laboratory investigation (Phase I) of acoustic roller bearing defect 

detection, determine if acoustic techniques can be reliably used in a wayside operation to identify 

the same specific defects that were used in the laboratory test bearing specimens. Specifically, 

defects and objectives as identified in the AAR Manual of Standards and Recommended 

Practices, Section H-II, Rule 1.15 were: 

1. Spun cone or loose components, in the absence of spalling of the raceway surfaces, 

for a bearing operating in the fully loaded or light car condition. 

2. Broken roller element condition for a bearing operating in the fully loaded or light-car 

condition. 

3. AAR condemnable cone spall defect for a bearing operating in the fully loaded or 

light-car condition. 

4. AAR condemnable multiple connecting cone spall defect for a bearing operating in 

the fully loaded or light-car condition. 

5. AAR condemnable cup spall defect for a bearing operating in the fully loaded or 

light-car condition. 

6. AAR condemnable multiple connecting cup spall defect for a bearing operating in the 

fully loaded or light-car condition. 

7. AAR condemnable water etching defects for a bearing operating in the fully loaded or 

light-car condition. 

8. Identify improvements in acoustic signal processing currently in use and improved 

signal processing techniques. Although many of the improvements may have been 

determined from the laboratory testing, the wayside acoustic processing will bring 

additional challenges to the inspection system function. 

9. Identify improvements in current wayside acoustic sensor arrays and/or improved 

array designs to enhance system performance (reliability and repeatability). 
2 

1.2 Background 

A meeting was held June 15, 1994, at what was then the AAR's Chicago Technical Center to 

initiate and review objectives of the Improved Freight Car Roller Bearing Wayside Inspection 

Program, sponsored by the AAR and the FRA. The objective of the meeting was to solicit 

participation by industry and academia to stimulate the development of improved wayside 

defective roller bearing detection techniques. Over 45 participants from industry, academia, and 

the national laboratories attended the meeting (Appendix A is a list of all participants). 

The planned means of accomplishing the objective was for the AAR to conduct a series of 

controlled laboratory and on-track tests to aid in the development of improved wayside defective 

railroad roller bearing detection. The controlled laboratory tests were conducted on the AAR's 

bearing test machines at the Transportation Technology Center (TTC), Pueblo, Colorado. A set 

of data from each of the good and defective bearings tested was made available to program 

participants for their bearing detection process development. 

Using many of the same defective bearings, the AAR conducted an on-track test series at the 

TTC, to provide an opportunity to develop improved detection techniques under controlled, 

simulated revenue service conditions. The tests were conducted in November 1996, using a 

combination of eight empty and loaded freight cars of different capacity with a mix of good, 

remanufactured, and defective bearings. This research program has and will continue to provide 

an indispensable database for developing and refining signal processing techniques for the 

identification of defective roller bearings on freight cars. 
3 

2.0 TEST SPECIMENS 

2.1 Test Train Make-up 

The test train consisted of one locomotive followed by eight 70- and 100-ton capacity freight 

cars, four loaded and four empty (see Figure 1). 

Figure 1. Test Train 

Wheel sets and/or trucks were switched between freight cars once during the testing to place 

defective bearings under different car loads. There was an AAR test/instrumentation car in the 

consist as well to provide onboard monitoring of defective bearings and other support services. 

Each car was weighed on a car scale before testing. Table 1 lists the car numbers and their 

weights. 

The test train was operated past the wayside instrumentation from both directions. Both train 

directions are shown in Figure 1. Note that in the lower illustration, the direction of movement 

and the location of the instrumentation car and locomotive have changed. The other cars are not 

turned. The side of the cars with the defective bearings were always toward the south, the side of 

the wayside instrumentation. 

For the purpose of presenting different combinations of bearings to the wayside sensor array(s), 

70- and 100-ton cars, empty and loaded, were distributed in the train in a pseudo-random 

manner. There were "good" bearings distributed between the defective bearings for the same 

purpose. Table 2 lists the locations of the defective bearings in the test consist for the first half 

and Table 3 for the second half of the test. Each figure shows the onboard instrumentation that 

was used to monitor the defective bearings. Photographs of each defective bearing, from leading 

end of first car sequentially down to the train, are in Appendix B. 
4 

Table 1. Car Numbers and Weights 

Car Number A-End 

Weight 

B-End 

Weight 

Total Weight 

(lbs.) Car Capacity 

DOTX 205 80467 80063 160530 Inst. Car 

TTX 479303 68182 78015 146197 70-Ton loaded 

AAR 704 133034 133018 266052 100-Ton loaded 

DOTX 307 78819 86739 165558 70-Ton loaded 

AAR 703 132885 133687 266572 100-Ton loaded 

TTWX 981423 34106 35891 69997 70-Ton empty 

AAR 707 39285 48459 87744 100-Ton loaded 

RTTX 152423 35046 35664 70710 70-Ton empty 

AAR 705 32103 33632 65735 100-Ton empty 

Table 2. Defective Bearing Location & Onboard Instrumentation 

First Half—Wayside Bearing Defect Detection Consist Table 

Car BEARING DEFECT TEMP ACCEL CONE SLIP 

 1 Single Cup Spall 

No. 1 2 Remanufactured 

70T 3 Single Cone Spall 

LOAD 4 Remanufactured 

 5 Single Cup Spall 

No. 2 6 Remanufactured 

100T 7 Single Cone Spall 

LOAD 8 Remanufactured 

 9 Broken Roller X 

No. 3 10 Remanufactured 

70T 11 Water Etched X 

 12 Remanufactured 

 13 Remanufactured 

No. 4 14 Spun Cone X X X 

100T 15 Spun Cone X X X 

LOAD 16 Remanufactured 

 17 Remanufactured 

No. 5 18 Spun Cone X X X 

70T 19 Spun Cone X X X 

EMPTY 20 Remanufactured 

 21 Remanufactured 

No. 6 22 Water Etched X 

100T 23 Remanufactured 

EMPTY 24 Broken Roller X 

 25 Remanufactured 

No. 7 26 Multiple Cone Spall 

70T 27 Mystery 

EMPTY 28 Multiple Cup Spall 

 29 Remanufactured 

No. 8 30 Multiple Cone Spall 

100T 31 Mystery X 

EMPTY 32 Multiple Cup Spall 
5 

Table 3. Defective Bearing Location and Onboard Instrumentation 

Second Half—Wayside Bearing Defect Detection Consist Table 

Car BEARING DEFECT TEMP ACCEL CONE SLIP 

 4 Remanufactured 

No. 1 3 Single Cone Spall 

70T 2 Remanufactured 

LOAD 1 Single Cup Spall 

 8 Remanufactured 

No. 2 7 Single Cone Spall 

100T 6 Remanufactured 

 12 Remanufactured 

No. 3 11 Water Etched X 

70T 10 Remanufactured 

LOAD 9 Broken Roller X 

 16 Remanufactured 

No. 4 15 Spun Cone X X X 

100T 14 Spun Cone X X X 

LOAD 13 Remanufactured 

 20 Remanufactured 

No. 5 19 Spun Cone X X X 

70T 18 Spun Cone X X X 

EMPTY 17 Remanufactured 

 24 Broken Roller X 

No. 6 23 Remanufactured 

100T 22 Water Etched X 

EMPTY 21 Remanufactured 

 28 Multiple Cup Spall 

No. 7 27 Mystery 

70T 26 Multiple Cone Spall 

EMPTY 25 Remanufactured 

 32 Multiple Cup Spall 

No. 8 31 Mystery X 

100T 30 Multiple Cone Spall 

EMPTY 29 Remanufactured 

2.2 Test Site 

Testing was conducted at TTC on the Railroad Test Track (RTT) at the existing Hot Bearing 

Detector (HBD) test farm (Station 14). This location is equipped with two bungalows with 100 

VAC power and telephone services. The track section at Station 14 is tangent with a grade of 

0.26 percent. Figure 2 shows the test site. 
6 

Figure 2. Wayside Test Site 

3.0 INSTRUMENTATION AND DATA COLLECTION 

3.1 Data Sensors 

The AAR, under this joint program, provided a microphone array to collect the wayside acoustic 

emissions of the passing test train. The data from this array comprised, in large part, the data 

distributed to the program participants. The 12-microphone array, Figure 3, was set back from the 

test track (measured from gage face of rail) approximately 38 inches, with a spacing between 

microphones of 35 inches. The microphones were mounted horizontally, as shown, and based at a 

compromise height of 35 inches (for 33- and 36-inch wheels) from top of rail at the same height as 

the centerline of the roller bearings. Each microphone was protected from wind noise by a wind 

sock. The microphones have a frequency response of 1 Hz to 40 kHz. The low frequency 

response of the microphones caused a problem by responding to the aerodynamic bow wave in 

front of the locomotive. This was seen in the data as a large DC offset with a rather slow recovery. 

High-pass filtering was added to some microphone channels during the testing to alleviate this 

problem. For the remainder of the channels, the data was digitally filtered after the test. 

Figure 3. Microphone Array 
7 

Wheel presence detectors, operating by electromagnetics, were used to indicate axle speed and to 

position the wheels in time relative to the location of the microphones. 

In addition to the wayside acoustic array, onboard bearing sensors were used to monitor 

temperature on those defective bearings whose performance at test speeds and loads was deemed 

critical. The critical bearing defects included spun cones and damaged rollers, because industry 

research has shown that these defects are the most likely to lead to rapid bearing burn off. 

Sensing was done for safety purposes and was not included in the data set CD. 

The spun cone bearings were also equipped with the cone motion sensor system that was used in 

the laboratory tests for measuring cone rotation. This sensing system consisted of small rare 

earth magnets attached to the axle, as a fixed reference, and to the bearing cone back face. "Hall 

Effect" (physical phenomena) sensors located off the axle and in the bearing seal case were used 

to trigger timers to reference cone motion to that of the axle. Identical values represented no 

relative cone to axle rotation. Differential readings indicate relative motion as well as the 

amount of cone slip. 

Train speed was recorded from onboard the test car within 1 mph, and train presence/speed 

pulses were recorded at wayside. An existing HBD system on the RTT (Servo 9000) was also 

used to monitor bearing temperatures and as a comparative performance measure for the onboard 

safety sensors. 

3.2 Data Collection System 

The wayside acoustic and wheel presence data was collected in parallel by fast digital computer 

and on analog tape. The tape was used as backup for the digital computer. A sample rate of 125 

kHz per channel was chosen for the microphones to fully support the highest expected useful 

frequency content of the data. The sample rate was based on frequency evaluation of the 

laboratory data. An analog filter for anti-aliasing was used between the microphones and the 

digital computer with an appropriate filter cut-off frequency. As stated previously, a high-pass 

filter, set to approximately 8 Hz was installed between some of the microphones and the 

computer during the testing. All data was digitally filtered in the post-test data processing. 

Figure 4 shows the wayside instrumentation. 
8 

Figure 4. Wayside Instrumentation Setup 

Data was sampled and stored in RAM (memory) on the computer during each test run. After 

each run, this data was written to a hard drive in a packed binary format. Subsequently, this data 

was re-formatted to standard binary for processing. 

In addition to the data collected under this program, several of the program participants brought 

their own instrumentation and data collection equipment. Data collection was proprietary to 

each participant, but the list of those involved is included here for information: 

1. Harmon Industries - wayside acoustic data 

2. Salient Systems/Battelle Labs - wayside acoustic data 

3. Vipac Inc. - wayside acoustic data 

4. SAIC - wayside thermal data 

5. GRS - onboard thermal data 

6. Elexor Associates - onboard thermal data 

7. Brenco - onboard bearing data 

8. Timken - onboard bearing data 

9. NSEW - wayside acoustic data 
9 

4.0 TEST PROCEDURES 

4.1 General Procedures 

The test was divided into two halves. Many identical test runs were made in both halves, but the 

test consist and defective bearings were rearranged between the halves. In this manner, the 

defective bearings were moved from lightly loaded to heavily loaded axles and vice-versa. 

A test run consisted of backing the train a sufficient distance to achieve the desired speed past 

the wayside instrumentation. After backing, the consist was accelerated to the desired speed and 

run past the wayside instrumentation. For test runs at 70 miles per hour (mph), a complete lap 

around the RTT was made. 

The train was braked to a stop after almost all runs. The test train was operated in three different 

modes past the instrumentation. In most cases, locomotive power was applied and speed was 

held constant. The train was also operated in coast mode, where speed was allowed to diminish 

slightly as locomotive power was put to idle. 

The third mode was braking. Here the train was accelerated to the desired speed, then before 

reaching the wayside instrumentation, a train air brake application was made. The amount of the 

brake application was typically half service. 

During a test run, the wayside instrumentation was operated for a period before train arrival and 

shortly after departure to ensure complete capture of the acoustic information. Data files were 

then trimmed to remove excess "zero" information during post test data processing. 

In addition to the wayside instrumentation, the critical bearing temperatures and cone movement 

in the spun cone bearings were monitored from the instrumentation car during all train 

movements. Onboard data was also collected during each test run for post-test review. 
10 

5.0 TEST RESULTS 

Table 4 lists the test run numbers and other pertinent information for the first half of the test. 

Table 5 shows data from the second half. 

Table 4. Test Run Information—First half 

Run No. Date Time Speed Mode 

1a 11/18/96 13:05 25 Power CW* 

1b 11/18/96 13:34 25 Power CW 

2a 11/18/96 13:50 30 Power CW 

3a 11/18/96 14:15 40 Power CW 

2b 11/18/96 14:48 30 Power CW 

4a 11/18/96 15:23 50 Power CW 

5a 11/18/96 16:08 55 Power CW 

6a 11/18/96 16:28 60 Power CW 

7a 11/18/96 16:55 70 Power CW 

1c 11/19/96 09:40 25 Power CW 

8a 11/19/96 10:15 30 Power CW 

9a 11/19/96 10:26 30 Power CW 

10a 11/19/96 10:46 50 Power CW 

10b 11/19/96 13:01 50 Power CW 

11a 11/19/96 13:26 30 Coasting 

12a 11/19/96 13:42 40 Coasting 

13a 11/19/96 13:54 50 Coasting 

14a 11/19/96 14:28 30 Braking 

15a 11/19/96 14:40 40 Braking 

16a 11/19/96 14:54 50 Braking 

17a 11/20/96 09:43 25 Power CCW** 

18a 11/20/96 09:55 30 Power CCW 

19a 11/20/96 10:05 40 Power CCW 

20a 11/20/96 10:36 50 Power CCW 

21a 11/20/96 10:53 55 Power CCW 

22a 11/20/96 13:02 60 Power CCW 

23a 11/20/96 13:13 70 Power CCW 

23b 11/20/96 13:34 70 Power CCW 

24a 11/20/96 14:44 30 Power CCW 

*Clockwise **Counterclockwise 
11 

Table 5. Test Run Information—Second half 

Run No. Date Time Speed Mode 

27a 11/25/96 11:22 25 Power CCW 

28a 11/25/96 11:41 30 Power CCW 

29a 11/25/96 13:33 40 Power CCW 

30a 11/25/96 14:13 50 Power CCW 

31a 11/25/96 14:35 55 Power CCW 

32a 11/25/96 14:53 60 Power CCW 

33a 11/25/96 15:42 70 Power CCW 

33b 11/25/96 15:58 70 Power CCW 

34a 11/25/96 16:21 30 Power CCW 

36a 11/25/96 16:47 50 Power CCW 

43a 11/26/96 09:32 25 Power CCW 

45a 11/26/96 09:46 40 Power CCW 

46a 11/26/96 10:05 50 Power CCW 

48a 11/26/96 10:47 60 Power CCW 

49a 11/26/96 11:08 70 Power CCW 

41a 11/26/96 11:32 40 Braking CCW 

42a 11/26/96 13:25 50 Braking CCW 

48b 11/26/96 13:43 60 Power CCW 

49b 11/26/96 13:59 70 Power CCW 

41b 11/26/96 14:18 40 Braking CCW 

Upon completion of the test runs, the digital data was checked for integrity by plotting select test 

run time histories at various operating speeds. Based on an analysis of these plots, a method was 

determined for trimming the files for excess data taken either before the train reached the 

microphone array or after it had passed. A program was written to process each of the test files, 

to trim them and to multiply the binary values for engineering units. These processed files were 

then plotted to check for spurious data points, offsets, and other obvious digitization errors. 

When the data was reviewed, and the quantity of data realized, a selection was made of the 

"best" or cleanest data files for inclusion in the CDs for release to the program participants. 

Ultimately, 19 test runs were included in the two CDs that were produced in April of 1997. 

These test runs encompassed the full range of train speeds and operating conditions. The run 

numbers and other information are shown in Table 6. 
12 

Table 6. Test Run Data Included in CDs 

Run No. Train Speed Operating 

Mode 

Consist 

Configuration 

12a 40 Power CW 1 

13a 50 Coasting CW 1 

14a 30 Braking CW 1 

15a 40 Braking CW 1 

16a 50 Braking CW 1 

18a 30 Power CCW 1 

19a 40 Power CCW 1 

20a 50 Power CCW 1 

21a 55 Power CCW 1 

22a 60 Power CCW 1 

23b 70 Power CCW 1 

24a 30 Power CCW 1 

34a 30 Power CCW 2 

36a 50 Power CCW 2 

41a 40 Braking CCW 2 

42a 50 Braking CCW 2 

45a 40 Power CCW 2 

48a 60 Power CCW 2 

49a 70 Power CCW 2 

Table 7 provides the statistics made from the laboratory data. A similar approach was initially 

tried for the wayside data. After examining statistics from a few runs, the signal processing 

methods better revealed the character and usefulness of the file. 

Table 7. Typical Statistical Table—Lab Data (volts) 

File Mean Var StDev Skew Kurtosis Min Max 

30hst90 -0.002 1.809 1.345 0.134 -1.411 -1.968 2.151 

30hsc90 0.216 125.589 11.207 -0.027 1.302 -57.976 70.898 

File Range C.V. Counts LMean UMean LVar UVar 

30hst90 4.120 -558.104 65536.000 -0.013 0.008 1.789 1.829 

30hsc90 128.874 51.926 65536.000 0.130 0.302 124.240 126.960 

Figure 5 shows a series of typical plots made for a single test run. In addition to the plots made, 

statistical analyses were performed for each of the data channels for each test run, as a means of 

determining offsets and other data variations. 
13 

Figure 5. Typical Test Run Data Plot 

Early in the first half of the test on November 18, 1996, a large pressure wave was shown to be 

preceding the lead locomotive, and to a lesser extent at the leading edge of each hopper car that 

trailed a flat car. The effect of these pressure or “bow” waves is exaggerated in Figure 6. The 

air pressure in the wave caused a large offset to each of the 12 microphones as it passed. The 

frequency content of the wave was less than 2 Hz. 

Figure 6. Exaggerated Illustration of Bow Wave Effect 
14 

To reduce the effect of the bow waves on the test data, filtering was obtained for some of the 

microphones to do high frequency passing (above 8 Hz), and thus to filter out the low frequency 

offset. There were not enough channels of filtering to accommodate all the microphones, so the 

bow wave effect was digitally filtered as part of the post test data processing. This effect was 

overlooked in test preparations. 

6.0 DISCUSSION 

6.1 Acoustic Data 

Acoustic data from 49 test runs at speeds ranging from 25 to 70 mph were gathered from the 

wayside microphones. With 12 microphones and 2 wheel sensors, there was enough recorded 

data collected to fill several CDs. 

Two CDs, which represented the full range of test conditions, were recorded for release to the 

program participants. Each CD contains 500 megabytes of acoustic time-based bearing data along 

with bearing defect photographs and other test operational information. The CDs contain 14 

binary files for every test run included. Each file name has been encoded so that running speed 

and other operating conditions can be interpreted from the alphanumeric title. Each file also has a 

unique 3-digit extension that indicates from which microphone and/or wheel sensor the data was 

received. Table 8 lists the test runs and the size of the associated stored files on the two CDs. 

Table 8. CD File Sizes and Names 

Run No. File Name Samples 

per File 

Sample 

Rate 

(kHz) 

CD 

No. 

12a 12AC1S40 1206620 1.25 1 

13a 13AC1S50 953575 1.25 1 

14a 14AB1S30 1520561 1.25 1 

15a 15AB1S40 1166823 1.25 1 

16a 16AB1S50 987238 1.25 1 

18a 18AP1N30 1645071 1.25 1 

19a 19AP1N40 1174448 1.25 1 

20a 20AP1N50 1016290 1.25 1 

21a 21AP1N55 866557 1.25 1 

22a 22AP1N60 800016 1.25 1 

24a 24AP1N30 1651274 1.25 2 

34a 34AP2N30 1699602 1.25 2 

36a 36AP2N50 1012640 1.25 2 

41a 41AP2N40 1328932 1.25 2 

42a 42AP2N50 1129141 1.25 2 

45a 45AP2N40 1242085 1.25 2 

48a 48AP2N60 837721 1.25 2 

49a 49AP2N70 749145 1.25 2 
15 

In addition to the acoustic data, each CD also contains photographs of the defective test bearings. 

Two of the bearings are shown in detail in Figures 7 and 8. The bearings have large spalls on the 

cup and cone raceways, respectively. The bearing with the cone spalls (Figure 8) is also one of 

the test bearings operating with a spun cone. The frequency content of the types of defects 

shown in these two figures is given in Figures 9 through 11. 

Figure 7. Large Cup Defect in Bearing on Axle 4 of Run 24 

The acoustic signature from Run No. 24a (first half - consist given in Table 2) is shown in Figures 

9 through 11. Figure 9 shows a plot of the numeric data from microphone 1 as stored on the CD 

(i.e., disk file 24AP1N30.001). This time based display contains over 1.65 million real data points. 

The first time derivative of the data is displayed in Figure 10. This data has essentially the same 

frequency content as the previous plot, but contain no bias offset on the vertical axis. The purpose 

of the following discussion is to illustrate that the raw acoustic data contained in the CDs contains 

good bearing defect data when properly processed. It is presented here to verify basic data 

integrity and its use in the development of systems for defect recognition. 
16 

Figure 8. Large Cone Defect in Bearing from Axle 19 of Test Run 24 

Figure 9. Raw Acoustic Microphone Output from "Run 24AP1N30.001"

Figure 10. First Derivative of Acoustic Microphone Output from "Run 24AP1N30.001" with Wheel 

Gate Signatures attached below. Spikes in Wheel Signature are near the Bearing Locations during the Test 

Run. Numbers below the Two-Time Traces indicate the Center of each of the Test Cars for the Run. 
17 

Figure 11. CD Data File 24AP1N30.001 after Envelope Detection Processing is Applied 

(Dotted boxed portions of the above signals are discussed more thoroughly in Technology Digest 96-004 issued 

February 1996) 

The frequency content of the time signatures ranges from 3 Hz to over 40 kHz. At the base of 

Figure 10 is the wheel presence detector, which provides a sharp spike for every one of the 32 

passing wheels (bearings). The wheel spikes provide time based reference points that can be 

used to identify the acoustic signal position (and thus the character) of any passing test bearing 

after it passed. The center of each test car is also shown by a number. 

Figure 11 shows the time data from Figure 10 after it has been detected by the envelope. This 

process extracts a smooth outline tracing of the upper portion of the time based signature and 

ignores the negative part of the signal. Details of the envelope detection process and its potential 

for defect diagnostics have been discussed thoroughly in Technology Digest 96-004 issued by 

TTCI February 1996. The bearing defects shown in Figures 7 and 8 generated the acoustic 

outputs that have been boxed in with dotted lines in Figure 4. 

Figure 12 provides an expanded view of the microphone envelope signal from the fourth bearing 

on car 1. The signature comes from the severely spalled cup raceway, Figure 8. 
18 

Figure 12. Expanded CD Data File 24AP1N30.001 Signature from the up Defective Bearing on Axle 

4 of Car 1 (See dotted boxed portion of Figure 11) 

Figure 13 shows a low-frequency spectrum of the time based signature displayed in Figure 12. 

The spectrum has two dominant peaks. The one at 3.8 Hz corresponds to the anticipated 

rotational rate of the bearing (4.6 Hz) at 30 mph. The 3.8 Hz peak is within the expected 

frequency range since a single microphone can only provide enough time based data from typical 

wayside passes to resolve any peak within 1 Hz. The second peak at 49 Hz comes directly from 

the cup defect repetition rate at 30 mph. 

Figure 13. Spectrum of Above Enlarged Trace from Cup Defective Bearing on Axle 4. The 49 Hz 

Peak Corresponds to the Cup Defect 
19 

Figure 14 is an expanded view of the data from bearing 19 on car 5. This bearing contains the 

severely damaged cone shown in Figure 8. Figure 15 shows the low-frequency content of the 

time signature in Figure 14. It contains two or three dominant peaks. As before, the peak at 3.8 

Hz corresponds to the rotational rate (4.6 Hz) of the bearing at the 30 mph running speed. The 

second peak at 61 Hz comes directly from the cone defect repetition rate at the same speed. In 

this spectra there is also a minor peak at 15 Hz. Since this bearing also contains a spun cone 

defect, this anomalous peak may be associated with that defect, as well as other possible internal 

component damage. 

Figure 14. Expanded CD Data File 24AP1N30 Signature from the Cone Defective Bearing on Axle 

19 of Car 5 (See boxed portion of Figure 11)

Figure 15. Spectrum of above Enlarged Trace from Cone Defective Bearing on Axle 19 

The 61 Hz Peak corresponds to the Cone Defect Repetition Rate (Frequency) at the 30 mph Running Speed 
20 

Figures 16 and 17 show a variety of signal characteristics collected form axles (bearings) 11, 15, 

17, 18, and 19 in consist two. The train running speeds were 50 mph 60 mph. The interesting 

feature is that all the defective bearings emitted high frequency 

sounds, above 15 kHz. These vibrations were observed in several microphones in the wayside 

array. Since several microphones were in a linear array, it is also possible to review signals from 

any single bearing as it approached (or receded) from any of the centrally located microphones. 

Doppler shifts from loud approaching (or receding) bearings were observed. 
21 

Figure 16. Spectral Plots from 12 Microphone Matrix Signatures for 3 Bearings 

 Note High Amplitude 18 KHz Signature, Doppler Shifts, and Microphone Spill-Over of 

Sounds to Adjacent Bearing's Reference Points of View During Run 

Note to Figure 16: Sound of Bearing 18 from 17's microphone point of reference is on approach (i.e. 

Doppler shifted frequency higher). Also from Bearing 19's microphone point of reference, the sound of 

Bearing 18 is receding (i.e. Doppler shifted frequency lower). Distance from Bearing 18 to Bearing 17 is 10 

feet and distance from 19 to 18 is about 40 feet, so the observed level of 18's sound in Bearing 19''s record 

is lower than it is in the spectral record of 17. The source of the sharp peak at 32 KHz on the right side of 

each spectrum in unknown. 
22 

Note to Figure 17: Signal at 40 KHz has a greater amplitude than shown since the microphones 

attenuated signals above 30 KHz. Peak spacing in the 3 to 6 KHz range is about 640 Hz which is the 

same as the side bands on either side of the 32 KHz signal. The source of the sharp peak at 32 KHz to 

the right of center has not been established.

 

Figure 17. Spectral Plots from 12 Microphone Matrix Signatures for 3 Bearings 

Note Significant High Frequency 35-40 KHz Peaks in Defective Bearings 
23 

Figure 16 is a composite of three spectra. The spectra shown here are higher in resolution than 

previously discussed. The increase in resolution is possible since the data from each spectrum 

comes from a composite of signals collected from 12 microphones positioned along the track. 

The composite signal is a long timeframe concatenation of 12 separate time slices taken from the 

12 microphone files stored on a CD from a single test run. 

Due to the greater noise from bearing 18 relative to its neighbors, each spectrum of Figure 16 

contains the full acoustic response from the spun cone. Time slices from the array can be 

selected so as to be centered on any bearing as it passes through the array. Any set of slices 

selected for tracking a single bearing are either just before (or just after) another bearing in the 

train. As a result, the acoustic energy from one bearing's output can spill over into an adjacent 

bearing's timeframe, if the defective bearing signal is loud enough. 

Figure 16 shows the spill over effect of bearing 18 noise and its associated Doppler shift as it 

passes through the wayside microphone array. The signal from bearing 18 is higher in frequency 

as it approaches and then drops in frequency as it passes its neighboring bearing's reference 

frame. In addition, bearing 19 has its own spun cone output, which is identified as a separate 

frequency peak in the last spectrum in the figure. These large high-frequency amplitudes range 

from 15 kHz to nearly 20 kHz. Notice that although the high-frequency peaks displayed in this 

example are clearly generated by two separate bearings with the spun cone defect, this result is 

not universal. In other words, every test bearing with a spun cone defect did not generate 

observable high-frequency signatures during every pass. 

Figure 17 is another composite of three spectra that shows the acoustic character from three 

additional test bearings. As before, the displayed spectra are derived from time slices taken from 

all 12 microphones in the sampling array, and cover the range of frequencies from 0 to 50 kHz. 

The top portion of the display comes from a bearing which has no internal defects. It is one of 

the re-manufactured test bearings. The middle plot is derived from a bearing with internal water 

etched surfaces, and the lower tracing is from a bearing containing an inherent spun cone. 

The features of the above discussed spectra are all potential diagnostics for identifying the types 

of defective bearings reviewed. Only a few of the rich frequency based characteristics of the 

data contained in the two CDs are presented here. This discussion is a simplified overview of 

many acoustic signature subtleties that are available to those who are interested in digging 

further into the data on the CDs for diagnostic purposes. 
24 

7.0 CONCLUSIONS 

The following conclusions resulted from the test program: 

• Envelope detected acoustic signatures (even from a single microphone) contain frequencies 

that are generated by defective internal bearing components. 

• Spectrum of envelope detected acoustic signatures collected from wayside microphones 

contain peaks at (or near) the expected rotational frequencies of defective bearing 

components. 

• Many of the same laboratory test bearing defects were used in the field test and identified 

as such, which was a goal in the test program. 

• High frequency diagnostic information (i.e. 5 kHz to 40 kHz) is contained in the recorded 

wayside data and available from the CD files produced in this program. 

• Adjacent microphones with the 35-inch spacing used in the test program pick up 

approaching (and/or receding) bearing signals when they are loud enough. 

• Doppler shifts in approaching or receding bearings are present and affect frequency based 

analyses. 

• Train speed relates directly to the rotation rate of the wheels (bearings), and must be 

determined precisely from the passing wheel gate signals before accurate frequency based 

analyses can be performed on the bearings. 

• Knowledge of wheel size (bearing class/size) is also needed to accurately establish the 

rotational frequencies of the passing bearings at any train speed. 

• Emitted bearing sound levels increase with train speed. 

• Sound levels generated by the test bearings are dependent on car (bearing) load. 

• Data contained in the two CDs has been thoroughly checked and is an excellent database 

for the development of improved acoustic bearing detection systems. 
25 

8.0 RECOMMENDATIONS 

Based on the field tests, the following recommendations are made: 

• The field test has provided a consistent and unique database for the development of 

wayside acoustic bearing detection technologies. However, an actual system, when 

developed, will need to be performance-tested under service conditions, such as long 

trains, diverse environmental conditions, typical North American train operations, diverse 

car fleets, etc. 

• The field test has produced much usable bearing defect signature data; however, there are 

many variations in bearing defect sizes and patterns not included in this test. Any future 

testing should include other bearing defect sizes and configurations to broaden the 

database. 

• Care was taken during the field test to preclude additional acoustic emissions from 

contaminating this developmental database. Other acoustic sources might typically 

include wheel tread defects, air hose leaks, high winds, ground borne vibrations, or urban 

noises. Future testing should include such emitters to fully test the discriminating 

capabilities of a bearing acoustic detector. 

• Any acoustic bearing detection system design should consider gathering such additional 

vehicle information as wheel load, wheel rotational speed, and train speed. 
26 

(blank page) 
A - 1 

APPENDIX A 

List of Participants 

No. Organization Name Address

1. Alliant Tech. Systems Ed Page 1911 Fort Meyer Dr., Ste 601 Arlington, VA 22201 

2. AWI/AHI Robert Allen 10628 Dutchtown Rd. Knoxville, TN 39922 

3. AMP, Inc. David Kahn 100 Amp Dr. Harrisburg, PA 17105-3608 

4. ASRI Jen-Yi Jong 3322 S. Memorial Pkwy Huntsville, AL 35801 

5. Argonne National Lab John Kramer 9700 S. Cass Ave Argonne, IL 60439 

6. Barron Associates, Inc. B. Eugene Parker 3046A Berkmar Dr. Charlottesville, VA 

7. Battelle Michael Kurre 505 King Ave Columbus, OH 43201 

8. Battelle Foster Stullen 505 King Ave Columbus, OH 43201 

9. BNSF Geoff Dahlman 1001 NE Atchison Topeka, KS 66616 

10. Brenco, Inc. Kurt Fisher PO Box 389 Petersburg, VA 23804 

11. Brenco, Inc. Craig Norris PO Box 389 Petersburg, VA 23804 

12. Boulder Vibration Duncan Carter PO Box 3395 Boulder, CO 

13. CAE Vanguard Walter Anderson 3500 W 80th Street Minneapolis, MN 55431 

14. CAE Vanguard Bill Reid 3500 W 80th Street Minneapolis, MN 55431 

15. Carnegie Mellon William Kaufman PO Box 2950 700 Tech Drive Pittsburgh, PA 

16. CASI Craig Harston PO Box 251 Signal Mountain, TN 37377 

17. Colorado State University Mick Peterson Dept of Mechanical Engr. Fort Collins, CO 80523 

18. Commonwealth Tech. Joel Billingsley 5875 Barclay Drive Alexandria, VA 22315 

19. Concurrent Tech. Robert Czarnek 1450 Scalp Ave Johnstown, PA 15904 

20. Conrail Terry Tse 2001 Market Street Philadelphia, PA 19101 

21. Conrail Mike Lovette 2001 Market Street Philadelphia, PA 19101 

22. EDO Corp. (Gov Sys Div) Jonathan Schere 14-04 111th Street College Point, NY 11356 

23. Elexor Associates Tim Slifkin PO Box 246 Morris Plains, NJ 07950 

24. Epoch Engineering Mike Holland 2001 Jefferson Davis Hwy Arlington, VA 

25. GE Harris Charles Zahm PO Box 8900 Melbourne, FL 32902-8900 

26. Harmon Industries Misa Janda 415 Oser Ave Hauppage, NY 11788-3260 

27. Harmon Industries William Schrack 415 Oser Ave Hauppage, NY 11788-3260 

28. Harmon Industries Mark Orlassino 415 Oser Ave Hauppage, NY 11788-3260 

29. International Electronic Mach. Zahid Mian 60 4th Ave Albany, NY 12202 

30. Kaman Sciences Jeff Brandt 1500 Garden of the Gods Rd Colo Spgs, CO 

31. Kaman Sciences Peter Snow 1500 Garden of the Gods Rd Colo Spgs, CO 

32. Matrix Corporation Laurent Meilleur 1203 New Hope Rd Raleigh, NC 27610 
A - 2 

No. Organization Name Address

33. National Research Council Jeff Xi 3250 East Mall Vancouver, BC V6T1W5 CANADA 

34. National Research Council G.K. Krishnappa 3250 East Mall Vancouver, BC V6T1W5 CANADA 

35. New York Institute of 

Engineering 

Jun Ma 116 Harry Schure Hall Old Westbury, NY 11568 

36. Norfolk Southern Lincoln Keegan 407 South Henry Alexandria, VA 22314 

37. Northrop/Grumman Alberd Taylor 1111 Stewart Ave Bethpage, NY 11714 

38. North South East West Richard Smith 4 North Nottingham Way Clifton Park, NY 12065 

39. Pacific Northwest National Lab Tom Ferryman PO Box 999 Battelle Blvd. Richland, WA 

40. Penn State ARL Karl Reichard North Atherton PO Box 30 State College, PA 

41. Peerless Instrument Thomas O’Brien 150 Executive Drive Edgewood, NY 11717 

42. Rail Bearing Services Rick Hickman 12224 Oakmont Circle Knoxville, TN 37922 

43. Rensselaer Polytechnic Inst. James Li Dept. Mech. Eng., Aero & Mechs. Troy, NY 

44. SAIC John Danyluk 1616 Broadway Street Kansas City, MO 64108 

45. SAIC Paul Peterson 1616 Broadway Street Kansas City, MO 64108 

46. SAIC John Donelson III 1710 Goodridge Drive McLean, VA 22102 

47. Salient Systems, Inc. Harold Harrison 4330 Tuller Rd. Dublin, OH 43017 

48. Salient Systems, Inc. Tom McCanney 4330 Tuller Rd. Dublin, OH 43017 

49. SASIB Railway GRS Joseph Denny 150 Sawgrass Drive Rochester, NY 14620 

50. SASIB Railway GRS Burt Vane 150 Sawgrass Drive Rochester, NY 14620 

51. Sandia National Labs William Sullivan Dept. 6111 MS 1033 Albuquerque, NM 87185 

52. Sandia National Labs Patrick Barney Structure Dynamics Albuquerque, NM 87185 

53. Signition, Inc. George Zweig PO Box 1020 Los Alamos, NM 87544 

54. SKF Cond. Monitoring Robert Jones 52 Shadow Lake Trail Newnan, GA 30265 

55. Texas A & M University Andy Chan TTI/Dept. of Elec. Eng. College Station, TX 

56. The Timken Company Rosendo Fuquen 1835 Dueber Av SW PO Box 6930 Canton, OH 

57. The Timken Company Sam Williams 1025 Cleveland Ave Columbus, OH 43201 

58. TTC/AAR Gerald Anderson PO Box 11130 Pueblo, CO 81001 

59. Union Switch & Signal Chris Detka 1000 Technology Drive Pittsburgh, PA 

60. University of North Texas Albert Haddad 1554 North Valley Pkwy Lewisville, TX 75067 

61. VAST, Inc. Anton Azoutseu 22 Rozenshteina St Petersburg, Russia 198095 

62. Wyle Labs Wade Dorland PO Box 077777 Huntsville, Al 35807 

63. FRA Monique Stewart 400 Seventh St SW Washington, DC 20590 

64. CSX Transportation Dr. Greg Martin 500 Water Street Jacksonville, FL 32202 

65. Vipac Engineers Dr. Uwe Kopke 21 King William St. Kent Town, South Australia 

66. Harmon Industries Mike Bartonek PO Box 600 Grain Valley, MO 64029 
B - 1 

Appendix B 

Defective Bearing Tables and Photographs
B - 2 

BEARING #1 CLASS E “SPUN CONE” SERIAL # 29814 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone Single 1/8 inch repaired spall  Not Under-Load No Defects Observed 

BEARING #3 CLASS E “SINGLE CONE SPALL” SERIAL # 84372 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race Single line spall manufactured by grinding  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #5 CLASS F “SINGLE CUP SPALL” SERIAL # 87958 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone Spalls, 1 severe, 3 less than or equal to 1⁄2”  Not Under-Load Water etched, single 1⁄2” spall  Field Side Loaded Zone Single line spall  Not Under-Load No Defects Observed 
B - 3 

BEARING #7 CLASS F E “SINGLE CONE SPALL” SERIAL # 34593 

CONE Inside Race Single 1⁄2” line spall manufactured by grinding  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load Single small repaired spall  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #9 CLASS E “BROKEN ROLLER” SERIAL # 83622 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers Single 1⁄2” flat manufactured by grinding CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #11 CLASS E “WATER ETCH” SERIAL # X-167 

CONE Inside Race Three very small spalls  Rollers Three each have very small spalls  Field Side Race Water etched  Rollers Water etched CUP Inside Loaded Zone Water etched with very small spalls  Not Under-Load Small repaired spalls  Field Side Loaded Zone Small repaired spalls  Not Under-Load Small repaired spalls 
B - 4 

BEARING #14 CLASS F “SPUN CONE” SERIAL # 10915 

CONE Inside Race Single 1/16 inch repaired spall  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #15 CLASS F “SPUN CONE” SERIAL # 61405 

CONE Inside Race Repaired non-condemnable, six each  Rollers No Defects Observed  Field Side Race Six large spalls  Rollers Steel flakes in grease CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Spacer Ring Worn 

BEARING #18 CLASS E “SPUN CONE” SERIAL # 18A 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load Small Repaired Spall 
B - 5 

BEARING #19 CLASS E “SPUN CONE” SERIAL # 83333 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #22 CLASS F “WATER ETCH” SERIAL # 85882 

CONE Inside Race Minor water etching  Rollers Minor water etching  Field Side Race Minor water etching  Rollers Minor water etching CUP Inside Loaded Zone Minor water etching  Not Under-Load Minor water etching  Field Side Loaded Zone Minor water etching  Not Under-Load Minor water etching 

BEARING #24 CLASS F “Broken Roller” SERIAL # 39164 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers Single defect manufactured by grinding CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone Very shallow repaired spalls  Not Under-Load No Defects Observed 
B - 6 

BEARING #26 CLASS E “MULTIPLE CONE SPALL” SERIAL # 54871 

CONE Inside Race Multiple spalls  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #27 CLASS E “MYSTERY” SERIAL # 18-T 

CONE Inside Race No Defects Observed  Rollers Several spalls  Field Side Race Three small line spalls  Rollers No Defects Observed, rollers are brown CUP Inside Loaded Zone Many small dents  Not Under-Load Many small dents  Field Side Loaded Zone Brinnell  Not Under-Load No Defects Observed 

BEARING #28 CLASS E “MULTIPLE CUP SPALL” SERIAL # 54900 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone Water etched  Not Under-Load Single spall  Field Side Loaded Zone Multiple Spalls  Not Under-Load Multiple Spalls 
B - 7 

BEARING #30 CLASS F “MULTIPLE CONE SPALL” SERIAL # 31401 

CONE Inside Race Many small spalls  Rollers No Defects Observed  Field Side Race One line spall and other spalls  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone No Defects Observed  Not Under-Load No Defects Observed 

BEARING #31 CLASS F “MYSTERY” SERIAL # 1041 

CONE Inside Race Multiple repaired spalls  Rollers Broken  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone Multiple Spalls, color shows excessive heat  Not Under-Load No Defects Observed  Field Side Loaded Zone Multiple Spalls  Not Under-Load No Defects Observed 

BEARING #32 CLASS F “MULTIPLE CUP SPALL” SERIAL # 34576 

CONE Inside Race No Defects Observed  Rollers No Defects Observed  Field Side Race No Defects Observed  Rollers No Defects Observed CUP Inside Loaded Zone No Defects Observed  Not Under-Load No Defects Observed  Field Side Loaded Zone Multiple spalls, large  Not Under-Load No Defects Observed 
B - 8 

B1. 

B2. 

B3. 
B - 9 

B4. 

B5. 

B6. 
B - 10 

B7. 

B8. 

B9. 
B - 11 

B10. 

B11. 

B12. 
B - 12 

B13. 

B14. 

B15. 
B - 13 

B16. 

B17. 

B18. 
B - 14 

B19. 

B20. 

B21. 
B - 15 

B22. 

B23. 

B24. 
B - 16 

B25. 

B26. 

B27. 
B - 17 

B28. 

B29. 

B30. 
B - 18 

B31. 

B32. 

B33. 
B - 19 

B34. 

B35. 

B36. 
B - 20 

B37. 

B38. 

B39. 
B - 21 

B40. 

B41. 

B42. 
B - 22 

B43. 

B44.