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Page 1 of 8

Fax : 0522-2452581/2465716

Telephone : 0522-2465716

e-mail:[email protected]

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Government of India - Ministry of Railways

Research, Designs & Standards Organization,

Lucknow – 226011

No. EL/2.2.13 Date: 11.05.2017

Chief Electrical Engineers,

1. CentralRailway,Mumbai CST-400001

2. East Coast Railway, Chandrashekharpur, Bhubaneshwar-751 016

3. Northern Railway, Baroda House, New Delhi-110 001

4. North Central Railway, Hasting Road, Allahabad-211 001

5. Southern Railway, Park Town, Chennai-600 003

6. South Central Railway, Rail Nilayam, Secunderabad-500 071

7. South Eastern Railway, Garden Reach,Kolkata-700 043

8. South East Central Railway, Bilaspur-495004

9. Western Railway, Churchgate, Mumbai-400 020

10. West Central Railway,Jabalpur-482001

11. Eastern Railway, Fairlie Place, Kolkata- 700 001

12. East Central Railway, Hazipur-844101 (Bihar)

13. Chittaranjan Locomotive Works, Chittaranjan- 713 331

Sub: Minutes of Meeting of Workshop-cum-seminar held at ELS/TKD on 27.04.2017

Ref: RDSO’s letter no. EL/2.2.13 dated 20.04.2017

1. Workshop-cum-seminar had been carried out at Electric Loco Shed TKD, West Central

Railway on 27.4.2017 for improving reliability of 3-phase traction motor bearings.

2. Minutes of meeting of Workshop-cum-seminar had been uploaded on RDSO website and

it may be downloaded using following path:-

www.rdso.indianrailways.gov.in → Directorates → Electric Loco →Important

Letters/Documents →Minutes of Meeting of Workshop-cum-seminar held at ELS/TKD

on 27.04.2017.

(P.K. Saraswat)

for Director General/ Electrical

Copy to:

1. Secretary (Electric Traction), Railway Board, Rail Bhawan, New Delhi-110 001 :-

(Kind Atten. Shri A.K. Goswami, DEE/RS) - for kind information please.

2. M/s FAG Bearings India Ltd., Maneja, Vadodara-390 013

3. M/s SKF India Limited, 17th Floor Building no. 5B,

Cyber City, DLF Phase-III, Gurgaon-122 002

(P.K. Saraswat)

for Director General/ Electrical

For information and necessary action please.

Page 2 of 8

Minutes of Meeting of Workshop-cum-seminar held at Electric Loco Shed Tuglakabad on

27.04.2017 on improving reliability of 3-phase Traction Motor bearings

1. Considering the recent line failures of three phase traction motor bearings, workshop-

cum-seminar was organized at ELS/TKD on 27.04.2017 in association with M/s FAG &

M/s SKF on bearing fitment procedure and condition monitoring of bearings for

improving reliability of 3-phase Traction Motor bearings vide RDSO’s letter no.

EL/2.2.13 dated 20.04.2017.

2. Adviser Electrical (RS) & DEE (RS)/Railway Board, EDSE (Co-ord)/RDSO

Sr.DEE/RS/TKD, AEE/TRS/KYN, AEE/TRS/TKD, and supervisors from various sheds

of Zonal Railways were present during the workshop-cum-seminar. Representatives of

bearing manufacturers M/s SKF India and M/s FAG India were also present. List of

Participants is attached as annexure-I.

3. ELS/TKD had arranged shop floor demonstrations of various stages of traction motor

bearing fitment and measurement of various dimensions and clearances. Presentations

were given by M/s FAG and M/s SKF covering the good maintenance practices, Do’s &

Don’ts, re-greasing and light run test of traction motor.

4. Adviser Electrical (RS) /Railway Board’s observations:-

Advisor Electrical (RS) stated that such type of workshop is an opportunity to learn best

practices from other sheds and improve own maintenance practices by comparing with

other sheds. He advised bearing manufacturers to tell what is wrong with maintenance

practices followed by sheds and infrastructure lapses if any. He had emphasized that

block section bearing failures cannot be accepted and advised RDSO to issue suitable

maintenance instructions and design improvements for better reliability of traction motor

bearings.

5. EDSE (Co_ord)/RDSO’s observations:-

Bearing seizure cases are serious setback on the performance of locos. Proper

maintenance practices should be followed by the shed to avoid line failures. Line failures

of bearings are not acceptable. Temperature monitoring of locomotive may help in

identifying potential line failure cases. Proper bearing fitment procedure needs to be

followed to improve the reliability of 3 phase traction motor bearings.

6. Failures due to rotation of NDE bearing clearly shows fitment problem and it can be

eliminated by ensuring adequate clearance between end shield and labyrinth by feeler

gauge. DE bearing failures can be eliminated by ensuring proper dimensions of mating

components to ensure proper interferences and following pinion fitment procedure.

Similarly proper fitment procedure of dummy pinion should also be followed. Complete

greasing should be done in IC0.

Page 3 of 8

7. Points noted during presentation by M/s FAG:-

i. M/s FAG informed that they had strengthened the cage and reduced one roller in

NU2236 bearing (DE) to improve the reliability. M/s FAG had supplied 3600 of

bearings from 2004-2014 (old design) and 1523 new design of bearings had been

supplied from 2015 till date.

ii. M/s FAG has calculated the initial grease quantity for 6FRA 6068 TM bearings as

given below:

Sl.

No.

Bearing

Designation

Empty Space /

Volume

(cm3)

Density of

Grease used

(gram/ cm3)

Total Qty. of

Initial fill

(gram)

1 NU2236 718 0.94 675

2 NJ320 204 0.94 190

As per FAG, re-greasing quantity is to be 50% -80% of initial grease quantity. Re-

greasing interval can be determined by tests under various field conditions. M/s FAG had

recommended to continue with re-lubrication quantity prescribed by ABB i.e. 400g for

DE & 130 g for NDE bearings. Re-lubrication period can be decided by Indian Railway

considering prevalent practices and field performance.

iii. Bearings are coated with rust preventive oil which has a shelf life of approximately

12 months. If bearings are required to be stored for longer periods, rust preventive oil

needs to be applied again.

iv. Use of hand gloves to handle the bearings is recommended.

v. Measurement of shaft: M/s FAG suggested measurement of the shaft at 4 places, 45°apart with dial indicator

snap gauge. An ovality of half of the tolerance range is permissible. No burrs, nicks,

and corrosion are allowed.

Fig. 1: Measurement Locations suggested by M/s FAG

Page 4 of 8

vi. Measurement of Housing: A bore dial gauge to be used to get accurate values.

Fig. 2: Bore dial gauge Fig. 3: Dial indicator snap gauge

vii. Measurement of free Radial Clearance (RC): Always check the radial clearance of bearing with feeler gauge.

Fig. 4: Measurement of free RC

viii. Measurement of Radial Clearance after mounting: It is advisable to check radial clearance after mounting of bearing.

ix. Temperature mode of induction heater to be used for heating.

x. Cleanliness of bearing assembly area is very important.

8. Points noted during presentation by M/s SKF:-

i. Reasons of premature bearing failure are as given below:-

a) 16% failure cases are because of poor fitting

b) 34% failures are because of poor lubrication

c) 36% failures are because of contamination

d) 14% are because of fatigue

Page 5 of 8

ii. Following parameter should be checked before fitment:

a) Motor OEM as well as Railway sheds must check End shield bore diameter &

shaft diameter before bearing fitment

b) Clearance of bearing should be checked after mounting with feeler gauge

c) Pilot / guide sleeve must be used during mounting of End shield & Roller,

cage & outer ring assembly.

iii. Matching of shaft & component of end shields to be ensured.

iv. Measurement of shaft & End shield at two point for ovality as shown in following figure:

Fig. 5: Measurement Locations suggested by M/s SKF

v. M/s SKF had suggested use of Microlog and Vibration Indicator for condition

monitoring of bearings:

Fig. 6: Microlog

Page 6 of 8

Fig. 7: Vibration Indicator

9. Decisions taken during the meeting:

i. M/s SKF had suggested use of polymer sleeve for bearing fitment for smooth

transition of rollers on inner racer. M/s SKF is requested to provide specification and

drawing to ELS/TKD & RDSO. ELS/TKD to procure and supply two sets of sleeves

to all the Electric Loco Sheds. Some samples of the sleeve are also to be provided by

M/s SKF to ELS/TKD.

ii. Both M/s SKF & M/s FAG had suggested condition monitoring equipments for

bearings. M/s SKF & M/s FAG are advised to give their separate detailed proposals

to RDSO for examination.

iii. SMI-278 prescribes fitment of dummy pinion before fitment of inner racer. Sheds had

observed that in case of WAP-7 locomotive, fitment of dummy pinion is required as

inner racer cannot be fitted after fitment of actual pinion. However, in case of WAG-9

locomotive traction motor, fitment of dummy pinion is not required as inner racer can

be fitted after fitment of actual pinion. ELS/AQ is providing inner racer in WAG-9

locomotive traction motor after fitment of actual pinion. It has been decided that in

6FRA6068 TMs to be used in WAG-9 locomotives, inner racer will be provided after

fitment of pinion to be used in service. However, for WAP-7 locomotive, existing

instructions of providing inner racer after fitment of dummy pinion will be followed.

Due care shall be taken while fitment of dummy pinion considering it as actual pinion

for service regarding pinion travel, pressure etc.

iv. Grease Gun equipped with Grease Dispensation meter to be used by sheds to

ascertain the prescribed quantity of grease is provided.

Page 7 of 8

v. Re-greasing practices followed by the sheds were discussed. It is observed that

different sheds are following different practices.

As per ABB Document No. 3EHM670403 following re-greasing schedule is

prescribed for 6FRA6068TMs:

TM Type DE (gm) NDE (gm) Periodicity

6FRA6068 400 130 After 0.20 million km or once per year

RDSO’s letter No. EL/3.1.35/16 dated 07.02.2012 (minor maintenance schedule)

prescribes re- greasing in IC schedule (270 days).

It has been decided during meeting to increase the periodicity of greasing from

existing 270 days (IC schedule) to 180 days i.e. in every alternative schedule (Ist IB,

2nd

IA, 2nd

IC). Re-Greasing quantity will be same as specified by ABB and given

above.

vi. All the sheds were advised to carry out re-greasing in IC0 schedule also.

vii. Light Run Test practices were also discussed and it was observed that different sheds

are following different practices. Both M/s FAG & M/s SKF had informed that for

proper functioning of bearings, minimum load must be on the bearings which is 2%

to 3% of rated load rating of the bearing and for 6FRA6068 TM, it comes around

2300Kg, whereas rotor weight is around 800Kg only. It was informed by bearing

manufacturers that if minimum load requirement of bearing is not met, there will be

tendency of rollers to slide instead of rolling which may damage the bearings. RDSO

will study the issue further with reference to TOT documents and issue instructions

separately.

viii. Zonal Railways were advised to increase the annual requirement of bearings so that

same are available for replacement as per schedule maintenance practices. Bearings

should not be allowed in service overdue for replacement.

Page 8 of 8

Annexure-I

List of participant of workshop cum seminar at TKD on 27.04.2017.

Serial No Name Designation Railway/Firm

1 Shri Sudhir Kumar Advisor Electrical (RS) Railway Board

2 Shri O.P. Kesari EDSE(Co_ord)/RDSO RDSO

3 Shri A.K. Goswami DEE/RS/RB Railway Board

4 Shri Suman Tiwari DME/MECH/RB Railway Board

5 Shri P.K. Saraswat Director Electrical RDSO

6 Shri S.P. Singh Sr. DEE/TRS/TKD WCR

7 Shri Kamal Kant Rastogi DEE/GZB NR

8 Shri Rahual Pachori DEE/TKD WCR

9 Shri Puneet DEE/TKD WCR

10 Shri Gaurav. K. Srivastava ADEE/TKD WCR

11 Shri Diwakar Kumar ADEE/BRC WR

12 Shri Mustaq Hussain ADEE/RS/CNB NCR

13 Shri Sanjeev Bhatia DGM(SKF) SKF

14 Shri Varun Sharma Business-head SKF

15 Shri Sandeep Lal Magager Tech Serve SKF

16 Shri Niraj Toppo SSE/TRS Railway

17 Shri G.Ajay Brahamachari SSE/ELS/LGD SCR

18 Shri R.K.Trivedi SSE/ELS/NKJ WCR

19 Shri Rajeev Kumar JE/ELS/KYN CR

20 Shri S.Jayanth SSE/ELS/RPM SR

21 Shri V.S.Gupta JE/ELS/LDH SCR

22 Shri Gautam Majumdar SSE/TM/KPA ER

23 Shri B.N.Singh SSE/TRS/GMO ECR

24 Shri N.B.Singh SSE/TRS/TATA SECR

25 Shri Sahil Kumar Asst Manager/SKF SKF

26 Shri Suvrajit roychaudhary Asst Manager/SKF SKF

27 Shri Mithun Gore Manager /FAG FAG

28 Shri Deepak Kumar JE/ELS/GZB NR

29 Shri C.R.S Bhandari SSE/ELS/GZB NR

30 Shri Himanshu Shekhar MCM/ELS/GZB NR

31 Shri S.K.Pandey SSE/CNB NCR

32 Shri Kunal Mishra SSE/BRC WR

33 Shri Mohd Azeem SSE/RDSO RDSO

34 Shri L.C.Mahawar SSE/TKD RDSO

35 Shri Arjun Kumar SSE/TKD NR

36 Shri T.C. Mathe SSE/TKD NR

37 Shri R.C. Gupta SSE/TKD NR

38 Shri Bhupal Singh SSE/TKD NR

39 Shri Abhay Kumar Tiwari Tech-GMO ECR

40 Shri N. Praveen Kumar Tech-1/LGD SCR

41 Shri Mukesh Kumar Tech-II/GZB NR

42 Shri Madan Pal Singh Tech-II/GZB NR

43 Shri S. P. Verma Steno/TKD WCR