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No. MC/LHB/Brake Date: 27.09.2018
Principal Chief Mechanical Engineers,
1. Central Railway, Chhatrapati Shivaji Terminus, 2. East Coast Railway, Chandrasekharpur,
Mumbai - 400 001 Bhubaneswar - 751 016
3. Eastern Railway, Fairlie Place, Kolkata - 700 001 4. North Central Railway, Allahabad - 211 001
5. Northern Railway, Baroda House, New Delhi - 110001 6. North Western Railway, Jaipur - 302 006
7. Southern Railway, Park Town , Chennai - 600 003 8. West Central Railway, Jabalpur - 482 008
9. South Central Railway, Rail Nilayam, Secunderabad - 10. South Western Railway, Hubli - 580 023
500071
11 . South Eastern Railway, Garden Reach, Kolkata - 700 12. South East Central Railway, Bilaspur - 495 004
043
13. North Eastern Railway, Gorakhpur - 273 001 14. Integral Coach Factory, Chennai - 600 038
15. Western Railway, Churchgate, Mumbai - 400 020 16. Rail Coach Factory, Hussainpur, Kapurthala,
Punjab - 144 602
17. Northeast Frontier Railway, Maligaon, Guwahati - 781 18. Modern Coach Factory, Raebareli, Lalganj -
011 229206
19. East Central Railway, Hajipur-844101 20. Konkan Railway Corp. Ltd . Corporate office,
Belapur Bhawan , Nawi, Mumbai-400 614
Sub: Modification in choke sizes of Dump Valves of WSP system in LHB
Coaches.
Ref: i). RDSO letter of even no. dated 11.04.2018.
ii). Railway Board letter no. 2007/M(C)/137/16 Vol.(XII)Pt. dated 05.04.18.
1. With reference to above, ROSa monitored field trials were conducted to study
the effect of dump valve choke sizes on wheel shelling in LHB coaches at
coaching depots Lucknow/Northern Railway, Bombay CentrallWestern Railway
and Sealdah/Eastern Railway.
2. The observations and results of the trials above are detailed in RDSO's CRR
report RDSO/CG/CRR-18002. A copy of the same is enclosed.
3. The actions listed in the report have resulted in substantial reduction in wheel
shelling as determined by trials conducted at Sealdah depot of Eastern Railway
over a period of 6 months.
4. Zonal Railways and Production Units are advised to take necessary action as
detailed in the report to address the problem of wheel sh lIing in LHB coaches.
/
DA: As above /'V'1~
(Samir Lohani)
Executive Director/Carriage
Copy to: EDME (Chg .), Railway Board, Rail Bhawan, New Delhi-110001 .
Scanned by CamScanner
Ref: CG-WI-4.2.1-1 Ver.1.0 Page 2 of 31 Date of issue: Sep., 2018 Carriage Research Report No.RDSO/CG/CRR-18002
INDEX
S.No. Description
1.0 Preface
2.0 Results
3.0 Validation from brake system suppliers
4.0 Other factors
5.0 Summary
Annexure-A1 Railway Board letter no. 2007/M(C)/137/16 Vol.(xii) Pt. dated
05.04.2018
Annexure-A2 RDSO letter to Railways & trial scheme
Annexure-B1 Trial Results of LKO/NR
Annexure-B2 Trial Results of BCT/WR
Annexure-B3 Trial Results of SDAH/ER
Annexure-C1 Validation results by Faiveley Transport
Annexure-C2 Validation results by Knorr Bremse
Annexure-C3 SWR letter regarding trial of self-lubricating bushes
Annexure-C4 Faiveley Transport letter regarding self-lubricating bushes
Annexure-C5 RDSO letter regarding self-lubricating bushes
Page 2 of 31
Ref: CG-WI-4.2.1-1 Ver.1.0 Page 3 of 31 Date of issue: Sep., 2018 Carriage Research Report No.RDSO/CG/CRR-18002
REPORT ON EFFECT OF CHOKE SIZES OF DUMP VALVE
ON WHEEL SHELLING IN LHB COACHES
1.0 PREFACE
1.1 RDSO vide CRR report RDSO/CG/CRR-18001 dated 23.03.2018 had investigated
the effect of choke sizes of Dump Valves on Wheel Shelling in LHB coaches.
Based on recommendation of RDSO in above research report, following trials were
advised by Railway Board vide letter no. 2007/M(C)/137/16 Vol.(xii) Pt. dated
05.04.2018:-
i. For M/s KBIL system exhaust choke of 7 mm to be removed from dump
valve while retaining 5 mm charging choke. This configuration to be put
on trial in 10 LHB coaches each at SDAH/ER, LKO/NR and BCT/WR for 3
months.
ii. For M/s FTRTIL system exhaust choke of 9 mm to be removed from dump
valve while retaining 6 mm charging choke. This configuration to be put
on trial in 10 LHB coaches each at SDAH/ER, LKO/NR and BCT/WR for 3
months.
1.2 In this connection, a trial scheme (T.S. No. RDSO/CG/TS-18003) was prepared by
RDSO and issued vide this office letter no. MC/LHB/Brake dated 11.04.2018 to
concerned Railways for conducting above trials.
Trials have accordingly been conducted at nominated depots. Relevant documents
are at Annexure A1-A2 and trial results are placed at Annexures B1-B3.
At SDAH/ER depot, the trial scheme proposed by RDSO (removal of exhaust
choke) was further refined by studying the effect of different sizes of charging
chokes in addition to the removal of exhaust choke in brake systems of M/s KBIL
and FTRTIL.
This report includes the results of trials carried out at LKO/NR upto 10-08-18,
BCT/WR upto19-08-18 and extended trials at SDAH/ER upto 25-09-18.
2.0 RESULTS
2.1 LKO/NR Depot: Trial results from 09.05.2018 to 10-08-18 (3 months) on 10
coaches each of M/s KBIL & M/s FTRTIL reported by Sr. DME (C&W) LKO vide
letter no. RS/7/C/Maint.chg/2018 dated 22.08.2018 are at Annexure B1.
Observations are as under:
No wheel shelling was observed in any of the coaches under trial.
Average kilometer earned without shelling from the commencement of trial
is 44000kms (approx.)
Out of 20 Coaches, electrical connections in Junction Boxes of Speed
Sensor & Dump Valves were modified in 10 Coaches having M/s FTRTIL
Page 3 of 31
Ref: CG-WI-4.2.1-1 Ver.1.0 Page 4 of 31 Date of issue: Sep., 2018 Carriage Research Report No.RDSO/CG/CRR-18002
fitted brake system. No wheel shelling and electrical connection failure has
been reported in these coaches.
2.2 BCT/WR Depot: Trial results from 20.04.2018 to 19-08-18 (4 months) on 10
coaches each of M/s KBIL & M/s FTRTIL reported by Sr. CDO/BCT vide letter no.
BCT/M442/41 dated 24.08.2018 are at Annexure B2. Observations are as under:
Average kilometer earned before shelling is 99000Kms (approx.)
Out of 20 coaches, 06 coaches were marked for wheel shelling (03 coaches
of M/s KBIL and 03 coaches of M/s FTRTIL). Minor wheel shelling was
observed in 03 coaches (01 coach of M/s KBIL and 02 coaches of M/s
FTRTIL).
No wheel shelling was observed in the 05 coaches of M/s FTRTIL where
modified junction boxes were provided to ensure integrity of connection
during run.
It was noted that intermittent connection / sensor failures in WSP system
have occurred in 10 nos. of trial coaches, in many cases more than once.
However, only one instance of intermittent sensor failure has been observed
among coaches of M/s FTRTIL where modified junction boxes were
provided.
2.3 SDAH/ER Depot: Trial results from 24-03-2018 to 25-09-2018 (6 months) reported
by Sr. DME/SDAH vide letter no. MC/8/LHB/18 dated 25-09-2018 are at Annexure
B3. Observations are as under:
Initially trial was conducted on 13 coaches as per choke size modifications
advised vide RDSO trial scheme. It is reported by Sr.DME/SDAH that initial
response was better regrading reduction in wheel shelling however, after
some time, thermal cracks started reappearing.
To fine tune the WSP system, an extended trial was conducted in SDAH
depot to study the effect of different sizes of charging chokes in addition to
the removal of exhaust choke.
Total 47 coaches were subjected to extended trial from 25.03.2018 to
25.09.2018 (06 months).In this trial, exhaust choke was kept removed
and charging choke was kept at 9mm in Dump Valves of both M/s KBIL
and FTRTIL. As per the report, except one coach (in which moderate
shelling was observed), no wheel shelling was observed in any of the
remaining 46 coaches.
As per Sr.DME/SDAH, there is a considerable reduction in wheel shelling
due to modification in Dump Valve choke sizes i.e. removal of exhaust
choke & increase in charging choke size to 9mm. As per details submitted
by Sr.DME/SDAH, the number of wheel shelling cases per 100 coaches has
been reduced from 10.52 Coach per month (in April’18) to 4.06 Coach per
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month (in Sep’18). The reduction in sick marking due to wheel shelling at
SDAH/ER can be attributed to modification in choke sizes of dump valves,
as well as attention given to electrical connections / monitoring of WSP and
Brake Calipers.
2.4 Based on the trials conducted at LKO, BCT & extended trials at SDAH, it is
observed that optimum configuration for choke sizes of dump valves which
leads to best performance of brake system with minimum shelling is as
under:
Brake System Make Exhaust Choke size Charging Choke size
Choke to be removed 9 mm
KBIL
Choke to be removed 9 mm
FTRTIL
This requires the following modification in Dump Valve chokes:
Brake System Make Exhaust Choke size Charging Choke size
Remove existing 7mm Replace existing 5mm
KBIL
choke choke with 9mm choke
Remove existing 9 mm Replace existing 6mm
FTRTIL
choke choke with 9mm choke
The trials also bring out that integrity of electrical connections of WSP
system and free movement of brake calipers during brake application /
release are absolutely vital in reducing wheel shelling.
3.0 VALIDATION FROM BRAKE SYSTEM SUPPLIERS
M/s KNORR-BREMSE: The modifications proposed in Dump Valve choke sizes
indicated in Para 2.4 have been validated by M/s KBIL. As per their Centre of
Competence at Munich, the results are well within design & commissioning
parameters i.e. the ratio of charging to exhaust timings (tb/te) is in conformance to
their criteria of selection of choke sizes (Annexure C2). They have also confirmed
that these modifications in choke sizes will not have any adverse effect on
functional performance of the brake system as a whole.
M/s FAIVELEY TRANSPORT: The modifications proposed in Dump Valve choke
sizes indicated in Para 2.4 have also been validated by M/s FTRTIL. Tests
conducted by M/s FTRTIL Lab at R&D facility in Hosur indicate that results are well
within design & commissioning requirements (Annexure C1), and that these
modifications in choke sizes will not have any adverse effect on functional
performance of brake system as a whole.
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4.0 OTHER FACTORS
a. Electrical Connections: Electrical connections and fixing of junction boxes needs
lot of attention. In many coaches, numbers of defects like loose electrical
connections, improper fixing of junction boxes of dump valve/speed sensor and
incorrect gap between phonic wheel and speed sensor were found. Few pictures
showing the condition are as below:
Before commencement of trial, such defects were found and corrected in 7
coaches to ensure integrity of electrical connections and proper working of WSP
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system. This clearly brings out that maintenance attention in these areas is
inadequate at present and needs to be improved.
Both M/s FTRTIL and M/s KBIL have been advised to improve design of WSP
electrical system connectors and junction boxes (IP65 rating with MIL grade
connectors) based on experience gained during the trial. The design proposals
submitted by OEMs are under examination at RDSO and will be issued shortly.
b. Free movement of Brake Calipers: It is essential to ensure free movement of
brake calipers during examination & maintenance of the brake system. Presently,
brake calipers in LHB coaches are provided with two types of bushes viz. metallic
& non-metallic type. The non-metallic type bushes (FTRTIL only) results in
frequent jamming due to lack of lubrication & also dust accumulation due to
lubricant itself. Jamming of brake calipers restricts their free movement which in
turn affects proper brake application & release.
To address the above problem & based on the feedback received from SWR
(Annexure C3), the brake caliper bush design has been standardized as self-
lubricating type bushes. M/s FTRTIL has also been advised (Annexure C5) to
discontinue metallic type bush design & supply only self-lubricating type bushes for
brake calipers for all future supplies.
5.0 CONCLUSION
5.1 The optimum configuration for choke sizes of dump valves which leads to
best performance of brake system with minimum shelling is as under:
Brake System Make Exhaust Choke size Charging Choke size
KBIL Choke to be removed 9 mm
Choke to be removed 9 mm
FTRTIL
This requires the following modification in Dump Valve chokes:
Exhaust Choke size Charging Choke size
Brake System Make
Remove existing 7mm Replace existing 5mm
KBIL
choke choke with 9mm choke
Remove existing 9 mm Replace existing 6mm
FTRTIL
choke choke with 9mm choke
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5.2 Action by Production Units
5.2.1 All newly manufactured LHB coaches should be turned out with modified choke
configuration only for brake systems of M/s FTRTIL and M/s KBIL.
5.2.2 M/s FTRTIL has already been advised (Annexure C5) to discontinue metallic type
bush design & supply only self-lubricating type bushes for brake calipers and
actuators for all future supplies. This should be ensured for all new supplies.
5.3 Action by Zonal Railways
5.3.1 Zonal Railways are required to carry out the modification in Dump Valve choke
sizes as detailed in para 5.1 above at the earliest by proper planning. Action
needs to be taken at workshops carrying out SS1 / SS2 schedules as well as at
coaching depots during D2 / D3 schedules and out-of-course repairs. Priority at
depot level should be given to coaches having repeated shelling.
5.3.2 Based on the experience gained during trials at SDAH/ER, this modification can be
carried out within 2 hrs. per coach. For brake system of M/s FTRTIL, no additional
material is required as the existing 9mm exhaust choke needs to be removed from
the exhaust port and refitted in place of existing charging choke. For brake system
of M/s KBIL, this modification requires a suitable 9mm choke to be supplied by
OEM, for which Zonal Railways should approach the OEM.
5.3.3 The trials also bring out that integrity of electrical connections of WSP system and
free movement of brake calipers during brake application / release are absolutely
vital in reducing wheel shelling. Zonal Railways need to launch a special drive to
ensure this.
5.4 OEMs of brake system have been advised to implement the above for all new
supplies of brake systems as well as in coaches covered under AMC. They are
also being advised to provide assistance for implementing this modification for
other coaches not covered under AMC.
-x-x-
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Annexure- A1
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Annexure- A2
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Annexure- B1
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Annexure- B2
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Annexure- B3
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Annexure-C1
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Annexure- C2
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Annexure- C3
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Annexure- C4
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Annexure- C5
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