The document provides instructions for modifying the air brake piping and associated fittings in LHB coaches. It summarizes: 1. Studies found that the existing flexible hoses connecting the coach body to bogies, which use washers, cause blockages and delays in brake release times up to 300ms. 2. RDSO has developed standardized flexible hose designs (Drg. Nos. CG-19036 and CG-19037) to replace the existing hoses. The new hoses eliminate washers, have larger diameters, and reduce the number of pipe joints. 3. Fitment trials showed the modifications reduce brake release times by approximately 300ms, improving wheel slip control and reducing wheel shell

1. No.MC/LHB/Brake Date: 24.06.2019
Principal Chief Mechanical Engineers,
1. Central Railway, Chhatrapati Shivaji Terminus, Mumbai -
400 001
2. East Coast Railway, Chandrasekharpur, 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 - 110 001 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 - 500
071
10. South Western Railway, Hubli - 580 023
11. South Eastern Railway, Garden Reach, Kolkata - 700 043 12. South East Central Railway, Bilaspur - 495 004
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 - 781 011 18. Modern Coach Factory, Raebareli, Lalganj - 229206
19. East Central Railway, Hajipur - 844 101 20. Konkan Railway Corp. Ltd. Corporate office, Belapur
Bhawan, Nawi, Mumbai-400 614
Sub: Modification in air brake pipeline & associated fittings in LHB Coaches.
Ref: 1) Consolidated instructions-Wheel Shelling vide RDSO L. No. MC/LHB/Brake dt. 15-4-19.
2) Item no.b(3) of CDE’s Minutes of Meeting dated 10.06.2019.
In continuation to the earlier studies & consolidated instructions on Wheel Shelling in LHB
Coaches, RDSO carried out studies at BCT/WR & SBC/SWR on wheel shelling which established that the
flexible air hose (600mm) connecting body to bogie of LHB Coaches provided with washer (Nylon/Teflon)
at hose ends adversely affects the post-dump release time by upto 300ms as washers get
perished/shrunk due to over tightening and routine maintenance during service. This leads to blockage of
air passage and thus causes brake binding/wheel shelling. The existing flexible pipeline joints are also not
metal-to-metal joints as recommended by M/s Alstom.
In the recent CDE’s meeting held on 31.05.2019 at MCF/RBL, the same issue was also discussed
at Item no.3 Part (b) of CDE’s MOM and it was decided that a standard piping layout should be issued by
RDSO.
RDSO has finalized standard piping layout in consultation with air-brake OEMs, and also validated
the same at RCF/KXH by fitment trials. Kindly find enclosed:
a. Brief overview & procedure for the modification (Annexure-A).
b. Piping scheme (existing arrangement as Annexure-B & modified arrangement as Annexure-C).
c. Standardized flexible hoses which are interchangeable across the existing LHB brake system
suppliers have been developed as Drg.No.CG-19036 (Flexible Hose-650mm for Bogie) at
Annexure-D & Drg.No.CG-19037 (Flexible Hose-500mm for Brake Actuators) at Annexure-E.

3. Page 1 of 3
Annexure-A
1. Flexible Air Hose (600mm) for Bogie
AIR BRAKE PIPING MODIFICATION
Existing design of flexible air hose (600mm) which is used to connect the air brake pipe running out from the
Dump Valve fitted on Underframe to Bogie is having Nylon/Teflon washers.
During the field studies by RDSO at BCT/WR & SBC/SWR; following problems are observed with the existing
hose results in restriction in smooth air flow in pipe line and ultimately affects the performance of brake system
which may leads to Wheel Shelling in case of wheel slip:
S.No. Observations Causes Photographs
i. Less inner diameter Insufficient air flow passage
ii. Washers The Nylon/Teflon washers provided
inside the hose gets perished/shrink
due to over tightening or during in
service of the coach, which results in
blockage of the air passage and thus to
inoperativeness of brake cylinders.
iii. More nos. of pipe
joints/fittings
Restriction in air flow & more chances
of occurring leakages.
To overcome above issues, RDSO has developed a standardized design of flexible hose (Drg.No.CG-
19036) which is interchangeable across all existing LHB brake suppliers. Further, based on the fitment trials
done at RCF/KXH no. of pipe joint fittings have also been reduced from 9 to 6 to ensure unrestricted &
leakage free air flow in brake system.
The upgraded flexible air hose for bogie has following advantages:
 Bigger Inner diameter: Sufficient air flow passage -The diameter of hose was increased from 9mm to
12mm.
 No washers: Avoids blocking of air passage and increase smooth operation of brakes- The new hose
eliminates the use of washers and have M26 (F) type ferrule arrangement at both ends.

4. Page 2 of 3
 Less pipe joints/fittings: Avoids air flow restriction & leakages- By the use of upgraded hose
associated joints/fittings for air connections were reduced from 9 to 6nos.
 Increase in hose length: Avoids stretching & rupture- The length of upgraded hose was increased from
600 to 650mm, as in original Alstom design and also to avoid stretching & rupture of the hose.
 Details of existing vis-a-vis modified pipe line arrangement from the Dump Valves to the other end of
flexible hose connecting bogie is as under:
Existing Arrangement (Fig 1) Modified Arrangement (Fig 2)
 For new LHB coaches:
Modification Procedure for the aforesaid marked portion
• Provide arrangement as per Fig 2.
 For existing LHB coaches:
• Remove the M26 (F) ferrule of elbow (Item no.4 of Fig 1) at flexible hose end of coach side, thus it becomes Item
no.9 of Fig 2 and therefore there is no need to purchase a new item.
• Connect the new flexible hose(item no.8 of Fig 2) one end at elbow end (coach side), and connect other end
directly in Clamp Nut of the bogie end side, as illustarted in above figure 2.
Note:- Recommended thread sealent must be used. Ensure that SS pipe (Item no.3) is adequately clamped & supported close to
Item no.9 of Fig.2.
Note:- The above mentioned modification & quantities are for one side of pipe arrangement from Dump Valve to
bogie connection. There are a total of 4 such connections per coach, i.e. 2 per bogie.
M26 (F) ferrule

5. Page 3 of 3
2. Flexible Air Hose (500mm) for Brake Actuators
Existing design of flexible air hose (500mm) which is used to connect the air brake pipe (brake cylinder pipe) of
bogie to brake cylinders/actuators also varies with suppliers. During the aforesaid discussed study, it was noted
that the size of the hose (Inner diameter) varies from supplier to supplier which results in variation of
charging/venting of Dump valves affecting the optimum working of WSP. It is also found that consequent to
optimization of Dump Valves chokes sizes, clear opening of 12mm is required in the above flexible hose.
To overcome above issues, RDSO has developed a standardized the design of flexible hose (Drg.No.CG-
19037) which is interchangeable across all existing LHB brake suppliers. Modified hose has clear opening (Inner
diameter) of 12mm to match the optimized Dump Valve choke sizes.
Implementation of the above air brake piping modifications results in :
Conclusion
a. Reduction in Pipe joints/fittings.
b. Elimination of the use of Washers in Flexible Hoses.
c. Clear openings in Flexible Hoses.
d. Interchangeability across LHB brake suppliers.
The above modifications (along with choke size modifications circulated earlier) result in quicker response of
venting of air from brake actuators on generation of ‘dump’ command from the WSP by approx. 300ms, which
substantially improves the control action of the WSP and reduces wheel shelling.
**********

6. Existing piping arrangement
Modified piping arrangement with reduced joints and modified hose

7. Annexure-B
LEGEND
S.No. Description Quantity
1. Adopter 01
2. Ferrule Stud ½” (M) X M26 (M) 03
3. 18 OD Pipe with M26 ferrule fittings 01
4. Elbow M26 (M) X M26 (F) ferrule 01
5. Hose ½” with ½” BSP (F) both sides 01
6. 18 OD Pipe with M26 ferrule fittings 01
7. Stud M26 both sides 01
Total Quantity 09
Existing Arrangement
M26 (F) ferrule
Modification to be carried out
in this portion only
Clamp
Nut
Clamp on bogie

8. Annexure-C
LEGEND
S.No. Description Quantity Remarks
1. Adopter 01 --
2. Ferrule Stud ½” (M) X M26 (M) 01 Quantity reduced from 3 nos. to 1 nos.
3. 18 OD Pipe with M26 ferrule fittings 01 --
4. Elbow M26 (M) X M26 (F) ferrule 00 Replace with S.No.9
5. Hose ½” with ½” BSP (F) both sides 00 Replace with S.No.8
6. 18 OD Pipe with M26 ferrule fittings 00 Eliminated
7. Stud M26 both sides 01 --
8. Hose 5/8” with M26 (F) both sides 01 To replace with S.No.5
9. Elbow Male Connector M26 (M) 01 To replace with S.No.4
Total Quantity 06
Note: Items at S.No.4, 5 & 6 (in Red) to be deleted and at S.No.8 & 9 (in Green) to be added.
Modified Arrangement
Clamp on bogie
Clamp
Nut
Modification to be carried out
in this portion only

9. Annexure-D

10. Annexure-E