Air suspension in Railway coaches

Ref: CGW 0001,Rev.-3 Date / Month of issue: September, 2009 Page 1 of 21 Maintenance Instruction No. CMI- RDSO/2009/CG/CMI-01
(For official use only)
INDIAN RAILWAYS
“MAINTENANCE INSTRUCTIONS
ON
AIR SUSPENSION
FOR
MAINLINE/RAJDHANI COACHES WITH ICF
TYPE BOGIES
RDSO/2009/CG/CMI-01
September 2009
RESEARCH DESIGNS AND STANDARDS ORGANISATION
MANAK NAGAR, LUCKNOW – 226011.
RDSO/Lucknow Page-1

SYNOPSIS
Requirement of greater passenger comfort with reduced maintenance and
have generated need for the Indian Railways to adopt air suspension for its
coaching stock.
For Indian Railways, air suspension is a new technology and hence there is a
need to impart awareness amongst officials engaged in handling of this system,
regarding its working principle, functions and details of hardware and maintenance
practices to be followed for various items.
This booklet has been prepared with above objectives in view. Any
suggestion directed towards improvement in the quality of the booklet shall be
welcome which may be sent to Executive Director Standards/Carriage or
Director/VDG/Carriage, Research Designs & Standards Organization, Manak
Nagar, Lucknow-226011.
RDSO/Lucknow Page-2

INDEX
Item DESCRIPTION Page No.
1. INTRODUCTION 4
2. WORKING PRINCIPLE OF PNEUMATIC SUSPENSION 4
3. COMPARISON WITH EXISTING COIL SUSPENSION 4
4. ADVANTAGES OF AIR SUSPENSION 5
5. CHARACTERISTICS FEATURES OF AIR SUSPENSION 5
6. CONSTRUCTION DETAILS/CHARACTERISTICS OF AIR SPRING 5
7. SCHEMATIC LAYOUT OF PNEUMATIC SUSPENSION CONTROL 5
EQUIPMENTS
8. MODIFICATIONS FOR AIR SPRING FITMENT 5
9. OPERATING INSTRUCTIONS 6
10. DISMANTLING OF AIR SPRING FROM LOWER SPRING BEAM 6
(CRADLE) AND BOGIE BOLSTER.
11. INSPECTION & MAINTENANCE OF AIR SPRING 6
12. INSPECTION & MAINTENANCE OF LOWER SPRING BEAM 7
13. INSPECTION OF PIPE LINE 7
14. MOUNTING AIR SPRING ON LOWER SPRING BEAM AND BOLSTER 7
15. TEST FOR LEAKAGE 7
16. PROCEDURE FOR CHECKING OF BOGIE CLEARANCES ON EMU’S & 8
DMU’SPROVIDED WITH AIR SPRING
17. PROCEDURE FOR CENTRE BUFFER COUPLER HEIGHT ADJUSTMENT 8
IN WORKSHOP
18. INSTALLATION LEVER ADJUSTMENT 9
19. CHARACTERISTICS OF AIR SPRING/PERIODICAL INSPECTION OF 9
AIR SPRING SYSTEM ON MAINLINE COACHES
20. AIR SPRING SERVICE 10
21. AIR SPRING CONTROL EQUIPMENTS SERVICE 10
22. FIGURES 1 to 9 11-19
23. ANNEXURES A to J
RDSO/Lucknow Page-3

MAINTENANCE INSTRUCTIONS
ON
AIR SUSPENSION
1. INTRODUCTION:
Railway Board had approved fitment of air spring on AC Mainline ICF coaches for the purpose
of oscillation trials. After simulation study at RDSO, design for mainline stock with air spring at
secondary suspension has been evolved. Simulation studies have revealed a significant
improvement in the quality of ride on ICF stock fitted with air springs over those fitted with
conventional coiled springs. This is particularly significant with regard to the requirement of
better riding on high speed Rajdhani and Shatabdi trains specially in Ist AC coaches.
Oscillation trials have been conducted on ICF mainline bogie coaches successfully, with good
results. Accordingly it has been decided by Railway Board to provide air springs (pneumatic
suspension) on all stainless steel shell coaches (LHB type shell) provide with ICF bogies.
The Pneumatic suspension has been proven, on DC-EMU, AC-EMU, AC-DC EMU and HHP-DMU.
2. WORKING PRINCIPLE OF PNEUMATIC SUSPENSION:
Air suspension is a suspension where properties of air are used for cushioning effect
(springiness). Enclosed pressurised air in a pre-defined chamber called air spring, made up of
rubber bellow & emergency rubber spring, provides various suspension characteristics including
damping. Air springs are height-controlled load levelling suspension devices. With changing
loads, air spring reacts initially by changing the distance between air spring support and vehicle
body. The height monitoring valve (called levelling valve) is in turn actuated, either taking the
compressed air pressure to the air spring or releasing air pressure from it to the atmosphere. This
process continues until the original height is restored. (See Fig.1 page No. 11). This mechanism
ensures a constant floor height on coaches provided with air springs, irrespective of the load. This
greatly reduce problems associated with low buffer / coupler heights.
3. COMPARISON WITH EXISTING COIL SUSPENSION:
Unlike steel spring, air springs retain their height under changing loads. The low natural
frequency of air spring suspension remains virtually constant.
In case of coil spring, deflection is proportionate to the load, therefore, under high payload
situation, space constraint become critical, leading to the use of stiffer springs resulting in
unsatisfactory ride behavior and reduced speed potential.
Air springs through their control mechanism, offer a load proportionate stiffness, constant floor
height and prospects of better ride behavior with higher speed potential. (See Fig.2 page No. 12).
RDSO/Lucknow Page-4

4. ADVANTAGES OF AIR SUSPENSION:
• Capable to sustain Super Dense Crush Loads typical of suburban traffic.
• Maintain constant floor height of coach.
• Provide superior ride comfort.
• Virtually Constant natural frequency from tare to full loads, reducing passenger fatigue.
• Isolation of structure borne noise, this improving comfort.
• Improved reliability, reduced maintenance effort.
• Flexibility to chose characteristics as per requirement at design stage.
5. CHARACTERISTICS FEATURES OF AIR SUSPENSION:
• Soft flexible characteristics in vertical direction
- Achieved by compression of air (See Fig.3 page No. 13).
• Excellent lateral spring characteristics, as desired.
- Achieved by variation in effective area in lateral direction (See Fig.3 page No. 13).
• Avoids excess air consumption due to instantaneous modes of vehicle oscillation or
change in air pressure.
- Achieved by designing delayed reaction levelling valve (See Fig.4 page No. 14).
6. CONSTRUCTION DETAILS:
• Construction details of air spring are shown in (See Fig.5 page No. 15). (air spring with
outside emergency spring), & Fig. 6 at page no.16 (air spring with inside emergency
spring).
7. SCHEMATIC LAYOUT OF PNEUMATIC SUSPENSION CONTROL EQUIPMENTS:
A schematic layout of pneumatic suspension control equipments has been provided in Fig.7 at
page no. 17.
8. MODIFICATION FOR FITMENT OF AIR SPRING IF REQUIRED:
8.1 Bogie Frame & Suspension:
• Air spring has been installed at secondary stage replacing steel coil springs.
• A fixed lower spring beam (as cradle) to accommodate the air spring has been provided
on bogie bolster.
• A lateral hydraulic damper and lateral bump stop have been provided at secondary stage.
• Primary springs have been retained as steel spring.
• Details are shown in Fig.8 at page no. 18
• Leveling valve provided between bogie frame and bogie bolster.
RDSO/Lucknow Page-5

8.2 Bogie bolster:
• Provision made for air inlet to air spring.
• 40 lit addl. Reservoir connected to each air spring is provided.
• Duplex check valve is provided.
8.3 Under frame:
• A pipeline is drawn from M.R pipe (feed pipe) for pneumatic suspension
• One isolating cock, one non return valve, one 150 lit air reservoir (auxiliary reservoir) one
air filter and two separate isolating cocks to isolate each bogie have been provided
• A schematic diagram is shown in fig.7 at page no 17.
8.4 BASE PLATE:
• Base plate to be used should be as per drawing No. RDSO sketch- K4018 alt ‘1’ is
enclosed as fig.9 at page no 19.
9. OPERATING INSTRUCTIONS:
• Train Driver to maintain 7 bar pressure in compressor.
• In case of heavy leakage of air from air spring system, Isolate the affected bogie and
observe speed restriction at 60 km/h up to the terminal point for maintenance.
10. DISMANTLING OF AIR SPRING FROM LOWER SPRING BEAM (CRADLE)
AND BOGIE BOLSTER:
• Remove All Body, Bogie connections
• Remove duplex check valve from bolster
• Remove lateral & vertical shock absorber
• Remove equalizing rod connection from both ends of lower spring beam if provided.
• Remove connection between arm of levelling valve & installation lever.
• Remove all 4 No. Bolts and nut with the help of M16 Allen key and suitable spanner from
bottom plate of air spring & lower spring beam.
• Lift bolster up to bogie frame to clear the spigot of air spring.
• Slide air spring from lower spring seat.
11. INSPECTION & MAINTENANCE OF AIR SPRING:
• Inspect for any water collection in rubber bellow of air spring
• Inspect the air spring for any damage or leakage.
• Inspect air spring seat and top plates for corrosion, if corrosion noticed is paint with
primer & black paint.
RDSO/Lucknow Page-6

12. INSPECTION & MAINTENANCE OF LOWER SPRING BEAM:
• Inspect all welding joints of the lower spring beam (cradle) and repair if required.
• Inspect air spring fixing holes of lower spring beam for elongation, if elongated build
them to dia.17 mm or dia. 26 mm.
• Inspect the corrosion on top surface of lower spring beam, Remove the corrosion paint
with primer and black paint.
13. INSPECTION OF PIPE LINE:
• The air spring piping may be checked for any leakage/damage by soap test and repair if
required.
14. MOUNTING AIR SPRING ON LOWER SPRING BEAM AND BOLSTER:
• "O" rings provided on air spring spigot must be changed.
• Mount air spring on lower spring beam and match the holes of bottom plate of air spring
and holes of lower spring beam.
• Tight all 4 nut-bolts with the help of M16 Allen key and suitable spanner.
• Place the bolster on air spring ensuring no damage to spigot of air spring.
• Connect levelling valve arm with installation lever.
• Mount vertical and lateral shock absorber.
• Connect all flexible/fixed pipe connections of bogie
• All the threaded joints of air spring be sealed with thread sealing tape to avoid air leakage.
• The filter of levelling valve must be cleaned.
15. TEST FOR LEAKAGE:
• Connect the hosepipes on the under frame piping with the levelling valves of the bogies.
• Connect pressure gauges to the drain plug locations of 150-litre reservoir.
• Provide packing in the gap between bolster & bogie frame.
• Connect the 150-litre reservoir on the under frame to the compressed air source of
pressure 9.0 kgf/cm2.
• Allow air into the air springs to a value of 9.0 kgf/cm2 in the pressure gauge by adjusting
the horizontal lever of the levelling valve and keep it in the same position.
• Close the isolating cock connecting MR pipe with 150-litre reservoir.
• Test all pipe joints for leakages.
• Check the pressure gauge readings after one hour. The pressure drop should be within 1%
of the test pressure 9.0 kgf/cm2.
• Release the air completely by dropping the horizontal lever.
• Remove the packing.
RDSO/Lucknow Page-7

16. PROCEDURE FOR CHECKING BOGIE CLEARANCES ON AC AND NON AC
COACHES PROVIDED WITH AIR SPRINGS :
• Firstly find out the type of bogie as AC EOG (16 T), AC SG (16T), or NON AC (13 T) coaches
and make RCF or ICF. List of relevant drawings are as under:
TYPE OF COACH ICF DRAWING No. RCF DRAWING No.
AC EOG(16 T) WTAC5-0-0-501
(ANNEXURE.-C)
-
AC SG(16 T) LWGSCWAC-0-0-001
(ANNEXURE.-D)
CA00001(ANNEXURE.-F)
NON AC (13 T) LGS-0-0-001
(ANNEXURE.-E)
CA00002(ANNEXURE.-G)
• Than the coach should be placed at leveled track.
• The primary springs should be grouped as per ICF drawing no. ICF/STD-9-0-003 placed at
Annexure-H, in which the different type of primary springs is grouped for air spring bogie and
other type of bogie.
• The primary springs are used for the air spring bogies as follows:
TYPE OF COACH ICF DRAWING No. RCF DRAWING No.
AC EOG(16 T) WTAC-0-1-202 WTAC-0-1-202
AC SG(16 T) WTAC-0-1-202 AW01101
NON AC (13 T) WTAC-0-1-202 CC01129
POWER CAR WLRRM8-0-1-801 -
• Place the proper primary springs and compensating rings in AC EOG,AC SG and NON AC
coaches with air spring bogie as per following suspension diagram:
TYPE OF
COACH
ICF DRAWING No. RCF DRAWING No.
AC EOG(16 T) WTAC5-9-0-501(ANNEXURE.-I) -
AC SG(16 T) - CA90001(ANNEXURE.-J)
NON AC (13 T) - CA90001
• Than maintain the bogie corner heights as per relevant suspension diagram.
• After the bogie corner height is maintained, adjust the air spring height as per relevant suspension
diagram with the help of installation lever.
17. PROCEDURE FOR CENTRE BUFFER COUPLER HEIGHT ADJUSTMENT IN WORKSHOP:
• After POH and before assembling the bogie, measure the wheel diameter.
• Depending upon the wheel diameter, place wooden packing of required thickness under the
flange of lower spring seat as indicated in the following table:
Average wheel dia. between the
Thickness of hard packing ring (mm)
two wheels on the same bogie
889 mm to 864 mm 13
863 mm to 840 mm 26
840 mm to 820 mm 38
819 mm 48
RDSO/Lucknow Page-8

18. INSTALLATION LEVER ADJUSTMENT:
Adjustment of installation levers is essential for proper levelling of coach body. The adjustment
needs to be carried out in AOH/POH or intermediate dismantling of levelling valve system. The
procedure to be followed is as under:
• Keep the coach on a level track.
• Connect pressure gauges to the drain plug locations of all 40-litre reservoirs in the bogie.
• Place the car body on the two bogies and hook it up to the air supply (by opening the
isolating cock 1a).
• First open only the isolating cock (1c0, thereby releasing the air supply for bogie “1”and
affix the level control rod assembly to the valves).
• On the rod assemblies (6) set the general level (-5mm) that the car body is ultimately to
have above the bogie frame and the upper edge of the bogie.
• Insert the suitable block (ca 10 mm under the nominal height and preferably of hardwood)
centrally between the bogie frame and the car body and lower the car body onto the block
by removing the valve rod assembly (6).
• Shut the isolating cock (1c) again, thereby interrupting the supply of air to bogie“1” and
open isolating cock (1b), and thereby releasing the air supply to bogie “2”.
• Affix level control rod assemblies (6) to the valves (5) and set the assemblies (6) to
desired level.
• Insert a suitable block (preferably hardwood) centrally between the bogie frame and the
car body and lower the car body onto block by removing the valve and assemblies (6).
• Shut isolating cock (1b) again, thereby cutting off the air supply to bogie “2” and open
isolating cock (1c), and thereby releasing the air supply to bogie “1”.
• Attach level control rod assemblies (6) to the valves (5) and, after aeration, carefully
adjust settings on both rod assemblies (6) simultaneously (proceeding from below) until
the desired car body height has been attained.
• Remove the block from bogie “1”.
• Reopen isolating cock (1b), thereby releasing air to bogie “2”, and while at the same time
hanging the rod assembly (6) back in place in bogie “2”.
• Remove the block from bogie “2”.
• Recheck the height at all measuring points.
CAUTION:
If the difference in pressure of the air in the air springs of the same bogie is more than setting
pressure of the duplex check valve i.e. 1.5 bar, then the air will continuously escape from one air
spring to the other through the duplex check valve and then to atmosphere.
• Tighten the installation lever lock nuts with the horizontal lever, so that the setting will
not be disturbed.
• Repeat the above procedure for the second bogie.
• Disconnect the pressure gauges and replace the drain plugs.
19. CHARACTERISTICS OF AIR SPRING / PERIODICAL INSPECTION OF AIR SPRING
SYSTEM ON MAINLINE COACHES:
These are provided at Annexure – A and B for reference and implementation.
RDSO/Lucknow Page-9

20. AIR SPRING SERVICE:
For the maintenance of the air springs, the respective vendors maintenance manuals should be
followed. These maintenance manuals shall be provided by the respective vendors at the time of
delivery of air springs.
21. AIR SPRING CONTROL EQUIPMENT SERVICE:
For the maintenance of the air springs control equipment, the respective vendor’s maintenance
manuals should be followed. These maintenance manuals shall be provided by the respective
vendors at the time of delivery of air spring control equipments.
-------------------------------------
RDSO/Lucknow Page-10

WORKING PRINCIPLE OF PNEUMATIC SUSPENSION
FIG. NO. 1

FIG. No. 2

FIG. No.3 VERTICAL AND LATERAL ACTION OF
AIR SPRING

DELAYED REACTION OF CONTROL VALVE TO AVOID EXCESSIVE AIR CONSULATION
FIG. No. 4

FIG. NO. 5: AIR SPRING WITH OUTSIDE
EMERGENCY SPRING

FIG. NO. 6 : AIR SPRING WITH INSIDE EMERGENCY SPRING

FIG.NO. 7: SCHEMATIC DIAGRAM OF AIR SUSPENSION EQUIPMENTS

CRADLE
FIG.No. 8 : BOGIE GENERAL ARRANGEMENT WITH AIR SPRING RETROFITMENT

FIG No. 9 : BASE PLATE FOR AIR SPRING

Ref: CGW 0001,Rev.-3 Date / Month of issue:
September, 2009 Page 20 of 21 Maintenance Instruction No.
CMI- RDSO/2009/CG/CMI-01
ANNEXURE-A
GENERAL TECHNICAL DATA AS PER RDSO STR C-K509
1. STATIC VERTICAL LOADS ON AIR SPRING
Tare load -------------------------- -- 50.0 KN
Full load --------------------------- -- 140.0 KN
2. VERTICAL STIFFNESS
At dz + 20 mm and constant speed of 5mm/sec, the vertical stiffness (Cz) shall be:
Load in KN (Static) Vertical stiffness Cz IN N/mm
Additional Volume 20dm3 Additional volume 40dm3
50 550±50 N/mm 400±50N/mm
115 875±75N/mm 625±75N/mm
140 1000±100N/mm 700±100N/mm
3. HORIZONTAL STIFFNESS
At dy +20 mm at constant speed of 5 mm/sec, the lateral stiffness (Cy) shall be:
Load in KN (Static) Lateral stiffness Cy IN N/mm
50 150 ±25 N/mm
115 175±25 N/mm
140 200±25 N/mm
4. Min. height of air spring under full load with no air and without spigot - 210 mm
5. Installed height without spigot - 255+0
-5 mm.

Ref: CGW 0001,Rev.-3 Date / Month of issue:
September, 2009 Page 21 of 21 Maintenance Instruction No.
CMI- RDSO/2009/CG/CMI-01
PERIODICAL INSPECTION OF AIR SPRINGS SYSTEM ON MAINLINE COACHES
EXISTING
SCHEDULE OF
INSPECTION
INSPECTION ON AIR SPRING SYSTEM INSPECTION
SITE
Primary /
Secondary
• Visual check: General conditions which includes any external damages, air leakage, infringement of any
fittings, etc.
• Draining of 150-liter air reservoir of air spring
• Check the position of isolating cock and drain cock, these should be on and off position respectively.
Pit line
Schedule-A • As in Primary / Secondary schedule and Draining of 40-liter reservoir.
• Cleaning of leveling valve filter as per manufacturer’s manual. The procedure is shown at Annexure B/1.
Pit line
Schedule -B • As in Schedule -A
• Checking of installation lever with inflated air spring for normal function, tightening of installation lever
nuts and protection screen nuts, tightening of bracket of all flexible hoses.
• Cleaning of air filter of 150-liter reservoir.
Pit line
Schedule -C • As in Schedule -B &
• Thorough checking of air spring, bulging of bellow, air leakage.
• Air suspension pipe leakage check by using soap water.
• Removing dust mud & oil deposit if any, on air spring and control equipment.
• Thorough checking of lower spring beam for any crack and deformation.
• Tightening of air spring bottom plate bolts and nuts.
• Measurement of bogie clearances related to air spring.
Sick line
AOH/POH • As in Schedule - C and
• Through visual check of air spring as per Annexure-C or D after dismantling as in clause 10.
• Remove all valves and carry out external cleaning, overhauling and function test should be done as given
in maintenance manual supplied by respective vendors.
• Checking securing arrangement of steel pipeline.
• Leakage test of air springs as per clause 15.
• Installation lever adjustment as per clause 18.
• Lateral damper condition should be checked and replace with fresh if damaged.
• Air spring bellow should not be painted.
Depot/
Work shop
ANNEXURE-B

Air suspension in Railway coaches

Air suspension in Railway coaches

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Air suspension in Railway coaches