Smoothness running of train on uneven tracks with the help of air springs

1. INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 9, September (2014), pp. 427-434 © IAEME
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ISSN 0976 – 6340 (Print)
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Volume 5, Issue 9, September (2014), pp. 427-434
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© I A E M E
SMOOTHNESS RUNNING OF TRAIN ON UNEVEN TRACKS WITH THE
HELP OF AIR SPRINGS
Dr. Jinesh Kumar Jain1, Dr. M. P. Singh2, Dr. G.S. Dangayach3, Dhananjay Chauhan4
1Associate Prof., Department of Mechanical Engineering, Govt. Engg. College, Ajmer(India)
2Associate Prof. Department of Mechanical Engineering, Jagannath University, Jaipur(India)
3Prof., Department of Mechanical Engineering, MNIT, Jaipur(India)
4PG Scholar Department of Mechanical Engineering, Govt. Engg. College, Ajmer(India)
ABSTRACT
The main purpose of the air spring is to restrict the vibration at a desirable level as per
requirements. Higher rail vehicle speeds generally results in increased vibrations in the car body,
which has a negative impact on ride comfort. The suspension of the vehicle has to be modified in
order to reduce the vibration and journey should be comfortable i.e. Jerk free journey. It is always
desirable to keep the vibration level as low as possible by introducing damping. One of the most
important techniques used in the present problem for improving damping is utilizing the air spring
in place of helical spring, because due to damping the helical spring gets break up and which
causes the serious accident. One of the techniques used in the present problem for improving
damping is utilizing the air spring in place of helical spring. This paper consists of two different
parts: a theoretical analysis of the problem and an experimental work.
In railway vehicles, air springs are used for improving comfort for the passengers and for
the prediction of the vibrations in the car body. The design concept evolved from this research
work in trusses and frames, transporting system and rail coaches where higher damping is
required, which can be made safely by utilizing the air spring system. This system is also help full
to reduce the maintenance cost in transportation system.
Keywords: Spring, Vibration, Ride Comfort, Air Spring, Cost, Life Time.
I. INTRODUCTION
The study on “Smoothness running of trains on uneven tracks with the help of air spring”
and its importance in structures has become increasingly significant for controlling the
undesirable effects of vibration. The manufacture of such structures also requires high damping

2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 9, September (2014), pp. 427-434 © IAEME
capacity and stiffness with light weight for its effective use. Such requirements demanded and
popularized the use of air spring as structural members with high damping capacity. In rail
operation today, there is a general trend towards increased vehicle speeds, directly which is
correlated with vibration. As we know rise the higher speeds usually generate increased forces and
accelerations on the vehicle, which has a negative impact, on ride comfort. Furthermore, the
demands for higher speeds in turn increase the requirements for lighter air spring which reduce the
impact between wheels and rails i.e. reduce the vibration. Active technology in rail vehicles can
be utilized in order to achieve one or more of the following goals;
a) Improve passenger ride comfort,
b) Maintain good ride comfort although vehicle speed is increased,
c) Maintain good ride comfort although track conditions are worse,
d) Reduce wheel and rail wear by means of improved curve negotiation,
e) Secure running stability at higher vehicle speed.
1.1 Objectives of Air spring
a) Improve passenger ride comfort, b) Maintain good ride comfort although vehicle speed is
increased, c) Maintain good ride comfort although track conditions are worse, d) Reduce wheel
and rail wear by means of improved curve negotiation, e) Secure running stability at higher
vehicle speed.
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1.2 Curve negotiation
When negotiate a curve at an excessive speed, vehicles will roll over and automobiles will
lose traction and slake out of a curve instead of rolling over. The more top-heavy a vehicle is, the
more likely it will roll over than slake out of a curve. If the ride comfort is already good, further
improvement at unchanged vehicle speed and track conditions is generally not justified due to the
high costs of implementing active suspension. However, goals b) and e) allow large possibilities
for cost-efficient improvements, since vehicle speed can be increased. Moreover, goals (c and d)
have good potential of being worth the investment of active technology, since bogie maintenance
will be saved .In order to achieve this control loop in the suspension of a rail vehicle, actuators,
sensors and a controller must be added to the mechanical system.
Fig. The concept of an active suspension system
1.3 Working principle of pneumatic suspension
Air suspension is a suspension where properties of air are used for cushioning effect
(springiness). Enclosed pressurized air in a pre-defined chamber called air spring, made up of
Rubber bellow emergency rubber spring, provides various suspension characteristics including

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 9, September (2014), pp. 427-434 © IAEME
damping. Air springs are height-controlled load leveling suspension devices. With changing loads,
air spring reacts initially by changing the distance between air spring support and vehicle body.
The height monitoring 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).
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Fig. Working principle of pneumatic suspension Passengers
Fig. Air spring at standard height
1.4 Comparison with existing coil suspension
Unlike steel spring, air springs retain their height under changing loads. 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 but air springs control mechanism, offer a load
proportionate stiffness, constant floor height and prospects of better ride behavior with higher
speed potential. Helical is springs are light, but they’re not perfect. Some advantages of air springs
are:
i) Capable to sustain Super Dense Crush Loads typical of suburban traffic. ii) Maintain constant
floor height of coach. iii) Provide superior ride comfort. iv) Virtually Constant natural frequency
from tare to full loads, reducing passenger fatigue. v) Isolation of structure borne noise, this
improving comfort. vi) Improved reliability, reduced maintenance effort. vii) Flexibility to choose
characteristics as per requirement at design stage.
1.5 Characteristics features of air suspension
i) Soft flexible characteristics in vertical direction - Achieved by compression of air. ii) Excellent
lateral spring characteristics, as desired. - Achieved by variation in effective area in lateral
direction. iii) Avoids excess air consumption due to instantaneous modes of vehicle oscillation or
change in air pressure- Achieved by designing delayed reaction leveling.

4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 9, September (2014), pp. 427-434 © IAEME
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2. LITERATURE REVIEW
In the early 1930's, the Firestone Tire and Rubber Company began experiments to develop
the potential of pneumatic springs. Between 1935 and 1939, several makes of U.S. automobiles
were equipped with air springs and extensively tested to prove the potential of automotive air
suspension systems. . In the early 1950's, after several years of intensive product development, the
air sprung bus finally went into production. That was the beginning of the air spring success story.
These systems generally employ small, electric or engine-driven air compressors which
sometimes fill an on-board air receiver tank which stores compressed air for use in the future
without delay. High-pressured industrial gas bottles (such as nitrogen or carbon dioxide tanks
used to store shielding gases for welding) are sometimes used in more radical air suspension
setups. The installation and configuration of these systems varies for different makes and models
but the underlying principle remains the same. The metal spring (coil or leaf) is removed, and an
air bag, also referred to as an air spring, is inserted or fabricated to fit in the place of the factory
spring. When air pressure is supplied to the air bag, the suspension can be adjusted either up or
down (lifted or lowered). General Motors used its experience with commercial bus air suspension
to introduce systems for its automobile lines, introducing it as standard equipment on the Cadillac
Eldorado Brougham in the 1957 model year. The following year it was offered as optional
equipment on all Cadillac’s, and in 1959 it was made standard equipment on all Eldorado’s. Air
bellows at each wheel replaced standard coil springs, and had sensors to keep the car level under
load and in turns. It was too slow to react in sudden maneuvers. Period reviews rated the air
suspension somewhat superior in ride quality, but not dramatically so. But now a day in air spring
system is become a reliable system whose design is changed according to ancient air spring which
was designs from Land Rover, Ssang Yong, Chrysler, Subaru, Audi, Volkswagen, Tesla, Porsche,
and Lexus models etc. Now a day’s its shape has been changed and made it more comfortable for
passenger and made it jerk free also designed as to reduce the maintenance cost in transportation
system by using air spring.
3. WORKING PRINCIPLE OF PNEUMATIC SUSPENSION
It enclosed pressurized 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 leveling suspension devices. With changing loads,
air spring reacts initially by changing the distance between air spring support and vehicle body.
The air springs replace only the secondary suspension, whereas primary suspension continues to
use steel coil springs. an auxiliary air reservoir of 150 litre capacity is provided below each coach
which is fed from feed pipe through a non-return valve. Maintains 7 bar pressure in loco
compressor and air springs operate at a limiting pressure of 6 kg/cm2
4. EXPERIMENTAL RESULTS
The following environmental conditions are maintained during the experiments:
Air suspension fitted in EMU/DMU stock shall be subjected to the following
environmental condition:
*Max. Temperature under sun: 60°C *Ambient temperature: 0° to 45°C in shade.*Average
relative humidity: 70% to 90%, 100% on several days. *Rainfall: Fairly heavy, maximum being
200mm in 24 hrs typical to the coastal areas.*Atmosphere: Duties for several months of the year.

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 9, September (2014), pp. 427-434 © IAEME
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4.1 Vertical stiffness of air spring assembly
Minimum air cushion provided under minimum tare load condition shall be 25mm, with
installed height of 255±0.5mm. At dz±20 mm at constant speed of 5mm/sec the vertical stiffness
(Cz) shall be:
Table A: Vertical stiffness of air spring
Load in
KN(static) Vertical stiffness Cz in N/mm
Additional Volume 20 dm3 Additional volume 40dm3
50 600±100 N/mm 550±100N/mm
165 1200±200/mm 1000±200N/mm
180 1350±200N/mm 1150±200N/mm
4.2 Lateral spring stiffness of air spring assembly
At dy ±20mm at constant speed of 5mm/sec the lateral stiffness shall be:
Table B: Lateral spring stiffness of air spring
Load in KN(static) Lateral stiffness Cy in N/mm
50 250±50N/mm
165 450±100N/mm
180 500±100N/mm
4.3 Horizontal Stiffness
At dy ±20mm at constant speed of 5 mm/sec, the horizontal stiffness shall be:
Table C: Horizontal Stiffness
Load in KN (Static) Lateral stiffness Cy in N/mm
50 150 ±25 N/mm
115 175±25 N/mm
140 140 200±25 N/mm

6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 9, September (2014), pp. 427-434 © IAEME
i) Installed height without spigot =255±0.5mm. ii) Maximum permissible diameter of air spring
=Ø740mm. iii) Maximum permissible external diameter of to plate of air spring =Ø750mm. iv)
Min, height of air spring under full load with no air without spigot =215 mm.
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5. SPACE CONSTRAINS
5.1 Pneumatic supply connection
Air inlet connection point to be air spring shall be located at the centre of top plate through
a spigot shall be as under:
i) Outer diameter=Ø85-0.036 -0.071mm. ii) Height=35±0.5 mm. iii) Diameter of “O” ring
=5.7±0.1mm
5.2 Tolerance test
Table A: Tolerance in measured valve during characteristics tests
S.No. Characteristic Tolerance
1 Pressure force Characteristic ±5%
2 Load deflection Characteristic ±10%
3 Stiffness under sinusoidal ±15%
Table B: Vertical acceleration and Lateral acceleration (PSD) in (m/s2) /Hz
Vertical acceleration(PSD) in (m/s2)/Hz Lateral acceleration(PSD) in (m/s2)/Hz
0.7Hz 1.0Hz 2Hz 4Hz 10Hz 3Hz 4Hz 7Hz 10Hz 15H
z
9.34 1.38 0.41 0.68 1.66 0.0156 11.48 0.0507 0.0968 0.2
5.3 CHARACTERISTICS TESTSAIR BELLOW
Characteristics tests
S.No Pressure in kg/cm2 Specific load in KN Observed load in KN
1. 1 kg/cm2 30.4 to 33.60 KN 31.25 KN
Specified inspections
Lot size upto 10 25 50 75 100
No of samples 2 3 4 5 6

7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Check list for inspection of air spring
S.NO Item Firm’s RDSO approved Drg.No.
1 Top plate 750 mm
2 Spigot Height-35mm, Ø-85mm
3 Base plate with fixing holes 400X 600 mm
4- “O” ring Ø-5.8mm
5.4 LIFE CYCLE
Table C: Comparison of life cycle of helical spring and air spring
S.NO Month (Year-2013) Helical spring Air spring
1. January No change
No change
2. February No change
3. March No change
4. April Change
5. May No change
6. June No change
7. July No change
8. August Change
9. September No change
10. October No change
11. November No change
12. December Change
By above data we concluded that the life cycle of air spring is much better than that of
helical spring. Cost of helical spring is Rs10000 and life cycle 4 months but cost of air spring is
Rs75000 and life cycle 12 years which is shown by below graph.
Fig. Cost Vs life cycle

8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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6. CONCLUSION
In the previous days, helical spring is used to design and demonstrate the wheel
monitoring system in train. The helical spring less reduce the vibration at most for current
researches. The current researches scenario the continuity improved the quality and safety purpose
and it announce new theme i.e. air spring suspension system. The air spring suspension reduces
the sudden failure rate and it is more comfortable in compare to helical spring. And one of best
thing with this spring is, it have emergency spring which keeps it safe after any problem. These
are the effective points because, when damping the helical spring the bogie frame structure get
damaged/cracked. One air spring capacity up to 180 KN=18Ton, and a coach have 45.5/46 Tare
load=Ton. In a coach has 2 bogie and a bogie have two air spring so; it is capable to bare the train
load at and situation. At and emergency situation emergency spring is also given. One helical
spring have 3-4 months life time but an air spring have 10-12 years life time. So it is more
effective. One of the important factor is emergency spring which keeps save as per the own name.
So at last we can say that this paper play an effective role in future.
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