Light Weight Individually Powered Railway Freight Wagons
Modified to Utilize Lost Energy during Braking
Gaurab Bhowmick & Gunjan De
Mechanical Engineering, Dr. Sudhir Ch. Sur Degree Engineering College, Kolkata, India
E-mail : [email protected], [email protected]
Abstract – EMU or the Electric Multiple Units are those
type of trains consisting of self-propelled carriages using
electricity as the motive power. An EMU requires no
separate locomotives, as electric traction motors are
incorporated within one or a number of carriages.
Generally EMUs are used for passenger train but the same
technology can be implemented in freight carriages also.
These EMU based freight cars will reduce the line
congestion mainly in India due to its rapid acceleration
and high speeds.In this study, the purpose of the carriage
is to be self-propelled using highly efficient traction motors
powering each carriage made of high strength Aluminum
having individual and independent wheel set. Also, the
wagon will harness the waste braking energy using
regenerative braking technique to power the traction
motors partially. This study addresses the problem of
severe line congestion, unwanted holding of freight trains
to make passageway for passenger trains, light weight
wagons, harnessing the wastage braking energy which are
generally removed as heat. Therefore, study of the
methodologies suggested has to be done in order to
determine the feasibility and effectiveness of the methods
both in terms of technology and financially. To achieve this
detailed analysis is carried out to understand the
modification of normal freight wagon to self-propelled
EMU type wagon.
Railway.[4] But, the advanced form of dynamic braking
i.e. the regenerative braking is not being used here in
India and the entire energy obtained from dynamic
braking is released in the form of heat.[5] Another
shortcoming is the use of steel, iron and its
corresponding alloys to make the wagons instead of
using light weight, robust material having same & better
properties as of steel & its derivatives.[6]The above
mentioned shortcomings results in some disadvantages,
which are discussed in the following sections.
II. DISADVANTAGES OF SOME OF THE
IMPLEMENTED TECHNIQUES:
Locomotive pulling the entire rake results in very
slow acceleration, highly inefficient operation,
more load on the engine , low avg. running speeds
results in line congestion.

The use of dynamic braking and releasing the
energy as heat result for huge loss.

Using heavy weight materials adds more weight to
the carriage and needs more power from the engine.
The disadvantages can be overcome by the technique
discussed in details below taking each case separately.
Keywords – EMU, Regenerative, aluminum, self-propelled.
I.

INTRODUCTION
III. NOMENCLATURE
Generally, in India freight trains are conventionally
pulled by a locomotive either electric or diesel.[1] In the
conventional method of hauling the locomotive has
tractions motors fitted only in its wheel.[2] So, in the
entire rake only the locomotive wheels are powered
which in turn provides the necessary force and torque
required for moving the train. The conventional freight
carriages have connected wheels sets with an axle,[3]
which in turn adds for some extra weight and restricts
operation for high speed resulting in line congestion.
Even though the technology of dynamic braking is
implemented in almost all locomotives of Indian
r - Radius of wheel
m – Mass of wheel
I – Moment of inertia
N – Newton, Angular Velocity in r.p.m.
T – Torque
α – Angular acceleration
V – Linear Velocity
ω – Angular velocity in rad/s
t – time , s
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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)
IV. ANALYSIS
4.1 Self-propelled carriages
Wheelbase
Unsprung mass
per axle
Body width
Cab length
Indian Railways has a wide range of locomotives
both diesel and electric type varying from 2500HP to
7000HP (approx.). These locos provide a variable range
of tractive forces to pull the rake. As these locos are the
only power source for the entire rake, it results in a very
slow rate of acceleration.

for IORE and China
HXD3B;
bogie
1850mm + 1850mm
15700mm
3.984t
Railways
wheelbase
3152mmn
2434mm
From the above technical specification it is seen
that the tractions motors (850KW) each are being used
in the loco. It takes around 10-15Km of track to reach an
optimum speed of 80-100kmph with a rake of 42 BCN
carriages. If instead of using the loco, each around
60KW high torque traction motors for powering each
independent wheel can be used, which will result in a
better acceleration.
Case I (WAG 9 IR)
Traction motor
specification –
considered
has
the
following
Table II : (HVH250 HT)[iii]
Fig. 1 [i]
Table i (Technical Specs.)[ii]
Manufacturers
Traction
Motors
Gear Ratio
Transformer
Power Drive
Hauling
capacity
Bogies
ABB Swiss Locomotive Works,
CLW
ABB's 6FRA 6068 (850 kW,
2180V,
1283/2484
rpm,
270/310A. Weight 2100 kg)
Axle-hung, nose-suspended.
77:15 / 64:18
ABB's LOT 6500, 4x1450kVA.
Power converter from ABB, type
UW-2423-2810 with SG 3000G
X H24 GTO thyristors (D
921S45 T diodes), 14 thyristors
per unit (two units). Line
converter rated at 2 x 1269V @
50 Hz, with DC link voltage of
2800V. Motor/drive converter
rated at 2180V phase to phase,
971A output current per phase,
motor frequency from 0 to
132 Hz.
4250t
Co-Co,
Fabricated Flexicoil Mark
bogies (Design later
Overall Length (mm)
180
Stator Outside Diameter (mm)
Rotor Inside Diameter (mm)
Mass – Complete Motor (kg)
Continuous Power Output (kW)
Peak Power Output (kW)
Continuous Torque Output (N-m)
242
132
43
60
87
243
Peak Torque Output (N-m)
Max. Input Current Peak/
Continuous (Amps)
440
Peak Efficiency (%)
Max. Operating Speed (rpm)
Base Speed (rpm)
Operating Voltage (VDC nom.)
Temperature Limits
Conductor Type
200/300
93 @
1,500-8,000
rpm
10,600
1,400
320
160° C
High Voltage
Hairpin
Estimated calculations for this case are as follows :
4.1.1 Sample calculation –
(Assuming wheels are directly driven by the motor shaft
with gears of ratio 1:1 in between and the calculation is
based on theoretical aspect and is just an estimation)
Power of each traction motor = 60KW
IV
used
No. of wheel in each carriage = 8
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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)
Total power (each carriage) = 60x8 = 480KW
same pantograph used to receive power. But, in India
there is no provision for adequate transfer of current
back to the grid lines.
Starting torque each motor = 440Nm
Total starting torque (each carriage) = 440x8 = 3520Nm
This problem can be solved by harnessing the
energy within the train itself. As already discussed that
each wheel will have its own traction motor to power
the rake. So, placing a battery next to each traction
motor and the battery can be used for additional supply
of current and power when required. Now, the battery
needs to be charged. The charging voltage will come
from the motor itself when used as a generator during
dynamic braking. The generated voltage will be used up
by the battery instead of losing it as heat to the
atmosphere. According to various studies done across
the globe, it is found that dynamic braking energy
accounts for up to 40% of the energy used to drive the
train. So, if this energy is harnessed and used again to
drive the train, the efficiency of the whole system will
increase. Since, these individual traction motors gives a
tremendous acceleration, similarly these motors when
used as generators will give almost same amount of
braking effort.
No. of carriages in a rake = 42 (generally)
So, Total starting torque for entire rake = 3520x42
= 147840Nm
Now, for BCN wagons radius of each wheel, r = 0.5m
Axle load = 20.32tonnes
Therefore, load on each wheel (assuming equal
distribution), m = 20.32/2 = 10.16x1000 = 10160kg
Moment of Inertia, I = ½ x mr 2
Or, I = ½ x 10160 x 0.5 x 0.5
Or, I = 1270kg/m2
Torque, T = Iα
Or, α = T/I
Or, α = 3520/1270
Or, α = 2.77 rad/s2
Flow Chart for utilizing the lost braking energy
Now, suppose we require reaching the speed of
100km/h, then
Velocity, V = ω x r
Or, ω = V/r
Or, ω = 27.78/0.5
Or, ω = 55.56 rad/s
We know,
ω=αxt
or, t = ω/α
or, t = 55.56/2.77
or t = 20.05sec
4.1.2 Result Analysis
Under Analysis
4.2 Harnessing the energy from Dynamic Braking
Conventional loco in India has the provision for
dynamic braking i.e. using the motors as generator to
slow down the train. But, the energy obtained from
dynamic braking is totally wasted as heat through the
network of resistors to the atmosphere. This is a total
waste of energy thus reducing the efficiency of the train.
4.2.1 Result Analysis
Under Analysis and experimentation
4.3 Use of light weight material
There is a provision of feeding back the generated
current from dynamic braking to the grid lines using the
Typically the freight wagons are made of steel and
sometimes stainless steel to reduce corrosion. Earlier
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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)
iron was used to build the wagons, but due to the
corrosive nature of iron , stainless steel was adopted to
manufacture the wagons. But, due to the tremendous
rise in price of steel, railway started to initiate
production of aluminum wagons on a trial basis. Since
aluminum is lighter than steel it reduced the tare by
4.2tonnes. Aluminum wagons besides being of a lower
cost and having a lower tare weight, also have the
advantage of suffering less corrosion in many
circumstances. A typical rake with aluminum wagons
instead of steel ones would carry almost 240t more
goods.
Chart I
Along with Aluminum, fiber glass sheet can be
used to manufacture the wagons, which will further
reduce the weight of the wagon and thus increasing
efficiency. An indicative comparison follows –
Chart II
Table III : (Properties of steel)[iv]
Properties
Density (1000 kg/m3)
Elastic Modulus
(GPa)
Carbon
Steels
7.85
190-210
Poisson's Ratio
0.27-0.3
Thermal Expansion
(10-6/K)
11-16.6
Alloy
Steels
7.85
190210
0.270.3
Stainless
Steels
7.75-8.1
9.0-15
9.0-20.7
Yield Strength (MPa)
Percent Elongation
(%)
Hardness (Brinell
3000kg)
0.27-0.3
Table V : (Fiber Glass Properties)[vi]
13711454
Melting Point (°C)
Thermal
Conductivity
(W/m-K)
Specific Heat
(J/kg-K)
Electrical Resistivity
(10-9W-m)
Tensile Strength
(MPa)
190-210
24.365.2
26-48.6
4502081
1301250
2761882
186-758
4521499
2101251
7581882
3661793
11.236.7
Polyester resin
(Not reinforced)
Polyester
and
Chopped Strand
Mat
Laminate
30% E-glass
Polyester
and
Woven Rovings
Laminate 45%
E-glass
Polyester
and
Satin
Weave
Cloth Laminate
55% E-glass
Polyester
and
Continuous
Rovings
Laminate 70%
E-glass
E-Glass Epoxy
composite
S-Glass Epoxy
composite
420-500
75.71020
515-827
207-552
10-32
4-31
12-40
86-388
149627
137-595
Table IV : (Properties of Aluminum Alloys)[v]
Density
Melting Point
Elastic Modulus
Poisson's Ratio
Tensile Strength
Yield Strength
Percent Elongation
Thermal
Expansion
Coefficient
Specific
gravity
Material
2600-2800 kg/m3
660 °C
70-79 GPa
0.33
230-570 MPa
215-505 MPa
10-25%
20.4-25.0 × 10-6/K
Tensile Compressive
strength strength MPa
MPa (ksi)
(ksi)
1.28
55 (7.98)
140 (20.3)
1.4
100 (14.5)
150 (21.8)
1.6
250 (36.3)
150 (21.8)
1.7
300 (43.5)
250 (36.3)
1.9
800 (116)
350 (50.8)
1.99
1770 (257)
410
1.95
2358 (342)
1912
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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)
4.3.1 Proposed Modifications
Or, N = 41.668 x 100.06
As seen above, physical properties chart of three
types of materials has been provided along with a graph
comparing the Tensile strength & Density of the
materials.
Or, N = 4169.3 kg of stainless steel reqd. (approx.)

Now, Cost of Fiber glass ((FRP) Corrugated Sheet) of
thickness 5mm/5ply = 3$ per sq. ft.

Cost = 4.1693 x 2965 $
Or, Cost = 12361.97 $
It is seen that out of Stainless Steel, Aluminum &
fiber Glass, stainless steel has the tensile strength a
little bit higher than that of aluminum but less than
that of fiber glass.
Area , A = 1077 ft2
Cost of Fiber glass = 1077 x 3$
Similarly, from the density graph it is seen that the
density of Fiber glass is the lowest than that of the
other two materials.

If the wagons are manufactured using aluminum
alloys or fiber glass, the weight of the wagons will
be much less than those made of stainless steel or
steel alloys.

If weight is less , then the efficiency of the engine
increases, it requires less energy .

Fiber glass is totally non-corrosive.

Cost of making fiber glass is very less as compared
to aluminum and stainless steel.

Less weight means more rapid acceleration.

Energy required to manufacture fiber glass is far
less than the energy wasted in obtaining aluminum
and steel from its ores, thus reducing carbon
footprint.
Or, Cost = 3231$
4.3.2 Sample Calculation (Approx. Estimation)
From the fig. it is seen that length, l = 12800mm
Width of the wagon, w = 3136mm
Height of wagon (above floor height), h = 1880mm
Surface area for the entire carriage with top open is
given by, A = (2xlxh) + (2xwxh) + (lxw)
Or, A = (2x12800x1880)
(12800x3136),
+
(2x3136x1880)
+
Or, A = 48128000 + 11791360 + 40140800
Or, A = 100060160 mm2
Or, A = 100.06m2
Now, Cost of stainless steel = 2965US$ / tonne
For a sheet of Gauge = 5 and Thickness = 5.314mm
Weight per unit area = 41.668kg/m2
Fig. BCXT Wagon[vii]
Therefore, Total steel required (approx.) is given by
[ This figure is used as the for section 4.3.2]
N = Weight X Area (A)
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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)
[7]
Govt. of India/Ministry of Railways Maintenance
Manual
[8]
“Indian Railway : The backbone of service sector
, “by Sarika Sharma (Research Scholar, Faculty
of Commerce, B.H.U., Varanasi-221005)
[9]
“Electric Railway Traction, Electric Traction &
DC traction motor drives “ by Hill, Roland John,
UK, IEEE.
[10]
“Indian Railway axle
maintenance guide”.
[11]
“Studies of Regenerative braking in electric
vehicle “, by Yoong, M.K., IEEE.
[12]
“Transportation: Dynamic braking: The kinetic
energy of rapid transit trains that is normally
dissipated as heat during braking can be
converted to potential energy”, by Kalra, P.,
IEEE.
[13]
“Fiberglass & Glass Technology”, Wallenberger,
Frederick T.; Bingham, Paul A. (Eds.)
[14]
Cost Comparison
4.3.3 Analysis of Result
Under Analysis
V. CONCLUSION


After analyzing the above cases, it is found that
implementing the suggested technique will have
various advantages over the initial disadvantages
stated using the conventional locos and carriages.
Designing and manufacturing considering the
methodologies suggested will result in less
manufacturing cost, more efficiency and will reduce
the carbon foot print by a huge margin.
manufacturing
&

The above aspects are just an theoretical
imagination and can be implemented after some
research and experimentation.
“FREIGHT
TRAIN
ROUTING
AND
SCHEDULING IN A PASSENGER RAIL
NETWORK:
COMPUTATIONAL
COMPLEXITY
AND
THE
STEPWISE
DISPATCHING HEURISTIC”, T. GODWIN
,Marketing and Planning Systems,

The calculations performed in this paper are based
on basic equations neglecting many additional
effects.
RAM GOPALAN, Fox School of Business and
Management, Temple University, Philadelphia,
PA 19122, USA

Detailed calculations can be done after initial
practical implementation.

T.
T.
NARENDRAN,
Department
Management Studies, Indian Institute
Technology, Madras, Chennai 600036, India.
So, the entire motive of this paper is to clear out the
line congestion caused by slow moving goods train
along with proper utilization of energy by Indian
Railways.
VI. REFERENCES
[1]
Image source www.en.wikipedia.org
[2]
CLW loco Driver’s Manual and handbook
[3]
Remy International Inc. motor specs. Chart
[4]
www.efunda.com
[5]
www.efunda.com/materials/alloys/aluminum/pro
perties.cfm
[6]
www.en.wikipedia.org
of
of
[15]
S.J. Clegg (1996), A review of regenerative
braking systems. Institute of Transport Studies,
Univ. of Leeds.”
[16]
“Govt. of India, Traction
Maintenance manual”
[17]
Maintenance Chart for Wagons by Indian
Railway
[18]
Ministry of Railways / Engineer’s handbook
[19]
Ministry of Railways Wagon Specification Chart
[20]
Theory of Machines – R.K. Bansal, Lakshmi
Publication
[21]
http://www.realfibre.com/price_list.html
Rolling
Stock,
ISSN : 2319 – 3182, Volume-2, Issue-3, 2013
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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)
[22]
http://www.worldsteelprices.com/
[23]
http://www.custompartnet.com/sheet-metal-gauge
[24]
http://irdindia.in/Journal_IJTARME/PDF/Vol1_I
ss2/4.pdf
[25]
Electrical Technology II – B.L Theraja, S.Chand
Publication.
[26]
“MECHANICAL PROPERTIES OF G10
GLASS-EPOXY COMPOSITE”, K. RaviChandar, S. Satapathy, The University of Texas
at Austin, USA.
[27]
”MECHANICAL
PROPERTIES
OF
POLYMERIC COMPOSITES REINFORCED
WITH HIGH STRENGTH GLASS FIBERS”,
Michael Kinsella, Dennis Murray, David Crane,
John Mancinelli, Mark Kranjc, Advanced Glass
fiber Yarns LLC, Aiken, South Carolina 29802,
Advanced Glass fiber Yarns LLC, Huntingdon
plant, Pennsylvania 16652, Bell Helicopter
Textron Inc., Fort Worth, Texas 76101.
[28]
”Composite Materials: Fatigue and Fracture,
Issue 1285”, By ASTM Committee D-30 on High
Modulus Fibers and Their Composite.

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