Analysis of bogie suspension system

1

A

PROJECT REPORT

ON

ANALYSIS AND MODIFICATION IN BOGIE SUSPENSION SYSTEM

SUBMITTED BY

Mr. PRAVIN.P.PAWAR ROLLNO: 60

Mr. SURAJ.S.RANA ROLLNO: 61

Mr. PANKAJ.E.RAWOOL ROLLNO: 62

Mr. KANNAN.T.REDDIAR ROLLNO: 63

UNDER THE GUIDANCE OF

PROF. DEEPAK CHAUDHARI

Department of Mechanical Engineering

Vidyavardhini's College of Engineering and Technology,Vasai

University of Mumbai

2012-2013


2

VIDYAVARDHINI'S COLLEGE OF ENGINEERING AND TECHNOLOGY

VASAI, THANE


CERTIFICATE

This to certify that requirements for the project work entitled


have been successfully completed by the following students:

Name Roll No.

Mr. PRAVIN.P.PAWAR 60

Mr. SURAJ.S.RANA 61

Mr. PANKAJ.E.RAWOOL 62

Mr. KANNAN.T.REDDIAR 63

In partial fulfillment of Bachelor of Engineering of Mumbai University the Department of

Mechanical Engineering, Vidyavardhinis College of Engineering & Technology, Vasai Road,

Thane, during the academic year 2012-2013.

Internal Guide ____________ External Guide_____________

(Prof. Deepak Chaudhari) (Mr. K. Sayyed, JR. INST. BTC)

H. O. D __________ Chief Instructor, BTC __________

(Prof. U. V. Asolekar) (Mr. P. L. Rane)

3

ACKNOWLEDGEMENT

It gives us immense pleasure to present this project report on


I would like to take this opportunity to express my gratitude to all the

individuals whose contribution have helped me in undergoing training and

successful completion of my project at Carriage Repair Shop, Central

Railway, Matunga , Mumbai-400019.

First of all I would like to thank Mr. A.K. Singh (CWM), Mr. G.R. Gadhe

(AWM(G)&Training Officer ) and Mr. C.R. Shetty (CI, BTC) for giving me

an opportunity to take training in this historic workshop.

I express my hearty gratitude to Mr. S.K. Sayyad (Jr. Inst., BTC), for their

unstinting support and suggestions which gave me direction to work.

Special thanks to Prof. Deepak Chaudhari (Internal Guide), Prof. U. V.

Asolekar (HOD, Mechanical) and Dr. Ashok A. Dhale (Project Co-ordinator).

I would also like to thank Mr Joshi Sir (J & T section) for helping us in our

project selection and directing us during the course of project. I would also like to

thank all Workshop Officials, Shop Superintendents, Staff members and

faculty members of J & T section for their invaluable help at all the time.

Last but not the least, I would like to thank all my colleagues and workers for

all the co-operation and for their direct or indirect help during the phase of

my training.

4

INDEX

CHAPTER

NO.

CONTENT

PAGE

NO

1

INTRODUCTION

1.1 INDIAN RAILWAYS

1.2 AN OVERVIEW OF MATUNGA

WORKSHOP

1.3 FUNCTIONS OF A BOGIE

1.4 KEY COMPONENTS OF A BOGIE

1.5 FACTORS AFFECTING BOGIE

SUSPENSION

7-17

2

BOGIE ASSEMBLY

2.1 DESIGN FEATURES

2.2 ALL-COIL ICF BOGIE

2.3 WORKING

2.4 AXLE BOX GUIDE WITH DASH

POT ARRANGEMENT

2.5 BOGIE BOLSTER SUSPENSION

2.6 SPRINGS

2.7 CENTRE PIVOT ARRANGEMENT

2.8 SIDE BEARERS

2.9 ANCHORLINKS & SILEN BLOCK

2.10 EQUALISING STAYS

2.11 BOLSTER SPRING SUSPENSION

HANGERS

2.12 SHOCK ABSORBERS

18-29

5

3

LITERATURE REVIEW

3.1 HOW BOGIES WORK BY ISAO

OKAMOTO

30

4

MATHEMATICAL MODEL

4.1 TYPES OF VIBRATIONS

4.2 MODELING VIBRATING SYSTEMS

4.3 MULTIPLE DOF MODELS

4.4 2 DOF SYSTEM

4.5 4 DOF SYSTEM

31-39

5

MATLAB

5.1 m CODE FOR 2 DOF SYSTEM

5.2 m CODE FOR 4 DOF SYSTEM

40-46

6

ANALYSIS IN UNIVERSAL MECHANISM

47-58

7

ANALYSIS RESULTS

59-63

8

CONCLUSION

64-76

6

LIST OF FIGURES

FIGURE NO.

FIGURE NAME

PAGE NO

1.5 BOGIE 17

2.1 ICF-BOGIE SIDE VIEW 19

2.2 BOGIE BOLSTER ARRANGEMENT 19

2.3 ICF BOGIE TOP VIEW 21

2.4 DASHPOT ARRANGEMENT 22

2.5 BOGIE BOLSTER DESIGN 23

2.6 SECONDARY COIL SPRING 24

2.7 CENTRE PIVOT ARRANGEMENT 25

2.8 SIDE BEARERS 26

2.9 ANCHOR LINKS WITH SILENT

BLOCK

27

2.10 EQUALISING STAYS 28

2.11 HANGER WITH HANGER BLOCK 28

2.12 SHOCK ABSORBERS 29

7

CHAPTER NO 1

INTRODUCTION

1.1 INDIAN RAILWAYS

Type Government Owned

Founded April 16, 1853, nationalized in 1951

Headquarters New Delhi, India

Area served India

Key people Pawan Kumar Bansal-State Railway Minister (V)

KJ. Suryaprakash Reddy-State Railway Minister (R)

Adhir Ranjan Chaudhari : Chairman

Railway Board: Mr.Vinay Mithal

Industry Railways and Locomotives

Products Rail transport, Cargo Transport, Services

Revenue INR 1,24,545 Crores (~30.5BUSD)

Employees ~1,400,000

Parent Ministry of Railways (India)

Divisions 16 Railway Zones

Slogan "lifeline of the nation"

Website www.indianrailways.gov.in

8

Indian Railways abbreviated as IR, is a Department of the Government of

India, under the Ministry of Railways, and is tasked with operating the rail network in

India. The Ministry is headed by a cabinet rank Railways Minister, while the

Department is managed by the Railway Board. Indian Railways is not a private

corporate body; however, of late IR has been trying to adopt a corporate management

style.

Indian Railways has a total state monopoly on India's rail transport. It is one of

the largest and busiest rail networks in the world, transporting sixteen million

passengers and more than one million tonnes of freight daily. IR is the world's largest

commercial or utility employer, with more than 1.6 million employees, and is second

to the Chinese Army in highest number of employees.

The railways traverse the length and breadth of the country; the routes cover a total

length of 63,140 km (39,233 miles). As of 2002, IR owned a total of 216,717 wagons,

39,263 coaches and 7,739 locomotives and ran a total of 14,444 trains daily, including

about 8,702 passenger trains.

HISTORY

Railways were first introduced to India in 1853. By 1947, the year of India's

independence, there were forty-two rail systems. In 1951 the systems were

nationalized as one unit, becoming one of the largest networks in the world. Indian

Railways operates both long distance and suburban rail

systems.

One of the earliest pictures of railways in

India

Extent of Great Indian Peninsular Railway

network in 1870. The GIPR was one of the

largest rail companies at that time.

9

A plan for a rail system in India was first put forward in 1832, but no further

steps were taken for more than a decade. In 1844, the Governor-General of India Lord

Hardinge allowed private entrepreneurs to set up a rail system in India. Two new

railway companies were created and the East India Company was asked to assist

them. Interest from investors in the UK led to the rapid creation of a rail system over

the next few years. The first train in India became operational on 1851-12-22, and was

used for the hauling of construction material in Roorkee. A year and a half later, on

1853-04-16, the first passenger train service was inaugurated between Bori Bunder,

Bombay and Thana. Covering a distance of 34 km (21 miles), it was hauled by three

locomotives, Sahib, Sindh and Sultan. This was the formal birth of railways in India.

The British government encouraged new railway companies backed by private

investors under a scheme that would guarantee an annual return of five percent during

the initial years of operation. Once established, the company would be transferred to

the government, with the original company retaining operational control. The route

mileage of this network was about 14,500 km (9,000 miles) by 1880, mostly radiating

inward from the three major port cities of Bombay, Madras and Calcutta. By 1895,

India had started building its own locomotives, and in 1896 sent engineers and

locomotives to help build the Uganda Railway.

Soon various independent kingdoms built their own rail systems and the

network spread to the regions that became the modern-day states of Assam, Rajasthan

and Andhra Pradesh. A Railway Board was constituted in 1901, but decision-making

power was retained by the Viceroy, Lord Curzon. The Railway Board operated under

aegis of the Department of Commerce and Industry and had three members: a

government railway official serving as chairman, a railway manager from England

and an agent of one of the company railways. For the first time in its history, the

Railways began to make a tidy profit. In 1907, almost all the rail companies were

taken over by the government.

The following year, the first electric locomotive appeared. With the arrival of

the First World War, the railways were used to meet the needs of the British outside

India. By the end of the First World War, the railways had suffered immensely and

were in a poor state. The government took over the management of the Railways and

10

removed the link between the financing of the Railways and other governmental

revenues in 1920, a practice that continues to date with a separate railway budget.

The Second World War severely crippled the railways as trains were diverted

to the Middle East, and the railway workshops were converted into munitions

workshops. At the time of independence in 1947, a large portion of the railways went

to the then newly formed Pakistan. A total of forty-two separate railway systems,

including thirty-two lines owned by the former Indian princely states, were

amalgamated as a single unit which was christened as the Indian Railways.

The existing rail networks were abandoned in favour of zones in 1951 and a

total of six zones came into being in 1952. As the economy of India improved, almost

all railway production units were indigenized. By 1985, steam locomotives were

phased out in favour of diesel and electric locomotives. The entire railway reservation

system was streamlined with computerization in 1995.

11

RAILWAY ZONES

A schematic map of the Indian

Railway network

For administrative purposes, Indian Railways is

divided into sixteen zones.

No. Name Abbr. Headquarters Date established

1. Northern Railway NR Delhi April 14, 1952

2. North Eastern Railway NER Gorakhpur 1952

3. Northeast Frontier Railway NFR Maligaon(Guwahati) 1958

4. Eastern Railway ER Kolkata April, 1952

5. South Eastern Railway SER Kolkata 1955,

6. South Central Railway SCR Secunderabad October 2, 1966

7. Southern Railway SR Chennai April 14, 1951

8. Central Railway CR Mumbai November 5, 1951

9. Western Railway WR Mumbai November 5, 1951

10. South Western Railway SWR Hubli April 1, 2003

11. North Western Railway NWR Jaipur October 1, 2002

12. West Central Railway WCR Jabalpur April 1, 2003

13. North Central Railway NCR Allahabad April 1, 2003

14. South East Central Railway SECR Bilaspur, CG April 1, 2003

15. East Coast Railway ECoR Bhubaneswar April 1, 2003

16. East Central Railway ECR Hajipur October 1, 2002

17. Konkan Railway KR Navi Mumbai January 26, 1998

Konkan Railway (KR) is constituted as a separately incorporated railway, with its headquarters at

Belapur CBD (Navi Mumbai). It comes under the control of the Railway Ministry and the Railway

Board.

12

The Calcutta Metro is owned and operated by Indian Railways, but is not a

part of any of the zones. It is administratively considered to have the status of a zonal

railway. Each zonal railway is made up of a certain number of divisions, each having

a divisional headquarters. There are a total of sixty-seven divisions.

Zonal Railway Divisions

Northern Railway Delhi, Ambala, Firozpur, Lucknow, Moradabad

North Eastern Railway Izzatnagar, Lucknow, Varanasi

Northeast Frontier

Railway

Alipurduar, Katihar, Lumding, Rangia, Tinsukia

Eastern Railway Howrah, Sealdah, Asansol, Malda

South Eastern Railway Adra, Chakradharpur, Kharagpur, Ranchi

South Central Railway Secunderabad, Hyderabad, Guntakal, Guntur, Nanded,

Vijayawada

Southern Railway Chennai, Madurai, Palghat, Tiruchchirapalli, Trivandrum,

Salem

Central Railway Mumbai, Bhusawal, Pune, Solapur, Nagpur

Western Railway Mumbai Central, Baroda, Ratlam, Ahmedabad, Rajkot,

Bhavnagar

South Western Railway Hubli, Bangalore, Mysore

North Western Railway Jaipur, Ajmer, Bikaner, Jodhpur

West Central Railway Jabalpur, Bhopal, Kota

North Central Railway Allahabad, Agra, Jhansi

South East Central

Railway

Bilaspur, Raipur, Nagpur

East Coast Railway Khurda Road, Sambalpur, Visakhapatnam

East Central Railway Danapur, Dhanbad, Mughalsarai, Samastipur, Sonpur

13

PASSENGER SERVICES

A long-distance express train

Indian Railways operates 8,702 passenger

trains and transports 15 million daily across

twenty-five states and three union territories

(Delhi, Puducherry (formerly Pondicherry)

and Chandigarh). Sikkim, Arunachal

Pradesh and Meghalaya are the only states

not connected.

The passenger division is the most preferred form of long distance transport in

most of the country.

A standard passenger train consists of eighteen coaches, but some popular

trains can have up to 24 coaches. Coaches are designed to accommodate anywhere

from 18 to 72 passengers, but may actually accommodate many more during the

holiday seasons and on busy routes. The coaches in use are vestibules, but some of

these may be dummied on some trains for operational reasons. Freight trains use a

large variety of wagons.

Each coach has different accommodation class; the most popular being the

sleeper class. Up to nine of these type coaches are usually coupled. Air conditioned

coaches are also attached, and a standard train may have between three and five air-

conditioned coaches. Online passenger ticketing, introduced in 2004, is expected to

top 100,000 per day by 2008, while ATMs in many stations will be equipped to

dispense long-distance tickets by the end of 2007. ATMs are slated for installation on

board select trains as well.

14

PRODUCTION SERVICES

A WAP5 locomotive

The Indian Railways manufactures a lot of its

rolling stock and heavy engineering components.

This is largely due to historical reasons. As with

most developing economies, the main reason is import substitution of expensive

technology related products. This was relevant when the general state of the national

engineering industry was immature.

Production Units, the manufacturing plants of the Indian Railways, are managed

directly by the ministry. The General Managers of the PUs report to the Railway

Board. The Production Units are:

Central Organization For Railway Electrification, Allahabad

Chittaranjan Locomotive Works, Chittaranjan

Diesel Locomotive Works, Varanasi

Diesel Locomotive Works, Ponmalaipatty, Tiruchirapalli

Diesel-Loco Modernisation Works, Patiala

Integral Coach Factory, Chennai

Rail Coach Factory, Kapurthala

Rail Wheel Factory, Bangalore

Rail Spring Karkhana, Gwalior

Bharat Earth Movers Limited, Bangalore

BEML is not part of railways, but they do manufacture the coaches for IR and

Metro coaches for DMRC and going forward for Bangalore Metro also.

15

1.2 CENTRAL RAILWAY WORKSHOP, MATUNGA

The Carriage Workshop, Matunga was set up in 1915 as the repair workshop

for broad gauge and narrow gauge coaches and wagons of the erstwhile great

Indian Peninsular (GIP) Railway. The covers the triangular piece of the land

/area of 35 hector, including a covered area of about 11 hectors, skirted by the

Central Railway suburban corridors on the east and the Western Railway

corridors on the west. The strength of the Employee is not more than 7500.The

machinery plant to activity Matunga W/S is about 6500.The consumption of

electricity is about 6 lakh-Units per month.

MAIN ACTIVITIES:

ACTIVITIES TARGET

POH of Mail/Express Coach

POH of Passengers Coach

173 coaches per month including 28 AC

coaches

POH of EMU Coach 60 Coaches per month

EMU rehab-mid-life

EMU rehab-end-life 7 Coaches per month

A few first of Matunga Workshop:

First zonal railway workshop to get ISO-14001 certification in the years 2002.

First railway coaching workshop to convert 99% of Mail/Express rakes into Air brake.

First zonal railway workshop to convert ARMEs and A class ARTs into AIR BRAKE in the year 2002.

First zonal railway workshop to start provision bogie mounted air brake system in1993-94.

First zonal railway workshop to provide nylon bushes in brake rigging in1980.

First zonal railway workshop to start the concept of END LIFE REHABILATION in EMU Coaches.

16

This workshop is awarded by ISO 9001:2000 as well as ISO

14001:1996.in 2001 &2002 respectively.

INTRODUCTION TO BOGIES

A bogie is wheeled wagon or trolley. In mechanics terms bogie is chassis or

framework carrying wheels attached to vehicle. It can be fixed in place as on a cargo

truck, mounted on a swivel as on a railway carriage or locomotive or sprung as in the

suspension of a caterpillar tracked vehicle.

1.3 MAIN UNITS OF A BOGIE

1. Bogie Frame

2. Wheel and Axle

3. Bearing Arrangement

4. Bogie Frame -Axle Joint

5. Bolster

6. Primary Suspension

7. Secondary Suspension

8. Bogie -Body Joint

9. Brake System

1.4 FUNCTIONS OF A BOGIE

To support the rail vehicle body.

To run stably on both straight and curved track.

To ensure ride comfort by absorbing vibration and minimizing centrifugal

forces when the train runs on curved tracks at high speed.

To minimize the effects generated by track irregularities and rail abrasion.

17

KEY COMPONENTS OF A BOGIE

Bogie frame.

Suspension to absorb shocks between the bogie, the bogie frame and rail

vehicle body. Common types are coil springs and rubber airbags.

At least two wheel set composed of axle with bearings and wheel at each

end.

Axle box suspension to absorb shocks between the axle bearings and the

bogie frame.

Brake equipment:-brake shoes are used which are pressed against the tread

of the wheels.

Traction motors for transmission on each axle.

1.5 FACTORS AFFECTING BOGIE SUSPENSION

Load on bogie.

Velocity of train.

Acceleration of train.

Radius of curvature of track.

Track irregularities.

Fig- 1.5 BOGIE

18

CHAPTER NO 2

BOGIE ASSEMBLY

2.1 DESIGN FEATURES

The main constructional and design features of the ICF/RCF all-coil bogies,

used on mainline BG coaches are briefly described in the following paragraphs.

Leading Parameters of ICF bogie are as under:

S.No. Description Parameters

1. Maximum Axle

load bearing

capacity

16.25t, 13t

2. Wheel base 2896mm

3. Wheel diameter

(New)

915mm

4. Axle guidance Telescopic axle guide

with oil damping

5. Primary

suspension

Coil spring

6. Secondary

suspension

Coil spring

7. Shock absorbers i) Vertical dashpot in

primary suspension.

ii) Hydraulic double acting

vertical shock absorber in

secondary suspension

8. Transfer of

coach body

weight

Through bogie side bearer

pitched at

1600mm.

19

Fig 2.1 ICF-BOGIE SIDE VIEW

Fig 2.2 BOGIE BOLSTER ARRANGEMENT

20

2.2 ALL-COIL ICF BOGIE

The bogies being currently manufactured by ICF/RCF which have been

accepted as standards of the Indian Railways and are of an all welded light weight

construction. Axles are located on the bogie by telescopic dash pot and axle guide

assemblies. Helical coil springs are used in both the primary and the secondary stages.

The axle guide device provides viscous damping across primary springs while

hydraulic dampers are provided across the secondary stage. Dampers are protected

against misalignment by resilient fittings. Isolation of vibration is effected by rubber

pads in primary and secondary suspension.

Deflection due to the tare weight is almost equally divided between axle and

bolster springs. Weight of coach body is transferred to its bogie by side bearers

pitched 1600 mm apart. Side bearers consist of lubricated metal slides immersed in oil

baths. No vertical weight transfer is affected through bogie pivot and the pivot acts

merely as a centre of rotation and serves to transmit tractive/braking forces only.

2.3 WORKING

The bogie frame and components are of all-welded light construction with a

wheel base of 2.896 metre. The wheel sets are provided with self-aligning spherical

roller bearings mounted in cast steel axle box housings. Helical coil springs are used

in both primary and secondary suspension. The weight of the coach is transferred

through side bearers on the bogie bolsters. The ends of the bogie bolsters rest on the

bolster helical springs placed over the lower spring beam suspended from the bogie

frame by the inclined swing links at an angle 7. Hydraulic shock absorbers and dash

pots are provided in the secondary and primary suspensions respectively to damp

vertical oscillations.

21

Fig 2.3 ICF BOGIE TOP VIEW

22

2.4 AXLE BOX GUIDE WITH DASH POT ARRANGEMENT

Axle box guides are of cylindrical type welded to the bottom flanges of the

bogie side frame with close dimensional accuracy. These guides together with lower

spring seats located over the axle box wings, house the axle box springs and also

serve as shock absorbers. These guides are fitted with guide caps having nine holes of

diameter 5 mm equidistant through which oil in the lower spring seat passes under

pressure during dynamic oscillation of coach and provide necessary damping to

primary suspension to enhance better riding quality of coach. This type of rigid axle

box guide arrangement eliminates any longitudinal or transverse relative movement

between the axles and the bogie frame.

Fig 2.4 DASHPOT ARRANGEMENT

23

2.5 BOGIE BOLSTER SUSPENSION

The bolster rests on the bolster coil springs - two at each end, located on the

lower spring beam which is suspended from the bogie side frame by means of

bolster-spring suspension (BSS) hangers on either

side. The two anchor links diagonally positioned are provided with silent

block bushes. The links prevent any relative movement between the bogie frame and

coach body.

Fig 2.5 BOGIE BOLSTER DESIGN

24

2.6 SPRINGS

In ICF bogie, helical springs are used in both primary and secondary

suspension. The springs are manufactured from peeled and centreless ground bar of

chrome vanadium/chrome molybdenum steel conforming to STR No. WD-01-HLS-

94.

Fig - 2.6 SECONDARY COIL SPRING

25

2.7 CENTRE PIVOT ARRANGEMENT

The centre pivot pin joins the body with the bogie and transmits the tractive

and braking forces on the bogies. It does not transmit any vertical load. It is equipped

with rubber silent block bushes which tend to centralize the bogies with respect to the

body and, to some extent, control and damp the angular oscillations of the bogies.

Fig 2.7 CENTRE PIVOT ARRANGEMENT

26

2.8 SIDE BEARERS

The side bearer arrangement consists of a machined steel wearing plate

immersed in an oil bath and a floating bronze-wearing piece with a spherical top

surface kept in it, on both sides of the bogie bolster. The coach body rests on the top

spherical surface of these bronze-wearing pieces through the corresponding

attachments on the bottom of the body-bolster. The whole arrangement is provided

with a cover to prevent entry of dust in the oil sump.

Fig 2.8 SIDE BEARERS

27

2.9 ANCHOR LINKS AND SILENT BLOCK

The floating bogie bolster which supports the coach body is held in position

longitudinally by the anchor links which are pinned to the bolster sides and the bogie

Transoms. One anchor link is provided on each side of the bolster diagonally across.

The links can swivel universally to permit the bolster to rise and fall and sway side

wards. They are designed to take the tractive and braking forces. The anchor links

are fitted with silent block bushes.

Fig 2.9

This is a synthetic rubber bush fitted in anchor link and center pivot of ICF

bogies to transmit force without shock and reduce noise.

28

2.10 EQUALISING STAYS

This device has been provided on bogies between the lower spring plank and

the bolster to prevent lateral thrust on the bolster springs which have not been

designed to take the lateral forces. These links have pin connections at both ends and,

therefore, can swivel freely.

Fig 2.10 EQUALISING STAYS

2.11 BOLSTER SPRING SUSPENSION HANGERS (BSS HANGERS)

In the secondary suspension, the bolster is supported on helical coil springs

which are placed on the lower spring plank. The lower spring plank is suspended from

the bogie side frame through BSS hangers on hanger blocks.

Fig 2.11 HANGER WITH HANGER BLOCK

29

2.12 SHOCK ABSORBERS

Hydraulic shock absorbers with capacity of 600 kg at a speed of 10 cm/sec.

are fitted to work in parallel with the bolster springs to provide damping for vertical

oscillations.

Fig 2.12 SHOCK ABSORBER

30

CHAPTER NO 3

LITERATURE REVIEW

3.1 HOW BOGIES WORK BY ISAO OKAMOTO

Okamoto defined the role of a railroad bogie in detail and discussed possible

different configurations. Bogies are classified into types first by the number of axles

in their configuration and the design of the suspension. The two axle bogie is the most

common type found in rail vehicles and in the three-piece bogie. The suspension of

the bogie is classified as either articulated or non-articulated. An articulated

suspension is one that is located between two car bodies, holding the backside of one

and the front side of the following car. A non-articulated suspension requires two

separate trucks to support each end of one rail car. A Swing Hanger Bogie and a

Small Lateral Stiffness Bolster Spring Bogie are two types of suspension designs

which absorb rolling motion of the rail vehicle. Bolster and bolster-less bogies are

another way to differentiate the suspension. The bolster bogie has a solid bolster

which is the third piece in a three-piece bogie and connects the side frames. The

bolster-less bogie has a centre plate and 2 separate suspensions on the side frames to

support the rail vehicle. This paper also discusses the key elements of a bogie, which

include the suspension gear, the bogie frame, the axle box suspension, wheels, axles,

bearings, transmission and brakes. Some recent improvements include a tilting bogie,

which tilts the rail vehicle toward the centre of the circle when turning.

Another improvement is the steering bogie which allows each of the axles on a bogie

to steer along a rail separately from the other.

31

CHAPTER NO 4

MATHEMATICAL MODEL

In order to create mathematical model of bogie suspension system every single

element is treated with a lumped element model.

It consists of three parts:

1. the Carriage

2. the Bogies

3. the Wheel-sets

The simplifying assumptions in this domain are:

All objects are rigid bodies with all the mass concentrated in the center

of gravity

All interactions between rigid bodies take place via kinematic pairs (joints),

Springs and dampers.

Therefore the lumped elements mathematical model, is that in which the

inertial, elastic and dumping properties of the physic continuous system

are concentrate in different single components; doing so the model consist of

rigid masses treatable as point masses and interlinked with springs and

dumpers without a mass. Increasing the number of masses the model would

better represent the real system, but obviously this would lead to a more

complicate model and so a less computationally efficient one.

4.1 TYPES OF VIBRATIONS

Mainly vibrations can be divided in two types:

FREE VIBRATIONS

FORCED VIBRATIONS

Free vibration occurs when a mechanical system is set of with an initial input

and then allowed to vibrate freely. Examples of this type of vibration are pulling a

child back on a swing and then letting go or hitting a tuning fork and letting it ring.

The mechanical system will then vibrate at one or more of its natural frequency

and damp down to zero.

32

Forced vibration is when an alternating force or motion is applied to a mechanical

system. Examples of this type of vibration include a shaking washing machine due to

an imbalance, transportation vibration (caused by truck engine, springs, road, etc.), or

the vibration of a building during an earthquake. In forced vibration the frequency of

the vibration is the frequency of the force or motion applied, with order of magnitude

being dependent on the actual mechanical system characteristics.

4.2 MODELING VIBRATING SYSTEMS

It is known that Continuous Elastic bodies possess infinite DOFs(i.e,

number of independent coordinates to completely describe motion). Considering that

an analytical solution for these physical systems exists only for a few ones, specially

those very simple, it is necessary to find a way to model those complicate systems

with a simpler mathematical model, that brings to a low cost computational problem

but at the same time resemble enough the real one.

4.3 MULTIPLE DEGREES OF FREEDOM MODELS

Clearly real life problems cant be studied often with a SDOF model but to

reach a certain accuracy of results. MDOF multiple degree of freedom models have

been studied and implemented.

It is only remembered that a general MDOF mathematical model can always

be expressed like this:

[M] {x} + [C] {x?} + [K] {x} = {f}

where symmetrical matrices [M], [C] and [K] and vectors {x} and {f} represents:

[M] : Mass matrix

[C] : Damping matrix

[K] : Stiffness matrix

{x} : displacements vector

{f} : force vector

Moreover it is important to notice that the dimension of the complete

mathematical problem is equal to the number N of DOF considered, that means that

the order of all the matrices is N x N and for the vectors N x 1.

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Actually we study an infinite physical space, whose basis has infinite

members, with a mathematical subspace whose basis consists of those N mode shapes

taken into consideration.

The mathematical problem is an eigenvalues one, where the natural

frequencies of the real system are provided exactly by the eigenvalues of the

mathematical one (i.e. 1,2 ...n ) and eigenvectors represent the mode shapes

f = f1,f2 .. fn.

In solving these kinds of problems lots of different mathematical ways have

been followed; because of the big size of these problems (as aforementioned a real

system has theoretically 8 DOF) the focus of the solver is on the reduction of it

without big losses in accuracy and this mathematical operation is called modal

truncation.

We considered only those modes shapes whose natural frequencies are

in the range of interest of our problem, and mainly mechanical one is that of low

medium frequencies.

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4.4 MATHEMATICAL MODEL FOR 2 DEGREE OF FREEDOM SYSTEM

Arranging above equations in matrix form, we get

Let be Eigen values,

Solving this, we get & Natural frequency

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To find Eigen vectors,

Now, Actual suspension system is as follows- Now the problem is Multi degree force vibration, with support excitation. Let movement of base is SHM i.e. y= Y sin wt

Where,

Now By De- Alemberts principle to this, we get

And

To find modal matrix

Eigen vector in matrix form, = and

=

Modal matrix

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Let damping be proportional i.e.

and

;

In Principle coordinates (Pi) Equation becomes

Whose solution is given as

Now the time response is given by

The above time responses were plotted in MATLAB by generating m code.

4.5 MATHEMATICAL MODEL FOR 4 DEGREE OF FREEDOM SYSTEM

Above sketch shows simple diagram for Four degree of freedom, Mathematical model.

Let,

Vertical displacement of Bogie from C.G.

Vertical displacement of Coach from C.G.

Angular rotation of Bogie through C.G.

Angular rotation of Coach through C.G.

Irregularities in Right rail

Irregularities in Left rail

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Mass of Bogie

Mass of Coach

M.I. of Bogie about longitudinal axis (in fig. Perpendicular to page)

M.I. of Coach about longitudinal axis (in fig. Perpendicular to page)

Now, the equations of the motion are derived by employing Lagranges Method.

Total Kinetic Energy of the system,

Total Kinetic Energy of the system,

Where, Displacement of Bogie at Right end Displacement of Bogie at Left end Displacement of Coach at Right end Displacement of Coach at Left end

From Fig. Similarly,

38

The Potential energy can be,

Also the total energy in damping,

Now, Lagrangian variable,

,

Now, Equation of Motion is given as,

Where, Equation of motion will be, ----(1) Similarly from solving,

39

We get, Following Equations of motions respectively, ----(2) Also, ----------------------------(3) And, ---------------------------(4)

Now, Above four Equations are solved with the help of MATLAB software by generating required m code. The results obtained were then plotted.

40

CHAPTER NO 5

MATLAB

The mathematical model made in the previous chapter is now solved in

MATLAB software.

For this purpose we solve differential equation from mathematical model

using Runge-Kutta method. In this we convert the nth order differential equation into

n first order differential equation.

5.1 MATLAB CODE FOR MATHEMATICAL MODEL OF 2 DOF

%twodof.m clc; tspan=0:0.5:50; y0=[0.0;0;0;0]; [t,y]=ode23('dfunc2',tspan,y0); subplot(211); plot(t,y(:,1),t,y(:,3),'-'); Xlabel('t'); Ylabel('x1(t)'); grid on; subplot(212); plot(t,y(:,3)); xlabel('t'); ylabel('x2(t)'); grid on;

%dfunc2.m function f=dfunc2(t,y) f=zeros(4,1); m1=1250; m2=25000; k1=270000*8; k2=315000*4; c1=6000*4; c2=6000*2; z=0.02; w=15; a=z*sqrt(k1*k1+c1*c1*w*w); phi=atan((c1*w)/k1); %F=8000*(stepfun(t,10)-stepfun(t,11)); F=a*sin(w*t+phi); f(1)=y(2); f(2)=F/m1-(k1+k2)*y(1)/m1+k2*y(3)/m1-(c1+c2)*y(2)/m1+c2*y(4)/m1; f(3)=y(4); f(4)=k2*y(1)/m2-k2*y(3)/m2+c2*y(2)/m2-c2*y(4)/m2;

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From above code we plot results for various values of w(excitation frequency).

1) For w=10 rad/sec.


3) For bump


Here x1(t) represents vertical displacement of frame whereas x2(t) represents

vertical displacement of coach (bolster).

In first plot both the results are plotted for ease of comparison.

Where blue line indicates x1(t) & green line indicates x2(t).

The excitation given to the track is 0.02 m at w=10 rad/sec.

From the graph we see that displacement of both frame & coach is same with

phase lag.

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2) For w=15 rad/sec

Above plot clearly indicates that as w increases the amplitude of coach is less

as compared to frame

Maximum displacement of frame= 1.2 cm whereas

Maximum displacement of coach= 0.7 cm

This means that vibrations transferred from frame to the coach decreases due to spring

& damping action which is the desired result.

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3)For bump

Bump represents initial excitation for a fraction of time. It resembles track

irregularities in actual condition.

In the code the bump expression is given as follows

F=8000*(stepfun(t,10)-stepfun(t,11));

where F represents force transferred to wheelsets from track.

The bump is given at time t=10 sec for a span of 1 sec.

The plot is as follows

From the above plot it is seen that due to bump at 10 sec the vertical

displacement of both frame and coach increases, the former being greater in

magnitude. And after the bump the vibrations gets damped due to spring & damping

action.

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5.2 MATLAB CODE FOR MATHEMATICAL MODEL OF 4 DOF

%fourdof2.m clc; tspan=0:0.5:50; y0=[0;0;0;0;0;0;0;0]; [t,y]=ode45('dfunc43',tspan,y0); x1=y(:,1)+y(:,3); x2=y(:,1)-y(:,3); x3=y(:,5)+y(:,7); x4=y(:,5)-y(:,7); subplot(211); plot(t,x1,t,x3,'-'); xlabel('t'); ylabel('x1(t) & x3(t)'); grid on; subplot(212); plot(t,x2,t,x4,'-'); xlabel('t'); ylabel('x2(t) & x4(t)'); grid on;

function f=dfunc43(t,y) f=zeros(8,1); m1=1250; m2=25000; k1=270000*4; k2=270000*4; k3=315000*2; k4=315000*2; c1=60000*2; c2=60000*2; c3=60000*1; c4=60000*1; i1=12000; i2=500000; w1=0; w2=15; phi1=atan(c1*w1/k1); phi2=atan(c2*w2/k2); z1=0.01; z2=0.01; a1=z1*sqrt(k1*k1+c1*c1*w1*w1); a2=z2*sqrt(k2*k2+c2*c2*w2*w2); %F1=a1*sin(w1*t+phi1); F1=43800*0.5*(stepfun(t,10)-stepfun(t,11)); %F2=a2*sin(w2*t+phi2); F2=43800*0.5*(stepfun(t,30)-stepfun(t,31)); f(1)=y(2); f(2)=(F1+F2-(k1+k2+k3+k4)*y(1)-(-k1+k2-k3+k4)*y(3)-(-k3-k4)*y(5)-(k3-

k4)*y(7)-(c1+c2+c3+c4)*y(2)-(-c1+c2-c3+c4)*y(4)-(-c3-c4)*y(6)-(c3-

c4)*y(8))/m1; f(3)=y(4); f(4)=(F1-F2-(-k1+k2-k3+k4)*y(1)-(k1+k2+k3+k4)*y(3)-(k3-k4)*y(5)-(-k3-

k4)*y(7)-(-c1+c2-c3+c4)*y(2)-(+c1+c2+c3+c4)*y(4)-(c3-c4)*y(6)-(-c3-

c4)*y(8))/i1; f(5)=y(6); f(6)=(-(-k3-k4)*y(1)-(k3-k4)*y(3)-(k3+k4)*y(5)-(-k3+k4)*y(7)-(-c3-

c4)*y(2)-(c3-c4)*y(4)-(c3+c4)*y(6)-(-c3+c4)*y(8))/m2;

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f(7)=y(8); f(8)=(-(k3-k4)*y(1)-(-k3-k4)*y(3)-(-k3+k4)*y(5)-(k3+k4)*y(7)-(c3-

c4)*y(2)-(-c3-c4)*y(4)-(-c3+c4)*y(6)-(c3+c4)*y(8))/i2;

From above code we plot results for

1) Bump on left & right rail

2) Irregularities of only left rail & right rail being even.

1) Bump on left & right rail

In right rail the bump appears at t=10 sec as follows

F1=43800*0.5*(stepfun(t,10)-stepfun(t,11));

In left rail the bump appears at t=30 sec as follows

F2=43800*0.5*(stepfun(t,30)-stepfun(t,31));

Here

x1(t)= displacement of right side of frame shown by blue line in first plot.

x2(t)= displacement of left side of frame shown by blue line in second plot.

x3(t)= displacement of right side of coach shown by green line in first plot.

x4(t)= displacement of left side of coach shown by green line in second plot.

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From above plots following results are obtained

a) At t=10 sec due to bump on right rail, the vertical displacements of right sides

of frame and coach increases. Also its effect can be seen on the left sides of

coach and frame as depicted in plot 2.

b) At t=30 sec due to bump on left rail, the vertical displacements of left sides of

frame and coach increases. Also its effect can be seen on the right sides of coach

and frame as depicted in plot 1.

2) Irregularities of only left rail & right rail being even.

For this case the excitation is given on left rail only & right rail is kept even.

w1=0; (excitation frequency for right rail)

w2=15; (excitation frequency for left rail)

Due to excitation on left rail only, the magnitude of vertical displacement of

left sides of frame & coach (as depicted in plot2) is more as compared to those

at right sides of frame & coach (as depicted in plot1).

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CHAPTER NO 6

DYMAMIC ANALYSIS IN UNIVERSAL MECHANISM 7.0

6.1 SETUP

MAIN PARTS OF THE SETUP

Red:- Frame Light Grey:- Hanger

Light Green:- Bogie Bolster Yellow:- Axle box

Blue:- Primary Spring

Dark Green:- Secondary Spring

Dark Grey:- Wheel Set

Bright Red:- Secondary Damper

Bright Red:- Primary Damper

Crimson Pink:- Anchor link

Orange:- Lower Spring beam

Light Pink:- Equalizing Stay

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INITIAL CONDITIONS

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6.2 STEPS IN UNIVERSAL MECHANISM

1) Import models into universal mechanism from CAD software

All the parts of a bogie were modeled in solid works and was imported in

universal mechanism in the form of an image file.

After this, subsequent bodies are created in universal mechanism and mass and inertia

parameters of the bodies are specified.

They are as follows

FRAME

BOLSTER

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AXLE BOX

LOWER SPRING BEAM

EQUALISING STAY

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HANGER

Other parameters like wheel sets, primary and secondary suspension springs,

and primary and secondary dampers were imported in universal mechanism itself.

WHEELSET

PRIMARY SPRINGS SECONDARY SPRINGS

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PRIMARY DAMPER

2) Create joints between various bodies.

In this, we assign joints between various bodies and assign degrees of freedom

to them. The various joints and degrees of freedom assigned are as follows:

a) Rotational joint between axle box and wheelset. (1 DOF)

b) 6 DOF between Frame and base.

c) 6 DOF between bolster and base.

d) 6 DOF between lower spring beam and bolster.

e) Rotational DOF between equalizing stay and bolster.

f) Rotational DOF between equalizing stay and lower spring beam.

g) Primary suspension springs between axle box and frame.

h) Secondary suspension springs between bolster and lower spring beam.

i) Primary dampers between axle boxes and frame.

j) Secondary dampers between bolster and lower spring beam.

k) Rotational DOF between anchor link and bolster.

l) Rotational DOF between anchor link and frame.

m) Generalized joint for hangers.

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a) Rotational joint between axle box and wheel sets

b) 6 DOF between bolster and base.

c) 6 DOF between bolster and base.

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d) 6 DOF between lower spring beam and bolster.

e) Rotational DOF between equalising stay and bolster.

f) Rotational DOF between equalizing stay and lower spring beam.

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g) Primary suspension springs between axlebox and frame.

h) Secondary suspension springs between bolster and lower spring beam.

i) Primary dampers between axle boxes and frame.

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j) Secondary dampers between bolster and lower spring beam.

k) Generalized joint for hangers.

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6.3 SIMULATION PARAMETERS

SOLVER : Park Method

SOLUTION TYPE: Range Space Method

If singularity is detected then Null Space Method

SOLVER OPTIONS

RAIL/ WHEEL

Rail & wheel profile can be assigned in universal mechanism as shown below

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WHEEL PROFILES

Standard from file

General Information about current simulation

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CHAPTER NO 7

ANALYSIS RESULTS

In universal mechanism bogie is run at different speeds & a graph of special

forces (i.e. forces induced in suspension springs) at ordinate along z direction v/s time

on abscissa is plotted for even track irregularities as well as bad track irregularities.

Following graphs show the results for

1) Bogie running at 40 m/s on even track

2) Bogie running at 40 m/s on uneven track (considering bad irregularities)



Condition 2), 3) & 4) is tested on following irregular track

The irregularities are assigned along Y & Z directions for a track of 1000 m distance.

The irregularities go upto 25 mm at some distances.

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1) BOGIE RUNNING AT 40 m/s ON EVEN TRACK

A) PRIMARY SUSPENSION

B) SECONDARY SUSPENSION

As the figure suggests, on even track there are no forces induced on the primary as

well as secondary coil springs

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2) BOGIE RUNNING AT 40 m/s ON UNEVEN TRACK

(Considering bad irregularities)



At 40 m/s, bogie running on bad track, high forces are transferred by track onto the

primary suspension springs & due to dampers & shock absorbers, comparatively less

forces are transferred onto the secondary suspension springs.

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At 45 m/s higher forces are induced on primary suspension springs as compared to 40

m/s. Also higher forces are induced on secondary suspension springs as compared to

40 m/s.

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From above result it is seen that at 46 m/s the amount of forces induced on suspension

springs are so higher that it cannot sustain it & the bogie derails. The following error

is shown in the simulation window wheelset 2 is out of rail

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CHAPTER NO 8

CONCLUSION

8.1 CREATING SCANNING PROJECT

Here a scanning project for bogie is considered. The aim of this scanning

project is to determine the critical speed of the bogie.

Preface

There are lots of criteria that engineers take into account during

carrying out re-searches and optimization of parameters for railway vehicles.

Stability of the rail-way vehicle is the one of the most important criteria of

dynamical properties of the vehicle. Nowadays the most common estimation

of the stability of the railway vehicle is its critical speed.

Here the approach, which helps us to estimate the critical speed of

the vehicle numerically with the help of series of computer experiments, is

shown. We will run the bogie with the various velocities on the even track

with the single lateral irregularity at the beginning of the track. Amplitude of

the irregularity is 20 mm and its length is 10 m. Then we will analyze lateral

oscillations of the vehicle and will see if the single irregularity leads to stable

or instable motion.

20 mm initial irregularity

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8.2 RAILWAY CONFIGURATION

It is necessary to set railway configuration.

1. Firstly, lets define track irregularities. Select the Alternatives | Wheel/Rail |

Track| Irregularities tab. Open file NoIrregularities.way for vertical irregularities (Z)

and g10_20.way in lateral (Y) direction..

2. Select the Alternatives | Wheel/Rail | Track | Macrogeometry tab. In the

Track type group choose Tangent.

3. Load rail profiles from the r65new.rpf file, and set newlocow.wpf profile for all

wheels.

Every numerical experiment will be done with such railway configuration.

CREATING NEW SCANNING PROJECT

1. From the Advanced analysis menu point to Scanning: new project.

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LOADING A MODEL

1. Select the Alternatives tab.

2. Click the button (add family of alternatives).

3. In the open dialog choose the required model.

The model is loaded and added to the list of Family of alternatives

4) In the List of parameters click Whole list

| v0.

5) In the new window Properties of

identifier input values of

20,30,32,34,36,38, and 40 m/s.

6). Rename group of parameters Group1 to

v0 (using popup menu).

New group of the parameters v0 appears

on the Hierarchy of parameters tab.

Thus 7 numerical experiments will be done.

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FINISH CONDITIONS

Here you can describe finish conditions for each numerical experiment in the

current family. Finish conditions are formulated in the following way:

Interrupt a numerical experiment if at least one of the conditions is satisfied.

Using scanning project you can set finish condition as

Variable [Condition] Numerical value.

You can use any variable from the Wizard of variables as stop criterion. By

default, for the railway vehicle the following finish condition is formulated:

Path Vehicle distance from the simulation start >= 500 m.

It means every numerical experiment finishes when vehicle goes 500 m.

Select the Alternatives | Variables tab.

Rename the No name tab to Stability.

Open Wizard of variables.

Point to the Liner var. tab, select the WheelSet1.Wset body, from the Component

group select Y (lateral direction). Create this variable and

drag it into the Stability tab.

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Point to the Wizard of variables | Railway tab. Select Path variable from the list

of characteristics. Create this variable and drag it into the Stability tab.

Now run the project

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8.3 ANALYZING OBTAINED RESULTS

Now we come to the analyzing of the bogie dynamics. Our analysis is based on

the results of the scanning project we have just finished

Let's have a look at the results of several single experiments. We will compare

results for lateral oscillation of the first wheelset at 20, 30, 32, 34, 36, 38 and 40 m/s.

Red colour- 20 m/s On X-axis- distance travelled in meters

On Y-axis- lateral amplitude

Green colour - 30 m/s

It is seen from the graph that due to single lateral irregularity at the

start, there is 25 mm maximum lateral displacement of first wheelset for both the

speeds. It is quite clear, from above fig, those lateral oscillations that rose by singular

lateral irregularity at 20 m/s diminish earlier as compared to 30 m/s. But the bogie

becomes stable for both the speeds.

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For 38 m/s

It is seen from the above fig that at 38 m/s the bogie cannot sustain the initial

irregularity and it derails.

Hence the critical speed of the bogie is somewhere between 30 m/s and 38 m/s.

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Now the simulation is tested for the speeds between 30 & 38 m/s.

Black-20 m/s Green-30 m/s

Crimson pink-32 m/s Blue-34 m/s

Red36m/s

From above figure it is seen that as speed increases, the lateral oscillations of

the wheelset increases. At 36 m/s the lateral oscillations of the wheelset is more as

compared to other speeds and it needs more time and distance to become stable.

However the bogie doesnt derail at above speeds. But from the previous result we see

that the bogie derails at 38 m/s.

Hence the critical speed of the bogie is 36 m/s.

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8.4 NEED FOR HIGHER SPEED

Railway administrations, the world over, plan for higher speed operation, driven

by the following considerations:

a) Public demand for cutting down the journey time

b) Competition for securing greater share of passenger market

c) Image building at national/international level

d) For improving operational efficiency,

for example:

i) Increase in speed helps in better utilization of rolling stock

ii) Could help in obtaining wider windows for track maintenance

iii) Helps in manpower reduction - reduced time on train will require

less number of staff

8.5 ON INDIAN RAILWAYS, THE POSITION IS DIFFERENT.

In India, for majority of passengers, the demand is to get an accommodation in a train

to reach their destination. It matters little to them, if the train reaches their destination

a few hours earlier, particularly when they have to struggle and wait for days together

to secure an accommodation in the train. Most of the trains on the important routes of

Indian Railways are overcrowded. The position becomes worse during festival season,

national holidays and summer holidays in the schools. For Indian Railways, the

requirement therefore is to increase the number of trains to have more accommodation

available to the travelers rather than the increase of speeds of their trains. On many of

the Indian railway routes where high speed trains, at the maximum permissible speed

of 140 kmph, have been introduced, the total journey time is still very high. Taking an

example of New Delhi- Chandigarh route, a distance of 250 kms, Shatabdi train has

a journey time of over 3 hours 15 minutes, whereas it should cover the distance in

about 2 hours. A quick study would reveal that considerable time is lost at the starting

and at intermediate stopping stations, on account of bad yard layouts and poor design

of turnouts. There is also considerable scope for reduction in the time allowance made

for permanent and temporary speed restrictions. Poor train control operation also

causes considerable loss of time, on account of bad planning of precedences and

crossings. Higher speed operation of a few trains is known to cause a loss of line

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capacity in the section, as they consume a number of paths of slow moving trains.

Unless the speeds of all the trains in the section, both passengers and goods are

proportionately increased, higher speed operation is counterproductive, reducing the

throughput capacity of the section.

8.6 POSITION WITH RESPECT TO HIGHER SPEED OPERATION ON

ADVANCED COUNTRIES

Advanced countries meet all the requirements for high speed operation; vociferous

public demand, competition from other modes of transport, image building etc. Their

passenger trains are seldom full to capacity and thus additional trains are not generally

needed. Railway administration in those countries continually made efforts in making

the train journey to their passengers more attractive by:

a) Making the journey more comfortable by improving track geometry

b) Making the stations more friendly, easy to entrain and for changeover to road

transport, elimination of foot over bridges etc.

c) Quicker interchange at junction, stations

d) Modern facilities in trains such as internet surfing, conference facilities etc.

Value added services in trains can earn higher revenues and help in meeting the extra

operational cost of higher speed operation. Value of time for a common person in

these countries is much higher than in India. Thus any reduction in train journey is

welcome.

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8.7 TRACK TECHNOLOGY FOR HIGHER SPEED OPERATION IN

ADVANCED COUNTRIES

While the basic track structure, consisting of 60 kg 90 UTS rails and concrete

sleepers is the same on advanced countries as on Indian Railways, the track

maintenance standards are very high compared to the Indian Railways. Train journey

even at higher speed is very smooth and comfortable. This has been achieved by

making improvements in track structure and track maintenance practices such as:

a) Stable formation- immediate attention to formation treatment given whenever

any bad patch is noticed.

b) Fool proof track drainage system- even by providing underground drains

wherever needed.

c) Rail welded into continuous lengths, through switches and crossings, bridges

etc.

d) Turnouts designed for high speed operation. At stopping station there is hardly

any loss of time on account of trains moving from main lines to platform lines.

As against that, even Shatabdi trains on Indian Railways loose considerable

time when approaching destination station on account of slower movements on

turnouts.

e) Introduction of sleeper pads for bringing down track maintenance needs.

f) Special treatment at places of change of track modulus such as approaches to

bridges, turnouts etc.

g) All track maintenance is carried out during traffic blocks only. Hardly a man is

visible during the train journey.

h) The need for manual track inspection has been minimized. Track monitoring

system has been made very reliable. The maintenance works are all carried out

based on the information, obtained from the track monitoring cars.

i) Rail/weld fractures during service are rare. Defective rails/welds are removed

well in time.

As against that, fractures in large numbers occur on even Rajdhani routes in

Indian Railways, affecting train operation. At higher speeds, such fractures can prove

to be dangerous.

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Apart from raising the standards of maintenance, the two important

requirements of higher speed operations are fully met with in advanced countries.

They are:

i) Complete fencing of the railway track one can hardly see any person moving

near the railway track. Even the track maintenance staffs cannot be seen

during the train running time.

ii) No level crossings.

8.8 CONCLUSIONS AND RECOMMENDATIONS

In conclusion, we may summarize as under:

a) Maximum permissible speed on Indian Railways has got stuck at 140kmph on

account of various limitations of fixed structures which include track and

signaling system, although locomotives and coaches are now available which

can operate at higher speed on the existing railway track maintained to present

laid down tolerances.

b) The need for higher speed on world railway systems has been driven by the

need for attracting more passenger traffic thereby earning more revenue in

addition to raising their international stature.

c) On Indian Railways, where trains are overcrowded what a passenger need is a

seat in the train. Only when this basic demand is fulfilled, the operation at

higher speed will be welcome.

d) Speeding up of the passenger trains on Indian Railways can be achieved by

better yard layouts, adopting high speed turnouts, minimizing time allowance

for permanent and temporary speed restrictions and by improving efficiency in

track monitoring and maintenance.

e) Complete fencing of the tracks, elimination of level crossings, better signaling

system is a pre requisite for any high speed operation.

f) Recent studies under the European project named Inno Track and the

conclusion drawn in that can be a good guide for Indian Railways, for

improving the efficiency of their track maintenance operation.

g) Railway routes with sharp curves, where higher speed operation is restricted

on account of limits of super elevations, deployment of tilting trains will

provide the right solution.

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h) Indian Railways must improve their track structure and track maintenance

system and bring it at par with the advanced countries. Without such an

improvement, higher speed operation will only be a nightmare for track men

and uncomfortable if not unsafe for passengers.

* * * * *

REFERENCES

www.universalmechanism.com.

Mechanical vibration- S.S. Rao.

Mechanical vibration- Schaum series.

Analysis of bogie suspension system

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