A PROJECT REPORT ON
ANALYSIS AND MODIFICATION IN BOGIE SUSPENSION SYSTEM
SUBMITTED BY
Mr. PRAVIN.P.PAWAR PRAVIN.P.PAWAR
ROLLNO:
60
Mr. SURAJ.S.RANA
ROLLNO:
61
Mr. PANKAJ.E.RAWOOL PANKAJ.E.RAWOOL
ROLLNO:
62
Mr. KANNAN.T.REDDIA KANNAN.T.REDDIAR R
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 Department of Mechanical Engineering
1
VIDYAVARDHINI'S VIDYAVARDHINI 'S COLLEGE OF ENGINEERING AND TECHNOLOGY VASAI, THANE
Department of Mechanical Engineering
CERTIFICATE
This to certify that requirements for the project work entitled “ANALYSIS AND MODIFICATION IN BOGIE
SUSPENSION SYSTEM”
have been successfully completed by the following students: Name
Roll No.
Mr. PRAVIN.P.PAWAR PRAVIN.P. PAWAR
60
Mr. SURAJ.S.RANA SURAJ.S.RA NA
61
Mr. PANKAJ.E.RAWOOL PANKAJ.E.RAWOOL
62
Mr. KANNAN.T.REDDIAR
63
In partial fulfillment of Bachelor of Engineering of Mumbai University the Department of Mechanical Engineering, Vidyavardhi ni’s ni’s College of Engineering & Technology, Vasai Road, Thane, during the academic year 2012-2013.
Internal Guide ____________
External Guide_____________ Guide_____________
(Prof. Deepak Chaudhari)
(Mr. K. Sayyed, JR. INST. BTC)
H. O. D __________
Chief Instructor, BTC __________
(Prof. U. V. Asolekar)
(Mr. P. L. Rane)
2
ACKNOWLEDGEMENT
It gives us immense pleasure to present this t his project report on “ANALYSIS AND MODIFICATION IN BOGIE SUSPENSION SYSTEM”
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 th e 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. 3
INDEX
CHAPTER
CONTENT
NO.
1
PAGE NO
INTRODUCTION
7-17
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
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
4
18-29
3
LITERATURE REVIEW
3.1
30
HOW BOGIES WORK BY ISAO OKAMOTO
4
5
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
MATLAB
31-39
40-46
5.1
„m‟ CODE FOR 2 DOF SYSTEM
5.2
„m‟ CODE FOR 4 DOF SYSTEM
6
ANALYSIS IN UNIVERSAL MECHANISM
47-58
7
ANALYSIS RESULTS
59-63
CONCLUSION
64-76
8
5
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
27
BLOCK 2.10
EQUALISING STAYS
28
2.11
HANGER WITH HANGER BLOCK
28
2.12
SHOCK ABSORBERS
29
6
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
7
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.
8
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 9
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.
10
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.
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
West Central Railway
†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.
11
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 Alipurduar, Katihar, Lumding, Rangia, Tinsukia
Railway 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
Bilaspur, Raipur, Nagpur
East
Central
Railway East Coast Railway
Khurda Road, Sambalpur, Visakhapatnam
East Central Railway
Danapur, Dhanbad, Mughalsarai, Samastipur, Sonpur
12
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 airconditioned 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.
13
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.
14
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
173 coaches per month including 28 AC
POH of Passengers Coach
coaches
POH of EMU Coach
60 Coaches per month
EMU rehab-mid-life
7 Coaches per month
EMU rehab-end-life 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 r akes 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.
15
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.
16
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.
1.5
Traction motors for transmission on each axle.
FACTORS AFFECTING BOGIE SUSPENSION
Load on bogie.
Velocity of train.
Acceleration of train.
Radius of curvature of track.
Track irregularities.
Fig- 1.5 BOGIE
17
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
16.25t, 13t
load bearing capacity 2.
Wheel base
2896mm
3.
Wheel diameter
915mm
(New) 4.
Axle guidance
Telescopic axle guide with oil damping
5.
Primary
Coil spring
suspension 6.
Secondary
Coil spring
suspension 7.
Shock absorbers
i) Vertical dashpot in primary suspension. ii) Hydraulic double acting vertical shock absorber in secondary suspension
8.
Transfer of
Through bogie side bearer
coach body
pitched at
weight
1600mm.
18
Fig – 2.1 ICF-BOGIE SIDE VIEW
Fig – 2.2 BOGIE BOLSTER ARRANGEMENT
19
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.
20
Fig – 2.3 ICF BOGIE TOP VIEW
21
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
22
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
23
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-HLS94.
Fig - 2.6 SECONDARY COIL SPRING
24
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
25
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
26
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.
27
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
28
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
29
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.
30
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 s ystem 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 ri ng. The mechanical system will then vibrate at one or more of its “natural frequency” and damp down to zero. 31
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 can’t 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. 32
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. λ1,λ2 ...λ 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.
33
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
34
To find Eigen vectors,
Now, Actual suspension system is as followsNow 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- Alembert’s principle to this, we get
And To find modal matrix Eigen vector in matrix form,
=
=
Modal matrix
35
and
Let damping be proportional i.e. and
; In Principle coordinates (P i) 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
36
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 Lagrange’s 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,
37
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,
38
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.
39
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;
40
From above code we plot results for various values of w(excitation frequency). 1) For w=10 rad/sec. 2) For w=15 rad/sec. 3) For bump
1) For w=10 rad/sec.
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.
41
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.
42
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.
43
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)-(k3k4)*y(7)-(c1+c2+c3+c4)*y(2)-(-c1+c2-c3+c4)*y(4)-(-c3-c4)*y(6)-(c3c4)*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)-(-k3k4)*y(7)-(-c1+c2-c3+c4)*y(2)-(+c1+c2+c3+c4)*y(4)-(c3-c4)*y(6)-(-c3c4)*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)-(-c3c4)*y(2)-(c3-c4)*y(4)-(c3+c4)*y(6)-(-c3+c4)*y(8))/m2;
44
f(7)=y(8); f(8)=(-(k3-k4)*y(1)-(-k3-k4)*y(3)-(-k3+k4)*y(5)-(k3+k4)*y(7)-(c3c4)*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 f irst plot. x4(t)= displacement of left side of coach shown by green line in second plot. 45
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 it’s 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 it’s 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).
46
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 47
INITIAL CONDITIONS
48
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
49
AXLE BOX
LOWER SPRING BEAM
EQUALISING STAY
50
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
51
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.
52
a) Rotational joint between axle box and wheel sets
b) 6 DOF between bolster and base.
c) 6 DOF between bolster and base.
53
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.
54
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.
55
j) Secondary dampers between bolster and lower spring beam.
k) Generalized joint for hangers.
56
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
57
WHEEL PROFILES Standard from file
General Information about current simulation
58
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) 3) Bogie running at 45 m/s on uneven track (considering bad irregularities) 4) Bogie running at 46 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.
59
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
60
2) BOGIE RUNNING AT 40 m/s ON UNEVEN TRACK (Considering bad irregularities)
A) PRIMARY SUSPENSION
B) SECONDARY SUSPENSION
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. 61
3) BOGIE RUNNING AT 45 m/s ON UNEVEN TRACK (Considering bad irregularities)
A) PRIMARY SUSPENSION
B) SECONDARY SUSPENSION
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.
62
4) BOGIE RUNNING AT 46 m/s ON UNEVEN TRACK (Considering bad irregularities)
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”
63
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
64
8.2
RAILWAY CONFIGURATION
It is necessary to set railway configuration. 1. Firstly, let’s 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….
65
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 al ternatives
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.
66
FINISH CONDITIONS
Here you can describe finish conditions for each numerical experiment in the current family. Finish conditions are formulated in the following wa y: “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.
67
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
68
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. 69
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 .
70
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
Red – 36m/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 doesn’t 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.
71
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 72
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.
73
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.
74
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. 75
