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Railways were introduced in India in 1853 and as their development progressed through to the twentieth century, several company managed systems grew up. To enforce standardization and co-ordination amongst various railway systems, the Indian Railway Conference Association (IRCA) was set up in 1903, followed by the Central Standards Office (CSO) in 1930, for preparation of designs, standards and specifications. However, till independence, most of the designs and manufacture of railway equipments was entrusted to foreign consultants. With Independence and the resultant phenomenal increase in country’s industrial and economic activity, which increased the demand of rail transportation - a new organization called Railway Testing and Research Centre (RTRC) was setup in 1952 at Lucknow for testing and conducting applied research for development of railway rolling stock, permanent way etc.
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SUMMER TRAINING REPORT
Axle Box Cylindrical Roller Bearing for Locomotive Bogies)
(14 JUNE 2010 to 12 JULY 2010 )
Submitted by Submitted toYadbir Singh S.k Sachan3rd year student of Mechanical Engineering Vehicle, Motive Power Bhabha Institute of Technology Kanpur Dehat RDSO Manak Nagar,Lucknow
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ACKNOWLEDGEMENT
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I would like to extend my heartfelt thanks and deep sense of gratitude to all those who helped me to writing this Report. First, I would like to express my sincere thanks to my sir Mr. S.K Sachan of RDSO, Manak Nagar, Lucknow. I would also like to express my thanks to Er. Bhupendra Singh, NTPC Singarulii, special thanks to Surjeet Kumar in RDSO. Motive Power.
This most sincere and important acknowledgement and gratitude is due to my parents, who have given their moral boosting support and encouragements at some stage of this endeavor.
Yadbir SinghStudents of Mechanical Engineering
Bhabha Institute of Technology, Kanpur, India.
Email Id. [email protected]@gmail.com
INDEXSr.No Contains Page NO.1. Introductions about RDSO 52. Quality objectives for the
year 2008- 096-7.
3. Infrastructure and RDSO Lab.
7-11
4. Nomenclature adopted by the Indian railways for the
11-15
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locomotives operating on the Indian railways.
5. Bearings (General Description)
16-20
6. Terminology for servicing tools 20-21.7. Disassembly of roller
bearing axle boxes21-22
8. Cleaning of bearings, axle boxes and components
23-24
9. Checking of axle journals, axle boxes, roller bearings and components
25-26
10. Assembly 26-2911. Lubrication 29-3112. Periodic attention and
service inspections31-37
13. Running instructions and inspection of bearings of locos involved in fire, floods and accidents
38-39
14. General instructions regarding cleanliness, storage and handling of bearing
39-40
15. Replacement of bearings parts and interchangeability of axle boxes
40-41
16. Terminology of bearing defects
42-45
17. Bearing used in Indian railways
46-48
18. Bearing life Calculation 48-49.
1 INTRODUCTION
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Railways were introduced in India in 1853 and as their development progressed through to the twentieth century, several company managed systems grew up. To enforce standardization and co-ordination amongst various railway systems, the Indian Railway Conference Association (IRCA) was set up in 1903, followed by the Central Standards Office (CSO) in 1930, for preparation of designs, standards and specifications. However, till independence, most of the designs and manufacture of railway equipments was entrusted to foreign consultants. With Independence and the resultant phenomenal increase in country’s industrial and economic activity, which increased the demand of rail transportation - a new organization called Railway Testing and Research Centre (RTRC) was setup in 1952 at Lucknow for testing and conducting applied research for development of railway rolling stock, permanent way etc.
Central Standards Office (CSO) and the Railway Testing and Research Centre (RTRC) were integrated into a single unit named Research Designs and Standards Organization (RDSO) in 1957, under Ministry of Railways at Lucknow. The status of RDSO has been changed from an RDSO is headed by a Director General The Director General is assisted by Additional Director General, Sr. Executive Directors and Executive Directors, heading different directorates. RDSO has various directorates for smooth functioning.
2.QUALITY ASSURANCE Hitherto, the quality assurance function in respect of vendor approval and purchase inspection of these items including publication of vendor directories was being looked after by individual technical directorates of RDSO along with their normal functions of research, development and standardization. To impart greater thrust to quality assurance, Railway Board has approved the creation of a separate
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Quality Assurance Organization at RDSO in Sept.2002 for Technical disciplines i.e. Mechanical Engineering. Including M&C, Civil Engineering. S&T & Electrical Engineering. Each headed by Executive Director under the overall charge of an HAG officer. With the creation of this Quality Assurance Organization, focused attention and close monitoring of vendor approval and purchase inspection activities.
FUNCTIONS
RDSO is the sole R&D organization of Indian Railways and functions as the technical advisor to Railway Board Zonal Railways and Production Units and performs the following important functions :
Development of new and improved designs.
Development, adoption, absorption of new technology for use on Indian Railways.
Development of standards for materials and products specially needed by Indian Railways.
Technical investigation, statutory clearances, testing and providing consultancy services.
Inspection of critical and safety items of rolling stock, locomotives, signaling & telecommunication equipment and track components.
GOVERNING COUNCIL Governing Council comprises of Chairman, Railway Board as Chairman; and Financial Commissioner, Member Engineering, Member Mechanical, Member Staff, Member Electrical, Member Traffic, Addl. Member (Plg)/ Railway Board and Director General, RDSO as its members. The functions of Governing Council are:
To identify and approve the R&D projects for technology development on Indian Railways.
To review the progress of projects.
To determine the quantum of direct investment in technology development within the overall allocation of funds under the plan head 'Railway Research'.
To give direction for improving the working of RDSO.
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CENTRAL BOARD OF RAILWAY RESEARCH Central Board of Railway Research (CBRR) consist of DG/RDSO as Chairman, Addl. Member (Civil Engineering.), Addl. Member (Mechanical Engineering), Addl. Member (Elect.), Addl. Member (Sig), Addl. Member (traffic), Advisor (Finance), Executive Director (E&R), Executive Director (Plg.)/Railway Board as members and Addl. Director General/RDSO as member secretary. Non- Railways members of CBRR consist of eminent scientists, technologists, engineers and senior executives of other research organisations, academic institutions and industrial units related to railway technology and materials. Functions of CBRR are:
To consider and recommend the programmers of research on Indian Railways.
To review the research programmers from time to time.
To ensure coordination and assistance from other research laboratories.
To review the ongoing projects from the technical angle.
3 INFRASTRUCTURE
RDSO has a number of laboratories which are well equipped with research and testing facilities for development, testing and design evaluation of various railway related equipments and materials. Some of these are:
1)Air Brake Laboratory is equipped with facilities for simulating operation of air brakes on freight trains up to 192 wagons and 3 locomotives as also for simulation of passenger trains up to 30 coaches.
Brake Dynamometer Laboratory has facilities to develop and test brake friction materials for locomotives, coaches and wagons. A unique facility in India, this laboratory has also been used by R&D organizations of Ministry of Defense like DMRL, DRDL and HAL for indigenization of brake pads for defense aircraft.
B&S Laboratory has a 6mx14m heavy/testing floor on which full scale models of beam (spans up to 10 m, slabs, columns, towers, shells and other components made of concrete, steel, brick etc can be tested under static, dynamic or pulsating loads. A high frequency ranging 250-700 cycles/min pulsate for the application of a pulsating loads varying from 2 to 20 tones and a maximum static load of 40 tonnnes on heavy duty testing floor. The Laboratory is equipped with analogue
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strain indicator, multi channel dynamic strain recording system, switching & balancing units, acoustic emission equipment, data acquisition system etc. for recording various parameters.
Diesel Engine Development Laboratory has four test beds capable of testing diesel engines from 100 to 6000 HP with fully computerized systems for recording of over 128 test parameters at a time. This facility has already enabled RDSO to develop technologies for improving fuel efficiency, reliability and availability of diesel engines as well as to extract higher output from existing diesel engines. Fatigue Testing Laboratory for testing prototype locomotive and rolling stock bogies, springs and other railway equipments subjected to stress and fatigue so as to ascertain their expected life in service. Geo-technical Engineering Laboratory is equipped with facilities for determining strength parameters of soil in lab and field condition. The State-of-art Sub-surface Interface Radar (SIR) system, Laser based soil particle analyzer, and computerized consolidation test apparatus have been installed in the lab. The lab also has computerized Static Triaxial Shear apparatus for determining the strength of soil as well as the design of embankment. Metallurgical & Chemical Laboratory is capable of destructive and non-destructive testing of metals, polymers, composites, petroleum products and paints for providing information to be used in design and also for monitoring performance of materials in service.
The M&C laboratory include Scanning Electron Microscope, Direct reading spectrometer, Ultrasonic Flaw Detector and other non destructive examination equipment, polymer and composite evaluation facilities, thermal analyser, corrosion engineering evaluation facilities including weather meter, static 760 hour AR test rig for grease testing. V2F dynamic test rig for grease testing, lube oil filter evaluation rig Cetane rating machine & 50t machine for rubber deflection characteristics.
Psycho-Technical2) Laboratory for assessment of critical psycho-physical attributes of operational
staff such as drivers, switchmen and station masters for efficient operation. The ergonomic laboratory of psycho-technical Dte is also equipped with bio-feedback system for assessment of EMG, GSR (Galvanic Skin Resistance) temperature, pulse and respiration rate & is used for stress management exercises.
Signal Testing Laboratory for testing of all types of signaling equipments such as safety signaling relays, block instruments, power supply equipments, point machines, signaling cables, electro-mechanical signaling equipments/ components etc. There is an exclusive environmental testing section equipped
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with environmental testing facilities as per ISO 9000. These is including, programmable heat, humidity & cold chambers, mould growth, dust, rain chambers. Signaling Equipment Development Centre has been set up in the Signaling Lab. In this Centre, working signaling equipment & systems have been set up. The working systems include SSI, universal axle counter, VLSI axle counter, AFTCs, block instruments etc. In addition, equipment developed by RDSO, such as signaling relays, poly-carbonate lenses, LED signal lamps, triple pole double filament lamps, power supply equipment etc., have also been displayed. This centre will be used for testing minor improvements in designs of SSI, axle counters etc., as well as for imparting training to newly inducted Inspectors.
3) Track Laboratory for testing full scale track panel under dynamic load patterns similar to those encountered in service. Stresses at the various locations of track components under simulated load conditions are measured and recorded for analysis. This has helped in rationalising and optimising design of track structures for Indian conditions. The facility of fatigue testing of welded rail joints is also available. n connection with joint research project of UIC on rail defect management, RDSO has been entrusted with lab testing of rail samples from various world railways under simulated loading conditions.Special rail tensioning system for application of longitudinal forces on rail samples to simulate the thermal forces of the field has indigenously been developed, installed and commissioned in track lab. This system, with capacity of up to 150 tonne in static condition, is being used to conduct testing of different rail samples.
Mobile Test Facilities 4) for recording of track parameters, locomotive power and conducting oscillograph
trials for evaluating vehicle-track interaction as also for monitoring track conditions. For condition monitoring of OHE under live line and to facilitate directed maintenance of electrification, a Network of testing and recording apparatus (NETRA) car, first of its kind, developed by RDSO is actively in service for scanning OHE in Railway.
Vehicle Characterization Laboratory for conducting vehicle characterisation tests on railway vehicles to study the behaviour of suspension systems and to determine natural frequencies
5) Centre for Advanced Maintenance Technology at Gwalior for upgrading maintenance technologies, and methodologies. Also to achieve improvements in productivity and performance of all railway assets and manpower. This covers reliability, availability, utilization and efficiency.
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6) LIBRARYConsiderable efforts and resources were devoted on the development of an outstanding Library collection to meet the expanding needs of Research and Development. The Library has more than 1.70 lakhs volumes which includes books, reports, specifications, and translations on Science, Engineering, Technology, Management and Railways. About 100 technical journals and magazines both Indian and foreign origin are received in the Library regularly.
4 Nomenclature adopted by the Indian railways for the locomotives operating on the Indian railways.
The numbering system of locomotives comprises two parts. First, the code prefix such as 'WDM-2' or 'WAM-4' which denotes the type/class of the loco; and second, a serial number such as '17604'. Each letter in the code-prefix has a specific significance, and the understanding of this would help us in the overall understanding of the nomenclature adopted on IR, as well as the varied types of locomotives running on the IR.
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The first (left-most) letter denotes the gauge. Thus, 'W' stands for Broad Gauge, 'Y' is Metre Gauge and 'Z' is Narrow Gauge. We will normally see one of these letters as the first letter in the number of the loco.
The Steam Saga
In the bygone era, life was simple, because there was only one category of loco, based on the fuel is used. Those were days of the elegant, huffing and puffing steam locos, also colloquially called 'coal engines'. In those days, on the broad gauge, we had:
'WP' class locos, with a hemispherical front, which gave the loco a very majestic and powerful look.
'WG' class locos, which had a flat front.
The letters 'P' and 'G' indicated Passenger service and Goods service, respectively. Its means that 'WP' was a broad gauge passenger service loco, while 'WG' was a broad gauge goods service locomotive. Due to the shift to diesel and electric traction, both these types of locos are no longer in service on IR, and can be seen only in museums.
On the meter gauge, we had the omnipresent 'YP' class locos, which, unlike their broad-gauge counterparts (WP), had a flat front. The goods trains on the meter gauge were pulled by 'YG' class locos, which had a look similar to the 'YP' locos.
Thus, in the days of steam traction, the second letter indicated the 'service class' of the loco, and mainly the 'WP'. 'WG', 'YP' & 'YG' class of steam locos dominated the IR scene.
The Change from Solid to Liquid Fuel
Then, in the sixties, came diesel traction, and life became a little more difficult. Most of the diesel locos operating on broad gauge are 'WDM-2' series, where 'W' is Broad Gauge, 'D' is Diesel, and 'M' is 'Mixed' (service). These versatile locos, made in India at DLW, Varanasi under license from ALCO, USA, have put in an exceedingly meritorious and long service in hauling passenger as well as goods trains, both singly and in pairs.
The number '2' indicates that it is a second generation loco, from design technology point of view. Its predecessor 'WDM-1' was used in much smaller numbers and were last seen on the Durg-Nagpur section of South Eastern Railway, hauling goods trains. The peculiarity of the WDM-1 was that it had the driver's cab only on one end, while the other end was flat -- like the ends of passenger coaches. So, while it appeared flush with the load behind it, the WDM- 1 had to be reversed for the journey in the opposite direction. On the other hand, 'WDM-2', though unsymmetrical, can be used in any direction without the need of reversing, thanks to the design of its driver's cab.
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WDM-2's cousin on the meter gauge is an equally versatile 'YDM-4', while that on the narrow gauge is ZDM-1. You will also find 'WDS-4' bringing passenger trains into platform at the starting stations. ('S' indicates 'shunting class'). There are other variants such as 'WDP-1' ('P' for 'passenger service', and higher-powered (3100hp), 'WDP-2' and 'WDG-2' locos for passenger and goods service respectively.
While 'WDM-2' and its related variants are based on ALCO designs, IR has recently gone in for a new technology, powerful (4000hp) locos based on the designs of General Motors, USA. These locos are christened 'WDG-4' ('G' for Goods), and these are manufactured at DLW. These locos can be seen operating on the Hubli Division of the South Central Railway, hauling goods trains carrying bulk ore.
On the narrow gauge, locos such as 'ZDM' operate on Kangra Valley Railway and Kalka-Shimla Railway, while other narrow gauge variants pull tourist trains on the Neral-Matheran Railway near Mumbai.
The Electric Locomotives
The advent and the progress of Electric Traction has further complicated the numbering system. From a simple 'WP' or 'WG', we now move on to more complex nomenclatures such as 'WCAM-3', an addition of as many as 3 characters. But this addition is not without adequate meaning, as we will realise after the following discussion.
Electricity comes in two forms -- AC (Alternating Current) and DC (Direct Current). On Indian Railways, the Mumbai-Pune, Mumbai-Igatpuri and Mumbai-Virar sections are fed by DC supply (1,500V DC), while all other sections are fed by AC supply (25,000V AC). Therefore, the nomenclature system for electric locos includes a letter to differentiate between locos with DC traction from those with AC traction. As per this system, 'A' indicates 'AC traction' while 'C' indicates 'DC traction (not 'D', so as to avoid any confusion with diesel). One can, therefore, find 'WCG' class locos (Broad Gauge, DC traction, Goods duty) operating on the Mumbai Division, while their counterparts 'WAG' locos haul broad gauge goods trains on AC traction elsewhere on LR. Similarly, trains, such as Mumbai-Pune Deccan Queen Express were, till recently, hauled by gigantic
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'WCM-l' and 'WCM-5' ('M' for 'Mixed' service, just as in 'WDM-2'), while Mail/Express trains in the other parts of the country are powered by AC electric locos such as 'WAM-4' (Broad Gauge, AC Traction, Mixed service).
The WAM-4 Ioco has been produced in very large numbers (upward of 500), and is in service very widely in India. Its predecessor WAM-1/2/3 can be seen operating on Eastern Railway, for instance, on Sealdah Division. 'WAG-2' is of Hitachi design and operates mainly on the Bhusawal Division of Central Railway. This is a very handsome-looking loco, which is also the case with its 'younger brother', the 'YAM-1' used for hauling trains on the only electrified metre gauge section on IR namely the Chennai-Chengalpattu section. Under Project Umgauge being implemented by the railways, this section will get converted to broad gauge, and rail enthusiasts will surely miss the sight of this lovely loco hauling a load of metre gauge coaches.
What WAM-4 is to Mail/Express trains, 'WAG-5' is to goods trains operating on the broad gauge. The WAG-S is the most common loco for hauling BG freight trains on AC traction. More than 700 locos of this variety can be seen on LR.
Driven by the ever-growing need for more speed & power, we have seen technological advancements on the IR scene too. Thus we now can commonly see a huge, 5000 horsepower, red-coloured, and well-contoured loco, the 'WAP-4' hauling super-fast Mail pr Express trains of as many as 24 coaches in various parts of the country. This BG-AC Passenger Service loco is capable of achieving speeds upto 140 kilometres per hour. Its predecessors, the 'WAP-l' and 'WAP-3' can be found in much lesser numbers -- they were probably used to improve the designs, which has now been adopted on the 'WAP4'
Modern Technology
The conventional locos had:
DC motors fed by DC overhead supply, such as for WCM, WCG locos (Electric locos, DC traction)
AC overhead supply, stepped down through a multi-winding transformer, rectified by static rectifiers, whose output was fed to the DC motors. Locos such
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as WAM, WAP, WAG are equipped with this technology. (Electric locos, AC traction).
Diesel fuel driving an engine, which operates an alternator, whose AC Electric output was rectified and fed to the DC motors, in locos such as WDM-2, WDP, WDG. Due to this the diesel locos are actually 'diesel-electric locos. These locos were actually with an on-board moving powerhouse operated on diesel fuel.
The latest technological innovation in traction is the use of 3-phase AC motors instead of DC motors as the prime movers in the loco. With a desire to implement this technology, IR purchased, under a transfer of technology agreement, two new types of electric locos from ADtranz. These locos, one with 6000hp, 160km/h (upgradable to 200km/h), and the other with 6000hp, 100km/h capability, are christened as WAP-5 and WAG-9 on the Indian Railways. These can be seen operating on the Northern and Eastern Railways hauling maillexpress and goods trains respectively.
The technology of AC motors as pnme movers applied to diesel traction is also now available with the IR. in the form of the WDG-4 loco, being produced at DLW under another technology transfer agreement (with General Motors, USA). This 4000hp, 160km/h loco will be found in increasing numbers as the production gradually increases.
While on one side this technology transfer was under progress, IR, through Chittaranjan Locomotive Works and RDSO, have in parallell developed an indigenous, powerful 5000hp loco for freight traffic, called the 'WAG-7'. This loco is already under manufacture at CLW, and can operate at speeds upto 100km/h.
A Technological Challenge for the Railway Engineer
Since Mumbai Division is the only division on IR to have DC overhead supply, there is a need to change from DC to AC (or vice-versa) for trains going out of (or coming into) Mumbai. This changeover takes place at three locations. On the Central Railway route towards north and east, this change takes place at Igatpuri -- on the platform -- in the form of change of the locomotive. On the south-bound route, the changeover is to a diesel loco, at Pune station. But the most interesting is the changeover on the Western Railway route, towards Vadodara/Delhi. This change happens while the train is in full motion -- without any stopping or jerks whatsoever. To achieve this, the trains on Mumbai Central - Vadodara / Ahmadabad route are operated by 'dual-traction' locos of WCAM series. (BG, DC and AC traction, Mixed service). The changeover takes place just north of Virar, over a neutral section, while the passengers inside the train normally remain oblivious of such a major (technical) happening!
The Numerals
After having discussed and understood the alphabetic nomenclature prevalent in naming the locos operating on IR, let us take a brief look at the numerals too. Today, most locos have a 5-digit number after the type-code. The first two digits (from left) also signify the type of the loco, and the remaining three digits denote the serial number in that category.
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Thus WAP-4 class locos always have numbers beginning 22, while WCG class locos start with 20. The new generation WAP-5 and WAG-9 locos have numbers in the 30 and 31 series.
Axle Box Cylindrical Roller Bearing for Locomotive Bogies)
5 BEARINGS
(GENERAL DESCRIPTION)
The cross-sections of cylindrical axle roller bearings with the location of all the parts of the assembly on the journal.
The assemblies are a combination of two separate bearings capable of taking radial as well as axial thrust loads.
The roller bearing is composed of a cylindrical inner and an outer race/ring along with rollers and cages. The cages while carrying no load keep the rolling elements axially apart and also prevent the later from falling out while handling. The outer ring is a slide fit on the axle box housing while the inner ring is an interference fit on the axle journal forming part of the axle when in place. The rollers have a special cylindrical profile, which enables uniform and effective load distribution.
The bearing parts are made of nickel-chromium / carbon chromium alloy steels except cage, which is of solid brass / brass riveted.
The full analysis of heavily loaded plain bearings is extremely complex. For so called ‘lightly-loaded bearings’ the calculation of power loss is simple for both journal and thrust bearings. Important factors are, load capacity, length ton diameter ratio, and allowable pressure on bearing material. Information is also given on rolling bearings.
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The terms rolling-contact bearing, antifriction bearing, and rolling bearing are all used to describe that class of bearing in which the main load is transferred through features inrolling contact rather than in sliding contact. In a rolling bearing the starting friction isnearly twice the running friction, but still it is negligible in comparison with the startingfriction of a sleeve bearing. Load, speed, and the operating viscosity of the lubricant doaffect the frictional characteristics of a rolling bearing. It is probably a mistake to describe a rolling bearing as “antifriction,” but the term is used generally throughout the industry, the study of antifriction bearings differs in several respects when compared with the study of other topics because the bearings they specify have already been designed. The specialist in antifriction-bearing design is confronted with the problem of designing a group of features that compose a rolling bearing: these features must be designed to fit into a space whose dimensions are specified; they must be designed to receive a load having certain characteristics; and finally, these features must be designed to have a satisfactory life when operated under the specified conditions. Bearing specialists must therefore consider such matters as fatigue loading, friction, heat, corrosion resistance, kinematic problems, material properties, lubrication, machining tolerances, assembly, use, and cost. From a consideration of all these factors, bearing specialists arrive at a compromise that, in their judgment, is a good solution to the problem as stated. We begin with an overview of bearing types; then we note that bearing life cannot be described in deterministic form. We introduce the invariant, the statistical distribution of life, which is strongly Weibullian.
Bearing TypesBearings are manufactured to take pure radial loads, pure thrust loads, or a combinationof the two kinds of loads. The nomenclature of a ball bearing is illustrated.which also shows the four essential parts of a bearing. These are the outer ring, the inner ring, the balls or rolling features, and the separator as shown in figure on next page.
To completely understand the statistical features
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separator is sometimes omitted, but it has the important function of separating the features so that rubbing contact will not occur. In this section we include a selection from the many types of standardized bearings that are manufactured. Most bearing manufacturers provide engineering manuals and brochures containing lavish descriptions of the various types available. In the small space available here, only a meager outline of some of the most common types can be given. So you should include a survey of bearing manufacturers’ literature in your studies of this section. Some of the various types of standardized bearings that are manufactured The single-row deep-groove bearing will take radial load as well as some thrust load. The balls are inserted into the grooves by moving the inner ring to an eccentric position. The balls are separated after loading, and the separator is then inserted. The use of a filling notch in the inner and outer rings enables a greater number of balls to be inserted, thus increasing the load capacity. The thrust capacity is decreased, however, because of the bumping of the balls against the edge of the notch when thrust loads are present. The angular-contact bearing provides a greater thrust capacity. All these bearings may be obtained with shields on one or both sides. The shields are not a complete closure but do offer a measure of protection against dirt. A variety of bearings are manufactured with seals on one or both sides. When the seals are on both sides, the bearings are lubricated at the factory. Although a sealed bearing is supposed to be lubricated for life, a method of relubrication is sometimes provided. Single-row bearings will withstand a small amount of shaft misalignment of deflection, but where this is severe, self-aligning bearings may be used. Double-row bearings are made in a variety of types and sizes to carry heavier radial and thrust loads. Sometimes two single-row bearings are used together for the same reason, although a double-row bearing will generally require fewer parts and occupy less space. The one way ball thrust bearings are made in many types and sizes. Some of the large variety of standard roller bearings is available, straight roller bearings carry a greater radial load than ball bearings of the same size because of the greater contact area. However, they have the disadvantage of requiring almost perfect geometry of the raceways and rollers. A slight misalignment will cause the rollers to skew and get out of line. For this reason, the retainer must be heavy. Straight roller bearings will not, of course, take thrust loads. Helical rollers are made by winding rectangular material into rollers, after which they are hardened and ground. Because of the inherent flexibility, they will take considerable misalignment. If necessary, the shaft and housing can be used for raceways instead of separate inner and outer races. This is especially important if radial space is limited.
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Bearing Life
When the ball or roller of rolling-contact bearings rolls, contact stresses occur on theinner ring, the rolling element, and on the outer ring. Because the curvature of the contacting features in the axial direction is different from that in the radial direction, the equations for these stresses are more involved than in the Hertz equations presented in If a bearing is clean and properly lubricated, is mounted and sealed against the entrance of dust and dirt, is maintained in this condition, and is operated at reasonable temperatures, then metal fatigue will be the only cause of failure. Inasmuch as metal fatigue implies many millions of stress applications successfully endured, we need a quantitative life measure.
Common life measures are• Number of revolutions of the inner ring (outer ring stationary) until the first tangibleevidence of fatigue
Bearing Load Life at Rated Reliability
When nominally identical groups are tested to the life-failure criterion at different loads, To establish a single point, load F1 and the rating life of group one (L10)1 are the coordinates that are logarithmically transformed. The reliability associated with this point, and all other points, is 0.90. Thus we gain a glimpse of the load-life function at 0.90 reliability. Using a regression equation of the form FL1/a = constant the result of many tests for various kinds of bearings result in • a = 3 for ball bearings• a = 10/3 for roller bearings (cylindrical and tapered roller)A bearing manufacturer may choose a rated cycle value of 106 revolutions (or inthe case of the Timken Company, 90(106) revolutions) or otherwise, as declared inthe manufacturer’s catalog to correspond to a basic load rating in the catalog for eachbearing manufactured, as their rating life. We shall call this the catalog load ratingand display it algebraically as C10, to denote it as the 10th percentile rating life fora particular bearing in the catalog.
Selection of Tapered Roller Bearings
Tapered roller bearings have a number of features that make them complicated. As weAddress the differences between tapered roller and ball and cylindrical roller bearings,Note that the underlying fundamentals are the same, but that there are differences in detail. Moreover, bearing and cup combinations are not necessarily priced in proportionto capacity. Any catalog displays a mix of high-production, low-production, and successful special-order designs. Bearing suppliers have computer programs that will
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take your problem descriptions, give intermediate design assessment information, andlist a number of satisfactory cup-and-cone combinations in order of decreasing cost.Company sales offices provide access to comprehensive engineering services to helpdesigners select and apply their bearings.FormThe four components of a tapered roller bearing assembly are the• Cone (inner ring)• Cup (outer ring)• Tapered rollers• Cage (spacer-retainer)The assembled bearing consists of two separable parts:(1) the cone assembly: the cone, the rollers, and the cage; and (2) the cup. Bearings can be made as single-row, two-row, four-row, and thrust-bearing assemblies.
Additionally, auxiliary components such as spacers and closures can be used.A tapered roller bearing can carry both radial and thrust (axial) loads, or any combinationof the two. However, even when an external thrust load is not present, the radial load will induce a thrust reaction within the bearing because of the taper. To avoid the separation of the races and the rollers, this thrust must be resisted by an equal and opposite force. One way of generating this force is to always use at least two tapered roller bearings on a shaft. Two bearings can be mounted with the cone backs facing each other, in a configuration called direct mounting, or with the cone fronts facing each other, in what is called indirect mounting. shows the nomenclature of a tapered roller bearing, and the point G through which radial and axial components of load act.
6 TERMINOLOGY FOR SERVICING TOOLS.
The following is the terminology of the commonly used tools for servicing and maintenance of axle roller bearings: -
TOOLS USES
a) Lead or copper hammer (sledge) For tapping races/rings etc. while assembling and disassembling
b) Micrometer (inside and out side) For measuring axle box bore and journal diameter etc.
c) Feeler gauge For measuring diametrical and axial clearances of the bearings, etc.
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d) L – Gauge (as shown in fig-6) For measuring the respective distance of inner races/rings and thrower/labyrinth ring from journal end.
e) Induction heater or oil bath heater with tank, scissor- tongs, asbestos hand gloves, stirrer, thermometer etc.
For mounting inner races/rings on axle journals.
f) Puller tool or induction heater. For extracting inner races/rings from axle journals.
g) General fitter tools like spanners, pliers etc.
--------
h) Torque wrenches of different capacity (from 5.0 to 100.0 Mkg.)
For tightening bolts and nuts.
i) Scrappers For general cleaning
j) Dial-indicators To check deflection on axle etc.
k) Magnifying glasses To examine spalls, etc. on races/rings.
l) Deep and shallow washing trays For washing bearing parts etc.
m) Thin hard wooden scoop For removing old grease from bearings and housings.
n) Wooden blocks For positioning under the housing lug liner to prevent the bearing housing from turning while disassembling etc.
o) Brushes (stiff and bristle type) For cleaning purpose, etc.
p) Lint-free towels To wipe bearing and components, etc.
q) Wire mesh basket For placing the bearing components, etc.
r) Ultrasonic machine To check the internal cracks on the axle journal
s) Metal top table For placing the axle box housing during assembly.
General Instructions & Precautions Work only with clean tools. Proper tools should be used for different operations. Avoid damage, injury or distortion to any part of the bearing while
working with tools.
Do not use any kind of mallet.
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Do not use gas torch to heat inner races and thrower / labyrinth ring.
7 DISASSEMBLY OF ROLLER BEARING AXLE BOXES
For disassembly of axle box bearings after service for inspection, repair and re-lubrication, the following procedure is recommended:-
Clean thoroughly axle box cover and outside portions of axle boxes with wire brush before attempting any work on bearing to prevent ingress of dirt into the bearing.
Take off the front covers after removing the bolts / nuts. Unfold the locking plate and take off the end clamping screws. Remove end clamping plate. Remove loose lip from the journal end. Withdraw the axle box assembly from the axle journal leaving the inner
races/rings, inner distance piece/journal distance ring and thrower/labyrinth ring in position on the axle journals. Use extractor/hand-sling, if necessary.
Place the axle box assembly in a horizontal position on a suitable table. Remove thrower end cover/labyrinth cover in case of separate, thrower end
cover / labyrinth cover axle box. Push out the outer races/rings with bearing assembly and distance pieces/rings
from the axle box housing without applying direct force on the bearings or cages.
General instructions and precautions: Ensure that the bearing with its other components, are not damaged during
disassembly. Keep some quantity of used grease in a dry container for subsequent
investigation, if necessary. Before disassembling the outer races/rings, divide the full circle of the
outer races into four parts of 90º each and number 1, 2, 3 and 4 consecutively; mark the date when any load bearing part is brought into service, with an electric etching pencil. The load bearing zone should be changed to improve the fatigue life of outer race whenever the bearing is disassembled.
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Do not interchange bearing parts. Keep them as matched sets and exercise care to see that the complete roller bearing set is returned to the outer race/ring from which it was removed.
Disassembly of inner races/rings, thrower/labyrinth ring etc. from journal :If it becomes necessary to remove inner races/rings and thrower/labyrinth ring from the axle journal, the following shall be the procedure: -Apply the extractor tool for removal of inner races/rings, inner distance piece/journal distance ring and thrower/labyrinth ring.
Use three-jaw or two-jaw puller (whichever is required) positioning behind the removable part, in the manner as shown in fig. 4.
Apply pressure to the end of the axle by rotating the long bolt.o Precaution: Do not apply puller tool bolt directly to the lathe centre
tapped holes of the axle end. Follow instructions furnished with the heater. Heat the inner races/rings and thrower/labyrinth ring by induction heater to a
temperature not exceeding 1200C (250ºF) and not longer than the period specified in the operating instructions of induction heater.
Then use the puller indicated above.o Precautions:
Do not use oxy-acetylene torch for the removal of races/rings and thrower/labyrinth ring.
Use asbestos gloves while handling hot components. Ensure that the journal does not get any heat.
8 CLEANING OF BEARINGS, AXLE BOXES AND COMPONENTS
Bearing and components cleaning: Whenever bearings are removed from bogie for overhauls, inspection, repairs and
replacement or re-lubrication, the following shall be the cleaning procedure if manual cleaning is done. :-
Remove the bulk of grease with a thick hard wood scoop from all bearing parts. Place roller bearing parts such as bearing assemblies, distance pieces/rings, loose lip
etc. except axle box and it accessories in a wire mesh basket.
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Suspend the basket suitably in a container of pure, clean oil, preferably kerosene or MTO.
Allow bearing and bearing parts to soak, preferably, overnight or until the grease has been sufficiently softened.
Agitate the basket slowly through the oil from time to time to remove as much as possible of dirt, grease, etc.
Lift the basket and drain the oil. If for any reason, it is necessary to ascertain the nature of foreign matter removed, strain the oil through a filter paper and collect the residue.
Transfer all parts to a second container of clean oil. Clean each part individually with a brush, partially submerging in oil. Do repeated soaking and cleaning if necessary until all traces of grit is removed. Sponge out all parts with a non-fluffy rag or with a wiping towel for inspections. Clean finally in petrol or white spirit before re-assembly.
General instruction and precautions : Do not use any alkaline degreasing agents. Water based cleaning methods may
lead to corrosion of the bearings. Take care that hairs from brush do not stick in cage pockets. etc. After final cleaning, the re-assembly should be done as early as possible, to avoid
any possibility of corrosion, etc. If bearing units are not to be re-assembled immediately, shake off the liquid, dry
and provide a protective coating of antirust compound, and wrap the parts in a water proof paper or polythene sheet and store in a dry room.
Use only clean and dry compressed air, if desired, for drying bearing parts. Do not spin uncleaned bearings. Do not use same container for initial cleaning and final rinsing of
bearings.Cleaning Mediums: Use only water-free cleaning medium, the following are some of
the cleaning mediums generally used :- Petrol White spirit (low Flash point) Kerosene MTO (Mineral Turpentine Oil)
Axle-box and accessories cleaning : Scrap accumulation of dirt off outside of the box.
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Wash axle box, covers, screws, nuts, spring washers, etc. after extracting bearings in a boiling soda solution.
Rinse thoroughly in clean, hot water. Wash inside and outside of box, cover etc. with clean kerosene. Ensure that the threaded holes on the box are clean. Blow out with compressed air and after drying, coat with light machine oil or
with the same grease as used for lubrication on the housing bore, and all machined or ground surfaces, after proper inspection and final repair.
Protect the box and its accessories from dirt and dust until re-assembly.Precaution: Sand-blast cleaning of roller bearing equipped axle assemblies is prohibited.
9 CHECKING OF AXLE JOURNALS, AXLE BOXES, ROLLER BEARINGS AND COMPONENTS
Checking of Axle journal : After thorough cleaning, check axle journal for any bending by measuring it
with the help of dial gauge at four places 90º apart. Bent axle may cause premature bearing failure.
Ensure that the axle journal diameter is within the permissible limits, laid down in relevant drawing.
Taper and opacity of axle journal should be within permissible limit. Axle journal should be examined for internal or superficial cracks by
ultrasonic testing machine.Checking of Axle box housing:
After thorough cleaning, check the damage, score mark and cracks on axle box body and covers for their soundness of material.
Examine traces of corrosion, if any, on working surfaces of the axle box body, remove it with fine emery paper.
Ensure that all the dimensions of the axle box housing and covers are within the permissible limits, laid down in relevant drawings.
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Check particularly the bore dia., depth, ovality and taper of the bore and other internal dimensions of axle box housing. If they are not within the limits as prescribed in relevant drawing, the housing should be set aside for rectification / rejections.
Inspect axle box lugs, liners, etc.Checking of roller bearings:
a) Any damage to the rollers and raceway should be brought to notice of the concerned section engineer.
b) In case, rotation is not free, this may be due to some dirt inside. The bearing may be washed with white spirit or petrol and re-dipped in rust preventive oil.
c) Dimensional details are shown in manufacturer's drawings and may be checked for better fitment.
d) Check and ensure radial internal clearances of the bearings to the value specified in the table below:
For NEI bearing For FAG bearing
Radial clearance(Under free condition)
0.100 to 0.165 mm. 0.165 to 0.215 mm.
Checking of components: Thrower/labyrinth ring: If the thrower/labyrinth ring is found damaged or
dismounted for any reason, the same should not be reused. Felt/Sealing ring: The felt rings should be changed compulsorily during the
overhauling of the axle box. Felt/Sealing ring must never be reused. Clamping plate and Distance pieces/rings: These components should be
examined for dimensional correctness, flatness and cracks before they are used.
Locking bolts/studs and nuts: If the nuts and bolts/studs do not fit properly to each other, they must be replaced.
Locking plates: The locking plates should be changed compulsorily when the axle box is dismantled.
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6 ASSEMBLY
Outer race/ring assemblies in housing Thoroughly clean the inside surface of “axle box housing” and “thrower end
cover/labyrinth cover” with kerosene oil and subsequently, after drying, with petrol.
Apply a thin coating of light machine oil or grease over the cleaned dry housing bore.
Place the axle box housing over a clean metal. Take out the outer race/ring assemblies from their original wrappings and place
squarely. Place one of the outer races (with its stamped face facing outwards) into the housing and slide it until it buts squarely against the housing mating surface
Next slide the outer distance piece/housing distance ring, keeping one of the grease hole of the outer distance piece/housing distance ring (if greasing is done through the axle box crown) concentric with the housing crown grease nipple hole.
Slide the second outer race/ring assembly in the same manner as previous one. For separate thrower end / labyrinth cover:-
I. Fix the studs for separate thrower end cover/labyrinth cover on the box rear end.
II. Place thrower end cover/labyrinth cover with rubber sealing ring in position. Ensure its proper bedding against the outer race/ring. Contact area should not be less than 60-70 % of total surface. Use feeler gauge for this purpose.
III. Place the tab-washer in position and tighten the four nuts evenly and lock them.
1) Follow on with the sliding of the end distance piece/ring i) j) Keep the axle box in a dry and clean place, after fixing a card-board on the
box openings for protection from dirt and moisture, until it is required for remounting.
k) Remove card-board just before the mounting on the axle journal.l) Apply lithium base grease of recommended brand into the axle box fitted
with outer races/rings before mounting.m) Smear well the annular grooves on the thrower/labyrinth ring end of the
box with specified grease to form an effective grease seal.To mount thrower/labyrinth ring, inner races/rings and inner distance piece/journal
distance ring on the axle journal, the following shall be the procedure a) Inspect the axle journal for its correct size, surface finish, permissible
taper and ovality, as per the relevant drawing.
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b) Clean thoroughly the axle journals and holes at the axle ends.c) Check for any bulging of the axle ends, which may occur at the time of
wheel pressing.d) Clean thoroughly the thrower/labyrinth ring, inner races/rings, and inner
distance piece/journal distance ring with kerosene oil and subsequently with petrol when dried up.
e) There are two methods for heating thrower/ labyrinth ring and inner races/rings to shrink fit on axle journal as given bellow:1. By oil bath heater:
1.1 Immerse inner races/rings and thrower/labyrinth ring in oil bath heater tank. These should not come in contact with hot plates.
1.2 Heat the inner races/rings and thrower/labyrinth ring to a temperature not exceeding 120ºC and not longer than 30 minutes. Ensure strict temperature control so that oil bath temperature does not exceed the above temperature.
2. By induction heater:2.1 Put the thrower/labyrinth ring and inner races/rings on the
induction heater. Follow instructions furnished with the heater.2.2 Heat the inner races/rings and thrower/labyrinth ring by induction
heater to a temperature not exceeding 120ºC (250F) and not longer than the period specified in the operating instructions of induction heater.
2.3 Demagnetise the inner races/rings and thrower/labyrinth ring. f) Shrink thrower/labyrinth ring on the axle and ensure its positive abutment
with axle shoulder. Check up its correct fitment in relation to the axle ends by means of suitable ‘L’ gauge.
g) Shrink the lip type inner races/rings, inner distance piece/journal distance ring and plain inner race/ring one after another on the axle journal
General instructions and precautions:a) Use only clean light transformer oil as heating medium.b) Prevent bearing parts making contact with the bottom of the tank by
providing wire-netting tray.c) Stir the oil during heating.d) Remove excess oil from bore of the inner races/rings and
thrower/labyrinth ring with clean lint-free cloth before mounting.e) Do not heat inner distance piece/journal distance ring.
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f) Hold firmly all the components (thrower/labyrinth ring, inner races/rings, etc.) against their relevant abutment surfaces on the axle journal until cooled down for gripping. For this purpose use of pusher tool as shown in Fig. 6.4 is recommended.
g) Use asbestos gloves while handling hot component.h) Ensure that 60-70% of abutting surfaces remain in contact with each other.
Use of feeler gauge is recommended for this purpose.
Mounting the axle box assembly :To mount the axle box assembly, the following procedure is recommended:-a) Pack axle box assembly with specified grease Smear grease between the
interstices of the cage and rolling elements by hand, rotating the bearing to assist penetration.
b) To increase the efficiency of seal, fill the concentric grooves in the shoulder of the box with grease.
c) Lift the box assembly in an upright position in level with the axle journal to bring bearing box horizontal axis in alignment with journal axis.
d) Keep box end in relations to axle
:Sl. No.
Screws Torque Values (in Mkg.)
1. M10 5.00
2. M16 22.00
3. M20 42.50
4. M 22 58.00
5. M26 98.00
6. 1 1/8" 7UNC 96.00
7. 7/8" BSW 53.25
8. 3/4" 10UNC 32.50
General Instruction and Precaution :a) Smear the threads of bolts, screws, etc. with oil.b) Do not resort to hammering action on axle box assembly while sliding the
axle box assembly on axle journal.c) Check for indications of slipping or rotations of thrower/labyrinth ring and
inner races/rings before mounting the axle box.
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11 LUBRICATIONWhenever lubricated surfaces slide together at low sliding speeds or with a high appliednormal load, the lubricant may not separate the two solid surfaces completely. However, the lubricant can still signiÞcantly reduce the friction coefÞcient by reducing the shear strength of adhesive junctions between the two surfaces. In this so-called boundary lubrication regime, the effectiveness of the lubricant can be improved if the lubricant molecules adhere well to the solid surfaces. This is best accomplished by introducing a lubricant or additive that forms a surface Þlm through adsorption, chemisorption, or chemical reaction with the surface. The ensuing reduced shear strength of the surface Þlm can lower the friction coefÞcient by as much as an order of magnitude from the dry friction value. When a good supply of a viscous lubricant is available, the separation between the surfaces will increase as the sliding speed increases or the normal load decreases. As the separation increases, the amount of solid/solid contact between the surfaces will decrease, as will the friction coefÞcient and wear rate. In this Òmixed frictionÓ regime, friction is determined by the amount of plowing deformation onthe softer surface by the harder surface asperities and by adhesion within the solid/solid contacts. When the surfaces become completely separated by a self-acting or externally pressurized lubricant Þlm, the lubricating regime is hydrodynamic, wear is reduced to nearly zero, and friction reaches a low value governed by viscous shear of the lubricant. Friction coefÞcients in such cases can be 0.001 or lower, depending on the surface velocities and the lubricant viscosity. This is the case for most journal or thrustbearings (see subsection on ßuid Þlm bearings). Bearings for Friction Reduction Most mechanical systems contain moving components, such as shafts, which must be supported and held in position by stationary members. This is best done by appropriate design or selection of bearings to be used wherever the moving member is to be supported. Most bearings may be classiÞed as either bearings, dry or semilubricated bearings, or rolling element bearings. Fluid Þlm bearings (see subsection below) have a conformal geometry, with a thin Þlm of ßuid separating the two surfaces. The ßuid lubricant could be a liquid, such as oil, or a gas, such as air. Fluid Þlm bearings are commonly used to support rotating cylindrical shafts, and the load on such a bearing could be either radial, in which case the bearing is called a journal bearing, or axial, for a thrust bearing.In most cases the ßuid Þlm is generated by the motion within the bearing itself, so the bearing is called self-acting or hydrodynamic. Whether or not a self-acting bearing can develop a ßuid Þlm sufÞcient to separate and support the two surfaces is determined by magnitude of the quantity mU/W, where m is the (absolute) ßuid viscosity, U is the relative sliding velocity, and W is the normal load. If that quantity is too small, the ßuid Þlm will be too thin and high friction will occur. This can be a problem during startup of equipment when sliding velocities are low. That problem can be overcome by pressurizing the ßuid Þlm from an external pressure source to create a hydrostatic bearing. Whether the ßuid Þlm is externally pressurized (hydrostatic) or self-acting (hydrodynamic), separation of the solid surfaces allows wear to be essentially eliminated and friction to be very low, even when very large loads are carried by the pressurized
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lubricant. Dry and semilubricated bearings (see subsection below) have conformal surfaces which are in direct contact with each other. This category includes bearings which run dry (without liquid lubrication) or those which have been impregnated with a lubricant. Dry bearings are made of a material such as a polymer or carbon-graphite which has a low friction coefÞcient, and they are generally used in low-load and low-speed applications. Semilubricated bearings are made of a porous material, usually metal, and are impregnated with a lubricant which resides within the pores. The lubricant, which could be oil or grease, cannot provide a complete ßuid Þlm, but usually acts as a boundary lubricant. Semilubricated bearings can carry greater loads at greater speeds than dry bearings, but not as high as either ßuid Þlm or rolling element bearings. The failure mechanism for both dry and semilubricated bearings is wear.
General instructions and precautions : Use only the approved and recommended lithium base greases listed under. Use calibrated pressure grease gun. Avoid excess lubrication. Excess lubrication will invariably result in increased
running temperatures, reducing the effectiveness of the lubricants. Do not heat the grease to facilitate application. Heating separates the oil from the
soap in the grease and grease loses the desirable properties. Keep lubricants in clean and covered container free from dirt and water. Used lubricant should never be re-used even though it may appear to be in good
condition.
Approved and recommended lubricants : Servogem RR3 of Indian Oil Corporation Multi-grease LL3 of Balmer Lawrie Note: Grease Servogem RR3 of Indian Oil Corporation and Multi-grease LL3 of
Balmer Lawrie are compatible to each other.o Quantity of lubricants recommended per axle box:
For topping up: About 0.027 to 0.045 kg. of specified grease is recommended for topping up after 6 months interval or covering 80,000 kms., whichever is earlier.
For re- /initial lubrication : About 2.71. kg. of specified grease is recommended for axle box to NEI drg. no.
92-4271C and X-115 applicable for WDM2, WDS5, WDS6, WDS8, WCG2, WAG5A, WAM4, WAM4A, WAM4B and WCAM1 locos.
About 2.3. kg. of specified grease is recommended for axle box to M/s FAG drg. no. 901-02-101 applicable for WDM2, WDS5, WDS6, WCG2, WAG5A, WAM4, WAM4A and WCAM1 locos.
About 1.75 kg. of specified grease is recommended for axle box to NEI drg. no. 92-4253 applicable for YDM4 and YDM4A locos. .
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12 PERIODIC ATTENTION AND SERVICE INSPECTIONS
Trip inspection
Recommendations Remarks
a) Visually examine the axle box for any damages from any striking objects or for any unusual condition.
-------
b) Check for missing or proper locking of cover studs/bolts and other parts.
-------
c) Investigate lubrication leakage at housing joints, etc.
Correct immediately even a slight leakage of grease observed at the front end of the box. However, a slight leakage of lubricant, if noticed at the rear end, it should be considered as normal.
d) Observe for any signs of over-heating on the outside portions of the box.
Do not allow running temperature more than 25º C (77º F) above ambient.
e) Look for loose, cracked or missing axle-box and pedestal liner.
Repair or replace missing liners.
f) Attend booked repairs, if any. --------
Half - yearly inspection (M-12) (12 months in case of electric locomotives to coincide with AOH Schedule):
a) Repeat items of trip inspection. --------
b) For checking of longitudinal and lateral clearances wear limits of axle box and pedestal liners, see bogie maintenance manual no. MP.MI. – 71/78 (latest revision)
Record figures in respective schedule forms.
c) Remove end cover of the axle boxes and examine visually the condition of the grease and
If grease is found discolored/disintegrated, then disassemble the axle box and
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locking arrangement of bearings. clean the bearing thoroughly according to instructions laid down in previous chapter. Examine the bearings with their elements minutely. Re-assembly, checking, re-lubrication should be done according to the instructions laid down in this manual.
d) Top up as required with specified grease to each axle box with pressure gun, if the condition of grease and bearing parts are satisfactory.
Use the same grease used in the box. Inject 27 to 45 grams. (30 to 50 cc) of recommended grease into the box through grease nipple without disturbing the bearing assembly.
e) Ultrasonic examination may be coincided with axle box greasing in M-12 schedule for convenience of the shed. The mandatory periodicity however remains 12 months only.
Yearly inspection (M-24) (24 months in case of electric locomotives to coincide with second AOH Schedule):
Where axle boxes are removed for wheel turnings or wheel changes, they have to be invariably overhauled.
The overhaul of axle-boxes can be done at the time of bogie/traction motor overhaul etc. Normally overhaul of axle boxes is not required earlier than three years. But at this stage it is recommended to overhaul the axle boxes every yearly schedule (24 months).a) Remove the axle box assembly from the bogie.b) Dismantle axle box assembly as indicated in chapter-3.c) Examine grease. If found discoloured, blackened or rust coloured, it may
be taken as evidence of wear or pitting rust. In such a case, the bearing should be examined carefully. If it does not show any discolouration, then clean thoroughly all bearing parts and axle box (complete) as indicated in chapter 4.
d) Look for evidence of possible defects or other imperfections, which might make the bearing unsafe for service. Examine all bearing parts for any of the following defects and scrap if such defects are discovered (use magnifying glasses where necessary).i) Severe smearing caused by abuse, etc.
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ii) Corrosive pitting caused by moisture or other corrosive agents.iii) Brinelling caused by vibrations, which result in depression or
grooves.i) Breaks or cracks.ii) Check for any indication of slipping or rotation of
thrower/labyrinth ring.iii) Pitting caused by electric currents.
e) Examine outer-races/rings as follows:-
Inspections Remarks
i) Look for evidence of rotation in the housing bore on the outer surfaces of the ring.
Remove the cause. It may be either due to excessive interference of the inner race/ring over the journal or defective bearing. Replace the bearing if rotation is severe.
ii) Examine roller paths (as far possible) carefully for any surface spalling or cracks or any other irregularities which will warrant removal from service.
This will minimise the danger of premature fatigue and / or spalling of the race load zone.
iii) Rotate the outer race/ring a quarter turn to bring into operation un-used part, mark the part quadrant number, date on which the said quadrant is brought into service by electric etching pencil on the side surface of the outer race/ring.
This will minimise the danger of premature fatigue and / or spalling of the race load zone.
f) Examine inner races/rings as follows:
i) Look for evidence of rubbing or turning on the journal.
The cause may be inadequate interference. If suspected, replace the bearing with under size bore bearing.
ii) Inspect roller path (load zone track) for spalling or any other defects.
There may be inadequate diametrical clearance. If suspected, replace the bearing
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iii) Look for the surface imperfection.
In case of any doubt, inner race/ring may be subjected to dye-penetration test. If found faulty, replace it.
g) Axle-box inspection and repairs :Remove excessively worn out manganese steel liners or which have cracked and replace them with new liners as outlined below :-i) Grind free at least two sides of the old liner welds, make free with
a steel chisel remaining welds.ii) Grind off remaining weld deposits, if any.iii) Apply new liners, make sure they fit flat.iv) Hold liners tight against box with clamps.v) Keep the box submerged in water except the area where welds are
to be done.vi) Do all welding in down-hand position.vii) Use approved low-Hydrogen welding electrode.viii) Follow the procedure for welding of manganese steel liners as laid
down in RDSO MP.MI.NO. 97/81.ix) No welding of liners should be done with bearing in position.x) Check the bore of the axle box housing and ensure that it is within
the permissible limits. If not, reject the axle box.h) Manganese steel liners:
For method of repair and precaution regarding Manganese steel liners, see RDSO MP.MI.-97/81.
For re-assembly of axle box for further service, follow procedure indicated in Chapter 6.
i) Precautions:i) Use of oxy-acetylene torch for removal of old liner plates from
axle box is not recommended to avoid possibility of distortion.ii) In the welding of manganese steel liners care must be taken in
order to prevent cracking, that is obtained from unfavorable weld metal dilution as well as heat build up.
iii) Factors within the control of the welder to reduce base metal heat build up are holding a short arc, short welding periods, lowest possible current and the use of the smallest diameter electrode consistent with the thickness of the section to be welded.
iv) The best ductility is retained in welding of the material (manganese), by keeping the work as cool as possible.
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v) Where there are number of boxes to be welded on, these shall be arranged in a row so that the same location can be welded on each box progressively. Then return to the first box and repeat in a different location on each box. In this way the boxes get maximum cooling time between welds.
vi) At no time shall the arc to be struck on the face of manganese liners. Arc-strikes on liners are potential crack starters and are known to cause base metal failure when highly stressed.
vii) No welding shall be done on liners to box until the preceding weld area is cooled to the touch of the hand.
viii) All welds shall be visually inspected.Six-yearly inspection or POH :
(a) Repeat items of yearly inspection.(b) Remove inner races/rings and thrower/labyrinth ring, (as per instructions
given in this manual) for visual inspection of their inner surfaces and for inspection of the axle journal surface, only if any cause for suspicion as to the proper fitment or functioning of the parts or defect is noticed. Proper fitment may be ascertained by individual’s experience on hearing the metallic sound of the mating surfaces between inner races/rings, thrower/labyrinth ring and axle journal.
It may be added that unnecessary withdrawal of bearing elements from their seatings causes deterioration of fitting surfaces and may damage the bearing races/rings too. Special care must be taken to ensure that the bearings and its components i.e. cage, rollers and races/rings are not damaged during dismantling operation.
(c) If inner races/rings and thrower/labyrinth ring are withdrawn from the journal, inspect them for fretting corrosion between inner race/ring and axle journal. Fretting reduces the solid contact between the inner race/ring and journal, causing the race/ring to loosen.
(d) Clean and examine the bearing seating on the axle, paying special attention to the shoulder for the thrower/labyrinth ring on the axle and all fillets. Ensure these dimensions are within the limits laid down. Scrap axles with any defect indications on the journal or journal fillets.
(e) Renew all sealing rings.(f) Check the rollers for any fretting or corrosion by rotating each roller.(g) Re-assemble axle box for further service if everything is in good
condition, as indicated in Chapter-6.(h) Mount only inner and outer races/rings with roller assemblies and insert
feeler gauge between the rolling elements and inner race/ring while lifting the outer race/ring to take its weight off the feeler gauge and see that the diametrical clearance between roller and races/rings(in free state) within the limits given in clause 5.3.d of chapter 5.
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General instructions and precautions:a) Keep a complete inspection record at the shed at all times using journal
box and axle serial number and box location on locos, as reference.b) While replacing new bearing or any new bearing parts from the original
packing, do not clean. Clean only when original packing are damaged or have become dirty.
c) Also do not remove any bearing parts from original packing until immediately before mounting.
d) When applying a used inner race/ring on a used axle journal, prefer to use an inner race/ring with little or no signs of fretting.
e) If journal is found under size, use under size bore inner race/ring.f) If races/rings are not immediately applied on journals that have passed
inspection, protect at all times against possible damage from water, dirt or other substances. This is applicable in the case of journal also.
g) If wheel and axle assemblies are not immediately applied to bogie, turn each axle box a few time every few days to prevent the parts from remaining in the same position for any appreciable length of time to prevent corrosion on contacting surfaces due to galvanic action and condensation due to atmospheric temperature changes.
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13 RUNNING INSTRUCTIONS AND INSPECTION OF BEARINGS OF LOCOS INVOLVED IN FIRE, FLOODS AND
ACCIDENTSRunning instructions:
When cleaning locomotives with the aid of steam, care should be taken to avoid spraying the axle boxes, which should be protected with covers of canvas or similar material.
In the event of any trouble developing in the axle box roller bearing when in service, in between terminals as indicated by noise, excessive heat at box or any abnormal condition, follow the procedure indicated bellow:a) Stop the loco, examine the axle box carefully.b) Move the loco, slowly under close observation to the next stopping, or to
the point where the loco can be conveniently set off for attentions, if the examination does not disclose any condition which makes it unsafe to run.
c) Stop the loco and intimate authorities concerned, if during this movement, excessive noise is present indicating any possible broken parts in the bearing or the wheels begin to slide, or the box does not cool down.
d) Consider as abnormal any running temperature 25ºC (77ºF) above ambient for operation.
e) Book any repairs or any abnormal condition observed in the run in the "Drivers booked repair card" giving the following particulars to receive closer attention at the next inspection points:i) Date of failure.ii) Details of operating sections, kilometerage where bearing has
failed or was found defective.iii) Train number and loco number.iv) Capacity and type of service.v) Loaded or empty.vi) Location of defective bearing on the loco.vii) Whether journal was hot.viii) Axle box serial number, if available.ix) Description of defects.
Locos involved in an accident:When locos with axle roller bearings are involved in a derailment or suspected or damaged from any such causes, the following procedure is recommended:a) Dis-assemble and inspect the bearings for any damages or other defects
before putting the loco back in to service.
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b) Check axle for bending by measuring inside distance on wheel flanges at four places 90º apart. A bent axle may cause premature bearing failure due to oscillation movement and uneven load distribution in the bearing, scrap all bend axles.
c) Inspect side frames also to see that they are not bent or distorted. Side frames, which are also bent or distorted, will cause undesirable loads on the bearing assembly, which can cause premature bearing failures.
d) Check spring sets for any evidence of cracks or breakage. If any crack/breakage found, replace the seat. Do not repair by welding or by any other method.
e) If it is found necessary to do electric welding any where on locos with axle roller bearings, the grounding cable must be clamped to near the part being welded to prevent any return current passing through the bearings.
Locos operating in floods:Do not operate locos equipped with axle roller bearings through water
except in emergency, when properly authorised to do. However, inspect for any accumulations of water in the journal, if suspected, mark the axle box for repacking of grease.
Locos involved in fire - hazards:a) Do not operate locos, which have been in fire. The heat might have
possibly done some injury to the bearing.b) Disassemble, clean, inspect and re-lubricate the bearings. Fire shows
appreciate discoloration of the surface of the parts, which would help to judge the suitability of the bearing for further service.
14 GENERAL INSTRUCTIONS REGARDING
CLEANLINESS, STORAGE AND HANDLING OF BEARINGCleanliness:
a) In all roller bearing work, the first and primary consideration is cleanliness. Therefore, the instructions listed here under should always be scrupulously observed.
b) Set apart a clean and dry area inside the shop for all roller bearing work. Protect the area by partition from wind blow, dirt, grit and moisture from adjacent areas, and allowing at the same time ample light at the workshop.
c) Work only with clean tools.d) Use clean wiping towels. Do not use waste or rags which will adhere to
the metal surfaces.e) Keep your hands clean while handling bearings.f) Work on clean benches covered with clean papers.
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g) Avoid contact of cleaning solvents, grease etc. with the skin as far as possible, as a possible precaution against skin trouble, such as dermatitis.
Storage and Handling:Extreme care must be exercised when storing and handling bearings and spare parts. The following is a list of suggestion, in general, which could be followed:
a) Store all bearings or bearing spares in dry and sheltered places. Dampness may ruin them in a short time.
b) Bearing should not preferably be stored in assembled condition.c) Except bronze cage, all bearing parts and all machined surfaces of axle box
and its parts should be kept greased to prevent rusting while in storage.d) Do not remove bearing parts from original packing until immediately before
assembly.e) Inspect occasionally parts in storage.f) Exercise care to prevent "finger-rust", on finished surfaces of bearings and
parts, while handling, due to moisture on the fingers.g) Do not allow bearings to lie around uncovered on bare floors where there
are accumulations of water, dust or dirt.h) Storage tracks for wheel mounted with roller bearing must be so arranged
that the wheel flanges of one pair of wheels can not strike the adjacent roller bearing box to avoid any damage.
15 REPLACEMENT OF BEARINGS PARTS AND
INTERCHANGEABILITY OF AXLE BOXESReplacement of bearing parts (individually) :
a) The inner races/rings, outer race/ring assemblies (with cages and roller),thrower/labyrinth ring and distance pieces etc. are inter-changeable within the same make.
b) If the journal is found under size, use the step size inner races/rings as shown in manufacturer’s drawing.
Interchangeability of axle boxes:Regarding interchangeability of NEI Roller bearing axle box to drg. no. 92-4271C with FAG roller bearing axle box to drg. no. 901-02-101, following guide-line should be followed:-a) FAG and NEI axle box assemblies are interchangeable in totality, not in
component level.
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b) No attempt should be made by the railways to intermix the components of one make with the others, as these components are not mutually interchangeable.
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16 TERMINOLOGY OF BEARING DEFECTS
Following is the list of bearing damages or defects and corrective actions:-
Sl. No.
Defect and condition Causes Corrective action
1. Rust and corrosion: Surface becomes partially or fully rusted. Sometimes rusted at spacing equal to distances between rolling elements.
Improper storage Improper packaging Insufficient rust preventative Invasion of moisture, acid etc. Handling with bare hands Bearing is stationary for long
period
Take measures to prevent rusting while in storage to eliminate the causes.
2. Fretting: Fretting surfaces wear producing red coloured particles that form hollows
Insufficient interference Insufficient lubrication Fluctuating load Vibration during transport or
when not operating conditions
Improve fit Check surface roughness of
journal and housing Check consistency of
grease Do not use worn out or
damaged housings3. Flaking: Flakes form
on the surfaces of the raceway and roller elements. When the flakes fall off, the surface becomes rough and uneven.
Excessive loads, fatigue life, improper handling
Improper mounting Insufficient precision of journal
and housing Insufficient clearance Contamination Rusting Passing of electric current
through bearing Softening due to abnormal
temperature rise
Find the cause of heavy load
Check internal clearance regularly
Improve precision of journal and housing
Improve operating conditions
Improve method of assembly and handling
Check grease and greasing method
4. Seizure: Bearing heats up, becomes discolored and eventually seizes up.
Insufficient clearance Insufficient grease Bad quality of grease Excessive load Rollers skewing
Check grease type and quantity
Check internal clearance regularly
Improve method of
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Softening due to abnormal temperature rise
assembly and handling
5. Cracking: splits and cracks in bearing rings and rollers.
Rapid heating during mounting Excessive shock load Improper handling, use of steel
hammer and impact of large foreign particles
Surface deformation due to improper lubrication
Excessive interference Large flaking Overheating by creeping
Avoid rapid heating of bearing during mounting
Reconsider operating condition
Improve method of assembly and handling
Prevention of creep Do not use excessively
worn-out or deformed housing
6. Rolling path skewing: Roller contact path in raceway surface strays of skews.
Deformation or tilt of bearing due to insufficient precision of journal or housing
Improper mounting Insufficient rigidity of journal
and housing
Re-check internal clearance
Re-check precision of journal and housing
Investigate rigidity of system
7. Smearing and scuffing: Surface becomes rough with small deposits.
Improper lubrication Invasion of foreign matter Roller skew due to excessive
misalignment Excessive surface roughness Excessive sliding of rolling
elements
Check the quality/quantity of grease
Improve sealing performance
Check operating conditions Improve method of
assembly and handling8. Indentations:
Hollows in raceway surface produced by solid foreign objects trapped or impacts (false brinelling)
Ingress of solid foreign objects Trapping of flaked particles Impacts due to careless
handling Due to impacts loads
Improve sealing performance
Improvement in handling and mounting practices
Check involved bearing for flaking if dents produced by metal practices
Always use clean grease9. Electrolytic
corrosion: Pits form on raceway and develop into ripples. Further development leads to corrugated surface.
Electric current flowing through raceway
Create a bypass for electric current
Insulate the bearing
10. Speckles and Foreign matter Use recommended good
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Discoloration: Surface luster disappears, and surface becomes matted and rough. Surface colour had changed. Surface becomes covered with tiny dents.
Improper lubrication Temper color by overheating Deposition of deteriorated
grease of surface
quality of grease Replacement of grease
after recommended interval
Improper sealing
11. Peeling: Peeling is a cluster of very small spalls. Peeling can also include very small cracks which develop into spalls.
Ingress of foreign matter Improper lubrication Foreign matter
Control of surface roughness and dust
Improve sealing performance
Use only recommended grease
12. Cage damage: Breaking or wear of cage.
Excessive moment load High-speed rotation or
excessive fluctuation of speed Trapping of foreign objects Excessive vibration Improper mounting
Investigate rigidity of system
Reconsider operating conditions
Improve method of assembly and handling
13. Spalling: Score accompanying seizing. Mounting score in axial direction. Scores on roller and face and guide rib-cyloidal scores. Scratches in spinning direction on raceway surface and rolling contact surfaces.
Poor mounting and removing practices
Oil film discontinuation on the contact surfaces due to excessive radial load
Foreign object trapping, or excessive pre-load
Slippage or poor lubrication rolling elements
Improvement in mounting and removing procedures
Improvement in operation conditions
Corrections of pre- load Selection of adequate
lubricant and lubrication system improvement of sealing efficiency
14. Wear: The surface becomes worn, resulting in dimension changes.
Foreign matter in the lubricant Insufficient lubrication Roller skew
Reconsider lubricant and lubrication method
Improve sealing performance
Prevent misalignment
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Wear is often accompanied by roughness and damage.
15. Chipping: Partial chipping of inner ring, outer ring, or rolling elements.
Trapping of large solid foreign objects
Impacts or excessive load Poor handling Extreme interference Material defective
Trouble shooting and improvements of impacts and excessive load
Improvement in handling Improvement in sealing
characteristics16. Creep: Surface
becomes mirror finished due to slipping of the inner and outer surfaces. Sometimes accompanied by discoloration or scuffing.
Insufficient interference of fitting parts
Insufficient sleeve tightening Abnormal temperature rise Excessive load
Reconsider interference Reconsider operating
conditions Recommended machining
precision or shaft and housing
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17 BEARING USED IN INDIAN RAILWAYS
(A)CYLINDRICAL ROLLER UNIT (CRU) FOR WDG3A, WDM3A & WDM3D LOCOMOTIVES
Introduction:
The existing design of cylindrical roller bearings being fitted in high speed diesel and electric locomotives are maintenance intensive requiring:
Frequent periodic attention of maintenance staff
Re-greasing every 6 months
Besides, since the current design does not have the rotating untouched volume sealed off, the whole bearing volume has to be greased at the aforesaid frequency requiring at least 500 gm of grease to be pumped in each axle box during re-greasing as observed in the maintenance sheds. The new design of sealed CRU roller bearings has the rolling volume sealed off through special metallic seals at both the bearing ends with very less radial gap between these seals and loose lip / lipped inner race mounted on the rotating axle. This feature along with a single outer race for two rows of rolling elements per axle box segregates the rotating volume into a completely sealed envelope. Thus, the excess loss of grease is prevented in service requiring a lesser re-greasing quantity (as discussed in the later part of this IB) compared to the conventional ones. Besides, this design feature also helps achieve lesser initial filling quantity of grease in CRUs as compared to the existing conventional bearings.
Also, unlike the conventional cylindrical roller bearings, the internal design of CRUs have lipped inboard inner race. This greatly reduces the possibility of thrower damage while negotiating the sharp curves.
The above merits of CRU bearings shall require lesser human interference in terms of enhancement of period between maintenance schedules and better performance reliability in the field. Thus, the locomotive down time on account of axle box bearing failures can be reduced.
Technical Details:
1. The CRU bearing is basically a double row cylindrical roller bearing and consisting of one Outer Ring, one Lipped Inner Ring, one Plain Inner Ring, 34 approx( nos). (17 Approx.( nos). x 2 Rows) Rollers, two Cages, one loose lip, two seals and 740 grms grease.
2. The CRU Bearing is a completely sealed unit and supplied to Indian Railways in pre-lubricated and ready to mount condition.
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3. Both inner rings and loose lip are held together in the sealed unit by a packing tube. Seals are fitted on both ends to keep the grease inside of this bearing and to prevent ingress of any dust, dirt and contaminants etc. into the bearing.
4. Bearing can withstand a static axle load of 21 tonnes (approximate unsprung axle weight of 1.0 ton) at a maximum speed of 150 Km/hr. It is calculated to reach or exceed under those given conditions the desired L10 life of more then 8.0 million kilometers.
5. CRU bearing are supplied with C4 (0.165 to 0.215 mm) of radial clearances. Loose lip of CRU bearings for end axle and middle axle are designed differently.
(B) CARTRIDGE TAPER ROLLER BARING (CTRB) 6 ½” X 12” CLASS ‘F’ BEARING FOR WDG4 & WDP4 LOCOMOTIVES
Introduction:
GM EMD locomotives fitted with CTRB 6 ½” X 12” Class ‘F’ bearing on the axle journal. This bearing is a self-contained, pre-assembled, pre-adjusted, pre-lubricated completely sealed unit and is applied to or removed from the axle without exposing the bearing elements, seals or lubricants to contamination or damage.
Technical Details:
1. The CTRB consisting of one double cup, two cone assemblies, one spacer, two seal wear rings, two grease seals and 680 gms grease.
2. A spaces with precision ground width is held between the two cone assemblies to achieve the proper axial clearance in an assembled bearing.
3. The CTRB is a completely sealed unit and supplied to Indian Railways in self-contained, pre-assembled, pre-adjusted, pre-lubricated and ready to mount condition.
4. Mounting and dismounting of CTRB to be done by the bearing Puller / Installer on the axle journal with the defined pressing pressure.
5. No need of grease topping up in the bearing in between the schedule maintenance of locomotives.
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18Bearing life Calculation
BEARING LIFE CALCULATION OF M/s BRECO's CTRB 6 1/2" X 12" CLASS 'F' BEARING FOR 5000 H.P. LOCOMOTIVE
Axle load of locomotives W 22.50 tones 220.73 NewtonUnsprung mass of wheel set Wo 1.60 tones 15.70 NewtonDynamic augment factor for CTRB brg. A 1.15Radial load on one bearing (W-Wo)/2 10.45 tones 102.51 NewtonEquivalent radial load on one bearing Fr = A*(W-W1)/2 12.02 tones 117.89 NewtonEquivalent thrust load on one bearing Fa = 0.20*Fr 2.40 tones 23.58 Newton
Fa/Fr 0.20e = 1.5 tan a 0.26 0.26Fa/Fr < eX = 1 1.00Y = 0.45 cot a 2.55 2.55
Equivalent combine load on bearing Pr = XFr + YFa 178.02 Newton
New wheel dia d11092.0
0 mm
Condeneming wheel dia d21016.0
0 mm
Mean wheel dia D = (d1+d2)/21054.0
0 mm
Distance traveled in one revolution pai * D3311.2
4 mm 0.00 Km.
Dynamic load rating of bearing Cr1053.0
2 Newton 273.00 K N
L10 life without any wheel flange contactL10a = (Cr/Fr)**10/3
1478.57 M Rev. 4.90 M Km
L10 life with wheel flange contactL10b = (Cr/Pr)**10/3 374.33 M Rev. 1.24 M Km
It is assumed that 20% of the time the wheel makes flange contact and 80% of the timewhen there is no flange contact.
Hence weighted average of L10 life 1/[.8/L10a+.2/L10b] 3.08 M Km
As per RDSO's specification no. MP.0.3600.01 required life is 2.56 M Km
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Speed of locomotives V 110.00 KmphMaximum R.P.M. of bearing for required S 553.67 R.P.M.Speed of locomotives
R.P.M. of bearing given by the manufacturer1000.0
0 R.P.M.
Axle journal diameter d mmBore dia of bearing 130 / 131.76 mm mm
Axle load of locomotives W 19.500 tones 191.295 NewtonUnsprung mass of wheel set Wo 1.600 tones 15.696 NewtonDynamic augment factor for CTRB brg. A 1.150Radial load on one bearing (W-Wo)/2 8.950 tones 87.800 NewtonEquivalent radial load on one bearing Fr = A*(W-W1)/2 10.293 tones 100.969 NewtonEquivalent thrust load on one bearing Fa = 0.20*Fr 2.059 tones 20.194 Newton
Fa/Fr 0.200e = 1.5 tan a 0.260 0.264Fa/Fr < eX = 1 1.000Y = 0.45 cot a 2.550 2.552
Equivalent combine load on bearing Pr = XFr + YFa 152.464 Newton
New wheel dia d1 1092.000 mmCondeneming wheel dia d2 1016.000 mmMean wheel dia D = (d1+d2)/2 1054.000 mmDistance traveled in one revolution pai * D 3311.239 mm 0.003 Km.
Dynamic load rating of bearing Cr 1047.000 Newton 1.047 K N
L10 life without any wheel flange contact L10a = (Cr/Fr)**10/3 2431.398 M Rev. 8.051 M Km
L10 life with wheel flange contact L10b = (Cr/Pr)**10/3 615.554 M Rev. 2.038 M Km
It is assumed that 20% of the time the wheel makes flange contact and 80% of the timewhen there is no flange contact.
Hence weighted average of L10 life 1/[.8/L10a+.2/L10b] 5.064 M Km
4.500 M Km
Speed of locomotives V 180.000 KmphMaximum R.P.M. of bearing for required S 906.005 R.P.M.Speed of locomotives
R.P.M. of bearing given by the manufacturer 1000.000 R.P.M.
Axle journal diameter D 157.264/ 157.239
mm
Bore dia of bearing d 157.175 (-0.025)
mm
BEARING LIFE CALCULATION OF M/s SKF's TBU 6 1/2" X 12" CLASS 'F' BEARING FOR WDP4 LOCOMOTIVE
As per RDSO's specification no. MP.0.3600.01 required life is
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