A STUDY OF CRANKSHAFT FAILURES ANALYSIS IN DIESEL LOCOMOTIVEA PROJECT REPORT

Submitted byR.KUMARESAN -95307114309S.SIRUMURUGAN-95307114318S.SIVASANKAR-95307114319in partial fulfillment for the award of the degreeof BACHELOR OF ENGINEERINGinMECHANICAL ENGINEERING

CAPE INSTITUTE OF TECHNOLOGY, LEVENGIPURAMANNA UNIVERSITY OF TECHNOLOGY: TIRUNELVELI APRIL 2011

ANNA UNIVERSITY OF TECHNOLOGY: TIRUNELVELIBONAFIDE CERTIFICATECertified that this project report A STUDY OF CRANKSHAFT FAILURES ANALYSIS IN DIESEL LOCOMOTIVE is the bonafide work of R.KUMARESAN, S.SIRUMURUGAN, S.SIVASANKAR who carried out the project work under my supervisor.

SIGNATURESIGNATUREPROF. M.S.RAGAVAN M.E.,ASS PROF. K.RAJKUMAR M.E.,HEAD OF THE DEPARTMENTSUPERVISOR

Dept of Mechanical EngineeringDept of Mechanical EngineeringCape Institute of TechnologyCape Institute of TechnologyLevengipuram-627114Levengipuram-627114

INTERNAL EXAMINEREXTERNAL EXAMINERSOUTHERN RAILWAY (CENTRAL WORKSHOP)THIRUCHIRAPPALI 620014. INDIA.

CERTIFICATEThis is to certify that the project work entitled A STUDY OF CRANKSHAFT FAILURES ANALYSIS IN DIESEL LOCOMOTIVE is the bonafide project work submitted by the following students in 2011 at SOUTHRN RAILWAY.Name Register NumberR.KUMARESAN -95307114309S.SIRUMURUGAN-95307114318S.SIVASANKAR-95307114319In partial fulfillment of the requirement for the award of degree of BACHELOR OF MECHANICAL ENGINEERING in CAPE INSTITUTE OF TECHNOLOGY(Affiliated to Anna University) is bonafide work done during the year 2011. Mr.B.RAJAMANI., PRINCIPAL.Date : BASIC TRAINING CENTRE.Place : Trichy SOUTHERN RAILWAY, TRICHY.

ACKNOWLEDGEMENTFirst and foremost, we would like to express our thanks to our beloved principal Dr.N.AZHAGESAN, M.E., Ph.D., and we would like to express our tanks to our Head of the Department Prof.M.S.RAGAVAN, M.E., and other staff members for undertaking this project and encourage for completing our project successfully.We would also like to express our thanks to our Ass Prof.K.RAJKUMAR, M.E., who guided us by providing the study materials, related to our project and helped us for completion of our project. We take the immerse pleasure in expressing Our hearty thanks to Mr.D.SHANMUGANATHAN IR SME (Chief Workshop Manager) for permitting us to this project work. I thank Mr.B.RAJAMANI (Principal/BTC) and Mr.B.GANESH (CI/BTC) for helping me to great extent in visiting the shop and getting enormous information about the workshop.I also take this opportunity to thank Mr.KASINATHA BOOBATHI (TRADE INSTRUMENTATION) coordinator of project work (BTC) helped me to a great extend in visiting the shops and gathering enormous information about the workshop. Finally we would express our sincere thanks to our technical advisor, Mr.CHANDRASEKAR, B.Com., We take this opportunity to thanks all teaching and non teaching staffs for their kind co-operation in completing our project. Last but not Least, we are grateful to everybody for encouraging and helping us to complete our project as a part of our academic course.

ABSTRACTIn basic PONMALAI RAILWAY YARD is the maintenance oriented company. So spare utilization can be decides organization efficiency. So reducing of spare failures can be increasing the organization efficiency. In our project analyzed failures of crankshaft in diesel locomotive. This project deals with the analysis about the various causes of failures of the Crankshaft of the diesel locomotive engine. It is found that the cost for the crankshaft is very high whereas the lifecycle is not satisfactory. The causes for the failure of the crankshaft and the possible ways of minimizing the failure effects were briefly studied from the past failure specimen. The load bearing capacity of the crankshaft is theoretically calculated and compared with the actual load acting on the crankshaft. The remedy for maximizing the lifecycle for the crankshaft was found and suggestions were made to reduce the frictional forces acting on the shaft. This prevents excessive wear and deformation of the crankshaft. Thus the lifecycle of the crankshaft is increased and the cost for the maintenance is reduced.

LIST OF CONTENTSCHPTER NOTITLES PAGE NO1. INTRODUCTION 10. SOUTHERN RAILWAY 10. GOLDEN ROCK PROFILE 21. DIESEL LOCOMOTIVE 31. DIESEL ENGINE 41. DIESEL ENGINE TYPES 51. PARTS OF DIESEL ELECTRIC LOCOMOTIVE 161. DETAILS ABOUT CRANKSHAFT 263. INTRODUCTION 273. MAINTENANCE & INSPECTION 293. CRANKSHAFT NOMENCLATURE 341. CRANKSHAFT DESIGN CONSIDERATIONS ANDPROPORTIONAL DIMENSIONS 354. CRANKSHAFT COUNTERBALANCE WEIGHTS 374. CRANKSHAFT MATERIALS 384. HEAT TREATMENT 414. CRANKSHAFT SERVICING 431. FAILURES OF CRANKSHAFT 485. FAILURES 495. CAUSES OF FAILURES 495. FAILURE MODE AND EFFECT ANALYSIS 505. TABULATION OF FAILURES AND CAUSES 515. REASONS OF BEARING SEIZURE 525. CAUSES OF CONNECTING ROD AND MAIN BEARING FAILURES 531. CONDEMNATIONS REPORT OF CRANKSHAFT 571. REMEDIES OF CRANKSHAFT FAILURES 607. REMEDIES OF ACTION 607. HOW TO MAINTAIN LOCOMOTIVE 611. HOW TO AVOID CRANKSHAFT FAILURES 638. SYMPTOMS OF FAILURES 641. CRNKSHAFT DRAWINGS 661. CONCLUSION 701. BIBILIOGRAPHY 72

SOUTHERN RAILWAY

The Southern Railway Company, which operated in England from 1923 to 1947. For the modern UK train operating company, see Southern (train operating company). For the US railroad merged into Norfolk Southern, see Southern Railway (U.S.).For other uses, see Southern Railway (disambiguation).The Southern Railway (SR) was a British railway company established in the 1923 Grouping. It linked London with the Channel ports, South West England, South coast resorts and Kent. The railway was formed by the amalgamation of several smaller railway companies, the largest of which were the London & South Western Railway (LSWR), the London, Brighton and South Coast Railway (LBSC) and the South Eastern and Chatham Railway (SECR). The construction of what was to become the Southern Railway began in 1838 with the opening of the London and Southampton Railway, which was renamed the London & South Western Railway.The railway was noted for its astute use of public relations and a coherent management structure headed by Sir Herbert Walker. At 2,186 miles (3,518km), the Southern Railway was the smallest of the "Big Four" railway companies and, unlike the others, the majority of its revenue came from passengers rather than freight. It created what was at that time the world's largest electrified railway system and the first electrified InterCity route (London--Brighton). There were two Chief Mechanical Engineers; Richard Maunsell between 1923 and 1937 and Oliver Bulleid from 1937 to 1948, both of whom designed new locomotives and rolling stock to replace much of that which was inherited in 1923. The Southern Railway played a vital role in the Second World War, embarking the British Expeditionary Force, during the Dunkirk operations, and supplying Operation Overlord in 1944; because the railway was primarily a passenger network, its success was an even more remarkable achievement.The Southern Railway operated a number of famous named trains, including the Brighton Belle, the Bournemouth Belle, the Golden Arrow and the Night Ferry (London - Paris and Brussels). The West Country services were dominated by lucrative summer holiday traffic and included named trains such as the Atlantic Coast Express and the Devon Belle. The company's best-known livery was highly distinctive: locomotives and carriages were painted in a bright Malachite green above plain black frames, with bold, bright yellow lettering. The Southern Railway was nationalised in 1948, becoming the Southern Region of British Railway.GOLDEN ROCK---A PROFILENamed after the PONMALAI situated in the rock city Tiruchirapalli, Tamilnadu, this workshop caters to the maintenance need of Indian Railways Rolling Stock.This workshop is well designed and constructed shop with mixed gauge track to carry out repairs to both MG and BG rolling stock. This workshop was accepted new challenges undertaking varied responsibilities and is known for its excellent quality of work. The workshop has a proud history and has even assisted Royal Air force in repairing Fighter Bombers during second world war.ARMOURY GATE PONMALAI (GOLDEN ROCK) WORKSHOPS:StatisticsYear Built:1926-1928Total Area:200 AcresArea Covered:26 AcresTrack Length:67KMSNo of Quarters:3807 Presently GOC shops is undertaking periodic over hauling of BG/MG Diesel locomotives, steam locomotives, x class locomotives, BG/MG coaches manufacturing of BOXNHS, BOXNHL, & BLC wagons.The Diesel LocomotiveThe modern diesel locomotive is a self contained version of the electric locomotive. Like the electric locomotive, it has electric drive, in the form of traction motors driving the axles and controlled with electronic controls. It also has many of the same auxiliary systems for cooling, lighting, heating, braking and hotel power (if required) for the train. It can operate over the same routes (usually) and can be operated by the same drivers. It differs principally in that it carries its own generating station around with it, instead of being connected to a remote generating station through overhead wires or a third rail. The generating station consists of a large diesel engine coupled to an alternator producing the necessary electricity. A fuel tank is also essential. It is interesting to note that the modern diesel locomotive produces about 35% of the power of a electric locomotive of similar weight. The UK Class 47 is typical of the general purpose diesel-electric locomotives introduced in the 1960s.New SD90MAC 6,000 hp heavy freight US diesel-electric locomotives with AC drive first built in 1998

The Diesel EngineThe diesel engine was first patented by Dr Rudolf Diesel (1858-1913) in Germany in 1892 and he actually got a successful engine working by 1897. By 1913, when he died, his engine was in use on locomotives and he had set up a facility with Sulzer in Switzerland to manufacture them. His death was mysterious in that he simply disappeared from a ship taking him to London. The diesel engine is a compression-ignition engine, as opposed to the petrol (or gasoline) engine, which is a spark-ignition engine. The spark ignition engine uses an electrical spark from a "spark plug" to ignite the fuel in the engine's cylinders, whereas the fuel in the diesel engine's cylinders is ignited by the heat caused by air being suddenly compressed in the cylinder. At this stage, the air gets compressed into an area 1/25th of its original volume. This would be expressed as a compression ratio of 25 to 1. A compression ratio of 16 to 1 will give an air pressure of 500 lbs/in (35.5 bar) and will increase the air temperature to over 800 F (427 C).The advantage of the diesel engine over the petrol engine is that it has a higher thermal capacity (it gets more work out of the fuel), the fuel is cheaper because it is less refined than petrol and it can do heavy work under extended periods of overload. It can however, in a high speed form, be sensitive to maintenance and noisy, which is why it is still not popular for passenger automobiles.Diesel Engine TypesThere are two types of diesel engine, the two-stroke engine and the four-stroke engine. As the names suggest, they differ in the number of movements of the piston required to complete each cycle of operation. The simplest is the two-stroke engine. It has no valves. The exhaust from the combustion and the air for the new stroke is drawn in through openings in the cylinder wall as the piston reaches the bottom of the down stroke. Compression and combustion occurs on the upstroke. As one might guess, there are twice as many revolutions for the two-stroke engine as for equivalent power in a four-stroke engine.The four-stroke engine works as follows: Down stroke 1 - air intake, upstroke 1 - compression, down stroke 2 - power, upstroke 2 - exhaust. Valves are required for air intake and exhaust, usually two for each. In this respect it is more similar to the modern petrol engine than the 2-stroke design. In the UK, both types of diesel engine were used but the 4-stroke became the standard. The UK Class 55 "Deltic" (not now in regular main line service) has a two-stroke engine. In the US, the General Electric (GE) built locomotives have 4-stroke engines whereas General Motors (GM) always used 2-stroke engines until the introduction of their SD90MAC 6000 hp "H series" engine, which is a 4-stroke design. The reason for using one type or the other is really a question of preference. However, it can be said that the 2-stroke design is simpler than the 4-stroke but the 4-stroke engine is more fuel efficient.Size Does CountBasically, the more power you need, the bigger the engine has to be. Early diesel engines were less than 100 horse power (hp) but today the US is building 6000 hp locomotives. For a UK locomotive of 3,300 hp (Class 58), each cylinder will produce about 200 hp, and a modern engine can double this if the engine is turbocharged. The maximum rotational speed of the engine when producing full power will be about 1000 rpm (revolutions per minute) and the engine will idle at about 400 rpm. These relatively low speeds mean that the engine design is heavy, as opposed to a high speed, lightweight engine. However, the UK HST (High Speed Train, developed in the 1970s) engine has a speed of 1,500 rpm and this is regarded as high speed in the railway diesel engine category. The slow, heavy engine used in railway locomotives will give low maintenance requirements and an extended life.There is a limit to the size of the engine which can be accommodated within the railway loading gauge, so the power of a single locomotive is limited. Where additional power is required, it has become usual to add locomotives. In the US, where freight trains run into tens of thousands of tons weight, four locomotives at the head of a train are common and several additional ones in the middle or at the end are not unusual.To V or not to VDiesel engines can be designed with the cylinders "in-line", "double banked" or in a "V". The double banked engine has two rows of cylinders in line. Most diesel locomotives now have V form engines. This means that the cylinders are split into two sets, with half forming one side of the V. A V8 engine has 4 cylinders set at an angle forming one side of the V with the other set of four forming the other side. The crankshaft, providing the drive, is at the base of the V. The V12 was a popular design used in the UK. In the US, V16 is usual for freight locomotives and there are some designs with V20 engines. Engines used for DMU (diesel multiple unit) trains in the UK are often mounted under the floor of the passenger cars. This restricts the design to in-line engines, which have to be mounted on their side to fit in the restricted space.An unusual engine design was the UK 3,300 hp Class 55 locomotive, which had the cylinders arranged in three sets of opposed Vs in an triangle, in the form of an upturned delta, hence the name "Deltic".Tractive Effort, Pull and PowerBefore going too much further, we need to understand the definitions of tractive effort, drawbar pull and power. The definition of tractive effort (TE) is simply the force exerted at the wheel rim of the locomotive and is usually expressed in pounds (lbs) or kilo Newtons (kN). By the time the tractive effort is transmitted to the coupling between the locomotive and the train, the drawbar pull, as it is called will have reduced because of the friction of the mechanical parts of the drive and some wind resistance. Power is expressed as horsepower (hp) or kilo Watts (kW) and is actually a rate of doing work. A unit of horsepower is defined as the work involved by a horse lifting 33,000 lbs one foot in one minute. In the metric system it is calculated as the power (Watts) needed when one Newton of force is moved one metre in one second. The formula is P = (F*d)/t where P is power, F is force, d is distance and t is time. One horsepower equals 746 Watts.The relationship between power and drawbar pull is that a low speed and a high drawbar pull can produce the same power as high speed and low drawbar pull. If you need to increase higher tractive effort and high speed, you need to increase the power. To get the variations needed by a locomotive to operate on the railway, you need to have a suitable means of transmission between the diesel engine and the wheels.One thing worth remembering is that the power produced by the diesel engine is not all available for traction. In a 2,580 hp diesel electric locomotive, some 450 hp is lost to on-board equipment like blowers, radiator fans, air compressors and "hotel power" for the train.StartingA diesel engine is started (like an automobile) by turning over the crankshaft until the cylinders "fire" or begin combustion. The starting can be done electrically or pneumatically. Pneumatic starting was used for some engines. Compressed air was pumped into the cylinders of the engine until it gained sufficient speed to allow ignition, then fuel was applied to fire the engine. The compressed air was supplied by a small auxiliary engine or by high pressure air cylinders carried by the locomotive.Electric starting is now standard. It works the same way as for an automobile, with batteries providing the power to turn a starter motor which turns over the main engine. In older locomotives fitted with DC generators instead of AC alternators, the generator was used as a starter motor by applying battery power to it. Governor

Once a diesel engine is running, the engine speed is monitored and controlled through a governor. The governor ensures that the engine speed stays high enough to idle at the right speed and that the engine speed will not rise too high when full power is demanded. The governor is a simple mechanical device which first appeared on steam engines. It operates on a diesel engine as shown in the diagram below.The governor consists of a rotating shaft, which is driven by the diesel engine. A pair of flyweights are linked to the shaft and they rotate as it rotates. The centrifugal force caused by the rotation causes the weights to be thrown outwards as the speed of the shaft rises. If the speed falls the weights move inwards.

The flyweights are linked to a collar fitted around the shaft by a pair of arms. As the weights move out, so the collar rises on the shaft. If the weights move inwards, the collar moves down the shaft. The movement of the collar is used to operate the fuel rack lever controlling the amount of fuel supplied to the engine by the injectors.Fuel InjectionIgnition is a diesel engine is achieved by compressing air inside a cylinder until it gets very hot (say 400 C, almost 800 F) and then injecting a fine spray of fuel oil to cause a miniature explosion. The explosion forces down the piston in the cylinder and this turns the crankshaft. To get the fine spray needed for successful ignition the fuel has to be pumped into the cylinder at high pressure. The fuel pump is operated by a cam driven off the engine. The fuel is pumped into an injector, which gives the fine spray of fuel required in the cylinder for combustion.Fuel ControlIn an automobile engine, the power is controlled by the amount of fuel/air mixture applied to the cylinder. The mixture is mixed outside the cylinder and then applied by a throttle valve. In a diesel engine the amount of air applied to the cylinder is constant so power is regulated by varying the fuel input. The fine spray of fuel injected into each cylinder has to be regulated to achieve the amount of power required. Regulation is achieved by varying the fuel sent by the fuel pumps to the injectors. The control arrangement is shown in the diagram left.

The amount of fuel being applied to the cylinders is varied by altering the effective delivery rate of the piston in the injector pumps. Each injector has its own pump, operated by an engine-driven cam, and the pumps are aligned in a row so that they can all be adjusted together. The adjustment is done by a toothed rack (called the "fuel rack") acting on a toothed section of the pump mechanism. As the fuel rack moves, so the toothed section of the pump rotates and provides a drive to move the pump piston round inside the pump. Moving the piston round, alters the size of the channel available inside the pump for fuel to pass through to the injector delivery pipe.The fuel rack can be moved either by the driver operating the power controller in the cab or by the governor. If the driver asks for more power, the control rod moves the fuel rack to set the pump pistons to allow more fuel to the injectors. The engine will increase power and the governor will monitor engine speed to ensure it does not go above the predetermined limit. The limits are fixed by springs (not shown) limiting the weight movement.Engine Control DevelopmentSo far we have seen a simple example of diesel engine control but the systems used by most locomotives in service today are more sophisticated. To begin with, the drivers control was combined with the governor and hydraulic control was introduced. One type of governor uses oil to control the fuel racks hydraulically and another uses the fuel oil pumped by a gear pump driven by the engine. Some governors are also linked to the turbo charging system to ensure that fuel does not increase before enough turbocharged air is available. In the most modern systems, the governor is electronic and is part of a complete engine management system.Power ControlThe diesel engine in a diesel-electric locomotive provides the drive for the main alternator which, in turn, provides the power required for the traction motors. We can see from this therefore, that the power required from the diesel engine is related to the power required by the motors. So, if we want more power from the motors, we must get more current from the alternator so the engine needs to run faster to generate it. Therefore, to get the optimum performance from the locomotive, we must link the control of the diesel engine to the power demands being made on the alternator.In the days of generators, a complex electro-mechanical system was developed to achieve the feedback required to regulate engine speed according to generator demand. The core of the system was a load regulator, basically a variable resistor which was used to very the excitation of the generator so that its output matched engine speed. The control sequence (simplified) was as follows:1. Driver moves the power controller to the full power position2. An air operated piston actuated by the controller moves a lever, which closes a switch to supply a low voltage to the load regulator motor.3. The load regulator motor moves the variable resistor to increase the main generator field strength and therefore its output.4. The load on the engine increases so its speed falls and the governor detects the reduced speed.5. The governor weights drop and cause the fuel rack servo system to actuate.6. The fuel rack moves to increase the fuel supplied to the injectors and therefore the power from the engine.7. The lever (mentioned in 2 above) is used to reduce the pressure of the governor spring.8. When the engine has responded to the new control and governor settings, it and the generator will be producing more power.On locomotives with an alternator, the load regulation is done electronically. Engine speed is measured like modern speedometers, by counting the frequency of the gear teeth driven by the engine, in this case, the starter motor gearwheel. Electrical control of the fuel injection is another improvement now adopted for modern engines. Overheating can be controlled by electronic monitoring of coolant temperature and regulating the engine power accordingly. Oil pressure can be monitored and used to regulate the engine power in a similar way.CoolingLike an automobile engine, the diesel engine needs to work at an optimum temperature for best efficiency. When it starts, it is too cold and, when working, it must not be allowed to get too hot. To keep the temperature stable, a cooling system is provided. This consists of a water-based coolant circulating around the engine block, the coolant being kept cool by passing it through a radiator. The coolant is pumped round the cylinder block and the radiator by an electrically or belt driven pump. The temperature is monitored by a thermostat and this regulates the speed of the (electric or hydraulic) radiator fan motor to adjust the cooling rate. When starting the coolant isn't circulated at all. After all, you want the temperature to rise as fast as possible when starting on a cold morning and this will not happen if you a blowing cold air into your radiator. Some radiators are provided with shutters to help regulate the temperature in cold conditions.If the fan is driven by a belt or mechanical link, it is driven through a fluid coupling to ensure that no damage is caused by sudden changes in engine speed. The fan works the same way as in an automobile, the air blown by the fan being used to cool the water in the radiator. Some engines have fans with an electrically or hydrostatically driven motor. An hydraulic motor uses oil under pressure which has to be contained in a special reservoir and pumped to the motor. It has the advantage of providing an in-built fluid coupling.A problem with engine cooling is cold weather. Water freezes at 0 C or 32 F and frozen cooling water will quickly split a pipe or engine block due to the expansion of the water as it freezes. Some systems are "self draining" when the engine is stopped and most in Europe are designed to use a mixture of anti-freeze, with Gycol and some form of rust inhibitor. In the US, engines do not normally contain anti-freeze, although the new GM EMD "H" engines are designed to use it. Problems with leaks and seals and the expense of putting a 100 gallons (378.5 liters) of coolant into a 3,000 hp engine, means that engines in the US have traditionally operated without it. In cold weather, the engine is left running or the locomotive is kept warm by putting it into a heated building or by plugging in a shore supply. Another reason for keeping diesel engines running is that the constant heating and cooling caused by shutdowns and restarts, causes stresses in the block and pipes and tends to produce leaks.LubricationLike an automobile engine, a diesel engine needs lubrication. In an arrangement similar to the engine cooling system, lubricating oil is distributed around the engine to the cylinders, crankshaft and other moving parts. There is a reservoir of oil, usually carried in the sump, which has to be kept topped up, and a pump to keep the oil circulating evenly around the engine. The oil gets heated by its passage around the engine and has to be kept cool, so it is passed through a radiator during its journey. The radiator is sometimes designed as a heat exchanger, where the oil passes through pipes encased in a water tank which is connected to the engine cooling system. The oil has to be filtered to remove impurities and it has to be monitored for low pressure. If oil pressure falls to a level which could cause the engine to seize up, a "low oil pressure switch" will shut down the engine. There is also a high pressure relief valve, to drain off excess oil back to the sump.TransmissionsLike an automobile, a diesel locomotive cannot start itself directly from a stand. It will not develop maximum power at idling speed, so it needs some form of transmission system to multiply torque when starting. It will also be necessary to vary the power applied according to the train weight or the line gradient. There are three methods of doing this: mechanical, hydraulic or electric. Most diesel locomotives use electric transmission and are called "diesel-electric" locomotives. Mechanical and hydraulic transmissions are still used but are more common on multiple unit trains or lighter locomotives. Diesel-Electric TypesDiesel-electric locomotives come in three varieties, according to the period in which they were designed. These three are:DC - DC (DC generator supplying DC traction motors);AC - DC (AC alternator output rectified to supply DC motors) and AC - DC - AC (AC alternator output rectified to DC and then inverted to 3-phase AC for the traction motors).The DC - DC type has a generator supplying the DC traction motors through a resistance control system, the AC - DC type has an alternator producing AC current which is rectified to DC and then supplied to the DC traction motors and, finally, the most modern has the AC alternator output being rectified to DC and then converted to AC (3-phase) so that it can power the 3-phase AC traction motors. Although this last system might seem the most complex, the gains from using AC motors far outweigh the apparent complexity of the system. In reality, most of the equipment uses solid state power electronics with microprocessor-based controls. For more details on AC and DC traction, see the Electronic Power Page on this site.In the US, traction alternators (AC) were introduced with the 3000 hp single diesel engine locomotives, the first being the Alco C630. The SD40, SD45 and GP40 also had traction alternators only. On the GP38, SD38, GP39, and SD39s, traction generators (DC) were standard, and traction alternators were optional, until the dash-2 era, when they became standard. It was a similar story at General Electric.There is one traction alternator (or generator) per diesel engine in a locomotive (standard North American practice anyway). The Alco C628 was the last locomotive to lead the horsepower race with a DC traction alternator. I have used the US example because of the large number of countries which use them. There are obviously many variations in layout and European practice differs in many ways and we will note some of these in passing. PARTS OF A DIESEL-ELECTRIC LOCOMOTIVEDiesel EngineThis is the main power source for the locomotive. It comprises a large cylinder block, with the cylinders arranged in a straight line or in a V. The engine rotates the drive shaft at up to 1,000 rpm and this drives the various items needed to power the locomotive. As the transmission is electric, the engine is used as the power source for the electricity generator or alternator, as it is called nowadays.Main AlternatorThe diesel engine drives the main alternator which provides the power to move the train. The alternator generates AC electricity which is used to provide power for the traction motors mounted on the trucks (bogies). In older locomotives, the alternator was a DC machine, called a generator. It produced direct current which was used to provide power for DC traction motors. Many of these machines are still in regular use. The next development was the replacement of the generator by the alternator but still using DC traction motors. The AC output is rectified to give the DC required for the motors. Auxiliary AlternatorLocomotives used to operate passenger trains are equipped with an auxiliary alternator. This provides AC power for lighting, heating, air conditioning, dining facilities etc. on the train. The output is transmitted along the train through an auxiliary power line. In the US, it is known as "head end power" or "hotel power". In the UK, air conditioned passenger coaches get what is called electric train supply (ETS) from the auxiliary alternator. Motor BlowerThe diesel engine also drives a motor blower. As its name suggests, the motor blower provides air which is blown over the traction motors to keep them cool during periods of heavy work. The blower is mounted inside the locomotive body but the motors are on the trucks, so the blower output is connected to each of the motors through flexible ducting. The blower output also cools the alternators. Some designs have separate blowers for the group of motors on each truck and others for the alternators. Whatever the arrangement, a modern locomotive has a complex air management system which monitors the temperature of the various rotating machines in the locomotive and adjusts the flow of air accordingly.Air IntakesThe air for cooling the locomotive's motors is drawn in from outside the locomotive. It has to be filtered to remove dust and other impurities and its flow regulated by temperature, both inside and outside the locomotive. The air management system has to take account of the wide range of temperatures from the possible +40 C of summer to the possible -40 C of winter.Rectifiers/InvertersThe output from the main alternator is AC but it can be used in a locomotive with either DC or AC traction motors. DC motors were the traditional type used for many years but, in the last 10 years, AC motors have become standard for new locomotives. They are cheaper to build and cost less to maintain and, with electronic management can be very finely controlled.To convert the AC output from the main alternator to DC, rectifiers are required. If the motors are DC, the output from the rectifiers is used directly. If the motors are AC, the DC output from the rectifiers is converted to 3-phase AC for the traction motors. In the US, there are some variations in how the inverters are configured. GM EMD relies on one inverter per truck, while GE uses one inverter per axle - both systems have their merits. EMD's system links the axles within each truck in parallel, ensuring wheel slip control is maximized among the axles equally. Parallel control also means even wheel wear even between axles. However, if one inverter (i.e. one truck) fails then the unit is only able to produce 50 per cent of its tractive effort. One inverter per axle is more complicated, but the GE view is that individual axle control can provide the best tractive effort. If an inverter fails, the tractive effort for that axle is lost, but full tractive effort is still available through the other five inverters. By controlling each axle individually, keeping wheel diameters closely matched for optimum performance is no longer necessary. Electronic ControlsAlmost every part of the modern locomotive's equipment has some form of electronic control. These are usually collected in a control cubicle near the cab for easy access. The controls will usually include a maintenance management system of some sort which can be used to download data to a portable or hand-held computer.

Control stand This is the principal man-machine interface, known as a control desk in the UK or control stand in the US. The common US type of stand is positioned at an angle on the left side of the driving position and, it is said, is much preferred by drivers to the modern desk type of control layout usual in Europe and now being offered on some locomotives in the US.BatteriesJust like an automobile, the diesel engine needs a battery to start it and to provide electrical power for lights and controls when the engine is switched off and the alternator is not running.CabMost US diesel locomotives have only one cab but the practice in Europe is two cabs. US freight locos are also designed with narrow engine compartments and walkways along either side. This gives a reasonable forward view if the locomotive is working "hood forwards". US passenger locos, on the other hand have full width bodies and more streamlined ends but still usually with one cab. In Europe, it is difficult to tell the difference between a freight and passenger locomotive because the designs are almost all wide bodied and their use is often mixed.Traction MotorSince the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to give the final drive. These motors were traditionally DC but the development of modern power and control electronics has led to the introduction of 3-phase AC motors.There are between four and six motors on most diesel-electric locomotives. A modern AC motor with air blowing can provide up to 1,000 hp.Pinion/GearThe traction motor drives the axle through a reduction gear of a range between 3 to 1 (freight) and 4 to 1 (passenger).Fuel TankA diesel locomotive has to carry its own fuel around with it and there has to be enough for a reasonable length of trip. The fuel tank is normally under the loco frame and will have a capacity of say 1,000 imperial gallons (UK Class 59, 3,000 hp) or 5,000 US gallons in a General Electric AC4400CW 4,400 hp locomotive. The new AC6000s have 5,500 gallon tanks. In addition to fuel, the locomotive will carry around, typically about 300 US gallons of cooling water and 250 gallons of lubricating oil for the diesel engine.Air reservoirs are also required for the train braking and some other systems on the locomotive. These are often mounted next to the fuel tank under the floor of the locomotive.Air CompressorThe air compressor is required to provide a constant supply of compressed air for the locomotive and train brakes. In the US, it is standard practice to drive the compressor off the diesel engine drive shaft. In the UK, the compressor is usually electrically driven and can therefore be mounted anywhere. The Class 60 compressor is under the frame, whereas the Class 37 has the compressors in the nose.

Drive ShaftThe main output from the diesel engine is transmitted by the drive shaft to the alternators at one end and the radiator fans and compressor at the other end. Gear BoxThe radiator and its cooling fan is often located in the roof of the locomotive. Drive to the fan is therefore through a gearbox to change the direction of the drive upwards.Radiator and Radiator FanThe radiator works the same way as in an automobile. Water is distributed around the engine block to keep the temperature within the most efficient range for the engine. The water is cooled by passing it through a radiator blown by a fan driven by the diesel engine. Turbo ChargingThe amount of power obtained from a cylinder in a diesel engine depends on how much fuel can be burnt in it. The amount of fuel which can be burnt depends on the amount of air available in the cylinder. So, if you can get more air into the cylinder, more fuel will be burnt and you will get more power out of your ignition. Turbo charging is used to increase the amount of air pushed into each cylinder. The turbocharger is driven by exhaust gas from the engine. This gas drives a fan which, in turn, drives a small compressor which pushes the additional air into the cylinder. Turbo charging gives a 50% increase in engine power.The main advantage of the turbocharger is that it gives more power with no increase in fuel costs because it uses exhaust gas as drive power. It does need additional maintenance, however, so there are some type of lower power locomotives which are built without it.Sand BoxLocomotives always carry sand to assist adhesion in bad rail conditions. Sand is not often provided on multiple unit trains because the adhesion requirements are lower and there are normally more driven axles.Truck FrameThis is the part (called the bogie in the UK) carrying the wheels and traction motors of the locomotive. Mechanical TransmissionA diesel-mechanical locomotive is the simplest type of diesel locomotive. As the name suggests, a mechanical transmission on a diesel locomotive consists a direct mechanical link between the diesel engine and the wheels. In the example below, the diesel engine is in the 350-500 hp range and the transmission is similar to that of an automobile with a four speed gearbox. Most of the parts are similar to the diesel-electric locomotive but there are some variations in design mentioned below.Fluid CouplingIn a diesel-mechanical transmission, the main drive shaft is coupled to the engine by a fluid coupling. This is a hydraulic clutch, consisting of a case filled with oil, a rotating disc with curved blades driven by the engine and another connected to the road wheels. As the engine turns the fan, the oil is driven by one disc towards the other. This turns under the force of the oil and thus turns the drive shaft. Of course, the start up is gradual until the fan speed is almost matched by the blades. The whole system acts like an automatic clutch to allow a graduated start for the locomotive.

GearboxThis does the same job as that on an automobile. It varies the gear ratio between the engine and the road wheels so that the appropriate level of power can be applied to the wheels. Gear change is manual. There is no need for a separate clutch because the functions of a clutch are already provided in the fluid coupling. Final DriveThe diesel-mechanical locomotive uses a final drive similar to that of a steam engine. The wheels are coupled to each other to provide more adhesion. The output from the 4-speed gearbox is coupled to a final drive and reversing gearbox which is provided with a transverse drive shaft and balance weights. This is connected to the driving wheels by connecting rods.Hydraulic TransmissionHydraulic transmission works on the same principal as the fluid coupling but it allows a wider range of "slip" between the engine and wheels. It is known as a "torque converter". When the train speed has increased sufficiently to match the engine speed, the fluid is drained out of the torque converter so that the engine is virtually coupled directly to the locomotive wheels. It is virtually direct because the coupling is usually a fluid coupling, to give some "slip". Higher speed locomotives use two or three torque converters in a sequence similar to gear changing in a mechanical transmission and some have used a combination of torque converters and gears. Some designs of diesel-hydraulic locomotives had two diesel engines and two transmission systems, one for each bogie. The design was poplar in Germany (the V200 series of locomotives, for example) in the 1950s and was imported into parts of the UK in the 1960s. However, it did not work well in heavy or express locomotive designs and has largely been replaced by diesel-electric transmission.Wheel SlipWheels slip is the bane of the driver trying to get a train away smoothly. The tenuous contact between steel wheel and steel rail is one of the weakest parts of the railway system. Traditionally, the only cure has been a combination of the skill of the driver and the selective use of sand to improve the adhesion. Today, modern electronic control has produced a very effective answer to this age old problem. The system is called creep control.Extensive research into wheel slip showed that, even after a wheel set starts to slip, there is still a considerable amount of useable adhesion available for traction. The adhesion is available up to a peak, when it will rapidly fall away to an uncontrolled spin. Monitoring the early stages of slip can be used to adjust the power being applied to the wheels so that the adhesion is kept within the limits of the "creep" towards the peak level before the uncontrolled spin sets in.The slip is measured by detecting the locomotive speed by Doppler radar (instead of the usual method using the rotating wheels) and comparing it to the motor current to see if the wheel rotation matches the ground speed. If there is a disparity between the two, the motor current is adjusted to keep the slip within the "creep" range and keep the tractive effort at the maximum level possible under the creep conditions. Diesel Multiple Units (DMUs)The diesel engines used in DMUs work on exactly the same principles as those used in locomotives, except that the transmission is normally mechanical with some form of gear change system. DMU engines are smaller and several are used on a train, depending on the configuration. The diesel engine is often mounted under the car floor and on its side because of the restricted space available. Vibration being transmitted into the passenger saloon has always been a problem but some of the newer designs are very good in this respect.There are some diesel-electric DMUs around and these normally have a separate engine compartment containing the engine and the generator or alternator. These weights ensure an even (balance) force during the rotation of the moving parts.

DETAILS ABOUT CRANKSHAFT

INTRODUCTIN ABOUT CRANKSHAFTThis unit contains, in brief, the essential details in respect of design, construction, working principle and maintenance procedure of the Diesel Engine components. The discussion has been kept confined to standard locomotives of Indian Railways that is WDM2.The Diesel engines consists of following major components & assemblies: -

1.Engine base2.Engine block3.Crank shaft4.Cam shaft

5.Cylinder head and Valves6. Liner7.Piston, Piston rings and Connecting rods.

CRANKSHAFT

The engine crankshaft is probably the singular costliest item in the diesel engine. It is the medium of transforming reciprocating motion to rotary motion. The crankshaft may be assembled type or two pieces bolted type or may be single piece forging. Balance weights can be either bolted up or welded. The standard Locomotives of Indian Railways are with single-piece crankshaft with welded counter weights. In case of CLW/MAK engines the counter weights are bolted.The ALCO crankshafts are manufactured from chrome-molybdenum steel equivalent to SAE 4140. The process of forging is such that continuous grain is maintained. In manufacture of crankshaft, following sequence of operation is generally followed: - a) Forging and forming operation b) Rough machining c) Drill of oil holes. d) Ultrasonic & Mechanical testing e) Welding of counter weights & their X-ray test. f) Stress relieving & shot blasting g) Final machining & for giving fillet radius at crank journal corners and making oil holes. h) Nitriding i) Grinding Lapping j) Static & dynamic balancing k) Final inspection There are two processes of surface hardening with details given below:- Method of hardening Hardness Depth of hardness

Induction hardening C-40 0.124"

Nitriding C-60 0.012 to 0.015"

Generally for low HP engines the first process is preferred, as depth of case is more and the crank journals and man bearing journals can be ground down to next step size. In case of high HP and high-speed engines, the preference is for the second process as it gives long life, the rate of wear being negligible. Maintenance & Inspection After cleaning thoroughly, Dye penetration / Magnaflux test is conducted to detect surface crack. Measure the following dimensions:Crank pin: Positioning it vertically check dimension at two locations just beside two oil holes (at two right angular planes in each location) to check ovality and taperness.Nominal Dia: 6", Limit upto 5.996"Ovality: .002"(max) Taperness: .001"(max)Main journal: Position the crankshaft, keeping No 1 crankpin in vertical location, measure the dimension as that of crank pin.Nominal Dia: 8.5", Limit upto 8.496"Ovality: 002" (max) Taperness: .001" (max)Fillet Radius: Checked through a special gadget. (.0005" filler gauge should not pass between the gadget and the fillet)Eccentricity checking: Eccentricity is checked between any three consecutive main journals (1,2,3) is given by the distance between the center points of journal 2 and the mid point of the line joining the center points of journals 1 & 3. The limit of eccentricity is .001". Eccentricity is checked by the following way: Place the crankshaft horizontally on a "V" block supported at No3 and No 7 Main Journals, keeping No 1 crank pin in vertical position. Mark Dial of a clock at the free end flange in this position, to understand angular location of the maximum deviated zone. Record the readings of maximum deviation of every main journal along with their angular location.An example of calculating the eccentricity (For No 1,2,3 Main Journals) is given below: Highest total indicator reading (TIR) for:No 1 M.J.0.0015" at 3 o'clock location.No 2 M.J. 0.004" at twelve o'clockNo 3 M.J. 0.0015 at 1-30 o'clock Plot the graph according to deflection and o'clock location, with suitable scale. Connect TIR position of No1 and No3 with a straight line. Mark the midpoint of the above straight line and connect it with the TIR of No 2. This is the relative runout of No 1,2,and 3 main journals. Divide the runout by 2. This is the eccentricity and must not exceed .001". (This case it is .00175" and not acceptable.)Repeat the above case for each group of three consecutive main journals

12 0'CLOCK 2.0035 TIR

3 13 O'CLOCK

Crank web deflection: Checking of crank web deflection is one of the major works while assembling engine.Main generator is coupled at one end of the crankshaft, whose other end is supported on a bearing housed at the magnet frame. As such, due to mislocation of magnet frame, if axis of armature does not completely align with the axis of the crankshaft, the unbalanced mass of armature will cause uneven loading on crank web at different angular positions during rotation. This causes deflection on crank web, which will be changing at various positions of crankshaft during rotation. Such kind of continuous cyclic variation of load leads to main bearing seizure and breakage of crankshaft.The crank web deflection can be measured by fitting a deflection gauge at the located punch mark on the 8th crank web, nearer to TG and rotating the crankshaft in both the directions The permissible limit of deflection on each side is . 0008", TIR . 0016".Correction is made by adding or subtracting shims at the mountings of magnet frame with engine block. The magnet frame is mounted at two locations with the engine block and at two locations at the base. Adjustable shims are provided at the mountings of the magnet frame with the block. The shims of the magnet frame with the base are fixed and normally not disturbed during crankshaft deflection.

1. Crankshaft Power from the burnt gases in the combustion chamber is delivered to the crankshaft through the piston, piston pin and connecting rod. The crankshaft (fig.3.62) changes reciprocating motion of the piston in cylinder to the rotary motion of the flywheel. Conversion of motion is executed by use of the offset in the crankshaft. Each offset part of the crankshaft has a bearing surface known as a crank pin to which the connecting rod is attached. Crank-through is the offset from the crankshaft centre line. The stroke of the piston is controlled by the throw of the crankshaft. The combustion force is transferred to the crank-throw after the crankshaft has moved past top dead centre to produce turning effort or torque, which rotates the crankshaft. Thus all the engine power is delivered through the crankshaft. The cam-shaft is rotated by the crankshaft through gears using chain driven or belt driven sprockets. The cam-shaft drive is timed for opening of the valves in relation to the piston position. The crankshaft rotates in main bearings, which are split in half for assembly around the crankshaft main bearing journals.

Both the crankshaft and camshaft must be capable of withstanding the intermittent variable loads impressed on them. During transfer of torque to the output shaft, the force deflects the crankshaft. This deflection occurs due to bending and twisting of the crankshaft. Crankshaft deflections are directly related to engine roughness. When deflections of the crankshaft occur at same vibrational or resonant frequency as another engine part, the parts vibrate together. These vibrations may reach the audible level producing a "thumping" sound. The part may fail if this type of vibration is allowed to continue. Harmful resonant frequencies of the crankshaft are damped using a torsional vibration damper. Torsional stiffness is one of the most important crankshaft design requirements. This can be achieved by using material with the correct physical properties and by minimizing stress concentration.

The crankshaft is located in the crankcase and is supported by main bearings. The angle of the crankshaft throws in relation to each other is selected to provide a smooth power output. V-8 engines use 90 degree and 6 cylinder engines use 120 degree crank throws. The engine firing order is determined from the angles selected. A crankshaft for a four cylinder engine is referred to a five bearing shaft. This means that the shaft has five main bearings, one on each side of every big end which makes the crankshaft very stiff and supports it well. As a result the engine is normally very smooth and long lasting.

CRANKSHAFT

Because of the additional internal webs required to support the main bearings, the crank case itself is very stiff. The disadvantages of this type of bearing arrangement are that it is more expensive and engine may have to be slightly longer to accommodate the extra main bearings. Counter weights are used to balance static and dynamic forces that occur during engine operation. Main and rod bearing journal overlap increases crankshaft strength because more of the load is carried through the overlap area rather than through the fillet and crankshaft web. Since the stress concentration takes place at oil holes drilled through the crankshaft journals, these are usually located where the crankshaft loads and stresses are minimal. Lightening holes in the crank throws do not reduce their strength if the hole size is less than half of the bearing journal diameter, rather these holes often increase crankshaft strength by relieving some of the crankshaft's natural stress. Automatic transmission pressure and clutch release forces tend to push the crankshaft towards the front of the engine. Thrust bearings in the engine support this thrust load as well maintain the crankshaft position. Thrust bearings may be located on any one of the main bearing journals. Experience shows that the bearing lasts much longer when the journal is polished against the direction of normal rotation than if polished in the direction of normal rotation. Most crankshaft balancing is done during manufacture by drilling holes in the counterweight to lighten them. Sometimes these holes are drilled after the crankshaft is installed in the engine.CRANKSHAFT NOMENCLATURECrank-throwThis is the distance from the main-journal centers to the big-end-journal centers. It is the amount the cranked arms are offset from the center of rotation of the crankshaft. A small crank-throw reduces both the crankshaft turning-effort and the distance the piston moves between the dead centers. A large crank-throw increases both the leverage applied to the crankshaft and stroke of the piston.Crank-websThese are the cranked arms of the shaft, which provide the throws of the crankshaft. They support the big-end crankpin. They must have adequate thickness and width to withstand both the twisting and the bending effort, created within these webs. But their excessive mass causes inertial effect, which tends to wind and unwide the shaft during operation.Main-bearing JournalMain-journal is the parallel cylindrical portions of the crankshaft, supported rigidly by the plain bearings mounted in the crankcase. The journals diameter must be proper to provide torsional strength. The diameter and width of the journal should have sufficient projected area to avoid overloading of the plain bearing.Connecting-rod Big-end (Crankpin) JournalsThese journals have cylindrical smooth surfaces for the connecting-rod big-end bearings to rub against.

CRANKSHAFT DESIGN CONSIDERATIONS AND PROPORTIONAL DIMENSIONS

The present design consideration is to increase the stiffness of the crankshaft and reduce its overall length by incorporating narrow journals of large diameter. For the required wall thickness and coolant passages, the minimum cylinder centers can be around 1.2 times the cylinder bore diameter for an engine having its stroke equal to the bore. The maximum diameter of the big-end for the connecting-rod assembly that can pass through the cylinder is 0.65 times of the bore. The proportions of the crankshaft are as follows :

Cylinder bore diameter = D

Cylinder centre distance = 1.20 D

Big-end journals diameter = 0.65 D

Main-end journal diameter = 0.75 D

Big-end journal width = 0.35 D

Main-end journal width = 0.40 D

Web thickness = 0.25 D

Fillet radius of journal and webs = 0.04 D

To increase the fatigue life of the shaft, the fillet radius between journals and webs should be as large as possible but not less than 5% of the journal diameter. The overlap between the diameters of the big-end crankpin and the main-end journal depends on the length of the stroke i.e. the crank-throw. A long-stroke engine has very little overlap, requiring thicker web sections, and a short-stroke engine has considerable overlap which strengthens the shaft.

INTEGRAL CRANKSHAFTCollars are machined on the webs adjacent to the journals to accurately align the crankshaft and the bearings with the correct amount of side-float and, if necessary, to absorb the crankshaft end-float. Most crankshafts dimensions are such that the nominal stresses in the material under operating conditions do not exceed 20% of the tensile strength in bending and 15% in torsion. Crankshaft journals are ground to provide a surface finish better than 0.5 urn, to minimize bearing wear.

CRANKSHAFT COUNTERBALANCE WEIGHTS :

Crankshafts normally have either integral or attachable counterweights. These counterweights counteract the centrifugal force created by each individual crankpin and its webs as the whole crankshaft is rotated about the main-journal axis. In absence of the counterweights, the crankpin masses tend to bend and distort the crankshaft causing excessive edge-loading in the main bearings. Therefore, each half crank-web is generally extended in the opposite direction to that of the crankpin, to counterbalance the effects of the crankpin. Bolt-on counterweights are, sometimes, used for large in-line and V engine because of the simplicity in casting or forging the crankshaft. The use of detachable weights allows their slight overlap on the webs and this increase in web width permits concentration of more mass at a smaller radius from the axis of rotation. The attaching weights to the web is to be located and attached very accurately, otherwise any error in assembly results in an unbalanced crankshaft.

Crankshaft with single diagonal oil drillings

Crankshaft Oil-hole Drillings Oil from the main oil gallery reaches each individual main-journal and bearing. Oil is fed through a central circumferential groove in the bearing and it completely surrounds the central region of the journal surface. Diagonal oil hole drills are provided in the crankshaft which pass through the webs between the main and big-end journals for lubrication of the big-end journal. For effective lubrication of the big-end, these oil holes emerge from the crankpin at about 30 degrees on the leading side of the crank's TDC position. The drilled oil passages should not be close to the side walls of the webs or near the fillet junction between the journal and the webs to avoid high stress concentration, which may cause fatigue failure. Also the oil holes on the journal surfaces must be chamfered to reduce stress concentration, but excessive chamfering can destroy the oil film. Crankshaft MaterialsCrankshafts materials should be readily shaped, machined and heat-treated, and have adequate strength, toughness, hardness, and high fatigue strength. The crankshaft are manufactured from steel either by forging or casting. The main bearing and connecting rod bearing liners are made of babbitt, a tin and lead alloy. Forged crankshafts are stronger than the cast crankshafts, but are more expensive. Forged crankshafts are made from SAE 1045 or similar type steel. Forging makes a very dense, tough shaft with a grain running parallel to the principal stress direction. Crankshafts are cast in steel, modular iron or malleable iron. The major advantage of the casting process is that crankshaft material and machining costs are reduced because the crankshaft may be made close to the required shape and size including counterweights. Cast crankshafts can handle loads from all directions as the metal grain structure is uniform and random throughout. Counterweights on cast crankshafts are slightly larger than counterweights on a forged crankshafts because the cast metal is less dense and therefore somewhat lighter.Generally automobile crankshafts were forged in past to have all the desirable properties. However, with the evolution of the nodular cast irons and improvements in foundry techniques, cast crankshafts are now preferred for moderate loads. Only for heavy duty applications forged shafts are favored. The selection of crankshaft materials and heat treatments for various applications are as follows.(i) Manganese-molybdenum Steel This is a relatively cheap forging steel and is used for moderate-duty petrol-engine crankshafts. This alloy has the composition of 0.38% carbon, 1.5% manganese, 0.3% molybdenum, and rest iron. The steel is heat-treated by quenching in oil from a temperature of 1123 K, followed by tempering at 973 K, which produces a surface hardness of about 250 Brinell number. With this surface hardness the shaft is suitable for both tin-aluminium and lead-copper plated bearings.(ii) 1%-Chromium-molybdenum Steel This forging steel is used for medium-to heavy-duty petrol- and diesel-engine crankshafts. The composition of this alloy is 0.4% carbon, 1.2% chromium, 0.3% molybdenum, and rest iron. The steel is heat-treated by quenching in oil from a temperature of 1123 K and then tempering at 953 K. This produces a surface hardness of about 280 Brinell number. For the use of harder bearings, the journals can be flame or induction surface-hardened to 480 Brinell number. For very heavy duty applications, a nitriding process can produce the surface to 700 diamond pyramid number (DPN). These journal surfaces are suitable for all tin-aluminum and bronze plated bearings.(iii) 2.5%-Nickel-chromium-molybdenum Steel This steel is opted for heavy-duty diesel-engine applications. The composition of this alloy is 0.31% carbon, 2.5% nickel, 0.65% chromium, 0.55% molybdenum, and rest iron. The steel is initially heat-treated by quenching in oil from a temperature of 1003 K and then tempered at a suitable temperature not exceeding 933 K. This produces a surface hardness in the region of 300 Brinell number. This steel is slightly more expensive than manganese-molybdenum and chromium-molybdenum steels, but has improved mechanical properties.(iv) 3%-Chromium-molybdenum or 1.5%-Chromium-aluminium-modybdenum Steel These forged steels are used for diesel-engine crankshafts suitable for bearing of hard high fatigue-strength materials. The alloying compositions are 0.15% carbon, 3% chromium, and 0.5% molybdenum or 0.3% carbon, 1.5% chromium, 1.1% aluminum, and 0.2% molybdenum. Initial heat treatment for both steels is oil quenching and tempering at 1193 K and 883 K or 1163 K and 963 K respectively for the two steels. The shafts are case-hardened by nitriding, so that nitrogen is absorbed into their surface layers. If the nitriding is carried out well in the journal fillets, the fatigue strength of these shafts is increased by at least 30% compared to induction and flame-surface-hardened shafts. The 3%-chromium steel has a relatively tough surface and hardness of 800 to 900 DPN. On the other hand the 1.5%-chromium steel casing tends to be slightly more brittle but has an increased hardness, of the order of 1050 to 1100 DPN.(v) Nodular Cast Irons These cast irons are also known as speroidal-graphite irons or ductile irons. These grey cast irons have 3 to 4% carbon and 1.8 to 2.8% silicon, and graphite nodules are dispersed in a pearlite matrix instead of the formation off fake graphite. To achieve this structure about 0.02% residual cerium or 0.05% residual magnesium or even both is added to the melt due to which the sulphur is removed and many small spheroids in the as-cast material are formed. The surface hardness of as-cast nodular iron is greater than for steel of similar strength, their respective hardnesses being 250 to 300 and 200 to 250 Brinell number. The flame or induction hardening can produce a surface with Brinell numbers of 550 to 580, and also a form of nitriding can be applied if necessary. Nodular cast iron has the advantageous properties of grey cast iron (that is, low melting point, good fluidity and cast ability, excellent machinability, and wear resistance) as well as the mechanical properties of steel (that is relatively high strength, hardness, toughness, workability, and harden ability). Now-a-days a large number of crankshafts for both petrol and diesel engines are made from nodular cast iron in preference to the more expensive forged expensive forged steel. To support the slightly inferior toughness and fatigue strength of these cast irons, larger sections and the maximum number of main journals are used.HEAT TREATMENT(a) Flame and Induction Surface-hardening These are the surface hardening methods for steel having 0.3 to 0.5% carbons without the use of special compounds or gases. The basic principle is to rapidly apply heat to the surface followed by only water quenching. As it is heated locally instead of heating the entire mass, the hardening is greatly reduced and distortion of the journal is avoided.

Flame hardening is carried out by oxyacetylene flame at the surface layer temperature between 993 and 1173 K. The surface temperature depends on the carbon content equivalent of the different alloying elements in the steel. The heating process is followed by a water-jet quenching operation. Since the actual period for heating and cooling is critical, it is predetermined and is mostly automatically controlled.

Induction hardening is carried out by inducting heat electrically into the surface to be hardened. This case eliminates the danger of either overheating or burning the surface of the metal as with a flame hardening. An induction coil surrounds the journal and carries a high-frequency current. This induces circulating eddy currents in the journal surface thereby raising of its temperature and heat is mostly confined to the outer surface of the journals. In this process the higher the frequency of the current, the closer the heat is to the skin. The current is automatically switched off when the required temperature is attained and the surface is simultaneously quenched by water jet, which passes through holes in the induction block.(b) Nitriding Surface-hardening Process In this process the journals are heated to 773 K for a predetermined time in an ammonia gas atmosphere, so that the nitrogen in the gas is absorbed into the surface layer. The alloying elements such as chromium, aluminium, and molybdenum, present in the steel, from hard nitrides. Aluminium nitrides form an intensely hard shallow case. Chromium nitrides diffuse to a greater depth than aluminium nitrides. The molybdenum increases hardenability, gives grain refinement, and improves the toughness of the core.

This process can use directly the journals ground to their final size as there is no quenching after nitriding thereby avoiding distortion unlike other surface-hardening processes. The slow rate of penetration of the surface makes the cost of the process high for example, it takes 20 hours to produce a case depth of about 0.2 mm.(c) Carbonitriding Surface-hardening Process. Tufftride' is the best-know salt-bath carbonitriding process. The crankshaft is immersed in a bath of molten salts at a temperature of about 853 Kfor a relatively short cycle time of two to three hours. In the process both carbon and nitrogen dissociate from the salts and diffuse into the surface. Since nitrogen is more soluble than carbon in iron, it diffuses further into the material. Hard iron carbides and tough iron nitrides are formed on the surface thereby resistance to wear, galling (surface peeling), seizure, and corrosion are greatly increased. Depending on the steel used, this outer layer is 6 to 16 jam deep with hardness varying from 400 to 1200 DPN. Underneath this outer layer, the excess nitrogen goes into solid solution with the iron due to which it is strengthened. This inner diffusion zone forms a barrier which prevents spreading of cracks leading to fatigue failure. This surface-hardening treatment, also known as soft FLYWHEEL nitriding, is becoming increasingly popular for both steels the cast irons, and is expected to replace other more expensive processes for the components using plain carbon steels requiring surface hardness and corrosion resistance. This process is much quicker and cheaper and produces similar properties to nitriding, but the depth of hardness is normally less, which can be a problem if the shaft is to be reground.CRANKSHAFT SERVICING 1. Condition The crankshaft is one of the most highly stressed engine components. The stress increases four times as the engine speed doubles. The crankshaft is rejected if there is any sign of a crack, because a cracked crankshaft may break if continues in service. Crankshaft cracks in high production passenger car engines can be detected with a close visual inspection. High-rpm racing crankshafts should be checked with Magnaflux to detect any minute crack that may lead to failure.CRANKSHAFT LUBRICATION 1. Crankshaft Oil-hole DrillingsOil from the main oil gallery reaches each individual main-journal and bearing. Oil is fed through a central circumferential groove in the bearing and it completely surrounds the central region of the journal surface. Diagonal oil hole drills are provided in the crankshaft which pass through the webs between the main and big-end journals for lubrication of the big-end journal. For effective lubrication of the big-end, these oil holes emerge from the crankpin at about 30 degrees on the leading side of the crank's TDC position. The drilled oil passages should not be close to the side walls of the webs or near the fillet junction between the journal and the webs to avoid high stress concentration, which may cause fatigue failure. Also the oil holes on the journal surfaces must be chamfered to reduce stress concentration, but excessive chamfering can destroy the oil film.

2. Lubrication Systems for Petrol Engines In order to ensure adequate supplies of oil to the engine parts, a reservoir of oil is provided by the sump which is the lower part of the lubrication system and in automobile engines the sump is the oil pan. From the reservoir, oil is distributed throughout the engine either by the splash system or the full pressure system. In case of two-stroke engines, the crankcase cannot be used as an oil reservoir. The lubrication, in this case, is provided by mixing a small proportion of oil with petrol. In the splash system the oil is maintained in little troughs. There are dippers at the ends of the connecting rods to splash the oil on the various parts like cylinder walls, camshafts, gudgeon pins etc. as they travel through the oil troughs towards the bottom of the stroke of the piston. The oil is supplied to the main bearings under pressure due to an oil pump through drilled passages, in the crankcase, called galleries. The oil pump also replenishes the troughs. The system is now practically obsolete.

Splash lubrication system.

3. Full Pressure System Automobile engines today use 'forced-feed' lubrication systems, generally of the wet-sump type in which the sump acts as both an oil-drain return and a storage container. A rotary-type oil-pump provides forced feed. The pump may be driven directly from the crankshaft or indirectly from the camshaft or any auxiliary shaft. Oil from the sump reaches the pump through the submerged gauze strainer and pick-up pipe. The oil is then compressed, which passes through a drilling to the lubrication system. A pressure-relief valve positioned on the output side of the pump controls the oil pressure. If the oil pressure becomes too high, the relief valve opens and bleeds surplus oil back to the sump. The relief valve may be installed on the filter unit, the crankcase, or the pump housing. The oil-pump forces the oil through drillings in the crankcase to a cylindrical full-flow filter unit. The oil circulates around the filter bowl, passes through the filter towards its centre, and flows out to the main oil passage, called main oil gallery which lies parallel to the crankshaft. In most car and commercial vehicle engines, the oil gallery is formed by drilling a hole in the crankcase for full length of the engine and plugging the ends.Main- and Big-end Bearing Lubrication. The oil is fed to the crankshaft main journal bearings and in some cases to the camshaft bearings through various branch cross-drillings in the crankcase. A few heavy commercial engines use a separate pipe located underneath the main-bearing caps and by pedestal brackets. Drillings in these brackets connect the gallery-pipe oil to the main bearings. By diagonal drillings in the crankshaft a continuous oil is fed to the big-end bearings from the oil grooves around the main-bearings liners. These drillings pass from the main-bearing journal to the big-end crankpins through the crankshaft web.

Forced-feed lubrication system.A. Front sectional view. B. Side sectional view.Crankshaft Oil Passages Crankshaft oil passages feed oil from the main-journal bearing to the big-end journal. In its simplest form, the oil passage is a diagonal drilling running from the main journal to the big-end journal. Normally the diagonal hole is drilled at an angle to the crank-web centre-line so that, when the crank-pin is in the TDC position and combustion force pushes the connecting rods downwards, some oil still enters between the journal and the bearing. It is because if the exit of the diagonal hole is exactly at the top of the big-end journal, oil can not enter between the bearing and the journal in the TDC position. Additionally the effective projected bearing area is also reduced by chamfered oil hole. To have an improvement in oil delivery, a cross-drilling runs straight through the big-end journal and a diagonal drilling from the main-bearing journal intersects the big-end cross-drilling. Another hole is also drilled diametrically opposite the diagonal-hole's entry in the main journal, so that when the bearing is loaded at the top or the bottom of the stroke, the other side of the bearing permits oil to enter.

Crankshaft oil passages

A. Crankshaft with single oil passage

B. Crankshaft with diagonal web passage and right-angled cross-drilling in the big-end journal.

FAILURES OF CRANKSHAFT

FAILURES OF CRANKSHAFT IN DIESEL LOCOMTIVE

FAILURES:1. Thermal cracks2. Breaking f Journal Bearing.3. Enlarged Keyway .4. Cracks in Thrust collar.5. Second main journal Thermal Crack.6. Excess run out at 915 main Journal.7. Fourth crankpin having cracks at both end.8. Bearing size is enlarged.9. Fifth crankpin has dart mark.10. Z type crack.11. 8th and 9th main journal excess run out.

CAUSES OF MAJOR FAILURES1. Viscosity of lubrication oil is too low.2. If there is fault OSD (Over speed dripper) equipment attach in engine which cause heavy failure in CRANKSHAFT.3. If the engine speed exceeds the rated RPM of the engine..4. If the engine is operated at over load.5. If the Lubricating oil is not changed periodically.6. If the oil filter is not changed periodically.7. Improper functioning of Engine monitoring system.8. Excessive wear of Journal bearing.9. Irregular maintenance of engine.10. Inefficient engine Operator.11. Drivers cannot follow the operator manual.12. Poor maintenance.FAILURE MODE AND EFFECTS ANALYSIS (FMEA) A procedure for analysis of potential failure modes within system for the classification by severity or determination of the failure's effect upon the system. These locomotives were used for dieselizing the pioneer section of the Indian Railways. When the first batch were to come a few staff. for training. These trainees had no background whatsoever of diesel locomotive maintenance and the training which they received was brief. Therefore most of the learning they had was at Gaya itself as and when problem arose. In the beginning, besides teething troubles, the locomotives gave satisfactory service. Out when they were two to three years old, problems began and the locomotive condition started to deteriorate.

THE MAIN REASONS AS WE HAVE NOW BEEN ABLE TO SEE, WERE:(a) Lack of staff experience.(b) Non-availability of certain spare parts. For the requirement of spare parts for the first two years we were guided purely by the recommendations of the manufacturers.(c) Viscosity of lubrication oil is too low.(d) If there is fault OSD (Over speed dripper) equipment attach in engine which cause heavy failure in CRANKSHAFT.(e) If the engine speed exceeds the rated RPM of the engine..(f) If the engine is operated at over load.(g) If the Lubricating oil is not changed periodically.(h) If the oil filter is not changed periodically.(i) Improper functioning of Engine monitoring system.(j) Excessive wear of Journal bearing.(k) Irregular maintenance of engine.(l) Inefficient engine Operator.(m) Drivers cannot follow the operator manual.(n) Poor maintenance.

TABULATION OF FAILURES AND CAUSESFAILURES PROBABLE CAUSES1. Thermal cracks

2. Main journal bearing failure

3. 6th crankpin step formed

4. Center counter weight bend

5. 7th main journal crack

6. Excessive run out 8th & 9th main journal

7. Broken into two pieces at 6th crankpin

8. Key way enlarged

9. Thrust collar crack

10. Counter weight damaged

11. Both side key way key way enlarge

12. 6th crankpin badly damage

13. Main journal corrosion

14. Excess run out of main journal

15. Thrust collar excessive hit point

Lubrication oil not enough.

Cant supply the enough&Low viscosity of lubrication oil.

Connecting rod having not tightened enough.

Crankshaft & connecting rod size not matching properly.

Main journal bearing seizure.

Mishandling of engine & 7th journal seizure.

Mishandling of engine & cant properly changed lubrication oil.

Unfitted key size&Over temperature.

Sudden moment of engine that means cant follows proper instruction.

Connecting rod unfitted.

Gear and key cannot matchingProperly.

Connecting rod having not tightened enough.

High temperature & low lubrication oil level & cannot changed lube oil periodically.

Low lubrication oil viscosity.

Engine can be operated over speed.

REASONS OF BEARING SEIZUREScoring and Scarring. Foreign materials such as metal particles, sand, and grit in the oil cause scoring and scarring of bearing. Poor finish of the crankshaft journals and crankpins also gives rise to this type of bearing failure. Foreign particles embedded in a bearing. The engine oil if contaminated with major abrasives, causes severe scores on the bearings in the main bearing caps and the upper half of the connecting rods, because these bearings are subjected to the heaviest load condition. When the vehicle is operated in extremely dusty conditions, the engine oil may be contaminated with fine sand, which results in fine abrasion of the bearings. Badly scored bearings. When a piston failure occurs, aluminium flakes may indent or scar the bearing surfaces. If the crankshaft surfaces have not been adequately polished after the journals have been ground, then many fine cuts appear on the bearing surfaces. These fine score marks look like the grooves on a record.

Causes of Connecting Rod and Main Bearing Failures.Dirt43.1%

Lack of lubrication14.9%

Misassemble13.6%

Misalignment10.0%

Overloading8.4%

Corrosion4.7%

Other5.3%

Bearing damage resulting from lack of lubrication.Bearing wears from a tapered journal.

Wiped and Burned Burning and wiping of bearings may take place due to a dry start and a lag in the oil supply. Insufficient bearing clearance also results in burned and wiped bearings. Severe overheating and inadequate lubrication cause lead smear and burned bearings. If the oil is diluted with gasoline, the bearings become burnished. The top half of the main bearing has an oil inlet hole for lubrication and the lower half of the bearing does not have an oil hole. If the bearing halves are interchanged, the oil supply to the bearing is shut off and the bearing is wiped and burned. illustrates bearing damage resulting from lack of lubrication. A lack of oil supply to the bearings causes burned and extruded bearings linings. If the bearings do not have the proper crush fit, they may move and turn with the crankshaft. If that happens the back of the bearings is burned when it turns in the connecting rod. If a rear main bearing seal is too tight it causes excessive heat build-up on the rear crankshaft journal so that the back half of the rear main bearing is burned. If the main bearing bores are misaligned, the centre main bearings and adjacent main bearings burn and seize. Beaning-edge burning results if the main beaning housing or connecting rod housing is tapered. Fatigue The crankshaft may become ridged in the journal area directly below the oil grooves in the upper halves of the main bearings. When such ridges occur, the crankshaft ridge causes a fatigue strip in the lower half of the main bearings. Figure 20.37 shows bearing fatigue failure.If a connecting rod is misaligned, a V-shaped fatigue occurs at the edge of the connecting rod bearings. Fatigue at the adjacent parting faces on the bearings takes place if the bearing housing is out of round. Bearing edge fatigue is caused by an hourglass-shaped crankshaft-bearing journal. The heaviest loading area in a bearing is a 120 degrees arc of the bearing due to the specified oil clearance space. The load is applied to the upper half of the connecting rod bearings and the lower half of the main bearings. If the bearing oil clearance exceeds specifications, the bearings are overstressed in a 30 to 45 degrees arc due to the excessive movement of the crankshaft or connecting rod. Heavy engine load causes bearing fatigue in the upper connecting rod bearings, especially at low engine speeds. Also excessive engine speed causes bearing fatigue in the upper and lower connecting rod bearings. Corrosion Corrosive acids may contaminate the engine oil because of excessive piston ring "blow-by", internal antifreeze leaks or the use of high-sulpher fuels. Infrequent oil change intervals also cause oil contamination by corrosive acids. These corrosive acids convert the lead in the bearing material to a lead soap, which is subsequently washed out of the bearing so that the other bearing materials are exposed. Erosion This is the uncommon type of bearing failure. When erosion occurs, there exists a gradual irregular deterioration of the bearing surface, which is caused by the hitting of surface by oil at high velocity and pressure.

Bearing Fatigue Failure

CONDEMNATIONS REPORT OF CRANKSHAFT: 1. Year of mfg-14.01.912. Date of inspection-03.01.08 to 15.02.20103. Nature of defect-2nd & 5th crank pin undersize bearing seizure1. Year of mfg-09.06.762. Date of inspection-15.03.08 to 15.02.20103. Nature of defect-Broken into two pieces at 6th main journal1. Year of mfg-26.09.752. Date of inspection-06.04.04 to 22.02.20103. Nature of defect-Broken into two pieces near 4th crankpin1. Year of mfg-22.06.932. Date of inspection-10.09.04 to 16.02.20103. Nature of defect-split gear journal thermal undersize/Thrust collar crack1. Year of mfg-14.04.972. Date of inspection-11.09.07 to 18.02.20103. Nature of defect-9th main journal thermal crack, 3rd crank pin damage1. Year of mfg-10.01.782. Date of inspection-09.10.07 to 19.02.103. Nature of defect-counter weight damaged, 8th crankpin undersize1. Year of mfg-26.10.962. Date of inspection-09.10.03 to 18.02.103. Nature of defect-Thrust collar crank excessive run out.1. Year of mfg-13.03.652. Date of inspection-30.07.07 to 19.02.103. Nature of defect-Location no.2, crankpin broken into two pieces.1. Year of mfg-02.02.982. Date of inspection-21.08.07 to 16.02.20103. Nature of defect-Broken into two pieces at 6th crank pin.1. Year of mfg-25.08.822. Date of inspection-06.06.07 to 22.01.103. Nature of defect-Thrust collar crack keyway oblong.1. Year of mfg-23.01.962. Date of inspection-19.06.08 to 23.01.963. Nature of defect-8th main journal thermal crack and bearing seizure.1. Year of mfg-14.04.972. Date of inspection-27.06.08 to 23.01.103. Nature of defect-5th main journal bearing seizure.1. Year of mfg-24.04.972. Date of inspection-27.06.08 to 22.01.103. Nature of defect-6th crankpin badly damaged.1. Year of mfg-17.11.832. Date of inspection-30.07.08 to 18.01.103. Nature of defect-location no 2nd crankpin hit mark1. Year of mfg-28.08.632. Date of inspection-05.01.05 to 04.01.20103. Nature of defect-crankpin undersize & counter weight hit marks.1. Year of mfg-21.07.862. Date of inspection-24.08.08 to 04.01.103. Nature f defect-both side keyway enlarged.1. Year of mfg-27.08.952. Date of inspection-03.10.08 to 31.12.20093. Nature f defect-Excessive run out 0.0025, 9th main journal bearing seizure.

REMEDIES OF CRANKSAFT FAILURES

REMEDIES ACTION: Properly check the lubrication oil viscosity.

Periodically change the high quality lubrication oil.

Engine can be operated by rated RPM (1110 to 1140)

Journal can be properly polished.

To check the lubrication oil hole. There is any foreign particles. That is must be removed.

To check the OST (over speed tripper) equipment has properly working. There is any fault that is must be replaced.

Engine can be operated limited load (or) torque.

Periodically replaced the lubrication oil filter.

Engine monitoring system can be properly maintained.

Engine can be checked every 24hr.

Periodically replaced the high quality journal bearing.

Engine must be operated only 2lacks KM. Then that was posted to workshop.

Properly check out the oil sump pipe. If there is any unwanted particles that should be replaced.

Properly trained person can be operated by the engine.

Lubrication oil level can be check at every day.

HOW TO MAINTAIN LOCOMOTIVE: Inspect and qualify, in-place, the turbocharger and clutch utilizing the EMD Roller clutch and run-down time tests. Clean and inspect the parts catcher. Upgrade the after-coolers to 4-pass for 16-cylinder engines; rebuild or install UTEX after-cooler cores for 12-cylinder engines; inspect after-cooler ducts for cracks and repair as required. Remove all engine power assemblies. Clean and inspect oil separator screen, ejector assembly, and educator tube assembly. Remove exhaust stack manifolds and replace exhaust manifold gaskets. Inspect manifolds and advise VRE of cracks, etc to determine disposition of the manifolds; inspect top deck exhaust manifold bolt holes to allow for proper torquing of stack manifolds - repair holes as required with Key locking thread repair inserts. Thoroughly clean the air boxes, oil pan, crankcase, and Michiana tank and remove dirt, debris, and chips. Inspect the engine for structural cracks and advise VRE of inspection results to determine disposition of material. Replace all Michigan lube oil filters. Clean the ice cream box strainer housing assembly. Remove clean and re-install inertial air filters. Replace engine air filters. Replace all fuel filters. Install new lower main bearings and main bearing thrust collars. Inspect and qualify the piston cooling tubes (P-pipes); replace as required. Power assemblies shall be rebuilt as follows: Completely disassemble, clean, and inspect each power assembly. Clean and inspect connecting rods for length, twist, piston pin surface and bore parallel. Pistons shall have tin plated skirts and ring sets with chrome faced no. 1, 2, and 3 compression rings for 645E3C engines. Carriers shall be checked visually and dimensionally, inspected, and reassembled with new thrust washer and snap ring. Cast iron cylinder liners with hardened upper bore shall be used. Rebuild cylinder heads with new Inconel valves, valve guides, valve springs, and valve retainers installed in rebuilt cylinder head. Heads shall be Diamond 5 or newer. Install new liner seals and head gaskets. Install new lower liner inserts. The completed assembly shall be hydrostatic pressure tested. Record the old and the new head, liner, and rod serial numbers by location. Plate-type crabs and new head seat rings shall be used when installing