Rebuilding Of Diesel Engines

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Study project YCMOU BTECH Marine Engg

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1.1 BACKGROUNDThe diesel engine is a technical refinement of the 1876 Otto cycle engine. Where Otto has realized in 1861 that the efficiency of the engine could be increased by first compressing the fuel mixture prior to its ignition, Rudolph Diesel wanted to develop a more efficient type of engine that could run on much heavier fuel. The Lenoir, Otto Atmospheric, and Otto Compression engines (both 1861 and 1876) were designed to run on Illuminating Gas (coal gas). With the same motivation as Otto, Diesel, wanted to create an engine that would give small industrial concerns their own power source to enable them to compete against larger companies, and like Otto to get away from the requirement to be tied to a municipal fuel supply. Like Otto, it took more than a decade to produce the high compression engine that could self-ignite fuel sprayed into the cylinder. Diesel used an air spray combined with fuel in his first engine.During initial development, one of the engines burst nearly killing Diesel. He persisted and finally created an engine in 1893. The high compression engine, which ignites its fuel by the heat of compression is now called the Diesel engine whether a four-stroke or two-stroke design.The four stroke diesel engine has been used in the majority of heavy duty applications for many decades. Chief among the reasons for this is that it uses a heavy fuel that contains more energy, requires less refinement, and is cheaper to make (although in some areas of the world diesel fuel costs more than gasoline). The most efficient Otto cycle engine runs near 30% efficiency. Some of the modern engines have more efficiency. It uses an advanced design with turbo charging and direct fuel injection. Some B&W ship Diesels with ceramic insulation have exceeded 60% efficiency.

1.2 NEED OF WORKThe prime requirement for the ships propulsion machinery and power generation are reliability, safety and efficiency. Much of the factors have its origin from manufactures skill relating to design, proceeding techniques and material specifications. The efficient maintenance of performance is another concern of engineers.Traditionally ships maintenance has been to prevent breakdown rather than rectification following the breakdown. The ship board machinery has become a little more sophisticated today than ever before. One must realize that condition of working has regards for temperature, stress, power, velocity and vibration, noise flow, handling of combustible material and so ones more extreme. From these facts it is clear that more careful examinations are required periodically covering vast number of items in order to prevent awkward failure of machinery. The systematic maintenances period of important machinery parts may be made overlapping and simultaneously with 5 years survey cycle. Maintenance should include documentation of observation and measurement noting defects, wear down rate etc for correct prediction of service life.

1.3 BRIEF IDEAA four-stroke engine (also known as four-cycle) is an internal combustion engine in which the piston completes for separate strokes- intake, compression, power, and exhaust- during two separate revolutions of the engines crankshaft, and one single thermodynamic cycle. There are two common types of four-stroke engines. They are closely related to each other, but have major differences in design and behavior. The earliest of these to be developed is the Otto cycle engine developed in 1876 by Nicholas August Otto in Cologne, Germany, after the operation principle described by Alphonse Beau de Rochas in 1861. This engine is most often referred to as a petrol engine or gasoline engine, after the fuel that powers it. The second type of four-stroke engine is the Diesel engine developed in 1893 by Rudolph Diesel, also of Germany. Diesel created his engine to improve efficiency compared with the Otto engine. There are several major differences between the Otto cycle engine and the four-stroke diesel engine. The diesel engine is made in both a two-stroke and a four-stroke version. Ottos company, Duetz AG, now primarily produces diesel engines. The Otto cycle is named after the 1876 engine of Nicholas A. Otto, who built a successful four-stroke engine based on the work of Jean Joseph Etienne Lenoir. It was the third engine type that Otto developed. It used a sliding flame gateway for the ignition of its fuel- a mixture of illuminating gas and air.

1. INTAKE stroke: on the intake or induction stroke of the piston, the piston descends from the top of the cylinder to the bottom, increasing the volume of the cylinder. A mixture of fuel and air, or just air in a diesel engine, is forced by atmospheric (or greater) pressure into the cylinder through the intake port. The intake valve(s) then closes. The volume of air/fuel mixture that is drawn into the cylinder, relative to the maximum volume of the cylinder, is called the volumetric of the engine.2. COMPRESSION stroke: with both intake and exhaust valves closed, the piston returns to the top of the cylinder compressing the air or fuel-air mixture into the combustion chamber of the cylinder head. During the compression stroke the temperature of the air or fuel-air mixture rises by several hundred degrees.3. POWER stroke: this is the start of the second revolution of the cycle. While the piston is close to Top Dead Center, the compressed air-fuel mixture in a gasoline engine is ignited, usually by a spark plug, or fuel is injected into a diesel engine, which ignites due to the heat generated in the air during the compression stroke. The resulting pressure from the combustion of the compressed fuel-air mixture forces the piston back down towards Bottom Dead Center.4. EXHAUST stroke: during the exhaust stroke, the piston once again returns to Top Dead Center while the exhaust valve is open. This action expels the spent fuel-air mixture through the exhaust valve(s).

SYSTEM OVERVIEW AND DESIGN2.1 PRINCIPLE OF OPERATIONDiesel Engine Stroke CycleDiesel and gasoline engines can be designed to operate on a four-stroke cycle or a two-stroke cycle. Each stroke in the cycle corresponds to the up or down movement of the piston within the cylinder . Four-cycle gasoline and diesel engines use four piston strokes to complete one operating cycle- one stroke each for intake, compression, power and exhaust using only two piston stroke, one Upward and one downward.Virtually all high horse power gasoline engines are four-cycle engines. Two-cycle gasoline engines are used primarily for power tools, lawn and garden equipment chain saws, outboard boat motors, and other relatively light-duty applications. In contrast, both two and four-cycle diesel engines can be used in high horsepower applications. All modern on-highway diesel engines are now four-cycle engines. Two-cycle diesel engines are popular in marine, power generation, and industrial applications. In a two-cycle Diesel engine, intake and compression occur on the upward piston stroke, while power and exhaust occur during the downward piston stroke. Diesel engines are also more efficient than gasoline.




Four-stroke cycle

The four-stroke cycle is completed in four strokes of the piston, or two revolutions of the crankshaft. In order to operate this cycle the engine requires a mechanism to open and close the inlet and exhaust valves. Consider the piston at the top of its stroke, a position known as top dead centre (TDC). The inlet valve opens and fresh air is drawn in as the piston moves down. At the bottom of the stroke, i.e. bottom dead centre (BDC), the inlet valve closes and the air in the cylinder is compressed (and consequently raised in temperature) as the piston rises. Fuel is injected as the piston reaches top dead centre and combustion takes place, producing very high pressure in the gases. The piston is now forced down by these gases and at the bottom dead centre the exhaust valve opens. The final stroke is the exhausting of the burnt gases as the piston rises to top dead centre to complete the cycle. The four distinct strokes are known as 'inlet' (or suction), 'compression', 'power' (or working stroke) and 'exhaust'. These events are shown diagrammatically on a timing diagram. The angle of the crank at which each operation takes place is shown as well as the period of the operation in degrees. This diagram is more correctly representative of the actual cycle than the simplified explanation given in describing the four-stroke cycle. For different engine designs the different angles will vary, but the diagram is typical.TWO-STROKE CYCLEThe two-stroke cycle is completed in two strokes of the piston or one revolution of the crankshaft. In order to operate this cycle where each event is accomplished in a very short time, the engine requires a number of special arrangements. First, the fresh air must be forced in under pressure. The incoming air is used to clean out or scavenge the exhaust gases and then to fill or charge the space with fresh air. Instead of valves holes, known as 'ports', are used which are opened and closed by the sides of the piston as it moves.Consider the piston at the top of its stroke where fuel injection andcombustion have just taken place. The piston is forced down on its working stroke until it uncovers the exhaust port. The burnt gases then begin to exhaust and the piston continues down until it opens the inlet or scavenge port . Pressurised air then enters and drives out the remaining exhaust gas. The piston, on its return stroke, closes the inlet and exhaust ports. The air is thencompressed as the piston moves to the top of its stroke to complete the cycle. A timing diagram for a two-stroke engine is shown in Figure 2.4. The opposed piston cycle of operations is a special case of the two-stroke cycle. Beginning at the moment of fuel injection, both pistons are forced apartone up, one downby the expanding gases. The upper piston opens the exhaust ports as it reaches the end of its travel. The lower piston, a moment or two later, opens the scavenge ports to charge the cylinder with fresh air and remove the final traces of exhaust gas. Once the pistons reach their extreme points they both begin to move inward. This closes off the scavenge and exhaust ports for the compression stroke to take place prior to fuel injection and combustion. This cycle is used in the Doxford engine, which is no longer manufactured althoughmany are still in operation.

MODULE DESIGN3.1 INDIVIDUAL PARTSCYLINDER HEADSIn aninternal combustion engine, thecylinder head(often informally abbreviated to justhead) sits above thecylinderson top of the cylinder block. It closes in the top of the cylinder, forming thecombustion chamber. This joint is sealed by ahead gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, and that allow the exhaust to escape. The head can also be a place to mount thevalves,spark plugs, andfuel injectors.In aflatheadorside valve engine, the mechanical parts of the valve train are all contained within the block, and the head is essentially a metal plate bolted to the top of the block; this simplification avoids the use of moving parts in the head and eases manufacture and repair, and accounts for the flathead engine's early success in productionautomobilesand continued success insmall engines, such as lawnmowers. This design, however, requires the incoming air toflowthrough a convoluted path, which limits the ability of the engine to perform at higherrevolutions per minute(rpm), leading to the adoption of theoverhead valve(OHV) head design, and the subsequent overhead camshaft(OHC) design.Internally, the cylinder head has a design. The cylinder head contains thepoppet valvesand the spark plugs, along with tracts or 'ports' for the inlet and exhaust gases. The operation of the valves is initiated by the engine'scamshaft, which is sited within the cylinder block, and its moment of operation is transmitted to the valvespushrods, and thenrocker arms mounted on a rocker shaft - the rocker arms and shaft also being located within the cylinder head.In the overhead camshaft (OHC) design, the cylinder head contains the valves, spark plugs and inlet/exhaust tracts just like the OHV engine, but the camshaft is now also contained within the cylinder head. The camshaft may be seated centrally between each offset row of inlet and exhaust valves, and still also utilizing rocker arms (but without any pushrods), or the camshaft may be seated directly above the valves eliminating the rocker arms and utilizing 'bucket'tappets.The number of cylinder heads in an engine is a function of theengine configuration. Almost allinline (straight) enginestoday use a single cylinder head that serves all the cylinders. AV (or Vee)engine has two cylinder heads, one for eachcylinder bankof the 'V'. For a few compact 'narrow angle' V engines, such as theVolkswagenVR6, the angle between the cylinder banks is so narrow that it uses a single head spanning the two banks. Aflat engine(basically a V engine, where the angle between the cylinder banks is now 180) has two heads. Mostradial engineshave one head for each cylinder, although this is usually of themono blocform wherein the head is made as an integral part of the cylinder. This is also common for motorcycles, and such head/cylinder components are referred-to asbarrels.Passages calledports or tractsfor the fuel/air mixture to travel to the inlet valves from the intakemanifold and forexhaust gasesto travel from the exhaust valves to the exhaust manifold. In awater-cooledengine, the cylinder head also contains integral ducts and passages for the engines' coolant - usually a mixture of water andantifreeze- to facilitate the transfer of excess heat away from the head, and therefore the engine in general.In the overhead valve (OHV) Some engines, particularly medium- and large-capacitydiesel enginesbuilt for industrial, marine, power generation, and heavy traction purposes (largetrucks,locomotives,heavy equipmentetc.) have individual cylinder heads for each cylinder. This reduces repair costs as a single failed head on a single cylinder can be changed instead of a larger, much more expensive unit fitting all the cylinders. Such a design also allows engine manufacturers to easily produce a 'family' of engines of different layouts and/or cylinder numbers without requiring new cylinder head designs.The design of the cylinder head is key to the performance and efficiency of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of thevolumetric efficiencyandcompression ratioof the engine.PISTONSApistonis a component ofreciprocating engines, reciprocatingpumps,gas compressorsandpneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by acylinderand is made gas-tight bypiston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to thecrankshaftvia apiston rodand/orconnecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting thefluidin the cylinder. In some engines, the piston also acts as avalveby covering and uncoveringportsin the cylinder wall.The piston of aninternal combustion engineis acted upon by the pressure of the expanding combustion gases in thecombustion chamberspace at the top of the cylinder. This force then acts downwards through theconnecting rodand onto thecrankshaft. The connecting rod is attached to the piston by a swivellinggudgeon pin(US: wrist pin). This pin is mounted within the piston: unlike the steam engine, there is no piston rod or crosshead(except big two stroke engines).The pin itself is of hardened steel and is fixed in the piston, but free to move in the connecting rod. A few designs use a 'fully floating' design that is loose in both components. All pins must be prevented from moving sideways and the ends of the pin digging into the cylinder wall, usually by circlips.Gas sealing is achieved by the use ofpiston rings. These are a number of narrow iron rings, fitted loosely into grooves in the piston, just below the crown. The rings are split at a point in the rim, allowing them to press against the cylinder with a light spring pressure. Two types of ring are used: the upper rings have solid faces and provide gas sealing; lower rings have narrow edges and a U-shaped profile, to act as oil scrapers. There are many proprietary and detail design features associated with piston rings.Pistons arecastfromaluminium alloys. For better strength and fatigue life, some racing pistons may beforgedinstead. Early pistons were of cast iron, but there were obvious benefits for engine balancing if a lighter alloy could be used. To produce pistons that could survive engine combustion temperatures, it was necessary to develop new alloys such asY alloyandHiduminium, specifically for use as pistons.A few earlygas engineshaddouble-acting cylinders, but otherwise effectively all internal combustion engine pistons aresingle-acting. DuringWorld War II, the US submarinePompanowas fitted with a prototype of the infamously unreliableH.O.R.double-acting two-stroke diesel engine. Although compact, for use in a cramped submarine, this design of engine was not repeated.CYLINDER LINERSThe cylinder liner of a small automobile might not look much different from a tumbler in which you drink water, but when it comes to ships, the cylinder liner is big enough that two thin people can inside it simultaneously. Just read and see this important component here.Basically the cylinder liner is a hollow cylindrical shell which acts as the enclosure in which the combustion takes place. Of course the word hollow does not imply that it is weak in strength for it is under the fluid pressure due to combustion and hence must withstand the high level of hoop stress induced in it.Another factor is the big temperature difference on the outside and inside (being in proximity of the combustion chamber) of the liner which tends to induce thermal stresses and the liner has to withstand those as well. Apart from the liner surface is also resistant to wear and corrosion.Given the stringent requirements of strength and anti-corrosion property and provide a good surface for the piston rings to slide along its length, Cast Iron is the most widely used material mainly because of its lubricating properties which is a result of graphite present in its micro-structure.Cast Iron is also porous in nature and this helps to prevent or minimize the risk of seizure of the piston during its operation and also is a remedial measure against extensive galling which takes place during piston motion.Yet CI is not strong enough a material so it is not used in its pure form but alloyed with small quantities of elements such as Chromium, Copper or Nickel and such alloying is of the order of 5%.Construction is done either by centrifugal casting in case of smaller liners and sand casting in case of larger liners. The inner surface of the cylinder liner is usually chrome plated to make it smooth but this smoothness also has its drawback that it does not allow oil to spread out properly thus affecting liner lubrication in a negative manner. This was rectified to a certain degree through the use of porous chrome honing.

CAMSHAFTAcamshaftis a shaft to which acamis fastened or of which a cam forms an integral part. An early cam was built intoHellenisticwater-drivenautomatafrom the 3rd century BC.The camshaft was later described inIraq(Mesopotamia) byAl-Jazariin 1206. He employed it as part of his automata, water-raising machines, andwater clockssuch as thecastle clock.The cam and camshaft later appeared in European mechanisms from at least the 14th century,or possibly earlier. Camshafts can be made out of several different types of material. These include:Chilled iron castings: this is a good choice for high volume production. A chilled iron camshaft has a resistance against wear because the camshaft lobes have been chilled, generally making them harder. When making chilled iron castings, other elements are added to the iron before casting to make the material more suitable for its application.Billet Steel: When a high quality camshaft is required, engine builders and camshaft manufacturers choose to make the camshaft from steel billet. This method is also used for low volume production. This is a much more time consuming process, and is generally more expensive than other methods. However the finished product is far superior. When making the camshaft,CNClathes, CNCmilling machinesand CNC camshaft grinders will be used. Different types of steel bar can be used, one example being EN40b. When manufacturing a camshaft from EN40b, the camshaft will also beheat treatedvia gasnitriding, which changes the micro-structure of the material. It gives a surface hardness of 55-60HRC. These types of camshafts can be used in high-performance engines.The relationship between the rotation of the camshaft and the rotation of thecrankshaftis of critical importance. Since the valves control the flow of the air/fuel mixture intake and exhaust gases, they must be opened and closed at the appropriate time during the stroke of the piston. For this reason, the camshaft is connected to thecrankshafteither directly, via agearmechanism, or indirectly via a belt or chain called atiming beltortiming chain. Direct drive using gears is unusual because the frequently reversing torque caused by the slope of the cams tends to quickly wear out gear teeth. Where gears are used, they tend to be made from resilient fibre rather than metal, except in racing engines that have a high maintenance routine. Fibre gears have a short life span and must be replaced regularly, much like a timing belt. In some designs the camshaft also drives thedistributorand theoilandfuel pumps. Some vehicles may have the power steering pump driven by the camshaft. With some earlyfuel injectionsystems, cams on the camshaft would operate the fuel injectors.An alternative used in the early days of OHC engines was to drive the camshaft(s) via a vertical shaft with bevel gears at each end. This system was, for example, used on the pre-WW1PeugeotandMercedesGrand Prix cars. Another option was to use a triple eccentric with connecting rods; these were used on certainW.O. Bentley-designed engines and also on theLeyland Eight.In atwo-stroke enginethat uses a camshaft, each valve is opened once for each rotation of the crankshaft; in these engines, the camshaft rotates at the same speed as the crankshaft. In afour-stroke engine, the valves are opened only half as often; thus, two full rotations of the crankshaft occur for each rotation of the camshaft.The timing of the camshaft can be advanced to produce better low RPM torque, or retarded for better high RPM power. Either of these moves the overall power produced by the engine down or up the RPM scale respectively. The amount of change is very little (usually < 5 deg), and affects valve to piston clearances.Duration is the number of crankshaft degrees of engine rotation during which the valve is off the seat. As a generality, greater duration results in more horsepower. The RPM at which peak horsepower occurs is typically increased as duration increases at the expense of lower rpm efficiency (torque). Duration can often be confusing because manufacturers may select any lift point to advertise a camshaft's duration and sometimes will manipulate these numbers. The power and idle characteristics of a camshaft rated at .006" will be much different than one rated the same at .002".Many performance engine builders gauge a race profile's aggressiveness by looking at the duration at .020", .050" and .200". The .020" number determines how responsive the motor will be and how much low endtorquethe motor will make. The .050" number is used to estimate where peak power will occur, and the .200" number gives an estimate of the power potential.A secondary effect of increased duration is increasingoverlap, which is the number of crankshaft degrees during which both intake and exhaust valves are off their seats. It is overlap which most affects idle quality, inasmuch as the "blow-through" of the intake charge which occurs during overlap reduces engine efficiency, and is greatest during low RPM operation. In reality, increasing a camshaft's duration typically increases the overlap event, unless one spreads lobe centers between intake and exhaust valve lobe profiles.he camshaft "lift" is the resultant net rise of the valve from its seat. The further the valve rises from its seat the more airflow can be released, which is generally more beneficial. Greater lift has some limitations. Firstly, the lift is limited by the increased proximity of the valve head to the piston crown and secondly greater effort is required to move the valve's springs to higher state of compression. Increased lift can also be limited by lobe clearance in the cylinder head construction, so higher lobes may not necessarily clear the framework of the cylinder head casing. Higher valve lift can have the same effect as increased duration where valve overlap is less desirable.Higher lift allows accurate timing of airflow; although even by allowing a larger volume of air to pass in the relatively larger opening, the brevity of the typical duration with a higher lift cam results in less airflow than with a cam with lower lift but more duration, all else being equal. On forced induction motors this higher lift could yield better results than longer duration, particularly on the intake side. Notably though, higher lift has more potential problems than increased duration, in particular as valve train rpm rises which can result in more inefficient running or loss of torque.Cams that have too high a resultant valve lift, and at high rpm, can result in what is called "valve bounce", where the valve spring tension is insufficient to keep the valve following the cam at its apex. This could also be as a result of a very steep rise of the lobe and short duration, where the valve is effectively shot off the end of the cam rather than have the valve follow the cams profile. This is typically what happens on a motor over rev. This is an occasion where the engine rpm exceeds the engine maximum design speed. The valve train is typically the limiting factor in determining the maximum rpm the engine can maintain either for a prolonged period or temporarily. Sometimes an over rev can cause engine failure where the valve stems become bent as a result of colliding with the piston crowns. Depending on the location of the camshaft, the cams operate the valves either directly or through a linkage of pushrods and rockers. Direct operation involves a simpler mechanism and leads to fewer failures, but requires the camshaft to be positioned at the top of the cylinders. In the past when engines were not as reliable as today this was seen as too much bother, but in modern gasoline engines theoverheadcam system, where the camshaft is on top of thecylinder head, is quite common.While today some cheaper engines rely on a single camshaft per cylinder bank, which is known as asingle overhead camshaft(SOHC), mostmodern engine designs (theoverhead-valve or OHVengine being largely obsolete on passenger vehicles), are driven by atwo camshaftsper cylinder bank arrangement (one camshaft for the intake valves and another for the exhaust valves); such camshaft arrangement is known as adoubleordual overhead cam(DOHC), thus, aV engine, which has two separate cylinder banks, may have four camshafts (colloquially known as aquad-cam engine).More unusual is themodernW engine(also known as a 'VV' engine to distinguish itself from thepre-warW engines) that hasfourcylinder banks arranged in a "W" pattern with two pairs narrowly arranged with a 15-degree separation. Even when there are four cylinder banks (that would normally require a total of eight individual camshafts), the narrow-angle design allows the use of just four camshafts in total. For theBugatti Veyron, which has a 16-cylinder W engine configuration, all the four camshafts are driving a total of 64valves.The overhead camshaft design adds more valvetrain components that ultimately incur in more complexity and higher manufacturing costs, but this is easily offset by many advantages over the older OHV design:multi-valve design, higherRPMlimit and design freedom to better place valves, ignition (Spark-ignition engine) and intake/exhaust ports. The rockers orcam followerssometimes incorporate a mechanism to adjust and set the valveplaythrough manual adjustment, but most modern auto engines havehydraulic lifters, eliminating the need to adjust the valve lash at regular intervals as the valvetrain wears, and in particular the valves andvalve seatsin thecombustion chamber.Sliding frictionbetween the surface of the cam and the cam follower which rides upon it is considerable. In order to reduce wear at this point, the cam and follower are bothsurface hardened, and modernlubricantmotor oilscontain additives specifically to reduce sliding friction. The lobes of the camshaft are usually slightly tapered, causing the cam followers or valve lifters to rotate slightly with each depression, and helping to distribute wear on the parts. The surfaces of the cam and follower are designed to "wear in" together, and therefore when either is replaced, the other should be as well to prevent excessive rapid wear. In some engines, the flat contact surfaces are replaced with rollers, which eliminate the sliding friction and wear but adds mass to the valvetrain.Camshaft bearings are similar to crankshaft main bearings, being pressure-fed with oil. However, OHC camshaft bearings do not always have replaceablebearing shells, meaning that a new cylinder head is required if the bearings suffer wear due to insufficient or dirty oil.CRANKSHAFTThecrankshaft, sometimes abbreviated tocrank, is responsible for conversion betweenreciprocating motionandrotational motion. In areciprocating engine, it translatesreciprocatinglinearpistonmotion into rotational motion, whereas in a reciprocating compressor, it converts the rotational motion into reciprocating motion. In order to do the conversion between two motions, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to which the "big ends" of theconnecting rodsfrom each cylinder attach.It is typically connected to aflywheelto reduce the pulsation characteristic of thefour-stroke cycle, and sometimes a torsional or vibrational damper at the opposite end, to reduce thetorsional vibrationsoften caused along the length of the crankshaft by the cylinders farthest from the output end acting on the torsional elasticity of the metal.Large engines are usuallymulti-cylinderto reduce pulsations from individual firingstrokes, with more than one piston attached to a complex crankshaft. Many small engines, such as those found inmopedsor garden machinery, are single cylinder and use only a single piston, simplifying crankshaft design. This engine can also be built with no riveted seam.The crankshaft has a linearaxisabout which it rotates, typically with severalbearing journalsriding on replaceablebearings(themain bearings) held in the engine block. As the crankshaft undergoes a great deal of sideways load from each cylinder in a multicylinder engine, it must be supported by several such bearings, not just one at each end. This was a factor in the rise ofV8 engines, with their shorter crankshafts, in preference tostraight-8engines. The long crankshafts of the latter suffered from an unacceptable amount of flex when engine designers began using highercompression ratiosand higher rotational speeds. High performance engines often have more main bearings than their lower performance cousins for this reason. The crankshaft has a linearaxisabout which it rotates, typically with severalbearing journalsriding on replaceablebearings(themain bearings) held in the engine block. As the crankshaft undergoes a great deal of sideways load from each cylinder in a multicylinder engine, it must be supported by several such bearings, not just one at each end. This was a factor in the rise ofV8 engines, with their shorter crankshafts, in preference tostraight-8engines. The long crankshafts of the latter suffered from an unacceptable amount of flex when engine designers began using highercompression ratiosand higher rotational speeds. High performance engines often have more main bearings than their lower performance cousins for this reason.Crankshafts can be monolithic (made in a single piece) or assembled from several pieces. Monolithic crankshafts are most common, but some smaller and larger engines use assembled crankshafts.THE MAIN AND BIG-END BEARINGSThe main and big-end bearings consist of indium-plated lead-bronze lined, steel shells. These bearings are precision manufactured and are ready for fitting.CONNECTING RODSIn a reciprocatingpiston engine, theconnecting rodconnects thepistonto thecrankorcrankshaft. Together with the crank, they form a simple mechanism that converts reciprocating motion into rotating motion.Connecting rods may also convert rotating motion into reciprocating motion. Historically, before the development of engines, they were first used in this way.As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank through both halves of a revolution, i.e. piston pushing and piston pulling. Earlier mechanisms, such as chains, could only pull. In a few two-stroke engines, the connecting rod is only required to push.Today, connecting rods are best known through their use in internal combustion piston engines, such asautomotive engines. These are of a distinctly different design from earlier forms of connecting rods, used in steam engines and steam locomotives.The earliest evidence for a connecting rod appears in the late 3rd century ADRomanHierapolis saw mill. It also appears in two 6th centuryEastern Romansaw millsexcavated atEphesusandGerasa. Thecrankand connecting rod mechanism of theseRoman watermillsconverted the rotary motion of the waterwheel into the linear movement of the saw blades.Sometime between 1174 and 1206, theArab inventorand engineerAl-Jazaridescribed a machine which incorporated the connecting rod with acrankshaftto pump water as part of a water-raising machine,but the device was unnecessarily complex indicating that he still did not fully understand the concept of power conversion.InRenaissance Italy, the earliest evidence of a albeit mechanically misunderstood compound crank and connecting-rod is found in the sketch books ofTaccola.A sound understanding of the motion involved displays the painterPisanello(d. 1455) who showed a piston-pump driven by a water-wheel and operated by two simple cranks and two connecting-rods.By the 16th century, evidence of cranks and connecting rods in the technological treatises and artwork ofRenaissanceEurope becomes abundant;Agostino Ramelli'sThe Diverse and Artifactitious Machinesof 1588 alone depicts eighteen examples, a number which rises in theTheatrum Machinarum NovumbyGeorg Andreas Bcklerto 45 different machines.In modernautomotiveinternal combustion engines, the connecting rods are most usually made ofsteelfor production engines, but can be made of T6-2024and T651-7075aluminum alloys(for lightness and the ability to absorb high impact at the expense of durability) ortitanium(for a combination of lightness with strength, at higher cost) for high performance engines, or ofcast ironfor applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the connecting rod and the piston can change as the rod moves up and down and rotates around thecrankshaft. Connecting rods, especially in racing engines, may be called "billet" rods, if they are machined out of a solidbilletof metal, rather than beingcastor forged.Thesmall endattaches to the piston pin,gudgeon pinorwrist pin, which is currently most oftenpress fitinto the connecting rod but can swivel in the piston, a "floating wrist pin" design. Thebig endconnects to the bearing journal on thecrank throw, in most engines running on replaceablebearingshells accessible via theconnecting rodboltswhich hold the bearing "cap" onto the big end. Typically there is a pinhole bored through the bearing and the big end of the connecting rod so that pressurizedlubricatingmotor oilsquirts out onto thethrustside of thecylinderwall to lubricate the travel of the pistons andpiston rings. Most smalltwo-stroke enginesand some single cylinderfour-stroke enginesavoid the need for a pumped lubrication system by using arolling-element bearinginstead, however this requires the crankshaft to be pressed apart and then back together in order to replace a connecting rod.A major source of engine wear is the sideways force exerted on the piston through the connecting rod by thecrankshaft, which typically wears thecylinderinto anovalcross-section rather than circular, making it impossible forpiston ringsto correctly seal against the cylinder walls. Geometrically, it can be seen that longer connecting rods will reduce the amount of this sideways force, and therefore lead to longer engine life. However, for a given engine block, the sum of the length of the connecting rod plus the pistonstrokeis a fixed number, determined by the fixed distance between the crankshaft axis and the top of the cylinder block where thecylinder headfastens; thus, for a given cylinder block longer stroke, giving greaterengine displacementand power, requires a shorter connecting rod (or a piston with smaller compression height), resulting in accelerated cylinder wear.The connecting rod is under tremendous stress from the reciprocating load represented by the piston, actually stretching and being compressed with every rotation, and the load increases to the square of the engine speed increase. Failure of a connecting rod, usually calledthrowing a rodis one of the most common causes of catastrophic engine failure in cars, frequently putting the broken rod through the side of thecrankcaseand thereby rendering the engine irreparable; it can result fromfatiguenear a physical defect in the rod, lubrication failure in a bearing due to faulty maintenance, or from failure of the rod bolts from a defect, improper tightening or over-revving of the engine. Re-use of rod bolts is a common practice as long as the bolts meet manufacturer specifications. Despite their frequent occurrence on televised competitive automobile events, such failures are quite rare on production cars during normal daily driving. This is because production auto parts have a much largerfactor of safety, and often more systematicquality control.FLYWHEELAflywheelis a rotating mechanical device that is used to storerotational energy. Flywheels have a significantmoment of inertiaand thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of itsrotational speed. Energy is transferred to a flywheel by applyingtorqueto it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.Common uses of a flywheel include: Providing continuous energy when the energy source is discontinuous. For example, flywheels are used inreciprocating engines because the energy source, torque from the engine, is intermittent. Delivering energy at rates beyond the ability of a continuous energy source. This is achieved by collecting energy in the flywheel over time and then releasing the energy quickly, at rates that exceed the abilities of the energy source. Controlling the orientation of a mechanical system. In such applications, the angular momentum of a flywheel is purposely transferred to a load when energy is transferred to or from the flywheel.Flywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a revolution rate of a few thousand RPM.Some modern flywheels are made of carbon fiber materials and employmagnetic bearings, enabling them to revolve at speeds up to 60,000 RPM.Carbon-composite flywheel batteries have recently been manufactured and are proving to be viable in real-world tests on mainstream cars. Additionally, they are more eco-friendly, as it is not necessary to take special measures in the disposal of them.Flywheels are often used to provide continuous energy in systems where the energy source is not continuous. In such cases, the flywheel stores energy when torque is applied by the energy source, and it releases stored energy when the energy source is not applying torque to it. For example, a flywheel is used to maintain constant angular velocity of thecrankshaftin a reciprocating engine. In this case, the flywheelwhich is mounted on the crankshaftstores energy when torque is exerted on it by a firingpiston, and it releases energy to its mechanical loads when no piston is exerting torque on it. Other examples of this arefriction motors, which use flywheel energy to power devices such astoy cars.A flywheel may also be used to supply intermittent pulses of energy at transfer rates that exceed the abilities of its energy source, or when such pulses would disrupt the energy supply (e.g., public electric network). This is achieved by accumulating stored energy in the flywheel over a period of time, at a rate that is compatible with the energy source, and then releasing that energy at a much higher rate over a relatively short time. For example, flywheels are used inriveting machinesto store energy from the motor and release it during the riveting operation.The phenomenon ofprecessionhas to be considered when using flywheels in vehicles. A rotating flywheel responds to any momentum that tends to change the direction of its axis of rotation by a resulting precession rotation. A vehicle with a vertical-axis flywheel would experience a lateral momentum when passing the top of a hill or the bottom of a valley (rollmomentum in response to a pitch change). Two counter-rotating flywheels may be needed to eliminate this effect. This effect is leveraged inreaction wheels, a type of flywheel employed in satellites in which the flywheel is used to orient the satellite's instruments without thruster rockets.The principle of the flywheel is found in theNeolithicspindleand thepotter's wheel.The flywheel as a general mechanical device for equalizing the speed of rotation is, according to the American medievalistLynn White, recorded in theDe diversibus artibus(On various arts) of the German artisanTheophilus Presbyter(ca. 10701125) who records applying the device in several of his machines.In theIndustrial Revolution,James Wattcontributed to the development of the flywheel in thesteam engine, and his contemporaryJames Pickardused a flywheel combined with acrankto transform reciprocating into rotary motion.A flywheel is a spinning wheel or disc with a fixed axle so that rotation is only about one axis. Energy is stored in therotoraskinetic energy, or more specifically,rotational energy: Where: is theangular velocity, and is themoment of inertiaof themassabout the center of rotation. The moment of inertia is the measure of resistance totorque applied on a spinning object (i.e. the higher the moment of inertia, the slower it will spin when a given force is applied). The moment of inertia for a solid cylinder is, for a thin-walled empty cylinder is, and for a thick-walled empty cylinder is,Wheremdenotes mass, andrdenotes a radius.When calculating withSIunits, the standards would be for mass,kilograms; for radius, meters; and for angular velocity,radianspersecond. The resulting answer would be in joules.The amount of energy that can safely be stored in the rotor depends on the point at which the rotor will warp or shatter. Thehoop stresson the rotor is a major consideration in the design of aflywheel energy storagesystem. Where: is the tensile stress on the rim of the cylinder is the density of the cylinder is the radius of the cylinder, and is theangular velocityof the cylinder.This formula can also be simplified using specific tensile strength and tangent velocity: Where: is the specific tensile strength of the material is the tangent velocity of the rim.OIL PUMPTheoil pumpin aninternal combustion enginecirculatesengine oilunder pressure to the rotating bearings, the sliding pistons and the camshaft of the engine. This lubricates the bearings, allows the use of higher-capacityfluid bearingsand also assists incoolingthe engine.As well as its primary purpose for lubrication, pressurized oil is increasingly used as ahydraulic fluidto power smallactuators. One of the first notable uses in this way was forhydraulic tappetsin camshaft and valve actuation. Increasingly common recent uses may include the tensioner for atiming beltorvariatorsforvariable valve timingsystems.The type of pump used varies.Gear pumpstrochoid pumpsandvane pumpsare all commonly used.Plunger pumpshave been used in the past, but these are now only used rarely, forsmall engines.To avoid the need forpriming, the pump is always mounted low-down, either submerged or around the level of the oil in the sump. A short pick-up pipe with a simple wire-mesh strainer reaches to the bottom of the sump.For simplicity and reliability, mechanical pumps are used, driven by mechanical geartrains from the crankshaft. Reducing pump speed is beneficialand so it is usual to drive the pump from thecam(if this is mounted in the cylinder block) ordistributorshaft, which turns at half engine speed. Placing the oil pump low-down uses a near-vertical drive shaft, driven by helicalskew gearsfrom the camshaft. Some engines, such as theFiat twin cam engineof 1964, began asOHVengines with an oil pump driven from a conventional camshaft in thecylinder block. When the twin overhead cam engine was developed, the previous oil pump arrangement was retained and the camshaft became a shortened stub shaft. Even when the distributor position was moved from the previous block-mount to being mounted on the cylinder head camshafts, the oil pump drive remained in the same position, the unused distributor position now covered by a blanking plate.Small engines, orscootersmay have internal gear pumps mounted directly on their crankshaft.For reliability, it is rare to use an external drive mechanism, either a separate belt drive or external gears, although camshaft-driven pumps often rely on the same timing belt. Additional separate belts are sometimes used wheredry sumppumps have been added to engines during tuning.Electric oil pumps are not used, again for reliability. Some 'turbo timer' electric auxiliary oil pumps are sometimes fitted toturbochargedengines. These are a second oil pump that continues to run after the engine has stopped, providing cooling oil to the hot bearings of a turbocharger for some minutes, whilst it cools down.These are supplementary pumps and do not replace the main, mechanical, oil pump.The oiling system addresses the need to properly lubricate an engine when its running. Properly lubricating an engine not only reduces friction between moving parts but is also the main method by which heat is removed from pistons, bearings, and shafts. Failing to properly lubricate an engine will result in engine failure. The oil pump forces themotor oilthrough the passages in the engine to properly distribute oil to different engine components. In a common oiling system, oil is drawn out of the oil sump (oil pan, in US English) through a wire mesh strainer that removes some of the larger pieces of debris from the oil. The flow made by the oil pump allows the oil to be distributed around the engine. In this system, oil flows through anoil filterand sometimes an oil cooler, before going through the engines oil passages and being dispersed to lubricate pistons, rings, springs, valve stems, and more.The oil pressure generated in most engines should be about 10 psi per every 1000 revolutions per minute (rpm), peaking around 55-65 psi.Local pressure (at the crankshaft journal and bearing) is far higher than the 50, 60 psi &c. set by the pumps relief valve, and will reach hundreds of psi. This higher pressure is developed by the relative speeds in feet per second (not RPM or journal size directly) of the crankshaft journal itself against the bearing, the bearing width (to the closest pressure leak), oil viscosity, and temperature, balanced against the bearing clearance (the leakage rate).All pump pressure does is fill in the hole and refresh the oil in the annular space faster than the leak expels it. This is why low-speed engines have relatively large journals, with only modest pump size and pressure. Low pressure indicates that leakage from the bearings is higher than the pumps delivery rate.The oil pressure at the pump outlet, which is what opens the pressure relief valve, is simply the resistance to flow caused by the bearing clearances and restrictions.The oil pressure gauge, or warning lamp, gives only the pressure at the point where its sender enters that part of the pressurized system not everywhere, not an average, nor a generalized picture of the systemic pressure.Despite the frequent comparison to hydraulic engineering theory, this is not a closed system in which oil pressure is balanced and identical everywhere. All engines are open systems, because the oil returns to the pan by a series of controlled leaks. The bearings farthest from the pump always have the lowest pressure because of the number of leaks between the pump and that bearing. Excess bearing clearance increases the pressure loss between the first and last bearing in a series.Depending on condition, an engine may have acceptable gauge pressure, and still only 5 psi pressure at one connecting rod, which will fail under high load.The pressure is actually created by the resistance to the flow of the oil around the engine.So, the pressure of the oil may vary during operation, with temperature, engine speed, and wear on the engine. Colder oil temperature can cause higher pressure, as the oil is thicker, while higher engine speeds cause the pump to run faster and push more oil through the engine. Because of variances in temperature and normal higher engine speed upon cold engine start up, its normal to see higher oil pressure upon engine start up than at normal operating temperatures, where normal oil pressure usually falls between 30 and 45 psi.Too much oil pressure can create unnecessary work for the engine and even add air into the system. To ensure that the oil pressure does not exceed the rated maximum, once pressure exceeds a preset limit a spring-loaded pressure relief valve dumps excess pressure either to the suction side of the pump, or directly back to the oil pan or tank.High oil pressure frequently means extremely high pressure on cold start-up, but this is a design flaw rather than an automatic consequence of high pressure. The observation if you raise the maximum pressure, the cold pressure goes too high is accurate, but not intentional.Even the stock pumps (regardless of brand and model) do not have enough relief valve capacity: the relief port is too small to handle the volume of cold oil. This is why there is a significant difference between cold & hot oil, high & low RPM, &c., but its typically not a problem with stock engines. A correctly designed relief port (which is not found in production engines) will flow any oil volume the gears will pass, regardless of oil viscosity or temperature, and the gauge reading will only vary slightly.The oil pressure is monitored by an oil pressure sending unit, usually mounted to the block of the engine. This can either be a spring-loaded pressure sensor or an electronic pressure sensor, depending on the type of sending unit. Problems with the oil pressure sending unit or the connections between it and the driver's display can cause abnormal oil pressure readings when oil pressure is perfectly acceptable.Low oil pressure, however, can cause engine damage. Low oil pressure can be caused by many things, such as a faulty oil pump, a clogged oil pickup screen, excessive wear on high mileage engines, or simply low oil volume. Indications of low oil pressure may be that the warning light is on, a low pressure reading on the gauge, or clattering/clinking noises from the engine. Low oil pressure is a problem that must be addressed immediately to prevent serious damage.The leading cause of low oil pressure in an engine is wear on the engines vital parts. Over time, engine bearings and seals suffer from wear and tear. Wear can cause these parts to eventually lose their original dimensions, and this increased clearance allows for a greater volume of oil to flow over time which can greatly reduce oil pressure. For instance, .001 of an inch worn off of the engines main bearings can cause up to a 20% loss in oil pressure.Simply replacing worn bearings may fix this problem, but in older engines with a lot of wear not much can be done besides completely overhauling the engine.Particles in the oil can also cause serious problems with oil pressure. After oil flows through the engine, it returns to the oil pan, and can carry along a lot of debris. The debris can cause problems with the oil pickup screen and the oil pump itself. The holes in the oil pickup screen measure about 0.04 square inches (0.26cm2).Holes of this size only pick up bigger pieces of debris and allow a lot of smaller pieces to flow through it. The holes in the screen are so big (relative to debris) because at low temperatures and slow engine speed the oil is very viscous and needs large openings to flow freely. Even with these large holes in the screen, it can still become clogged and cause low oil pressure. A .005-inch-thick (0.13mm) coating on the screen can reduce hole size to about .03 square inches (0.19cm2), which in turn reduces the flow of oil by 44 percent.Even after passing through the oil pickup screen and the oil filter, debris can remain in the oil. It is very important to change the oil and oil filter to minimize the amount of debris flowing through your engine. This harmful debris along with normal engine wear in high mileage engines causes an increase in clearances between bearings and other moving parts.Low oil pressure may be simply because there is not enough oil in the sump, due to burning oil (normally caused by piston ring wear or worn valve seals) or leakage. The piston rings serve to seal the combustion chamber, as well as remove oil from the internal walls of the cylinder. However, when they wear, their effectiveness drops, which leaves oil on the cylinder walls during combustion. In some engines, burning a small amount of oil is normal and shouldnt necessarily cause any alarm, whereas burning lots of oil is a sign that the engine might be in need of an overhaul.Conventionalwet sumpengines have one oil pump. It is generally located inside the lower part of the engine, usually below and/or to one side of the crankshaft. Ondry sump engines, at least two oil pumps are required: one to pressurize and distribute the oil around the engine components, and at least one other 'scavenge pump' to evacuate the oil which has pooled at the bottom of the engine.This scavenge pump is sometimes (but not always) located in the 'sump' of the engine, and crucially, this scavenge pump's flow-rate capacity must exceed that of the pump which pressurizes and distributes oil throughout the engine.Because of the dry sump's external oil reservoir, excess air can escape the oil before the oil is pumped back through the engine. Dry sumps also allow for more power because it reduces the amount ofwindage, oil sloshing up into the rotating assembly, and the vacuum from the scavenge pump improves ring seal.Dry sumps are more popular in racing applications because of the improved power and reduced oil sloshing that would otherwise reduce oil pressure. Disadvantages of dry sumps are increased weight, additional parts, and more chances for leaks and problems to occur.RELIEF VALVEThe lubricating oil pressure is limited by a relief valve. The valve is located in the lubricating system immediately before the oil filter and is fitted in the filter bracket on the cylinder blocks right hand side. The valve opens at an excessively high pressure and feeds oil back into the sump.OIL COOLERThe lubricating oil carries away from the engines most heated parts and evens out, by its circulation, the temperature differences within the engine. The heat is removed from the lubricating oil in the oil cooler. On marine engines the engines oil cooler is connected to the fresh-water system.OIL FILTERAnoil filteris afilterdesigned to remove contaminants fromengine oil,transmission oil,lubricating oil, orhydraulic oil. Oil filters are used in many different types ofhydraulic machinery. A chief use of the oil filter is ininternal-combustion engines in on- and off-roadmotor vehicles, lightaircraft, and variousnavalvessels. Other vehicle hydraulic systems, such as those inautomatic transmissionsandpower steering, are often equipped with an oil filter.Gas turbineengines, such as those on jet aircraft, also require the use of oil filters. Aside from these uses, oil production, transport, and recycling facilities also employ filters in the manufacturing process.Early automobile engines did not use oil filters. For this reason, along with the generally low quality of oil available, very frequent oil changes were required. The first oil filters were simple, generally consisting of ascreenplaced at theoil pumpintake. In 1923, American inventors Bobby Evans devised an automotive oil filter and called it thePurolator, aportmanteauof "pure oil later".This was abypass filter: most of the oil flowed directly from the oil pan to the engine's working parts, and a smaller proportion of the oil was sent through the filter via a second flow path in parallel with the first. The oil was thus filtered over time. Modern bypass oil filter systems for diesel engines are becoming popular in consumer applications, but have been in commercial use for some time due to potential reduction in maintenance costs.Oil filters are generally located near the middle or bottom of the engine.FUEL SYSTEMFuel is sucked by the feed pump from the fuel tank and then pumped through the fine filters to the injection pump. Surplus fuel is returned via the relief, located on the injection pump. The injection pump then pumps the amount of fuel, corresponding to the output required, at high pressure through the delivery pipes to the injectors. The injectors atomize the pressurized fuel into the engines combustion chambers. Return fuel from the injectors is led back through the fuel leak-off line via the relief valve and return line back to the tank.INJECTION PUMPAnInjection Pumpis the device that pumps fuel into the cylinders of adiesel engine. Traditionally, the injection pump is driven indirectly from thecrankshaftby gears, chains or a toothed belt (often thetiming belt) that also drives thecamshaft. It rotates at half crankshaft speed in a conventionalfour-stroke engine. Its timing is such that the fuel is injected only very slightly beforetop dead centreof that cylinder's compression stroke. It is also common for the pump belt on gasoline engines to be driven directly from the camshaft. In some systems injection pressures can be as high as 200MPa (30,000 PSI).Because of the need forpositive injectioninto a very high-pressureenvironment, the pump develops great pressuretypically 15,000 psi (100 MPa) or more on newer systems. This is a good reason to take great care when working on diesel systems; escaping fuel at this sort of pressure caneasily penetrate skin and clothes, and be injected into body tissues with medical consequences serious enough to warrantamputation.Earlier diesel pumps used an in-line layout with a series of cam-operated injection cylinders in a line, rather like a miniature inline engine. The pistons have a constant stroke volume, and injection volume (i.e., throttling) is controlled by rotating the cylinders against a cut-off port that aligns with ahelicalslot in the cylinder. When all the cylinders are rotated at once, they simultaneously vary their injection volume to produce more or less power from the engine.Inline pumps still find favour on large multi-cylinder engines such as those on trucks, construction plant, static engines and agricultural vehicles.For use on cars and light trucks, the rotary pump or distributor pump was developed. It uses a single injection cylinder driven from an axial cam plate, which injects into the individual fuel lines via a rotary distribution valve. Later incarnations such as theBoschVE pump vary the injection timing with crank speed to allow greater power at high crank speeds, and smoother, more economical running at slower revs. Some VE variants have a pressure-based system that allows the injection volume to increase over normal to allow aturbochargeror superchargerequipped engine to develop more power under boost conditions.All injection pumps incorporate agovernorto cut fuel supply if the crank speed endangers the engine - the heavy moving parts of diesel engines do not tolerate over speeding well, and catastrophic damage can occur if they are over-revved. Poorly maintained and worn engines can consume their lubrication oil through worn out crankcase ventilation systems and 'run away', causing increasing engine speed until the engine destroys itself. This is because most diesel engines only regulate their speed by fuel supply control and don't have a throttle valve to control air intake.Mechanical pumps are gradually being phased out in order to comply with international emissions directives, and to increase performance and economy. From the 1990s an intermediate stage between full electronic control were pumps that used electronic control units to control some of the functions of the rotary pump but were still mechanically timed and powered by the engine. The first generation four and five cylinder VW/Audi TDI engines pioneered these pumps before switching toUnit Injectors. These pumps were used to provide better injection control and refinement for car diesel engines as they changed from indirect injection to much more efficient but inherently less refined direct injection engines in the 1990s. The ECUs could even vary the damping of hydraulic engine mounts to aid refinement. BOSCH VP30 VP37 VP44 are example pumps. Since then there has been a widespread change tocommon rail diesel systems and electronicunit direct injectionsystems. These allow for higher pressures to be developed, and for much finer control of injection volumes, and multiple injection stages compared to mechanical systems.FEED PUMPAfuel feed pumpis a frequently (but not always) essential component on acaror otherinternal combustion enginedevice. Many engines (older motorcycle engines in particular) do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine. But in non-gravity feeddesigns, fuel has to be pumped from thefuel tankto the engine and delivered under low pressure to thecarburetoror under high pressure to thefuel injectionsystem. Often, carbureted engines use low pressure mechanical pumps that are mounted outside the fuel tank, whereas fuel injected engines often use electric fuel pumps that are mounted inside the fuel tank (and some fuel injected engines have two fuel pumps: one low pressure/high volume supply pump in the tank and one high pressure/low volume pump on or near the engine).Prior to the widespread adoption ofelectronic fuel injection, most carbureted automobile engines used mechanical fuel pumps to transfer fuel from the fuel tank into the fuel bowls of the carburetor. Most mechanical fuel pumps are diaphragm pumps, which are a type of positive displacement pump.Diaphragm pumpscontain a pump chamber whose volume is increased or decreased by the flexing of a flexiblediaphragm, similar to the action of a piston pump. Acheck valveis located at both the inlet and outlet ports of the pump chamber to force the fuel to flow in one direction only. Specific designs vary, but in the most common configuration, these pumps are typically bolted onto the engine block or head, and the engine's camshaft has an extraeccentriclobe that operates a lever on the pump, either directly or via a pushrod, by pulling the diaphragm to bottom dead center. In doing so, the volume inside the pump chamber increased, causing pressure to decrease. This allows fuel to be pushed into the pump from the tank (caused by atmospheric pressure acting on the fuel in the tank). The return motion of the diaphragm to top dead center is accomplished by a diaphragm spring, during which the fuel in the pump chamber is squeezed through the outlet port and into the carburetor. The pressure at which the fuel is expelled from the pump is thus limited (and therefore regulated) by the force applied by the diaphragm spring.The carburetor typically contains a float bowl into which the expelled fuel is pumped. When the fuel level in the float bowl exceeds a certain level, the inlet valve to the carburetor will close, preventing the fuel pump from pumping more fuel into the carburetor. At this point, any remaining fuel inside the pump chamber is trapped, unable to exit through the inlet port or outlet port. The diaphragm will continue to allow pressure to the diaphragm, and during the subsequent rotation, the eccentric will pull the diaphragm back to bottom dead center, where it will remain until the inlet valve to the carburetor reopens.Because one side of the pump diaphragm contains fuel under pressure and the other side is connected to thecrankcaseof the engine, if the diaphragm splits (a common failure), it can leak fuel into the crankcase.The pump creates negative pressure to draw the fuel through the lines. However, the low pressure between the pump and the fuel tank, in combination with heat from theengineand/or hot weather, can cause the fuel to vaporize in the supply line. This results in fuel starvation as the fuel pump, designed to pump liquid, not vapor, is unable to suck more fuel to the engine, causing the engine to stall. This condition is different fromvapor lock, where high engine heat on the pressured side of the pump (between the pump and the carburetor) boils the fuel in the lines, also starving the engine of enough fuel to run. Mechanical automotive fuel pumps generally do not generate much more than 10-15 psi, which is more than enough for most carburetors.As engines moved away from carburetors and towards fuel injection, mechanical fuel pumps were replaced with electric fuel pumps, because fuel injection systems operate more efficiently at higher fuel pressures (40-60psi) than mechanical diaphragm pumps can generate. Electric fuel pumps are generally located in the fuel tank, in order to use the fuel in the tank to cool the pump and to ensure a steady supply of fuel.Another benefit of anin-tank mounted fuel pumpis that a suction pump at the engine could suck in air through a (difficult to diagnose) faulty hose connection, while a leaking connection in a pressure line will show itself immediately. A potential hazard of a tank-mounted fuel pump is that all of the fuel lines are under (high) pressure, from the tank to the engine. Any leak will be easily detected, but is also hazardous.Electric fuel pumps will run whenever they are switched on, unless a safety device such as aninertial switchis fitted, which can lead to extremely dangerous situations if there is a leak due to mechanical fault or an accident. Mechanical fuel pumps are much safer, due to their lower operating pressures and because they 'turn off' when the engine stops running.In many modern cars the fuel pump is usually electric and located inside thefuel tank. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode (seeflammability limit) and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.The ignition switch does not carry the power to the fuel pump; instead, it activates a relay which will handle the higher current load. It is common for the fuel pump relay to become oxidized and cease functioning; this is much more common than the actual fuel pump failing. Modern engines utilize solid-state control which allows the fuel pressure to be controlled via pulse-width modulation of the pump voltage. This increases the life of the pump, allows a smaller and lighter device to be used, and reduces electrical load.Cars with electronic fuel injection have anelectronic control unit(ECU) and this may be programmed with safetylogicthat will shut the electric fuel pump off, even if the engine is running. In the event of a collision this will prevent fuel leaking from any ruptured fuel line. Additionally, cars may have aninertia switch(usually located underneath the front passenger seat) that is "tripped" in the event of an impact, or aroll-over valvethat will shut off the fuel pump in case the car rolls over.Some ECUs may also be programmed to shut off the fuel pump if they detect low or zero oil pressure, for instance if the engine has suffered a terminal failure (with the subsequent risk of fire in the engine compartment).The fuel sending unit assembly may be a combination of the electric fuel pump, the filter, the strainer, and the electronic device used to measure the amount of fuel in the tank via a float attached to a sensor which sends data to the dash-mountedfuel gauge. The fuel pump by itself is a relatively inexpensive part. But a mechanic at a garage might have a preference to install the entire unit assembly.Manyjet engines, includingrocket enginesuse aturbo pumpwhich is acentrifugal pumpusually propelled by a gas turbine or in some cases a ram-air device (particularly inramjet engineswhich lack a shaft).RELIEF VALVEThe valve both limits the feed pressure and provides continuous venting of the fuel system. When the feed pressure is too high the valve opens and fuel passes through the return line back to the tank. The relief valve is located on the injection pump. This means that the return fuel flushes through the injection pump before it is fed back to the tank. The fuel flow thereby cools the fuel in the pumps fuel chamber, at the same time equalizing the temperature and thus the viscosity of the fuel. The quantity of fuel delivered to each cylinder is, in this way, more evenly distributed.INJECTORSThe Fuel Injector is an electronically controlled valve that is supplied with pressurized fuel by the fuel pump and when energized atomizes the fuel into a fine mist so that it can burn easily by the vehicles engine. The fuel injector is mounted in the intake manifold so that fuel is sprayed directly at the intake valves. A fuel supply rail connects all of the fuel injectors to the fuel supply.A failing sensor can illuminate the MIL and cause the engine to run too rich or lean, leading to misfire and loss of power. Improper fuel filter maintenance can cause the injector to clog with debris. Poor quality fuel often results in deposits on the fuel injector disrupting the fuel spray pattern. TheCLEENFuel Injection Cleaning Kit (CST100C) can test fuel pumps, pressure regulators and diagnose leakingfuel injectors. An injector balance test with a scan tool will determine fuel contribution and an injector drop test will determine fuel flow through each injector.

FUEL FILTERSAfuel filteris afilterin the fuel line that screens out dirt andrustparticles from the fuel, normally made into cartridges containing afilter paper. They are found in mostinternal combustion engines.Fuel filters serve a vital function in today's modern, tight-tolerance engine fuel systems. Unfiltered fuel may contain several kinds of contamination, for examplepaintchips and dirt that has been knocked into thetankwhile filling, or rust caused by moisture in a steel tank. If these substances are not removed before the fuel enters the system, they will cause rapid wear and failure of the fuel pump and injectors, due to theabrasiveaction of the particles on the high-precision components used in moderninjection systems. Fuel filters also improveperformance, as the fewer contaminants present in the fuel, the more efficiently it can beburnt.Fuel filters need to be maintained at regular intervals. This is usually a case of simply disconnecting the filter from the fuel line and replacing it with a new one, although some specially designed filters can be cleaned and reused many times. If a filter is not replaced regularly it may become clogged with contaminants and cause a restriction in the fuel flow, causing an appreciable drop in engine performance as the engine struggles to draw enough fuel to continue running normally.Some filters, especially found ondiesel engines, are of abowl-like design which collectwaterin the bottom (as water is moredensethan diesel). The water can then be drained off by opening avalvein the bottom of the bowl and letting it run out, until the bowl contains only diesel. Many fuel filters contain awater sensorto signal to theengine control unitor directly to the driver (lamp on dashboard) if the water reach the warning level. It is especially undesirable forwater in fuelto be drawn into a diesel engine fuel system, as the system relies on the diesel forlubricationof the moving parts, and if water gets into a moving part which requires constant lubrication (for example an injector valve), it will quickly causeoverheatingand unnecessary wear. This type of filter may also include asensor, which will alert the operator when the filter needs to be drained. In proximity of the diesel fuel filter there might be a fuel heater to avoid the forming ofparaffin wax(in case of low temperatures) inside the filtrating element which can stop the fuel flow to the engine.AIR FILTERA particulateair filteris a device composed of fibrous materials which removes solidparticulatessuch asdust,pollen,mold, and bacteriafrom theair. A chemical air filter consists of anabsorbentorcatalystfor the removal of airborne molecular contaminants such as volatile organic compoundsorozone. Air filters are used in applications where air quality is important, notably in buildingventilation systems and in engines.Some buildings, as well asaircraftand other man-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spunfiberglassfilter elements. Another method,air ionisers, use fibers or elements with astatic electriccharge, which attract dust particles. The air intakes of internal combustion engines and compressors tend to use eitherpaper,foam, orcottonfilters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid-dynamics of the air-compressor part of the Gas Turbines.The combustion air filter prevents abrasive particulate matter from entering the engine's cylinders, where it would cause mechanical wear and oil contamination.Mostfuel injectedvehicles use a pleated paper filter element in the form of a flat panel. This filter is usually placed inside a plastic box connected to thethrottle bodywith ductwork. Older vehicles that usecarburetorsor throttle body fuel injection typically use a cylindrical air filter, usually a few inches high and between 6 inches (150mm) and 16 inches (410mm) in diameter. This is positioned above the carburetor or throttle body, usually in a metal or plastic container which may incorporate ducting to provide cool and/or warm inlet air, and secured with a metal or plastic lid.

FIRING ORDER OF DIESEL ENGINEThe firing order of the engine re-builded is found to be:1-2-4-6-5-3

Piston headFuel injectorCam shaftCylinder linerCrank shaft

Air filterRocker armEngine cross-section

Cylinder linerCylinder headRelief valveConnecting rod

Cam shaftAir start valveAir filter

Air start valvePistonRocker arm



Traded asTYO:7202



Founder(s)Yoshisuke Aikawa

HeadquartersTokyo, Japan

Key peopleSusumu Hosoi,President& Representative Director

ProductsCommercial vehicles,diesel engines

Isuzu Motors Ltd.(Isuzu Jidsha Kabushiki-Kaisha), (TYO: 7202)trading asIsuzu(Japanese pronunciation:[isuu],/isuzu/) is a Japanesecommercial vehiclesanddiesel enginemanufacturing company headquartered inTokyo,Japan. Its principal activity is the production, distribution and sale of Isuzu commercial vehicles and diesel engines. The company was founded byYoshisuke Aikawain 1916, as theTokyo Gas Company, a Japaneseoilandgasolinemanufacturer, which in 1934 fused with the carmaker and was renamed Isuzu, after theIsuzu River.Isuzu has assembly and manufacturing plants in the Japanese city ofFujisawa, as well as in the prefecturesTochigiandHokkaid. Isuzu is famous for producing commercial vehicles anddiesel engines. Isuzu-branded vehicles are sold in most commercial markets worldwide.In 2004, Isuzu was re-launched in Europe, primarily selling vehicles manufactured byGeneral Motors. By 2009, Isuzu had produced over 21 million diesel engines, which can be found in vehicles all over the world.Isuzu diesel engines are used byRenault-Nissan AllianceandGeneral Motors. It operates a 50:50 joint venture withAnadolu GroupcalledAnadolu Isuzu, which was formed in 1984 and is developing a range of minibus, city bus and intercity bus for sale in Turkey.Isuzu's history begins in 1916, when TokyoIshikawajimaShipbuilding and Engineering Co., Ltd. plan a cooperation with the Tokyo Gas and Electric Industrial Co. to build automobiles. The next step is taken in 1918, when a technical cooperation withWolseley Motors Limitedis initiated, meaning exclusive rights to the production and sales of Wolseley vehicles in East Asia.In 1922 the first Wolseley model, the A-9 car, is domestically produced. The CPtruckfollows two years later; 550 of these are built until 1927.In 1933, Ishikawajima Automotive Works merges with DAT Automobile Manufacturing Inc. (a predecessor ofDatsun) and changes its name to Automobile Industries Co., Ltd. The products of this company, marketed as "Sumiya" and "Chiyoda",were renamedIsuzu(after the Isuzu River) in 1934, following a meeting with the Ministry of Trade and Industry (MITI). The word Isuzu translated into English means "fifty bells" - hence the focus on "bell" in both the laterBelleland theBellett.In 1937 Automobile Industries is reorganized and formed into a new company, Tokyo Automobile Industries Co., Ltd. It was founded with a capital of one million yen. Only in 1949 is Isuzu also adopted as the company name. Meanwhile, in 1942,Hino Heavy Industrieswas split off from Isuzu, becoming a separate corporation.Truck production (TX40 and TU60) began anew in 1945, with the permission of theoccupation authorities.Beginning in 1953 theHillman Minxpassenger car is produced under license ofRootes Group. The Minx remained in production until 1962,after the 1961 introduction of Isuzu's first own car, theBellel.Being a small producer making cars which were somewhat too large and pricey for the Japanese market at the time, Isuzu spent some time looking for a commercial partner. Under pressure from MITI, who were attempting to limit the number of automobile manufacturers in Japan, a co-operation withFuji Heavy Industries(Subaru) began in 1966. TheSubaru 1000was even shown in Isuzu's 1967 annual vehicle brochure, as a suitable complement to the larger Isuzu lineup.This tie-up was over by 1968, when an agreement withMitsubishiwas formed. This ended even quicker, by 1969, and the next year an equally short-lived collaboration was entered withNissan.A few months later, in September 1971, what was to prove a more durable capital agreement was signed withGeneral Motors.The first result of GM taking a 34% stake in Isuzu is seen in 1972, only months later, when theChevrolet LUVbecomes the first Isuzu-built vehicle to be sold in the United States. To symbolize the new beginning, Isuzu also developed a new logo for 1974, with two vertical pillars which are stylized representations of the first syllable in ("Isuzu").In 1974 Isuzu introduced theGemini, which was co-produced with General Motors as the T-car. It was sold in the United States asBuick's Opel by Isuzu, and in Australia as the Holden Gemini. As a result of the collaboration, certain American GM products are sold to Japanese customers through Isuzu dealerships. Holden'sStatesmanwas also briefly sold (246 examples) with Isuzu badging in Japan during the seventies.Isuzu exports also increased considerably as a result of being able to use GM networks, from 0.7% of production in 1973 to 35.2% by 1976; this while overall production increased more than fourfold in the same period.In 1981 Isuzu began selling consumer and commercial vehicles under their own brand in the United States. TheIsuzu P'Upwas the first model sold to consumers as an Isuzu, rather than as aChevroletor Buick. Isuzu's then president Toshio Okamoto then initiated a collaboration with small-car expertSuzukito develop a global small car for GM, theS-car.A three-way agreement of co-ownership was signed in August 1981, with Isuzu and Suzuki exchanging shares and General Motors taking a 5% share of Suzuki.During this period Isuzu also developed a worldwide presence as an exporter of diesel engines, with their powerplants in use byOpel/Vauxhall,Land Rover,Hindustan, and many others. In the domestic Japanese market, OEM deals with other manufacturers were entered to aid the poorly performing passenger car arm. It led to the badging of Suzukis, beginning in 1986,and Subaru small commercial vehicles as Isuzus (Geminett,Geminett II). This OEM tie-up occurred alongside the establishment of SIA (Subaru-Isuzu Automotive), an American joint venture with Fuji Heavy Industries (the parent company ofSubaru). Shortly afterwards, theLafayette, Indianaplant became operational.In 1992 Isuzu ended US sales of theImpulse(Geo Storm). The following year it stopped exporting theStylus(the basis for theGeo Spectrum), the last Isuzu-built car sold in the US.In 1994 Isuzu began a new vehicle exchange program withHonda, whereby Honda sold theIsuzu RodeoandIsuzu Trooperas theHonda PassportandAcura SLX, respectively. In return Isuzu began selling theHonda Odysseyas the Isuzu Oasis. Thus, Honda's lineup gained two SUVs, and Isuzu's lineup gained a minivan. In the Japanese market, the Gemini (Stylus) was now a rebadgedHonda Domaniand the Aska (originally based on the GMJ-car) was aHonda Accord.In 1996 theIsuzu Hombrepickup, a badge-engineered GM truck, was introduced, and Isuzu's United States sales reached a peak. 1998 -General Motorsand Isuzu formDMAX, a joint venture to producediesel engines. Isuzu resurrects the beloved Amigo. The uniquely styledVehiCROSSconcept is unveiled. 1999 - GM raises its stake in Isuzu to 49%, effectively gaining control of the company. GM quickly follows this up with the appointment of an American GM executive to head Isuzu's North American Operations. This is the first time a non-Japanese executive has ever held such a high position at Isuzu. The U.S. introduction of the production version of the heralded VehiCROSS is met with mixed reviews, as its high pricetag, unique styling and two-door configuration don't seem to meet with market demands. 2001 -Joe Isuzu, the immensely popular pitchman with implausible claims, is hired once again to promote the newAxiom. Isuzu sales begin to slide due to the aging of theRodeoandTrooper, and poor management & lack of assistance from GM. Isuzu changes the name of the 2-door Amigo convertible to Rodeo Sport in an attempt to associate it with the better selling 4-door Rodeo. MovieSpy kidsfeatures Isuzu Axiom and Trooper. Early 2002 - Fuji Heavy Industries (Subaru's parent company) buys Isuzu's share of Lafayette, Indiana plant. Subaru Isuzu Automotive (SIA) becomesSubaru of Indiana Automotive. After 8 years of heavy Honda Passport sales and light Isuzu Oasis sales, Honda and Isuzu cooperatively end their vehicle exchange agreement. The Oasis is dropped, and Honda replaces the Passport with the Pilot. Also, it was Isuzu's last year for passenger vehicles inCanada, as Isuzus in Canada were mostly sold atSaturn-Saabdealerships. Late 2002 - Isuzu begins the re-purchase of its stock from shareholders, primarily General Motors. Isuzu reduces GM's 49% share to 12% as part of this comprehensive recapitalization plan. As part of this reorganization, GM gains full control ofDMAXandIsuzu Motors Polska, as well as ownership of all diesel engine designs from Isuzu. Isuzu drops the venerable Trooper from the North American lineup. 2003 - The Rodeo Sport is discontinued. July 2004 - Production of the Rodeo and Axiom cease. Sales in North America slow to just 27,188, with the discontinued Rodeo and Axiom making up 71% of that total. The number of Isuzu dealerships in the U.S. begins a rapid decline. 2005 - Isuzu dealers in the United States have only 2 models: the Ascender and the i-series pickup truck. The i-series is a rebadged Chevrolet Colorado, the Ascender is a re-badged GMC Envoy. At this point, Isuzu in the United States is primarily a distributor of medium duty trucks such as the NPR series. These vehicles are sourced both from Japan and U.S. plants in Janesville, Wisconsin and Flint, Michigan. Isuzu has 290 light-vehicle dealers in the U.S. as of August 2006, and sells an average of just two Ascenders per dealer per month. Plans to introduce a new Thai-builtSUV, expected to be added for 2007, are shelved; Isuzu Motors Limited believes that a new SUV would be too risky and proceeds with the launch of the i-series trucks. Rumors of Isuzu's withdrawal from the U.S. market are rampant. Despite extremely low sales figures of 12,177 passenger vehicles for 2005 (with leftover Axiom and Rodeos making up 30% of this), Isuzu Motors America announces its first profit in years, mainly due to restructuring cuts. 2006 - Production of the 7-passenger Ascender ends in February with the closure of GM'sOklahoma City Assemblyplant, leaving Isuzu with the 5-passenger Ascender, built in Moraine, Ohioand the low-selling i-Series as its only retail products. The company sold just 1,504 vehicles in North America in the first two months of 2006. Isuzu finally purchases its remaini