27-08-2014, 12:15 PM
INTRODUCTION The country, India, is basically an agricultural country where more than 65 % of population population, enough food has to be produced. This cannot be produced with our conventional bullock drawn implements. So there was need felt to invent such machine which speeds up the agricultural production. Due to this reason the tractor was invented. Before we start, it is necessary to know how the word ‘tractor’ is derived. Prior to 1900, the machine i. e. tractor is known as traction machine (pulling machine). After 1900, both the words joined by taking ‘tract’ from traction and ‘tor’ from motor calling ‘tractor’. The tractor is the machine which is used for applying high traction. In our country, tractors were started manufacturing in real sense after independence and at present, we are self sufficient in meeting demand of country’s requirements for tractors. At present in India, there are different tractor producing factories present like Hindustan machine tools, Punjab tractors, Kirloskar tractors, etc is directly o
II. COMPANY PROFILE 2.1 Birth of HMT In 1949 the idea of public sector tools was commissioned to be a corner stone for the government’s industrial development plans. This led to the birth of HINDUSTAN MACHINE TOOLS at Bangalore in 1953 which started a single machine tools factory to produce lathes at Bangalore, in collaboration with M/s Oerlikon of Switzerland. Next, the company widened its product range beyond lathes by entering into technical collaboration with other international leaders in machine tools such as Fritz Werner, Herman Kolb, Errantly Somua, Gildermeister, Liebherr etc. The second machine tool unit was set up in Bangalore in 1961 making use of the Company’s own resources. The company diversified itself when, in collaboration with Citizen Watch Company of Japan, the first watch factory was setup in Bangalore in 1962 to produce hand watches. The third machine tool unit was set up in 1963 at Pinjore, Haryana to produce milling machines. In next few years, Machine Tool Units were set up at Kalamessary in Kerala and in Hyderabad. The Printing Machinery division was attached to machine tools factory at Kalamessary to qualities Printing Machine. HMT’s tractor business commenced its operations in 1971 in technical collaboration with M/s MOTOKOV, Czechoslovakia because of the priority given to the agriculture in the national development plan and to take advantage of the green revolution. HMT started the operations with the manufacturing of 25 Hp tractors. Over the years, it has developed tractors ranging from 25 – 75 Hp. The unit in Hyderabad began to make lamps and lamp making machines in 1973 to cater to the growing needs of rural. This was followed by producing automatic watches. A third watches factory was established in Srinagar to manufacture hand wound watches for men. In 1975, the company took over the machine tool corporation of India’s unit in Ajmer, Rajasthan and its name was changed to HMT Limited. In 1975, a separate international scales network called HMT was set up comprising of company’s own agencies as well as other sales agents in Australia, Europe and America. This network was to handle the marketing strategy and operations of the company overseas and it also extended its services to the other leading Indians and overseas engineering companies. Since then this international arm of the company has set up the turkey project in Algeria, Indonesia, Iraq, Kenya, Nigeria and Srilanka. 2.2 HMT’s Products The main products produced by HMT ltd are – • Machine tools, • Watches, • Tractors, • Bearings, • Printing Machinery, • Die Casting Machinery. The divisions of HMT are described below – 2.2.1 Bangalore It produces lathes (both CNC and Non CNC), milling/ machining centers, grinding machines, gear cutting machineries, simple drilling machines, special purpose machines, die casting and plastic injection moulding. It also produces refurbishing and retrofitting like heavy duty, turret lathe, multi spindle drilling machines and fine boring machines. The other application components include the jigs, fixtures, some radar and transonic components. It also develops hinomerik control system, Hyderabad. 2.2.2 Hyderabad It produces the machining centers, CNC, Boring machines, milling machines, die and mould machining centers, presses and brakes. It also produces special purpose machines like CNC tube chamfering machines, cam shaft milling machines, filament winding machines, horizontal and vertical coil winding machines, multi spindle machining centers. 2.2.3 Kalamessary It produces CNC lathes and printing machineries. 2.2.4 Ajmer It produces grinders and lathes. It also manufactures some application components like hydraulic lift mechanism for tractors, valve devices and oil priming pump. The retrofitting includes center less grinders and double disc grinders. After establishing two machine factories and a watch factory in Bangalore, the Pinjore unit was established as the third machine tool factory. Breaking the ground on 2nd may, 1962, this factory III. TRAINING CENTRE In training centre, the basic machines are studied such as Lathe Machine, Milling machine, Drilling Machine, etc. 3.1 Structure of Training Centre Training center is divided into four sections, 1. Turning section, 2. Fitting section, 3. Milling section, 4. Tractor training section. 3.2 Turning Section In turning section, we have learnt about the lathe machine which is mother of all machines and play a basic role in mechanical line. 3.2.1 Lathe Machine Lathe is probably the oldest machine tools. The basic idea about turning or lathe machine came out in 17 century. Until 1770, lathes were useless metal cutting because they lacked power and holding device, were not strong enough and accurate enough to guide the tools. For its development to the form in which we know it now, we owe much to Henry Muldsley, who developed the sliding carriage and in 1880 built a screw cutting lathe. 3.2.2 Classification of Lathe Machine 1. Engine Lathe, 2. Speed Lathe, 3. Turret Lathe, 4. Toll Room Lathe, 5. Hollow Spindle Lathe, 6. Capstan Lathe, 7. Bench Lathe. Lathe is also called Complete Machine. This single machine can do number of operation. 3.2.3 Facing This operation is carried out to produce flat surface at the end of part, which is useful for parts that are attached to other components, or face grooving to produce grooves for O-ring seals. 3.2.4 Drilling In this process a drilling of desire diameter is held in the tail stock and the operation of drill is carried out. 3.2.5 Boring In this enlargement of hole or cylinder cavity made by previous process is done. It improves accuracy and surface finish. 3.2.6 Threading In this operation internal and external threads on the surface are prepared. 3.2.7 Knurling In this operation a regularly shaped roughness is prepared on the cylindrical surface for fascinating easy gripping. 3.3 Fitting Section Fitting work is very important work in engineering. In fitting shop unwanted material is removed with the help of hand tools. It is done for mating, repair and manufacturing purpose. The person working in fitting shop is called as fitter. Commonly used tools are hacksaw, files, chisels etc. 3.3.1 Tools Used in Fitting Shop 1. Clamping Tools 2. Measuring and Marking Tools 3. Cutting Tools 4. Striking Tools 5. Drilling Tools 3.4 Milling Section Milling machine were basically developed to machine flat surface. But, the present machine can machine flat, countered and helical surfaces, cut gears and do various other jobs. Due to this all milling machine is one of the most useful and necessary machine tools found in the shop and it rank next to the lathe in importance. Milling machine are designed to hold and rotate milling cutter or cutters, hold the work piece and feed the work piece to the milling cutter in one several directions. IV. FOUNDRY MECHANISMS Since there are certain basic steps in the metal casting process, these may be used as unit of mechanism. Processing steps which lead them to the mechanism are, 1. Sand preparation, 2. Core making, 3. Moulding, pouring and shakeouts, 4. Melting, 5. Cleaning. Foundry is divided into following section, 1. Sand plant system, 2. Sand handling system, 3. Core making and baking system, 4. Moulding making and handling, 5. Core setting system, 6. Melting system, 7. Metal pouring system, 8. Testing lab, 9. Fettling section, 10. Painting and printing section. 4.1 Sand plant system The main objective of it is to reuse the used lad to the installation of sand plant system. The vital task of sand plant system is to deliver well prepared sand at required place that will determine the efficient working of the foundry. After casing are knocked out of moulding box on a vibratory shakeout box that the used sand is returned to the fixed amount of new sand, binders, catalysts and hardeners to get to the required composition of the sand. Green sand, dry sand and oil sand are being prepared in the sand plant. These constitutes are added in Muller in which all contents are mixed thoroughly and then supplied via belt conveyor system to working stations. Green sand composition: Muller batch capacity 700 kg New sand 35 kg (5%) Bentonite 660 kg (94.4%) Water 3.6 kg (0.4 %) Return sand 1.4 kg (0.2%) Dry sand composition: Return sand 80% New sand 10% Bentonite 1.2% Dextrin 1.8% Moisture 7% Composition of oil sand (100 kg of sand): Bentonite 12 kg Dextrin 25 kg Linseed oil 15 kg Moisture 20 G 4.2 Sand handling system For handling the sand i. e. move it from one place to another, the bucket elevator and belt conveyor are used. 4.2.1 Bucket elevator When sand is to be conveyed vertically upward, a bucket is ideal. There are two pulleys, one at the top and other at the bottom which carry an endless belt. The belt carries number of buckets all around and the whole assembly is enclosed in steel casting which has two openings, one at bottom for feeding and other at top for discharge. 4.2.2 Belt conveyor It is used for transferring sand from one place to another. It consist of endless belt, two pulleys or idlers for carrying a loaded belt and returning the empty belt, a belt tightening mechanism and the belt cleaner. The angle of inclination should not be exceeding 150 for dry sand. 4.3 Core making and baking system As patterns are made to get to outer shape of the casting, the inner shapes are used to for whole generation core placed in the moulds. As the core comes in contact of molten metal that must possess following characteristics: 1. Core sand must have high strength to bear the pressure of metal when poured. 2. The sand must have high refractory characteristics so that it may not fuse due to high temperature being in contact with molten metal. 3. It must have high cohesive property so as to get good finish castings. Zircon paint (alcohol base) dried just by lightning it up. Large and heavy cores are baked along with the dry sand moulds in oven. Core drying cycles for oven: 3000 C – 1 hrs. 2000 C - 2 hrs. Cooling time in oven 3 hrs. After baking, the hardness is tested by using hardness meter 4.4 Mould making section Moulds are being made on moulding machine pedantically powered rammers. Metallic patterns are being used. After mould being made on moulding machine, it goes to sand cutter which removes extra sand present and level the mould base, from on to the power operated roller conveyor, the mould is handled using the swing type crane. Core setting is done in drag part of mould. Zircon painting is sprayed on to the mould (as paint is alcohol based hence get dry up by lighting fire). 4.4.1 Mould baking Dry sand moulds are to bake to acquire hardness to with sand the pressure produced by the flow of molten metal. These are baked in ovens. Mould baking cycles for ovens 300C for 2 hrs. and Cooling time in oven 3 hrs. 4.4.2 Melting section It is having two types of furnace. 1. Electric induction furnace, 2. Copula furnace. 4.5 Fettling After they are knocked out on vibrator shake, the casting head to be finished by the removal of projections whether they are gets riser or runner that where there as a part of design aspect or the projection which has appeared as a defect like fins or blow holes. The process that involves all these procedure of casting finish is termed as fettling. Fettling operation is divided into following stages: 1. Knocking out of dry sand cores, 2. Removal of gates and risers, 3. Extraction of fins and other projections, 4. Cleaning and smoothing of the surface, 5. Repair casting by filling of the blow holes, straightening the wrap or deformed casting. 4.6 Priming and painting After all the cleaning process has been performed then the final step is priming and the painting casting. The machine tool castings are generally big and are handled with crane during painting. Painting is done by brushes only. V. HEAY MACHINE SHOP 5.1 Introduction In heavy machine shop all the heavy part of tractor are machined like gear box housing, Main transmission housing, Front cover etc. all the parts undergoes different operations like milling, boring, drilling, tapping, slotting etc. in HMS section. The entire machines in this section are special purpose machine; it means the machine doing special or specific operation on a job. The advantage of special purpose machine is that it increases the rate of production. The machines are capable of machining any number of identical parts in a very less time. 5.2 Parts Machined in HMS 1. Gear box housing 2. Main transmission housing 5.2.1 Gear Box Housing Gear box housing is used for fitment of gears and shafts. The material used for Gear box housing is cast iron. 5.2.1.1 Process of Gear Box Housing Sr. no. Operation 1. Marking the gear box housing With help of crane, we put the housing on the surface plate and after this with the help of vernier height gigue we mark the gear box housing. Marking is done of the gearbox is done for remove the all allowances material. 2. Bottom Milling With help of crane we put the work piece on the milling machine (SPM). Bottom milling is done for removing the extra material on the gear box housing. 3. Drill the location hole on the gear box housing. Location holes are made for fix the housing on the different machine. 4. Top Milling Put the housing on milling machine according to location holes. Top milling done for removing the extra material on the housing. 5. Front and Rear Cover According to their location of hole we fix the work piece on the milling machine. For removing the all allowance on to the housing. 6. Left And Right Milling For removing the all allowance on to the housing. 7. Slot milling In this milling we made the slots for gear forks which used for change the gears. Dimension of slot is 16mm. 8. Boring Boring is done for removing extra material from bores to make the bore according to their dimensions. 9. Pre Boring of Steering Bore Pre boring is done for removing the allowance from steering bore. 10. Heavy Duty Drilling It is done for making the drilling in to the housing for joining purpose. 11. Bottom Milling Housing 20 drills simultaneous. 12. Tapping Tapping is for making the internal thread in to the drilled holes and for joining purpose. 13. Drill for Clutch and Pedal For joining the clutch and pedal drilling is done on both faces right and left on the gear box housing. 14. Final bores on the all bores i. e. steering bore, reverse gear and shaft boring on the boring machine. 15. Washing for the gear box housing in the washing machine. 16. Inspection of the Gear box housing according to design. 5.2.2 Main Transmission Housing Main Transmission Housing is manufacturing in heavy machine shop. M.T. Housing is used for setup the differential and axle assembly. Material used for M.T Housing is cast iron. 5.2.2.1 Manufacturing procedure of M.T Housing Sr. no. Operations 1. Marking M.T Housing With help of crane we put the housing on the surface plate and after this with the help of vernier height gauge we mark the M.T. Housing according to their dimension. White paint is used foe marking. 2. Horizontal Milling. Horizontal milling is done for removing the extra material or allowances according to their drawing 3. Radial Drilling Radial drills are used for the made the location holes in the housing and these locations are used for seat the job on the different type of machine. 4. Milling of M.T. Housing In this operation milling of four faces is done front, rear, left and right. In operation we fix the job on their location and holes and after we do milling 5. Boring In this boring operation we do rough boring of front, left & right bores. 6. Dimensions of bores: Left hand bore: 290mm. Right hand bore: 288& front hand bore: 90mm 7. Horizontal milling on front: Horizontal milling is done for remove the extra material or allowances according to their drawing. Horizontal milling is done on SPM milling machine. 8. Boring finish After horizontal milling we put the housing on the boring machine on their location holes. it is done for finishing purpose. 9. Washing Washing is done to remove chips and oil. this is done after all the operation. 10 Inspection Inspection of work piece according to their drawing. VI. LIGHT MACHINE SHOP 6.1 Introduction As the name suggests that in this section light parts or small parts of tractors are machined such as speed gears of tractor, sun & planet gears crown wheel, PTO shaft, clutch shaft, spline shaft, front and rear axle. 6.2 Spline shaft A shaft with longitudinal gear like ridges along its interior or exterior surface is called spline shaft. the function of spline shaft is to transmit the power from flywheel to lay shaft. Material used for spline shaft is low carbon steel. 6.2.1 Process for spline shaft 1. Raw material from vendors. 2. Cutting of shaft. 3. Facing and centering. 4. CNC turning. 5. Inspection 6. Gear hobbing. 7. Gear tooth rounding. 8. Fitting. 9. Washing. 10. Inspection. 11. Gear shaving. 12. Bench drilling. After these process spline shaft send to heat treatment plant for hardening process. 1. Gas carburizing & hardening. 2. Tempering 3. Shot blasting. 4. Straightening. 5. Centre grinding. 6. Internal grinding. 7. Fitting. 8. Inspection 6.3 Bevel Pinion Shaft Bevel pinion shaft is used for transmit the power from gear box to differential. The material used for it is low carbon steel. 6.3.1 Process for Bevel Pinion Shaft 1. Raw material from vender. 2. Material cutting. 3. Facing and centering 4. Turning on s-pilot machine. 5. Inspection according to drawing. 6. Gear hobbing. 7. Fitting. 8. Washing and inspection work piece. 9. Gas carburizing & hardening. 10. Annealing. 11. Turning. 12. Cylindrical grinding. 13. Thread rolling. 14. Drilling. 15. Tempering. 16. Shot blasting. 17. Straightening. 18. Washing & inspection of the bevel pinion shaft. 6.4 Wheel Shaft Wheel shaft is assembled in axle housing and its transmit torque to wheels. 6.4.1 Process for Wheel Shaft 1. Raw material from vender. 2. Facing and centering on lathe machine. 3. Drilling. 4. Radial drilling. 5. Gear hobbing. 6. Inspection according to drawing. 7. Induction hardening. 8. Tempering. 9. Cylindrical grinding. 10. Threading. 11. Fitting. 12. Horizontal milling. 13. Fitting 14. Inspection according to drawing. VII. HEAT TREATMENT All components (manufactured in LMS) after undergoing machining operation are subjected to heat treatment. It is done so as to improve hardness and strength of these components viz. gears and shafts. Basic operations performed during heat treatment: 1. Hardening, 2. Quenching, 3. Annealing, 4. Tempering, 5. Normalizing, 6. Carburizing. Melting temprature: 6400C, Carburizing media 13- 15 % sodium cyanide + 85 % BaCl + NaCl 7.1 Hardening For medium carbon steel and high carbon steel 8400C- 8500C For other 770 – 8200C Hardening is performed on the various metals and its alloys to provide them with strength and wear resistance. It is accomplished by heating the component above its hardening temperature and quenching it in water. 7.2 Quenching Emercing hot metal in desired water or oil does quenching. Here transfer of heat is ensured at slow rate so as to remove internal stresses to permissible limit. 7.3 Normalizing In this process, iron alloy casting is heated to 50 – 600C above critical temperature range. The casting is held for definite time and then allowed to cool in still air. Normalization eliminates casting or cooling strains and resultant casting is easy to machine. 7.4 Carburizing Process of adding carbon to surface layer of the component is called carburizing. It is the process of casehardening, which is addition of some elements like carbon, nitrogen to the surface by diffusion for surrounding medium at high temperature the purpose of carburizing is to obtain high surface wear resistance and obtain a hard surface. 7.5 Tempering For medium carbon steel and high carbon steel 6700 - 6800 C for fasteners tempering to be done at 3500 – 4000 C for 1 – 2 hrs. In tempering long grains formed during quenching are broken into smaller grains so as to improve elasticity of the material. Here heating is done at around 1800 - 2000 C for around 2 hrs. and then cool in air. It reduces internal stress and stabilizes the structure of metal. 7.6 Annealing For medium carbon steel and high carbon steel 6800 – 6900 C. 7.7 Case hardening Carburizing + hardening. 7.7.1 Process used for blackening 1. Job is clean with cotton waste. 2. Put the job in the NaOH solution for 10 to 20 min. for de-greasing or decomposition. 3. Wash it with warm water. 4. De-rust the job in the rust solution. 5. Wash it with water. 6. Shift it to blackening furnace at 1200 C for 10 – 20 min. according to sectional area VIII. ENGINE ASSEMBLY AND TESTING The engines of different models are assembled and tested in this shop as per standard procedures. 8.1 Engine Assembly In this shop, whole of the engine is completed and ready for the tractor assembly. The various parts of engine from manufacturing section are brought in this section and they are assembled to prepare the whole engine. The engine assembly can be divided into following steps. 1. Washing of crank case with a special soap solution and drying it by means of air jets. 2. Fitting of cylinder sleeve. 3. Fixing of studs and fitment of crank shaft in crank case. 4. Inserting pistons in cylinder sleeve. 5. Assembling the lubrication pump and fitment of cam shaft. 6. Mounting of flywheel with clutch assembly. 7. Fixing of cylinder head on the top of the cylinder sleeve. 8. Putting tappets, push rods and rocker arm for opening and closing the valves. 9. Attaching the fuel filters and oil filter. 10. Mounting the fuel injection pump and injection lines. 11. Fitting the self starter and alternator. Now the engine is ready for testing. Among the all parts fuel injection system is the heart of the engine. 8.1.1 Function of Injection Pump The purpose of injection pump is the ensure injection of the flue at high pressure in to cylinder space at certain instance and in correct amount. In gallery of injection pump there are fitted in operates. The injection pump is driven from the timing gear with shaft of injection pump to which it is connected with dog clutch. The cams of the camshaft causes movement of plunger in their barrels by mean of roller tappet to which plunger to is pressed with which rest at the lower spring late. The barrels are secured against turning with pins roller tappet are secured with tannens of roller which mesh with the grooves of pump body. Rollers which contact the camps are fitted on pins. In the recesses of top part of roller tappets adjusting screw with nuts are fitted by mean which the angular distribution of injection start of individual plunger can be adjusted. The working space of barrel are closed with delivery valve the tappers of which are pressed in to the valve bodies by means of spring with peg. The delivery valve are tightened to the cylinder head with the cylinder neck thread union to which the injection line is fixed connection the injection pump to injector. The deliver amount of fuel is changed by turning plunger i. e. by length over lapping the transverse intake orifice in barrel. The plunger is provide in its bottom part with a plunger vane which mesh with recess of control sleeve. The control sleeve gear with the teeth is mounted on the top part of control sleeve the teeth engaging into gearing of common control rack. The sleeve is tightened to the control sleeve by a screw. When the shifting the control rack plunger are turned their barrel and helix formed on the plunger opens sooner or later the transverse (intake) orifice in the barrel. In the plunger has been turned in such way that the transfer groove connection the face of the plunger with the helix edge flushes with transverse orifice in the barrel. The pump does not deliver any fuel and control rack is in its stop position. If the control rack is in its opposite position he pump deliver the maximum amount of fuel. At the side fuel gallery into intake parts a relief valve is mounted which maintains a constant pressure of 1 kg/cm2 on the intake port and the excessive amount of fuel is returned by this valve back to the tank. When starting the engine, by making the use of excess fuel, starting spring is fitted in governor which returns the control rack is obtained for the purpose of maximum delivery of fuel at maximum injection delay. At the opposite side of drive, the output governor is mounted which serves for regulating the engine output at higher performance revolutions. The range of governing is given by variable speed of engine. The governor controls the amount of injected fuel into the engine, with set up revolutions, in accordance with the taken of power. Decrease or increase of revolutions at a higher or lower load of engine is called unevenness of output governor. If the governing spring is set up from operator place to certain revolutions, the governor shift the link member of pump into such position which at a certain instantaneous load of engine corresponds to these selected revolutions. Terminology Connected with Engine Power 1. Bore: Bore is the diameter of the engine cylinder. 2. Stroke: It is the linear distance traveled by the piston from top dead center to bottom dead center. 3. Stroke bore ratio: the ratio of length of stroke and diameter of bore of the cylinder is called stroke bore ratio this ratio vary between 1 to1.45 and for tractor engine and this ratio is about 1.25. 4. Swept volume: It is the volume (A × L) displaced by one stroke of the piston. Where A is the cross sectional area of the piston and L is the length of stroke. 5. Compression ratio: it is the ratio of the volume of the charge at beginning of the compression stroke to that at the end of compression stroke that’s mean ratio of total cylinder volume to clearance volume. 6. Power: It is the rate of doing work. It is expressed in watt in SI unit. 7. Indicated power: it is the power generated in the engine cylinder and received by the piston. It is the power developed in the cylinder without friction or auxiliary unit. 8. Break power: It is the powered delivered by the engine and is available at end of the crankshaft. 9. Belt power: It is the power of the engine measured at the end of a suitable belt receiving drive from the PTO shaft. 10. Drawbar power: It is the power of a tractor, measured at the end of the drawbar. It is the power, which is available for pulling loads at the drawbar. 11. Power take off power: it is the power delivered by a tractor through its PTO shaft. 12. Frictional power: It is the power required to the engine at a given speed without producing any useful power. It represents the friction and pumping losses of an engine. 13. Mean effective pressure: it is the average pressure during the power stroke minus the average pressure during other strokes. This pressure actually forces the piston down during the power stroke. 14. Volumetric efficiency: It is the ratio of actual weight of air introduced by the engine on the suction stroke to the theoretical weight of air that should have been introduced by filling the piston displacement volume with air at atm. Pressure and temp. 15. Torque: A turning effect due to force applied on some point is called torque. 16. Specific fuel consumption: It is the quantity of fuel consumed per kW-hr. in an engine. 17. Brake mean effective pressure: It is the average pressure acting throughout the entire power strokes, which are necessary to produce brake power of the engine. 18. Mechanical efficiency: It is the ratio of brake power to indicated power. 19. Thermal efficiency: It is the ratio of output in the form of useful mechanical power to the power value of the fuel consumed. Engine components Internal combustion engine consists of number of parts which are given as below 1. Cylinder: It is part of the engine which confines of the expanding gases and forms the combustion space. It provides space in which piston operates to suck the air or air fuel mixture. Cylinders are usually made of high grade cast iron. 2. Cylinder block: It is the solid casting which includes the cylinder and water jackets. 3. Cylinder head: It is detachable portion of an engine which covers the cylinder and includes the combustion chamber, spark plug and valves. 4. Cylinder liner or sleeve: It is cylindrical lining either wet or dry which is inserted in the cylinder block in which the piston slides. Cylinder liners are fitted in the cylinder bore and they are easily replaceable. The overhauling and repairing of the engines, fitted with liners is easy and economical. Liners are classified as a. Dry liner and b. Wet liner A) Dry liners make meal to metal contact with the cylinder block casting. B) Wet liners are come in contact with the cooling water, where as dry liners do not come in contact with the cooling water 5. Piston: it is cylinder part closed at one end which maintains a close sliding fit in the engine cylinder. It is connected to the connecting rod by a piston pin. The force of the expanding gases against the closed end of the piston , forces the piston down in the cylinder. This causes the connecting rod to rotate the crankshaft. Aluminum and its alloy are preferred to made piston. Head (Crown) of piston: it is the top of the piston. Skirt: it is that portion of the piston below the piston pin which is designed to absorb the side movements of the piston. 6. Piston rings: it is split expansion ring, placed in the groove of the piston. They are usually made of cast iron or pressed steel alloy. the functions of the rings are : A) It forms a gas tight combustion chamber for all positions of piston. B) It reduces contact area between cylinder wall and piston wall for preventing friction losses and excessive wear. C) It controls the cylinder lubrication. D) It transmits the heat away from the piston to the cylinder wall. Piston rings are of two types; A) Compression ring and B) Oil ring 7. Piston pin: it is also called wrist pin or gudgeon pin . it is used to join the connecting rods to the piston.. it provides a flexible or hinge like connection between the piston and the connecting rod. It is usually made of case hardened alloy steel. 8. Connecting rod: it is special type of rod. One end of which is connected to piston and the other to the crankshaft. It transmits the power of combustion to the crankshaft and makes it rotate continuously. It is usually made of drop forged steel. 9. Crankshaft: It is the main shaft of an engine which converts the reciprocating motion of the piston in to rotary motion of the flywheel. Usually the crankshaft made of drop forged steel or cast steel. Crankshaft is provided with counter weights throughout its length to have counter balance of the unit. 10. Flywheel: Fly wheel is made of cast iron. It stores energy during power stroke and returns back the same energy during the idle strokes .engine timing marks are usually stamped on the flywheel which helps in the adjusting the timing of engine. 11. Crankcase: the crankcase is that part of the engine supports and encloses the crankshaft and camshaft: it provides the reservoir for the lubricating oil of the engine. It also serves as a mounting unit for such accessories as the oil pump , oil filter, generator, starting motor and ignition components. 12. Camshaft: It is shaft that raises and lowers the inlet and exhaust valves at proper time. The speed of the camshaft is exactly half the speed of crankshaft in four stroke engine. It is mounted in the crankcase parallel to the crankshaft. 13. Timing gear: timing is a combination of gears one gear of which mounted at one end of camshaft and other gear on the end of crankshaft. Timing gear controls the timing of ignition, timing of opening and closing of valves as well as fuel injection timing. 14. Inlet manifold: it is that part of engine through which air or air fuel mixture enters into the engine cylinder. It is fitted by the side of the cylinder head. 15. Exhaust manifold: it is that part of engine through which exhaust gases go out from engine cylinder. It is fitted by the side of the cylinder head. 8.2 Engine testing After assembly, engine is brought to engine testing section. In this section, practical checking of engine is done on engine. Firstly the water supply is given to the engine and then started it with external DC supply. During running the engine, the load is varied and various terms are checked such as lubricating oil pressure, load capacity, fuel consumption, torque, operating temperature, etc. Then proper operating of valves is checked. 8.2.1 Procedure for Engine Testing 1. Note starting time of engine and also bed no. which it is being tested. 2. Check oil level of engine and FIP. 3. Check clearance of valve tappets for inlet and exhaust. 4. Check oil pressure at idle and rated rpm. 5. Check any unusual sound. 6. Check idle and fly up rpm. 7. Check leakage of water, fuel and oil at rated rpm. 8. Check load and torque at rated rpm, fuel timing in seconds for 100cc and recheck oil pressure. 9. Check outlet water temp. 10. Check leakage in front and rear oil seal. 11. Check visible blow hole in component, if any. 12. Pix OK sticker. 13. Check engine no. punched on engine. It is to be same as on sticker. The engine is kept running for 2 hours. For proper working, load capacity is checked by applying load on the shaft of engine through water. The lubricating oil pressure in the engine should be 3.8 to 4.2 Kg/ cm2. The maximum RPM of the engine are kept 2200. Supplying a measured quantity of fuel, the fuel consumption is checked. For this test, 100 cc (cm3) fuel is supplied to the engine. Corr. Power = Where, C. F. = P= atm. Press. (mm of Hg ) T= ambient temp. (0c) Corr. SFC. = Volume of fuel is 100cc or 200cc and fuel time is in sec. 8.2.2 Engine testing cycle time Running time (min) RPM Load, l 10 700 Nil 20 1000 20 30 1400 50 30 1700 75 10 1600 75 5 1800 100 5 Rated 2100/2200 100 8.3 Specifications of HMT Tractors 8.3.1 Model 2522 Sr. no. Particulars Specifications 1. Bore × Stroke (mm) 95 × 110 2. Engine rated speed (rpm) 2100 3. Engine fly up rpm 2300 + 60 4. Static injection timing (0 BTDC) 14 5. Tappet clearance - Inlet valve (mm) 0.3 Exhaust valve (mm) 0.4 6. Height of cylinder liner above cylinder block (mm) 0.06 - 0.12 7. Bumping clearance (mm) 0.75 + 0.4 8. Injection tip (mm) 2.2 – 2.5 9. Injection pressure (bar) 190 + 8 10. Piston ring end gap (mm) - First ring 0.2 – 0.4 Second ring 0.4 – 0.6 Third ring 0.25 - 0.5 11. Nozzle spray holes 5 × 0.2 × 150 12. H. P. pipe size (mm) 6 × 1.8 × 500 13. Ring colour on injector Utility green 8.3.2 Model 3022 Sr. no. Particulars Specifications 1. Bore × Stroke (mm) 102 × 110 2. Engine rated speed (rpm) 2100 3. Engine fly up rpm 2300 + 60 4. Static injection timing (0 BTDC) 22 5. Tappet clearance - Inlet valve (mm) 0.25 Exhaust valve (mm) 0.25 6. Height of cylinder liner above cylinder block (mm) 0.02 - 0.06 7. Bumping clearanc