The Propulsion System Engineering Essay

The Propulsion System locomotiveering EssayThe actuation g everywherening body with respect to this application cornerst wholeness be defined as the scheme which provides fomite motion. Thus, this project involves the design of a corpse of rules for streamlined power gene dimensionn and transmission of power from power plant to the operate hertzs with minimum power drag going awayes.All design features must keep an eye on with the shell Eco-Marathon Asia 2010 rules and regulations 1Main objectivesSelection of a qualified energy asc destroyent to power the vehicleOverall dust designStock choice and design of componentsDetailed analysis and optimisation of for each one(prenominal) sub remains for ut about force out expertnessheel role modeling and detailed order of paymentVerification of selected and designed components through calculation and sui remit simulation softw are programFinal performance estimationAll design features must be approved by shell Eco-M arathon organizersParts quotation1.2 About the ambitionThe principle of the Shell Eco-Marathon is simply to design and build the most go off efficient vehicle while producing the hardly a(prenominal)est emissions. 1, 30Teams croup enter devil main categoriesFuturistic prototypesThese are streamlined vehicles where the primary design friendliness is cut back drag and maximizing power train force. This category has little restrictions. 1Urban Concept vehiclesThese are built to to a greater extent conventional 4-wheel roadworthy criteria. 1 design leadments and other rules related to the propulsion system are listed in appendage F1.3 Competition category and energy source plectron aft(prenominal) few days of research and discussion considering time, cost and expertise of team, it was decided to compete under the prototype category with an internal electrocution locomotive running on ethanol as the power plant.CHAPTER 2.0LITERATURE look back2.1 IntroductionThis fiftyatu re reassessment provides details on retiring(a) endurance vehicles and the latest developments in the area of fork up talent, alternative give the sacks and future propulsion systems.Articles and reports were put in related to vehicles designed and developed mainly for Shell Eco-Marathon and SAE Supermileage competitions.2.2 The domain recordThe most furnish efficient car in the world, political action committee Car II designed and developed by ETH Zurich (Swiss Federal embed of Technology) was powered by a Hydrogen provoke cell and it had a record of 12600 Miles per Gallon (US) during the Shell Eco-Marathon, France in 2005 3. This clearly omend the level of competition, touchstone of potential for go off efficiency and alternative arouses.2.3 Ethanol as vehicle give the sackArticles 4 on ethanol combustion and conversion of petrol locomotive locomotive railway locomotives were found which provided detailed practical commentary.An ethanol powered car locomotiv eered by cut steep school students from Lyce La Joliverie had achieved the best send away efficiency at the European Shell Eco-marathon 2006, winning the race at the Nogaro cable car racing circuit in southwest France by jauntling 2885 kilometers per liter of gasoline equivalent. It also took the Climate Friendly laurels for producing the least babys room gas emissions. 6Currently ethanol E85 (85% ethanol) powered vehicles are produced by leading(p) automotive manufacturers such as Ford, Chevrolet, Chrysler, Toyota, Nissan etc 82.4 Engine and assume trainfomite designed and built by Alerion Supermileage team from Laval University of Quebec, Canada won the grand prize of the Shell Eco-Marathon Americas 2010 recording 1057.5 kilometers per liter. This vehicle consisted of an internal combustion locomotive locomotive.The Dalhousie University team had utilise the Honda GX35 railway locomotive for their vehicle with a direct lead transmission system for Shell Eco-Marathon Americas in 2008/2009 which travelled 332.8 km/l gasoline 5. observational determine obtained by dynamometer testing for the GX35 railway locomotive were also published. 22.5 fuel delivery systemsMost endurance vehicles in previous competitions had mechanic fuel fondnesss to pressurize fuel. The Dalhousie team employ a pressurized fuel system in 2008/2009 which yielded successful results. fuel injection systems are known to be much efficient than carburetor systems since in that respect is more(prenominal) control over the sprinkle of fuel.2.6 Intake and get systemThe internal combustion engines and fluid chemical mechanism online lecture nones published by the Colorado State University provided base explanation about consumption/exhaust tuning. Current developments in this field are related to variable valve quantify.Fiat was the first automotive manufacturer to sheer a variable lift system. Developed by Giovanni Torazza 1960, the system physical exertiond hydrau lic expression pressure level level to vary the fulcrum of the cam followers (US Patent 3,641,988). The hydraulic pressure changed according to engine speed and intake pressure. 43After continued improvement, a system with variable valve quantify, 2 stage valve lift on the intake valves and variable timing of the exhaust valves was developed by Porsche in 2009. 40In 2010, Mitsubishi developed and started mass production of the 4N13 1.8 L Diesel Overhead Cam Inline 4 cylinder engine. This is the first passenger car with a diesel engine that features a variable valve timing system. 392.7 Latest trends in fuel efficiencyThere is much research and development in the area of atomic number 1 fuel cells and hybrid systems. Although the principle of the fuel cell was discovered in 1838, it has not been a popular topic until recent years. Currently, hybrid systems and henry fuel cells are considered the future of vehicle propulsion systems.CHAPTER 3.0ENGINE THE organization POWER PL ANT3.1 IntroductionA small four gibe gasoline engine was call for to be selected and modified for ethanol combustion with maximum fuel efficiency.3.2 Fuel Ethanol EcenturyThe main idea scum bag selecting ethanol as the fuel for the engine is that ethanol has a high octane jimmy (Higher auto ignition point). wherefore the engine go away not knock at higher concretion symmetrys. 8, 4It is also a renewable fuel produced by corn, sugar nominatee etc and although controversial is regarded as generating less toxic emissions. 83.3 Stock engine choiceMain special(prenominal)ation guidelines bent-grass in order to select few potential engines that can be utilize for the systemEngine typeAir cooled, four stroke, wizard cylinder petrol engineDisplacement35 to 50 cm3 force play OutputMaximumMassMinimumTable 1.0 Specification guidelines for selectionAdhering to the set guidelines (refer table 1.0) few potential engines were selected.Scooter engine, 139QMB, 9350R/S 35cc redbreast/ Subaru 4-Stroke engine used for bicycles, 10Honda GX35 mini 4 stroke used in lawn mowers, 11 gas pedal engine (142F) manufactured and supplied by Shandong Huasheng Zhongtian Machinery group CO.LTD, 12Detailed peculiar(prenominal)ations for these engines are accustomed in supplement C3.3.1 Parametric studyMain parameters considered for this study were specific fuel consumption, mass, ease of modification, availability, versatility and reliabilityThe fuel efficiency of an engine is instantly related to the brake specific fuel consumption. 13During the autumn semester, the amaze train was assumed to be 100% efficient and mass of car without engine was estimated as 330lbs.These set were only used for comparing engines.The miles per congiuslon value were estimated employ the Bowling and Grippo program for various BSFC values. 7The estimates for coefficient of drag, frontal area, wear off inflation pressure, vehicle weight were obtained from other team members in sharpen of ea ch sub assembly.Program inputsCoefficient of drag0.13Frontal area (Square feet)8.04Vehicle miles per minute (MPH)18Vehicle weight in lbs330Tire inflation pressure in psi80Engine Brake Specific Fuel Consumption (gal/hr-hp)Inputs from 0.01 to 0.25Drive train horsepower lossAssumed 0 for engine comparisonTable 2.0 Bowling and Grippo program inputs(Refer Table 6.0 in Appendix D for results) invention 1.0 Estimated MPG vs. BSFCThe specific fuel consumption of the engine should be a minimum to obtain high miles per gal of fuel (from pick up 1.0).The engines selected were further short listed considering the information available and ease for modification.142F Gasoline engineBrake specific fuel consumption = 480 g/kW-htightness of gasoline = 2790.38 g/gal, 15480 g/2790.378 g/gal = 0.1720 gal0.1720 gal/1.341 hp-hBSFC = 0.1283 gal/hp-hHonda GX35Brake specific fuel consumption = 360 g/kW-hThis value in gal/hp-h = 0.0962 gal/hp-hMiles per gallon was estimated (assuming no power loss in drive train) for each engine while considering the mass of each engine.Estimated weight of vehicle without engine = 330 lbs lean of vehicle with 142F engine = 335.5 lbs, this gives an estimated MPG of 790.84.Weight of vehicle with Honda GX35 = 333.8 lbs, this gives an estimated MPG of 1058.84.7Figure 2.0 MPG for 142F and GX35 enginesAlthough miles per gallon value would be lower when drive train power loss is considered, the engine was compared assuming a 100% efficient drive train.These calculations are based on gasoline fuel for engine comparison purposes.Study results clearly indicate that the Honda GX35 is the most suitable engine for this system and also considering the reliability factor of Honda further proves that this engine should be selected for this application.3.4 Honda GX35Main vantages of Honda GX35 engine 11Lower brake specific fuel consumptionMass is almost 2 kg less than 142F bump reliability and it has been improved over the past 10-11 years.Over Head Cam engine Carryi ng out modifications on the cylinder head is easier.360o inclinableThe only dis proceeds is that it consists of a carburetor. A fuel injection system would have been more fuel efficient but electronic fuel injection would also require an Engine management system and alternator which would add more weight to the vehicle. and so weight is less with carburetor.Performance curvesCDocuments and SettingsPulsaraDesktopFYP RESEARCHcurve_GX35.gifFigure 3.0 Performance and fuel consumption curves 11Basic calculationsheadway Volume (Stock GX35)Swept Volume = 35.8 cm3, condensate proportionality, rc = 81Compression symmetry = Total Volume, (Vc+Vd)/ dynamic headroom Volume, VcClearance Volume, Vc = 5.114 cm3Brake mean effective pressure (BMEP), (Stock GX35)Maximum power product = 1.3 HP at 7000rpmL is displacement in liters, L = 0.0358 lBMEP = 67.44 lbf/in2Calculation of specific fuel consumption with ethanol without any system modificationsFuelNCV (KJ/l)NCV (KJ/gal(US))Gasoline31627.841197 24.42Ethanol21229.4880362.34Table 3.0 Net calorific values by tawdriness 1, 15BSFC with ethanol0.0962 gallons of gasoline = 119724.42 x 0.0962 KJ = 11517.45 KJTherefore BSFC of Honda GX35 engine with ethanol fuel = 0.1433 gal/hp-h(GX35 specifications in appendix C).3.5 ModificationsFigure 4.0 Engine modifications3.5.1 Mandatory modifications for ethanol combustionCarburetor modificationMain outpouring changesSince the energy density of ethanol is lower than gasoline, the fuel/ breeze symmetry should be change magnitude. The main jet curtain raising can be world-weary out to increase the size of the orifice by around 30% of the original size. The argumentation/fuel proportion for ethanol combustion should be 10.071. 4, 1Idle orifice changesWhen the throttle plate is at swooning slip, the air/fuel mixture is only allowed to enter the manifold through the idle orifice. The idle mixture screw could be loosened or orifice could be bored out to increase the size by 30% in order t o provide sufficient ethanol to keep the engine running at idle speed. 4Overall engine and piping systemEthanol is a strong cleaning agent and has the ability to drop off certain engine parts such as, natural rubber, plastics, and even metals over time. Therefore, all rubber and plastic components should be replaced by synthetic material. 4It is recommended to use neoprene hoses for the fuel delivery system. 4Durability of various plastics Ethanol vs. Gasoline in table 3.1in appendix D.3.5.2 Modifications for maximum fuel efficiencyCompression dimension alte rationThis is discussed with detailed analysis in chapter 5.0Intake and exhaust optimizationThis is discussed with detailed analysis in chapter 6.0Starting systemAn electric grouch would be installed which would enable the driver to turn off the engine and bank by and by reaching a particular speed and restart later(prenominal) with ease.ChokeA manual(a)ly controlled trammel is better for ethanol engines and especially f or this competition. Therefore if the engine is equipped with an automatic choke it can be adapted for manual control using a manual choke conversion kit.CHAPTER 4.0COMPRESSION RATIO ALTERATION4.1 IntroductionThis is the main advantage of using ethanol as fuel. The crunch ratio can be increased up to 16-201 without engine knock. 20Increasing the compression ratio increases the thermal efficiency of the engine but it should only be increased to an extent to which the engine could withstand the pressure and temperature.Methods to increase the compression ratio 21Cylinder head and block can be shaved by milling (planning) the surfaces.Modify or change the piston head.Inlet conditions (High pressure, temperature etc) ignore gasket thickness4.2 AnalysisFor this analysis, the combustion chamber of the engine was assumed to be cylinder shapedr = Bore/2 = 1.95cmXVC (Stock) = 5.114 cm3r2 X = 5.114X = 0.428 cmMilling the head/block or reducing thickness of the gasket would reduce X which wou ld result in a littler clearance volume, VC.A smaller clearance volume results in a higher compression ratio which also generates more power.Valve clearance for Honda GX35This is the maximum distance the valve travels beyond the engine head.Intake Valve clearanceExhaust Valve Clearance0.08 +/- 0.02mm0.11 +/- 0.02mmTable 4.0 GX35 Valve clearance 17The value of X after modifications must be greater than 0.13 mm to avoid valve/piston collision.Let Y be the amount of head/block milled or reduced from gasketX = (4.28 Y) mmThere is no direct theoretical relationship betwixt horsepower and compression ratio but the Bowling and Grippo program provides a rough estimate which was tabulated in table 6.1 in appendix D. 7For specific new fuel consumptionTabulated results can be found in Table 6.1 in Appendix DFigure 5.0 Compression ratio vs. reduction in combustion chamber height (Y)Figure 5.1 Estimated engine HP vs. reduction in combustion chamber height (Y)Figure 5.2 BSFC vs. reduction in c ombustion chamber height (Y)Figure 5.3 Estimated miles per gallon vs. reduction in combustion chamber height (Y)From research it was found that the compression ratio could be increased to 16-201 with ethanol fuel without knock problems but there was no credible information on how much compression the engine could withstand. Therefore, it was specified to increase the compression ratio only up to 121.This increase in compression ratio would result in an increase of 55 miles per gallon (US)(Refer figures 5.0, 5.1, 5.2 and 5.3)4.2.1 Engine cyclical analysisFigure 6.0, P-V diagram for naturally aspirated Spark ignition engine 25Inlet conditions blackmail (P) = 1 bar, Temperature (T) = 303 K, Ideal Gas ageless (R) = 287 J/kg. K,proportion of specific heats () = 1.4, CV = 717.6,For perfect gas,Where, is the total mass of charge mixtureFrom fuel consumption calculations using net calorific valuesFuel /Air ratio (FAR) of Ethanol = 1.49 x FAR of gasolineFAR (Ethanol) = 1/15 x 1.49 = 0.0993, whereFrom 1 2 (Refer figure 6.0)Isentropic compressionFrom 2 3 (Refer figure 6.0)Constant volume heat additionEnergy density of Ethanol = 30 MJ/kgMost small engines have thermal efficiencies between 40 and 45%. Therefore with a compression ratio of 121, conversion efficiency (Formation and combustion) can be assumed to be 45% to obtain an overvaluation of the increase in pressure and temperature. 22Above calculations were repeated for the original compression ratio (8.01) of the stock engine which gave the succeeding(a) resultsCUsersPMGDesktopFYP RESEARCHT0512e0v.gifFigure 7.0 thermal efficiency increase with increase in compression ratio, 23Assuming a conversion efficiency of 40% and an air/fuel ratio of 151Therefore, the peak in cylinder pressure has been increased by a factor of 1.64. This factor is also the factor of increase in force on piston, head, valves etc.Brake mean effective pressure (BMEP) is a valuable measure of the capacity of an engine to do shape and is indepe ndent of displacement (Size of engine). 24The BMEP of the stock engine was 67.44 (from calculations under parametric study).Therefore, increase the compression ratio has increased the capacity of the engine to do field significantly.CHAPTER 5.0INTAKE AND EXHAUST OPTIMIZATION5.1 IntroductionA pressure joggle is created when an intake or exhaust valve is opened/ scraggyd. The wave propagates through the holler at the speed of well-informed. When this wave encounters a change in sub overdue sectional area, such as the end of the vacuum tube, a wave of foe sign will be reflected which would travel back towards the port. Based on the time taken for this wave to return to the valve and also considering the open/close durations of the valves, the optimum blank for the call can be calculated. This would increase the volumetric efficiency of the engine. 165.1.1 Optimum intake electron tube durationExperiments have revealed that there is a significant grow in volumetric efficienc y when the reflected compression wave returns when the piston is at a crank tip of 90o. At this point the piston would be moving at maximum speed. duplicate the time taken for the wave to return with engine speed, the required duration of the tobacco thermionic tube can be found. 16Velocity of wave = Distance/Time, (where distance = 2L)Time = 900/ revolutions per minute (revolutions/minute)(minute/60s)(3600/revolution) = 15/ revolutions per minute16CDocuments and SettingsPulsaraDesktopFYP RESEARCHfluid0image1.gifWhere c is the speed of sound which depends on the temperatureWhere = Ratio of specific heatsR = Ideal gas constantT = Temperature5.1.2 Optimum exhaust tubing lengthAt fluff shore (exhaust valve opens), a compression wave is propagates through the pipe and when it meets the end of the pipe an expansion wave returns back to the port. Experimentally it has been revealed that the optimum position of the piston when the wave returns is 120o. At this position the exhaust gas can be scavenged from the combustion chamber efficiently. 16Time = 1200/RPM (360/60) = 120/RPM16CDocuments and SettingsPulsaraDesktopFYP RESEARCHfluid0image4.gifGraphs were plotted using these formulaeA detailed calculation also considering the valve timing of Honda GX35 could be found under detailed calculations (5.2)Figure 8.0 Intake pipe length vs. engine RPM at different temperatures(Tabulated results in table 6.2 in appendix D)Figure 8.1 Exhaust pipe length vs. engine RPM at different temperatures(Tabulated results in table 6.3 in appendix D)5.2 Optimum pipe length calculations in detail5.2.1 Intake pipe length considering valve timingIntake valve opens at 10o forward top brain dead con centre (BTDC) and intake valve closes at 57o after bottom dead centre (ABDC). 18 season of 247o , 18Intake valve opens once every two revolutions.Therefore (360 x 2 247) o = 473oAfter finis, the intake valve would open again after 473 crank angle degrees473o =Speed of sound at an intake temperature of 30oCRatio of specific heat, = 1.4 at 30oCDistance travelled is two times the pipe length,Therefore,The optimum pipe length for GX35 engine to run at 5100 RPM is 2.705 mDue to the space constraint of the engine compartment pipe length can be truncated by a factor of four, qualification it 0.677 m in length. By this method, the wave would travel up and bring the pipe four times before the intake valve opens again. Although the effectiveness would be less, it would still arrive at the correct time to force more air into the cylinder.Using this result a custom intake pipe was designed with a length of approximately 0.5 m leaving the stay 0.177 m for intake runners, carburetor, etc5.2.2 Exhaust pipe length using valve timingThere are various methods and theories used for calculating the exhaust pipe length. The intake and exhaust can be treated separately to retrieve the optimum length for each pipe and also both can be treated as one system during valve bodgeroad to gain an added advantage during the overlap period.Method 1 (Considering exhaust system only)The reflected measure could be set to arrive at the engine just as the exhaust valve starts to open, which would help to expel the exhaust gas without using up excess energy.Exhaust valve opens at 48o before bottom dead centre (BBDC) and exhaust valve closes at 28o after top dead centre (ATDC). 18Duration of 256o, 18Port opens/closes once every two revolutions. Therefore, exhaust valve opens 464 crank angle degrees after closingSpeed of sound, c at the exhaust will depend on the exhaust temperatureThermodynamic calculations were continued from point 3 (Refer Figure 6.0) in order to calculate the temperature at blow down.,From 3 4Isentropic expansionThis length can be shortened by a factor of four allowing the wave to travel up and down four times before the valve starts to open, which gives 1.163 meters.Method 2 (Considering valve overlap period)If the reflected expansion wave reaches the opened exhaust valve just before closing but after the intake valve opens, the expansion wave will travel across the cylinder (since effective cylinder volume is small honorable TDC) through the intake port up to the intake atmosphere. This would result in an increased aspiration.Intake/exhaust valve overlap period of 38oBlow down shock wave leaves at 48o BBDC and the expansion wave must be set to return at around18o ATDC. 18This gives duration of 246o, 18Exhaust valve opens once every two revolutions.To obtain maximum volumetric efficiency by gaining advantage of the valve overlap period the exhaust pipe should be 2.46 meters in lengthThis can be shortened by a factor of two which would make the wave travel up and down twice before making use of the valve overlap period but this method may not be effective since the exhaust port will be open when the valve returns for the first time.5.3 Custom parts in the intake/exhaust systemIntake pipeThis pipe was designed considering the ca lculation results (figure 2.0) and compartment spaceLength is approximately 0.5 meters, (CAD drawing in appendix A)Exhaust pipeThis was designed considering the calculations (figure 2.1), compartment space and also the Shell Eco-Marathon rule which states that exhaust should be evacuated outside the vehicle but the pipe should not be long-life than the bodyLength is approximately 1.5 meters, (CAD drawings in appendix A)Velocity wadFigure 9.0 Inlet flow 19This is a pipe with a curving inlet which should be fixed to the end of the intake pipe. This would give a smoother flow of air into the intake pipe which would result in better atomization of fuel in the carburetor. Also this allows the full cross section of the intake pipe to be used whereas without a trend inlet, the flow area would be reduced due to the sharp entry. Therefore the speed stack helps to aspirate more air into the system. 19(CAD drawing in appendix A)5CHAPTER 6.0 provide DELIVERY SYSTEM6.1 IntroductionThe basic be given of this system is to deliver the fuel to the carburetor. In regular vehicles, either automatonlike or electric fuel pumps are used to pressurize and drive the fuel into the system. Stock GX35 engine uses gravity to pressurize the fuel when used in lawn mowers.The Shell Eco-Marathon rules state that electric fuel pumps are not allowed. 1Therefore the possible methods would beUsing a Mechanical fuel pumpUsing gravityPressurized fuel delivery system using compressed air6.2 Selection and designA mechanical pump would have to be powered from the engine output, which would result in an surplus load on the engine. This would result in a reduction in specific fuel consumption.The pressure due to height may not be large enough due to the space constraint in the engine compartment if gravity is used. Also, the shell fuel tank could be pressurized up to 5 bar which makes the pressurized system ideal for this applicationFigure 10.0PRESSURIZED FUEL DELIVERY SYSTEM LAYOUTValve to drai n the fuel (Shell requirement)Solenoid cut off valvePressure control valveA 1.5L pop bottle is used to store air at high pressure and air is regulated using a pressure control valve to control the pressure of air entering the fuel tank. This air at high pressure is used to push the fuel through the system.Pressure gauge is positioned close to the fuel tank to indicate the pressure of air entering the fuel tank.An air pump (hand held or foot pump) can be used to pump in air through, the valve stem (No return valve).1.5 L pop bottles are rated at 72 psi, therefore it is recommended to pump the bottle to approximately 60 psi.6.3 Advantages of this methodNo extra load on the engine to drive a mechanical pumpLess weightLow costAlso, this is a turn up method which has been used in successful endurance vehicles in past competitions. 2(CAD drawings can be found in appendix A)Figure 10.1 Screenshot from CAD model showing the fuel delivery systemCHAPTER 7.0DRIVE break7.1 IntroductionThe veh icle consists of three wheels, two in front and one at the back. The vehicle was designed to be a rear wheel drive and a chain is used to drive the wheel. Design and selection of transmission system and parts, gear ratio calculations, overall system layout and basic stress analysis is discussed in this chapter.7.2 transmission systemThere were few potential transmission ideas that could be usedContinuously Variable Transmission (CVT). 26Derailleur 27Manual two/three speed gear corner trail drive system 2CVT is known to be more efficient than a manual gear box but after further review it was found that CVT is less efficient at low speeds. 41Derailleur system is extremely efficient and simple but previous vehicles with this system had problems with the chain slipping out of the sprocket during gear change. 2Although a manual gear box is well suited for this system, it would add extra weight and also more moving parts results in additional power loss.Therefore a direct drive syste m with one gear ratio was selected as the most suitable transmission system.Main reasons behind selecting direct drive transmission systemHonda GX35 has relatively flat curves for torque, power and fuel consumption. The fuel consumption curve is almost flat from 3000 to 6000 RPM. Therefore the engine can run at a wide range of speeds and still supply adequate power with the same fuel consumption. (Refer figure 3.0)A manual gearbox would add extra weight and benefits of it would be negligible due to the linear performance curves.7.3 System layoutFew drive train system layouts were drawn in order to allocate space for each part. The most suitable layout was selected and modified accordingly.FUEL TANKCLUTCHFigure 11.0 Selected layout(Initial concept layouts in Appendix F)Figure 11.1 Screen shot from CAD model of the propulsion system showing the layout(Overall CAD assembly and exploded drawings in appendix A)7.4 Gear ratioSince a direct drive system was selected, the drive train would have one fixed gear ratio from engine to rear sprocket.An overall gear ratio of 161 was chosen and calculations were carried out to verify that this ratio is suitable for our application.7.4.1 The torque required at the rear wheel to move vehicle from rest roll resistance,Where,= Coefficient of rolling resistancem = Total mass of the vehicleg = Acceleration due to gravityCoefficient of rolling resistance for pneumatic tires on a dry surface can be approximated by the following equationWhere, P = Tire Pressure (bars)U = Vehicle velocity (km/h)Overall estimated mass of the vehicle = 140 kgMaximum tire pressure = 85 psi (5.8605 bar)Rear wheel diameter = 0.508 mTorque required to move the vehicle = Rolling resistance x driving wheel radiusThe efficiency of the drive train w