Leaderboard


Popular Content

Showing most liked content since 03/28/2017 in all areas

  1. 48 likes
    Basically a Pump is used for liquid or fluid to transform it to a much high pressure head while a Compressor is used for gases to transform from low to a much high pressure. From Mechanical Engineering point of view liquid is incompressible so Compressor cannot be used for liquid substances. Posted by AbdulQadir Abba Sheriff on linkedin
  2. 35 likes
    1. What is the difference between scavenging and supercharging ? Ans: Scavenging is process of flushing out burnt gases from engine cylinder by introducing fresh air in the cylinder before exhaust stroke ends. Supercharging is the process of supplying higher mass of air by compressing the atmospheric air. 2. What are the names given to constant temperature, constant pressure, constant volume, constant internal energy, constant enthalpy, and constant entropy processes.Ans: Isothermal, isochroic, isobaric, free expression, throttling and adiabatic processes respectively. 3. In a Rankine cycle if maximum steam pressure is increased keeping steam temperature and condenser pressure same, what will happen to dryness fraction of steam after expansion ?Ans: It will decrease. 4. Why entropy change for a reversible adiabatic process is zero ? Ans: Because there is no heat transfer in this process. 5. What are two essential conditions of perfect gas ? Ans: It satisfies equation of state and its specific heats are constant. 6. Enthalpy and entropy are functions of one single parameter. Which is that ? Ans: Temperature. 7. Why rate of condensation is higher on a polished surface compared to rusty surface ? Ans: Polished surface promotes drop wise condensation and does not wet the surface. 8. How much resistance is offered to heat flow by drop wise condensation ? Ans: Nil How are these questions - please do add comments and if you like them please do share this post on facebook, linkedin, twitter and google plus. 9. What is the relationship between COP of heating and cooling ? Ans: COP of heating is one(unity) more than COP of cooling. 10. How much is the work done in isochoric process ? Ans: Zero. 11. When maximum discharge is obtained in nozzle ? Ans: At the critical pressure ratio. 1. Under what condition the work done in reciprocating compressor will be least ? Ans: It is least when compression process approaches isothermal. For this purpose, attempts are made to cool the air during compression. 13. What is the difference between stalling and surging in rotary compressions ? Ans: Stalling is a local phenomenon and it occurs when How breaks away from the blades. Surging causes complete breakdown of flow and as such it affects the whole machine. 14. Why the electric motor of a fan with backward curved blades is never got overloaded under any condition ? Ans: The maximum power is consumed at about 70% of maximum flow in case'of fan with backward blades. For higher flow, power consumption gets lower. 15. Why the work per kg of air flow in axial flow compressor is less compared to centrifugal compressor for same pressure ratio ? Ans: Isentropic efficiency of axial flow compressor is higher. 16. What is the name given to portion of thermal energy to be necessarily rejected to environment ? Ans: Anergy. 17. What is pitting ? How it is caused ? Ans: Non uniform corrosion over the entire metal surface, but occuring only in small pits is called pitting. It is caused by lack of uniformity in metal. 18. What is caustic embrittlement ? Ans: It is the actual physical change in metal that makes it extremely brittle and filled with minute cracks. It occurs particularly in the seams of rivetted joints and around the rivet holes. 19. Which impurities form hard scale and which impurities soft scale ? Ans: Sulphates and chlorides of lime and magnesium form hard scale, and carbonates of lime and magnesium form soft scale. 20. What is the difference between hard water and soft water ? Ans: Hard water contains excess of scale forming impurities and soft water contains very little or no scale forming substances. 21. Which two elements in feed water can cause corrosion of tubes and plates in boiler ? ' Ans: Acid and oxygen in feed water lead to corrosion. 22. What should be done to prevent a safety valve to stick to its seat ? Ans: Safety valve should be blown off periodically so that no corrosion can take place on valve and valve seat. 23. Why large boilers are water tube type ? Ans: Water tube boilers raise steam fast because of large heat transfer area and positive water circulation. Thus they respond faster to fluctuations in demand. Further single tube failure does not lead to catastrophy. 24. What type of boiler does not need a steam drum ? Ans: Super-critical pressure boiler. 25. Why manholes in vessels are usually elliptical in shape ? Ans: Elliptical shape has minimum area of opening and thus plate is weakened the least. Further it is very convenient to insert and take out the cover plate from elliptical opening. 26. Low water in boiler drum is unsafe because it may result in overheating of water tubes in furnace. Why it is unsafe to have high water condition in boiler drum ? Ans: High drum level does not allow steam separation to be effective and some water can be carried over with steam which is not desirable for steam turbine. 27. Why boiler is purged everytime before starting firing of fuel ? Ans: Purging ensures that any unburnt fuel in furnace is removed, otherwise it may lead to explosion. 28. What is the principle of mechanical refrigeration ? Axis. A volatile liquid will boil under the proper conditions and in so doing will absorb heat from surrounding objects. 29. Why high latent heat of vaporisation is desirable in a refrigerant ? Ans: A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage. 30. What is the critical temperature of a refrigerant ? Ans: Critical temperature is the maximum temperature of a refrigerantrat which it can be condensed into liquid and beyond this it remains gas irrespective of pressure applied. 31. Maximum combustion temperature in gas turbines is of the order of 1100 to 10°C whereas same is around 00°C in I.C. engine ? Why ? Ans: High temperature in I.C. engine can be tolerated because it lasts for a fraction of second but gas turbines have to face it continuously which metals can't withstand. 32. Why efficiency of gas turbines is lower compared to I.C. engines ? Ans: In gas turbines, 70% of the output of gas turbine is consumed by compressor. I.C. engines have much lower auxiliary consumption. Further combustion temperature of I.C. engines is much higher compared to gas turbine. 33. What do you understand by timed cylinder lubrication ? Ans: For effective lubrication, lub oil needs to be injected between two piston rings when piston is at bottom of stroke so that piston rides in oi during upward movement. This way lot of lub oil can be saved and used properly. 34. What is IIUCR in relation to petrol engine ? Ans: HUCR is highest useful compression ratio at which the fuel can be used in a specific test engine, under specified operating conditions, without knocking. 35. In some engines glycerine is used in place of water for cooling of engine. Why ? Ans: Glycerine has boiling point of 90°C which increases its heat carrying capacity. Thus weight of coolant gets reduced and smaller riadiator can be used. 36. Why consumption of lubricating oil is more in two-stroke cycle petrol engine than four-stroke cycle petrol engine ? Ans: In two-stroke engine lub oil is mixed with petrol and thus some lub oil is blown out through the exhaust valves by scavenging and charging air. There is no such wastage in four stroke petrol engine. 37. As compression ratio increases, thermal n increases. How is thermal n affected by weak and rich mixture strength ? Ans: Thermal n is high for weak mixture and it decreases as mixture strength becomes rich. 38. How engine design needs to be changed to burn lean mixture ? Ans: Engine to burn lean mixture uses high compression ratio and the highly turbulent move¬ment of the charge is produced by the geometry of the combustion chamber. 39. Horse power of I.C. engines can be expressed as RAC rating, SAE rating, or DIN rating. To which countries these standards belong ? Ans: U.K., USA and Germany respectively. 40. What is the use of flash chamber in a vapour compression refrigeration cycle to improve the COP of refrigeration cycle ? Ans: When liquid refrigerant as obtained from condenser is throttled, there are some vapours. These vapours if carried through the evaporator will not contribute to refrigerating effect. Using a flash chamber at some intermediate pressure, the flash vapour at this pressure can be bled off and fed back to the compression process. The throttling process is then carried out in stages. Similarly compression process is also done in two separate compressor stages. 41. Why pistons are usually dished at top ? Ans: Pistons are usually hollowed at top to (i) provide greater spa'e for combustion, (ii) increase surface for flue gases to act upon, and (iii) better distribution of stresses. 42. What is the function of thermostat in cooling system of an engine ? Ans: Thermostat ensures optimum cooling because excessive cooling decreases the overall efficiency. It allows cooling water to go to radiator beyond a predetermined temperature. 43. What are the causes of failure of boiler tubes ? Ans: Boiler tubes, usually are made from carbon steel and are subject to (a) high rates of heat transfer,( b ). bending stresses due to uneven heating, especially at expanded or welded joints into headers or drums, © external erosion from burners and flue gas, (d) possible corrosion on the boiler side, and (e) occasional manufacturing defects. Failure may occur due to following reasons : (a) High thermal ratings may lead to rapid failure if the internal fluid flow is reduced for any reason. The resultant overheating leads to a failure by creep, characterised by the bulging of the tube with the eventual development of a longitudinal split. (b ) Fatigue cracking due to bending stresses occur. These are associated with change of section and/or weld undercut, where tubes are expanded or welded into headers. © Failure may arise due to overstressing of a reduced section of metal. (d) Sudden failure of the boiler tube due to corrosion arises from embrittlement of the carbon steel due to interaction between atomic hydrogen from the corrosion process and the iron carbide present in the steel. (e) Defects in tube manufacture, although far from being a regular occurrence, can be a cause of serious trouble. Lamination in boiler tubes or score marks arising from the cold drawing of tubes, give rise to premature failure and may promote corrosion at these regions. 44. What are the causes of failure of superheater tubes ? Ans: Superheater tubes are subjected to the most severe combination of stress, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be used at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr. Failures in superheater tubes may arise from : (a) Prior fabrication history (b ) Faulty heat treatment © Consequences of welding (d) Overheating of the tube metal (e) Gas-side corrosion (f) Stress corrosion (austenitic steels). 45. Why supercritical boilers use less amount of steel compared to non-supercritical boilers ? Ans: Supercritical boilers do not head heavy drum for separation of steam from mixture of water and steam. 46. Out of electric heater and heat pump, which is economical in operation ? Ans: Heat pump. 47. Which furnace burns low-ash fusion coal and retains most of the coal ash in the slag? Ans: Cyclone furnace. 48. How the thickness of thermal boundary layer and thickness of hydrodynamic boundary layer related ? Ans: Ratio of their thickness = (Prandtl number)-1/3. 49. What is the effect of friction on flow of steam through a nozzle ? Ans: To decrease both mass flow rate and wetness of steam. 50. Why gas turbine power plant needs efficient compressor ? Ans: Because a large portion of turbine work is eaten away by compressor and its inefficiency will affect net power output and cost of generation. 51. Why rockets using liquid hydrogen have higher specific impulse compared to liquid hydrocarbon ? Ans: Liquid hydrogen has higher burning velocity. 52. Why axial flow compressor is preferred for gas turbines for aeroplanes ? Ans: Because it has low frontal area. 53. What is the effect of inter cooling in gas turbines ? Ans: It decreases thermal efficiency but increases net output. 54. Why iso-octane is chosen as reference fuel for S.I. engines and allotted 100 value for its octane number ? Ans: Iso-octane permits highest compression without causing knocking. 55. Why thermal efficiency of I.C. engines is more than that of gas turbine plant ? Ans: In I.C. engine maximum temperature attained is higher than in gas turbine. 56. Which are the reference fuels for knock rating of S.I. engines ? Ans: n-heptane and ISO-octane. 57. When effect of variations in specific heats is considered then how do maximum temperature and pressure vary compared to air standard cycle ? Ans: Temperature increases and pressure decreases. 58. Quantities like pressure, temperature, density, viscosity, etc. are independent of mass. What are these called ? Ans: Intensive properties. 59. The amount of radiation emitted per scm per sec is called .... ? Ans: Emissive power. 60. In convection heat transfer, if heat flux intensity is doubled then temperature difference between solid surface and fluid will ? Ans: Get doubled. 61. How you can define coal ? Ans: Coal is a naturally occurring hydrocarbon that consists of the fossilised remains of buried plant debris that have undergone progressive physical and chemical alteration, called coalification, in the course of geologic time. 62. Which pollutant is major greenhouse gas and what is its effect ? Ans: CO is major greenhouse gas and it traps the radiation of heat from the sun within earth's atmosphere. 63. In order to increase efficiency and reduce CO emissions and other emissions, clear coal technologies are receiving major attention. What are these ? Ans: (i) Advanced pulverised and pressurised pulverised fuel combustion. (ii) Atmospheric fluidised bed combustion and pressurised fluidised bed combustion. (iii) Supercritical boilers. (iv) Integrated gasification combined cycle systems. (v) Advanced integrated gasification, including fuel cell systems. (vi) Magneto hydrodynamic electricity generation. 64. What are the important operational performance parameters in design of fuel firing equipment ? Ans: Fuel flexibility, electrical load following capability, reliability, availability, and maintenance ease. 65. What is the differenc between total moisture and inherent moisture in coal ? Ans: The moisture content of the bulk as sampled is referred to as total moisture, and that of the air dried sample is called inherent moisture. 66. Proximity analysis of coal provides data for a first, general assessment of a coal's quality and type. What elements it reports ? Ans: Moisture, volatile matter, ash and fixed carbon. 67. Ultimate analysis of coal is elementary analysis. What it is concerned with ? Ans: Carbon, hydrogen, nitrogen, and sulphur in coal on a weight percentage basis. 68. Explain the difference between AFBC, BFBC, PFBC and PCFB in regard to fluidised bed technologies. Ans: AFBC (Atmospheric fluidised bed combustion) process consists of forming a bed of inert materials like finely sized ash or ash mixed with sand, limestone (for sulphur removal), and solid fuel particles in a combustor and fluidising it by forcing combustion air up through the bed mixture. The gas flows thorugh bed without disturbing particles significantly but gas velocity is high enough to support the total weight of bed (fluidisation). At slightly higher velocity excess gas passes through the bed as bubbles (fluidised bed) and gives the bed the appearance of a boiling liquid. Bubbling fluidised bed combustion (BFBC) has a defined height of bed material and operates at or near atmospheric pressure in the furnace. Pressurised fluidised bed combustion (PFBC) system operates the bed at elevated pressure. Exhaust gases have sufficient energy to power a gas turbine, of course, gases need to be cleaned. In fluidised combustion, as ash is removed some unburned carbon is also removed resulting in lower efficiency. In circulating fluidised bed combustion (CFBC) system, bed is operated at higher pressure leading to high heat transfer, higher combustion efficiency, and better fuel feed. Circulating fluidised beds operate with relatively high gas velocities and fine particle sizes. The maintenance of steady state conditions in a fast fluidised bed requires the continuous recycle of particles removed by the gas stream (circulating bed). The term circulating bed is often used to include fluidised bed sys¬tems containing multiple conventional bubbling beds between which bed material is exchanged. 69. What for Schmidt plot for is used in heat transfer problems ? Ans: Schmidt plot is a graphical method for determining the temperature at any point in a body at a specified time during the transient heating or cooling period. 70. In which reactor the coolant and moderator are the same ? Ans: Pressurised water reactor. 71. Which reactor has no moderator ? Ans: Fast breeder reactor. 72. What are thermal neutrons ? Ans: Thermal neutrons are slow neutrons (having energy below 1 eV) which are in thermal equilibrium with their surroundings. 73. What is big advantage of fast breeder reactor ? Ans: It has rapid self breeding of fissile fuel during the operation of the reactor, and thus, it offers about sixty times the output with same natural uranium resources through ordinary non-breeder nuclear reactor. 74. What is the purpose of biological shield in nuclear plants ? Ans: Biological shield of heavy concrete prevents exposure to neutrons, beta rays and gamma rays which kill living things. 75. Which two elements have same percentage in proximate and ultimate analysis of coal? Ans: Moisture and ash. 76. On which analysis is based the Dulong's formula for the heating value of fuel ? Ans: On ultimate analysis. 77. Which element causes difference in higher and lower heating values of fuel ? Ans: Hydrogen. 78. Which heating value is indicated by a calorimeter and why ? Ans: Gross heating value because steam is condensed and heat of vapour formed is recovered. 79. State the difference between ultimate and proximate analysis of coal ? Ans: In ultimate analysis, chemical determination of following elements is made by weight: Fixed and combined carbon, H, O, N, S, water and ash. Heating value is due to C, H and S. In proximate analysis following constituents are mechanically determined by weight. Moisture, volatile matter, fixed carbon and ash. Heating value is due to fixed carbon and volatile matter. 80. What is fuel ratio ? Ans: Fuel ratio is the ratio of its % age of fixed carbon to volatile matter. 81. How the analyses and calorific values of fuels can be reported ? Ans: It may be reported as (a) as received or fired (wet) basis (b ) dry or moisture free basis © combustible or ash and moisture free basis 82. What is the difference between nuclear fission and fission chain reaction. Ans: The process of splitting of nucleus into two almost equal fragments accompanied by re¬lease of heat is nuclear fission. Self sustained, continuing, sequence of fission reactions in a con¬trolled manner is fission chain reaction. 83. Explain difference between fissile and fertile materials. Ans: The materials which can give nuclear fission e.g. U 35, Pu 39, U 33 are fissile materi¬als. Fertile material itself is not fissionable, but it can be converted to a fissionable material by irradiation of neutrons in a nuclear reactor. 84. What do you understand by fuel cycle in nuclear plants ? Ans: Fuel cycle a series of sequential steps involved in supplying fuel to a nuclear power reactor. The steps include : Mining, refining uranium, fabrication of fuel elements, their use in nuclear reactor, chemical processing to recover remaining fissionable material, re-enrichment of fuel from recovered material, refabrication of new fuel elements, waste storage etc. 85. What is heavy water and what is its use in nuclear plants ? Ans: Water containing heavy isotopes of hydrogen (Deuterium) is known as heavy water. Heavy water is used as a moderator. Heavy water has low cross section for absorption of neutrons than ordinary water. Heavy water slows down the fast neutrons and thus moderates the chain reaction. 86. What is a converter reactor ? Ans: A reactor plant which is designed to produce more fuel than it consumes. The breeding is obtained by converting fertile material to fissile material. 87. Explain nuclear reactor in brief. Ans: A plant which initiates, sustains, controls and maintains nuclear fission chain reaction and provides shielding against radioactive radiation is nuclear reactor. 88. What is the difference between conversion and enrichment ? Ans: The process of converting the non fissile U 38 to fissile U-35 is also called "Conversion". The material like U 38 which can be converted to a fissile material by the neutron flux is called "fertile material". The conversion is obtained within the nuclear reactor during the chain reaction. Enrichment is the process by which the proportion of fissile uranium isotope (U-35) is increased above 0.7% (original % in natural uranium). The concentration of U-35 in the uranium hexafluoride is increased from the 0.7% in natural uranium to to 4%. This is called enrichment and is accomplished in an enrichment plant. 89. Disposal of radioactive waste materials and spent fuel is a major and important technology. How the waste radioactive material is disposed off ? Ans: Nonusable fission products are radioactive and take short/medium/long time for radioactive decay to reach safe level of radioactivity. Accordingly three methods of disposal are : (a) Zero or low radioactivity material is dispersed or stored without elaborate shielding. (b ) Medium radioactivity material is stored for short duration of about 5 years to allow decay of radioactivity. © High radioactive material. They are stored in water for several months to permit radioactive decay to an accepetable low level. 90. Which nuclear reactor uses water as a coolant, moderator and reflector ? Ans: Pressurised water reactor. 91. Which reactor produces more fissionable material than it consumes ? Ans: Breeder reactor. 92. Which reactor uses natural uranium as fuel ? Ans: Gas cooled reacator. 93. Which reactor uses heavy water as moderator ? Ans: CANDU. 94. Which reactor requires no moderator ? Ans: Breeder reactor. 95. Which reactor uses primary coolant as fluoride salts of lithium, beryllium, thorium and uranium ? Ans: Molten salt breeder reactor. 96. Why an increase in area is required to produce an increase of velocity in case of supersonic flow ? Ans: Increase in area for increase in velocity for supersonic flow is required because the density decreases faster than velocity increases at supersonic speeds and to maintain continuity of mass, area must increase. 97. Under what circumstances would there be an increase in pressure in a diver¬gent nozzle ? Ans: For subsonic flow at inlet section of a diffuser a lower velocity and higher pressure will exist at the exit section. For supersonic isentropic flow at the inlet section a higher velocity and lower pressure will exist at the exit but if a shock wave occurs in the diffuser then a higher pressure will exist at the exit. 98. Why water can't be used as refrigerant for small refrigerating equipment ? Ans: The refrigerant should be such that vapour volume is low so that pumping work will be low. Water vapour volume is around 4000 times compared to R- for a given mass. 99. Which parameter remains constant in a throttling process ? Ans: Enthalpy. 100. What is the difference between isentropic process and throttlinglprocess ? Ans: In isentropic process, heat transfer takes place and in throttling process, enthalpy before and after the process is same.
  3. 31 likes

    Version

    6,449 downloads

    ANSYS offers engineering simulation solution sets in engineering simulation that a design process requires. Companies in a wide variety of industries use ANSYS software. The tools put a virtual product through a rigorous testing procedure (such as crashing a car into a brick wall, or running for several years on a tarmac road) before it becomes a physical object. This pdf gives good start to understand and learn ANSYS
  4. 27 likes

    Version

    9,306 downloads

    Dear Folks, Enjoy with useful Engineers pocket guide
  5. 24 likes
    What is the difference between pump and compressor ? When we use pump and When we use compressor? You can answer this questionYou can like the best answerYou can share the question.....You can get updates of new questions on Facebook linkedin twitter & google plus
  6. 19 likes
    Shaft is a mechanical element that transmit power and torque moment. Usually shafts are the elements with gears and pulleys attach on them (power transmission). The axle on the other hand is a mechanical element that does not transmit power. It can rotate or it can stand still. It is only loaded with bending moments. In vehicles, the terminology is same. The shafts that transmit power to the wheels are called drive shafts. The driven wheels have axles. Some people like to call the drive shafts axles (or half axles), from where the confusion can occur. The right term is drive shafts.
  7. 16 likes
    As an older engineer, I am rather dismayed by what I see as the results of engineering education today. I have seen most young engineers come out of their college degree programs with a modest familiarity with come CAD program and a related Finite Element program, and an almost complete lack of capability to analyze machine components without the use of FEA. Thus they are unfamilliar with basic design calculations relating shear stress in a shaft to the power being transmitted, the shaft sped and the shaft diameter. Instead, they want to create an FEA model and run the numbers that way which is simply not the way you make any progress in designing a machine. It is certainly true that FEA allows for a good detailed stress analysis of complex geometries, something that was not possible in general by the older methods. But the results obtained are highly dependent on the skill of the user in applying the correct boundary conditions, something that is a bit of an art in itself. I have observed a tendency to even want to use FEA to do kinematics, rather than using simple, rigid body kinematic relations. This seems like pure foolishness in almost all cases. Are we not developing a tendency to lean too heavily on the computer, rather than to learn to think as engineers? I would be happy to hear some comments and discussion from others on these matters.
  8. 16 likes
    While both devices provide a form of forced induction for internal combustion engines The primary difference lies in how the devices are powered. Turbochargers are powered by exhaust gasses. Superchargers are powered by a belt, chain link, or gears, directly to the engine (the crankshaft in most cases). Turbochargers perform better at higher rpm's do to more exhaust gases spinning the turbine which then in turn causes the compressor to draw in more air. This has a downside due to lag time which can be referred to as spooling up. Superchargers work better at low RPM's due to the direct link to the engine and lack of lag time however they are limited to rotating at a max speed matching that which the crankshaft can turn the mechanical linkage to the supercharger itself. One system not mentioned in this article is the twin charger system. This combines the benefits of both the supercharger and a turbocharger in creating a zero gap power band. The supercharger takes care of the lower RPMs while the turbo kicks in during the higher rpm's. The applications of this are mostly seen on engines with smaller displacement and a wide rpm range.
  9. 14 likes
    Why first angle and third angle method is used and why second and fourth angle method is not used? 1. You can answer this question 2. You can like the best answer 3. You can share the question...
  10. 14 likes
    In DTSi, instead of 1 we are using 2 spark plugs. Flame front formed is able to consume more air-fuel mixture as compared with 1 spark plug, thus more complete burning and more efficiency. in DTS-Si, with addition of 2nd spark plug, what they are doing is relocating valves position. With proper designing of inlet and outlet valves you can induce extra swirl for inoming air fuel mixture. Due to turbulence, extra efforts are provided for proper mixing of air and fuel. (We can not allow petrol to go in liquid droplet form, it should be finely atomized). With well atomized air fuel mixture, efficiency increases.
  11. 13 likes
    This is one important point missing in the two previous answers. The "cc rating" of an engine is a volume measure, as previously stated, but it is not the actual cylinder volume. Rather, it is the swept volume of the cylinder, also called the "displacement" of the cylinder. The actual cylinder volume is always somewhat greater than this value because the piston at TDC does not leave zero cylinder volume. The small volume remaining at TDC is called the "clearance volume," the volume available for the early stage of combustion. DrD
  12. 13 likes

    Version

    5,226 downloads

    Powerpoint Notes on Metal forming Topic includes— Hot &Cold working Forging Extrusion Rolling Drawing
  13. 13 likes

    Version

    6,062 downloads

    Presentation on Design of- Clutch Brake Belts Chain Gears
  14. 12 likes
    Most of the time gears are used for reduction. So pinion is smaller as compared to gear, i.e. no of teeth on pinion are less as compared to gear. This in accordance affects the number of cycles. Thus in any operation, pinion performs more cylces as compared to gear. More cycles means more wear and hence generally pinion material is selected such that its hardness is more than material of Gear.
  15. 12 likes
    Basic Difference is the how their are measured.. [1] i.e. A pipe is measured by ID(inner diameter) and a tube is measured by OD(outer diameter). [2] a pipe is like a vessel to store a liquid/gas so inside volume is important factor, while a tube is seen as structual member so total volume is important factor.
  16. 11 likes

    Version 1.1.0

    11,523 downloads

    A COMPLETE INSTRUCTOR AND STUDENT SUPPLEMENT PACKAGE - Continued These ppts are set of instructor and student supplements. . A FOCUS ON DIAGNOSIS AND PROBLEM SOLVING The primary focus of these ppts is to satisfy the need for problem diagnosis. Time and again, the author has heard that technicians need more training in diagnostic procedures and skill development. To meet this need and to help illustrate how real problems are solved, diagnostic stories are included throughout. Each new topic covers the parts involved as well as their purpose, function, and operation, and how to test and diagnose each system.
  17. 10 likes
    Please reply Name Engineering college Location (City/ Country) Engineering Batch Engineering Company/ Dream company to work for Area of Interest Project undertaken Any other info you want to share
  18. 10 likes
    DrD

    How To Become An Expert

    Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD © Machinery Dynamics Research, 2016 How To Become An Expert Introduction This is going to be another of those personal experience/opinion pieces, so if these bore you, be warned! This may be the time to click on something else. A reader recently wrote to me asking how to become an expert. I have to tell you, I don't spend much time thinking about being an expert, but I suppose on some reflection, the shoe probably fits. (Most of the time, I see myself as simply a tired old man, still enjoying the things I have done almost all my working life.) In the discussion below, I will describe a few events and observations that seem to relate to the question at hand. Find Your Place Nobody can hope to be an expert on everything, there is simply too much to know. You have to find the area that excites you, the area that really makes you want to dig in more. If you do not really enjoy it, you will never be an expert! I was very fortunate in this regard. When I was in High School, I was rather good in Mathematics, and my school advisers all told me, "You should become an engineer." Sadly, I really had no idea what that meant, and neither did they. The town where I grew up had rather little industry, and no one in my family knew an engineer of any sort. I did a little bit of research on engineering (this was thousands of years before the Internet), and it sounded interesting in a very vague way; there seemed to be little specific information available to me. But I went off to college, intending to study mechanical engineering, whatever that was. In my first semester of college, I took a Physics course in classical mechanics, and I really enjoyed it. This was exactly what I wanted to do, I just did not know the right name for it. I thought Newton's Second Law was the greatest thing ever discovered, and when implemented with Calculus, it was really fun. I was astounded at the power of it all, the questions that could be answered. If I could just get a job doing mechanics problems, I was sure I would be happy. HowToBecomeAnExpert.pdf
  19. 9 likes
    ABS- it allows the brakes to be applied while maintaining a tractive contact with the road. it does not allow the wheels to be stopped a once. if it was stopped at once due to inertia(because of the speed with which it comes), the vehicles skids. it is more prominent in low friction surfaces like on ice, wet road etc. In ABS the wheels are not stopped at once. It grips the disc mounted on the wheel. the disc is pressed and released with a gap of nanoseconds. thus the driver do not actually feel it. It increases the braking distance. EBD- It is an electronic device that is mounted on the vehicle, that actually varies the amount of braking force on each wheel depending upon the road conditions. if one wheel is on a high friction surface less braking force is required on that wheel. thus by sensing the road conditions the amount of brake force is varied.
  20. 8 likes
    Washers are used when bolting to make stronger the joint and to reduce bolt fatigue due to inconsistent loads. Any stretch or flattening of parts is likely to be less than the compression of the washer thus, the bolt won't loosen much.
  21. 7 likes
    Tyres are mixture of various rubbers with carbon black added. Carbon black improves traction and wear resistance of pure rubber. Another reason is that black color has higher absorption capability by which the tyre of any vehicle becomes adhesive to road
  22. 6 likes

    From the album Engineering images

    The above diagram is for a Caterpillar series 3600 turbo charged after cooled engine. As can be seen from the timing diagram, the induction stroke commences when the inlet valve opens 10° before TDC when air is drawn into the cylinder as the piston moves down. The inlet valve closes 1° before BDC. The air is now trapped in the cylinder and as the piston rises on the compression stroke, the air is compressed. As the air is compressed, it rises in temperature. When the piston reaches 19° before TDC, the injection of fuel commences and continues until 73° after TDC. The heat in the compressed air ignites the fuel and combustion takes place. The gases expand forcing the piston down on the power stroke. The exhaust valves opens at 26° before BDC and the exhaust gases commence and are discharged as the piston rises on the exhaust stroke. Most of the exhaust gases have been discharged as the piston nears TDC. However, at 10° before TDC, the inlet valve opens and air enters the cylinder and helps discharge any remaining exhaust gases until the exhaust valve closes at 3° after TDC. The whole cycle is then repeated. Both the exhaust valve and inlet valve are open from 10° before TDC to 3° after TDC, an overlap of 13°. This is referred to as “valve overlap” and ensures that all the exhaust gases are discharged from the cylinder and the cylinder receives a fresh charge of air to make it more efficient when combustion next takes place. Therefore there is one power stroke for every cycle or two revolutions of the crankshaft.
  23. 6 likes
    Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD © Machinery Dynamics Research, 2017 Last Post Time to Hang It Up This will be the final post of Mechanics Corner here on Mechanical Engineering Forums. It has run almost exactly two years, and there have been ups and downs along the way. In this final post, I want to reflect a bit on my original goals for the blog, and also on what has actually happened. When our host first proposed to me that I might write a blog for ME Forums, I was excited about it. About half of my career had been spent in engineering education, and I always loved working with students. It seemed like a way to get back to something that I had long enjoyed, and so I accepted his suggestion. A long time ago, back when I was about 14 or 15 years old, in Junior High School, my shop teacher mentioned, in an off-hand way in class, that various curves could be described mathematically. I’d never heard that before, but I thought immediately, “This has interesting possibilities.” Moving ahead a few years, I discovered that I wanted to study and build my career around was the area known as Applied Mechanics, although it was a time before I first heard that term. In my freshman physics class, I discovered the laws of motion, and thought to myself, “This is great stuff! I can use math to describe how things move!” All of that happened back in the 1950s, and I’m still doing the same thing today (some might say I am in a rut!). As a teacher, I taught mostly undergraduate engineering courses, although I taught my share of graduate courses as well. It was the undergraduate courses that I liked most, because I firmly believe that the economy of a nation is strongly dependent on the quality of the baccalaureate level engineers produced in that nation. Engineers with graduate degrees are valuable as well, but the vast majority of the national engineering workload falls to BS level engineers. Thus, I envisioned Mechanics Corner as a sort of continuation of the several undergraduate courses I most enjoyed teaching — kinematics, dynamics of machines, vibrations, and mechanics of materials. For the most part, I have stuck to the plan, so that most of the technical posts I have made have dealt with problems that I considered suitable for undergraduate engineering students, say perhaps, junior level. I have posted a few topics from my industrial experience, but those have been situations that baccalaureate level engineers would be expected to handle. Now I knew it would not be exactly like continuing to teach my classes. In particular, you would not have any homework or tests, and I would not have any grading to do – a win-win, or so I thought. I did hope, that even with no assigned homework, readers would take an interest in the problems discussed, even to the point of working through the details for themselves (I was terribly naive, apparently!). I knew from my own experience that the only way I ever really learned a new idea was to get in and work with it, work some problems, make some numbers, plot some curves, until I really understood what it was all about. I’ll venture to say that nobody ever learned any technical material simply by reading only. In actual fact, in the early days, I had one or two folks say that they would in fact work through the problems, so I was encouraged. What I was not prepared for, however, was the fact that the vast majority never seemed to even read very carefully, much less work through the problems! The questions that have come, and there have been a few, have largely been about matters totally unrelated to the posts. The most common question has been, “Suggest a topic for my final project,” which relates to not a single post. Needless to say, that aspect of my vision was totally unfulfilled. But there is another side. I ventured to write a few “philosophical” articles, items dealing with academic integrity and cheating, with how to ask for help, with how to write a report or a paper, and various other matters. I really thought all of this would be considered obvious and trivial, so I was completely unprepared for the excitement that some of these articles generated. There were, in some cases, many, many comments, and people seemed to really be interested. I’m left to wonder: why? Are these ideas foreign to the culture of India and SE Asia? Are these things not all taught at home and in the public schools? I don’t know, but there was a lot of interest in these matters. But Mechanics Corner was intended to be primarily a technical blog, and there, it just did not excite the interest of the readership. As time passed, there was less and less interest. First, the comments dropped off to just about zero, and later, there were fewer and fewer who even bothered to “like” the articles. Finally, the number of reads has dropped to almost nothing (there may be no one left to read this final note). Well, there could hardly be any more clear indication that it is time to stop. I asked for opinions about this from some of the administrators, and was told that the blog was just over the heads of the readership. That makes me sad; that was never the intent. If it is true, I do not see how engineering has a very bright future among this readership. Even so, I wish all of you the best for your careers. I hope that you are able to find rewarding and beneficial work in which you will be happy and make a real contribution to your societies. To use an old cowboy metaphor perhaps familiar to many of you from Bollywood, “It is time to hang up the bridle and saddle, and say, ‘Adios’ (Adios is literally, “to God”).
  24. 6 likes
    What’s the difference between Mig and Tig Welding? 1. You can answer this question 2. You can like the best answer 3. You can share the question...
  25. 6 likes
    Oh god... I guess diesel engines don't use spark plugs because the air/fuel mixture isn't as explosive as is in the case of petrol (or gasoline). Therefore you cannot spark ignite it. That is the reason why diesel engines have a high compression ratio (close to 20 as has been said), which heats up the air being compressed in the cylinder to a high enough temperature. Fuel is then injected straight into the cylinder, where it ignites because of the high temperature of the air and that is it. That's why spark plugs are not needed. The thing is, in petrol engines you used to squirt the fuel into the air intakes, where it mixed with the incoming air and filled the cylinders. If you used compression ratios as high as diesels, you would get premature explosions, i.e. knocking. That's why the ratios are lower and that's why you need a spark plug to ignite it. Directly comparing the two engines at the same compression ratio, gasoline engines are more efficient (at least at ratios of around 10 to 15). It would be possible to make a gasoline engine with a ratio of 15 these days, since we have mastered direct injection in petrol engines as well, but that would stress the heads (and pistons) a whole lot more - petrol mixture burns at ~1200°C, while diesel does at ~800°C - a big difference. Plus the pressures would be very high, etc. It is possible in theory, but is not practical (emissions would be a b*tch as well, i think higher cylinder temps cause more NOx to form in the exhaust gases). EDIT: that's how i see it, but i could be wrong. Correct me if i am.
  26. 5 likes
    Turbines are machines which convert fluid energy to mechanical energy. When the fluid used is water, they are called hydraulic turbines. Hydraulic turbines may be classified on the basis of four characteristics : On the basis of the type of energy at the turbine inlet Impulse turbine total head of the incoming fluid is converted in to a large velocity head at the exit of the supply nozzle ( entire available energy of the water is converted in to kinetic energy.) water entering the runner of a reaction turbine has only kinetic energy the rotation of runner or rotor (rotating part of the turbine) is due to impulse action Flow regulation is possible without loss Unit is installed above the tailrace Casing has no hydraulic function to perform, because the jet is unconfined and is at atmospheric pressure. Thus, casing serves only to prevent splashing of water. It is not essential that the wheel should run full and air has free access to the buckets. eg - Pelton wheel turbine ( efficient with a large head and lower flow rate.) Reaction or Pressure turbine the penstock pipe feeds water to a row of fixed blades through casing that convert a part of the pressure energy into kinetic energy before water enters the runner water entering the runner of a reaction turbine has both pressure energy and kinetic energy the rotation of runner or rotor (rotating part of the turbine) is partly due to impulse action and partly due to change in pressure over the runner blades Water leaving the turbine is still left with some energy (pressure energy and kinetic energy) It is not possible to regulate the flow without loss Unit is entirely submerged in water below the tailrace Casing is absolutely necessary, because the pressure at inlet to the turbine is much higher than the pressure at outlet. Unit has to be sealed from atmospheric pressure. Water completely fills the vane passage. eg - Francis and Kaplan turbines ( efficient with medium to low heads and high flow rates ) On the basis of the direction of flow through the runner Tangential flow turbine Direction of flow is along the tangent of the runner eg - Pelton wheel turbine. Radial flow turbine Direction of flow is in radial direction radially inwards or centripetal type, eg- old Francis turbine radially outwards or centrifugal type, eg -Fourneyron turbine Axial flow turbine Direction of flow is parallel to that of the axis of rotation of the runner the shaft of the turbine is vertical, lower end of the shaft is made larger which is known as hub (acts as runner) eg - Propeller turbine ( vanes are fixed to the hub and they are not adjustable ) Kaplan turbine (vanes on hub are adjustable ) Mixed flow turbine Water flows through the runner in the radial direction but leaves in a direction parallel to the axis of rotation of the runner eg- Modern Francis turbine. On the basis of the head at the turbine inlet High head turbine net head varies from 150m to 2000m or even more small quantity of water required eg -: Pelton wheel turbine. Medium head turbine net head varies from 30m to 150m moderate quantity of water required eg -: Francis turbine. Low head turbine net head less than 30m large quantity of water required eg -: Kaplan turbine. On the basis of the specific speed of the turbine Before getting into this type, one should know what the specific speed of a turbine is. It defined as, the speed of a geometrically similar turbine that would develop unit power when working under a unit head (1m head). Low specific speed turbine specific speed is less than 50. (varying from 10 to 35 for single jet and up to 50 for double jet ) eg -: Pelton wheel turbine. Medium specific speed turbine specific speed varies from 50 to 250 eg -: Francis turbine High specific speed turbine specific speed more than 250 eg -: Kaplan turbine References : 1. Course contents on NPTEL website 2. A textbook of Fluid Mechanics and HydraulicMachines - R.K. Bansal 3. Fluid Mechanics: Including Hydraulic Machines - A.K. Jain 7 hours, 59 minutes ago
  27. 5 likes
    Why Tractors have their exhaust system(Silencer) fitted in the front of the vehicle,while other automobiles have their silencer at their back? 1. You can answer this question 2. You can like the best answer 3. You can share the question.
  28. 5 likes
    State the difference between turbocharger and supercharger You can answer this question. You can like the best answer. You can share the question You can get updates of new questions on Facebook linkedin twitter & google plus
  29. 5 likes
    Flexible coupling are mostly used to protect the pipelines connected to any machines carrying fluids . It may be used for a pump or some engines carrying coolants through it. Another use of flexible coupling is to transmit power from an engine . If the coupling was rigid , it could transmit the vibration from the power producing engine. Mostly in four stroke marine propulsion engine flexible couplings are used to connect the flywheel and the intermediate shaft for rotating the propeller and prevents misalignment of the shaft. Mostly it is made of rubber.
  30. 5 likes

    From the album Gears

    Planetary gear sets contain three major components or members. They are: • The Ring Gear or Annulus which has internal teeth and wraps around the entire assembly. • The Sun Gear (shown above in orange) which is the smallest gear and sits in the center of the assembly. The planetary pinions orbit around the sun gear, hence the name of the gear set. • The Planetary Carrier (shown above in yellow) which holds a set of Planetary Pinion Gears. The Pinion Gears (shown above in green) interact with the Ring Gear and the Sun Gear at the same time.
  31. 5 likes

    Version

    1,763 downloads

    Tips, advise and suggestions to engineers for a sucessful career path....& success in engineering profession
  32. 5 likes

    Version

    2,053 downloads

    FUTURE TRENDS IN AUTOMOBILE ENGINEERING
  33. 5 likes
    CC means Cubic Centimeter, It basically denotes the Volume of Cylinder, whether it may be a car or Bike.Technically it's the Bore Diameter and the stroke length of the cylinder.If a car as 1.8L Engine it's nothing but 1800 cc..Hence More the cc, more the power nd torque.
  34. 5 likes
    The bush material would be of a softer material than the shaft/spindle that runs inside it, often bronze, even oil impregnated bronze. The reasons for using the bush are that the bush will wear out before the bearing or the shaft/spindle, therefore reducing the time and costs of replacing the bearing or shaft. It would usually be sensible to carry spare bronze bearings already made to size to allow for a fast replacement. Usually these bronze bearings would be turned up from a length of bronze bearing material, ask your bearing supplies company for it, and make a few up in one go on the lathe, then label them and put them somewhere you will find them again!
  35. 5 likes
    A forming process that adds a pattern on the exterior of a workpiece, either for cosmetic reasons or better handling. Knurling is a manufacturing process, typically conducted on a lathe, whereby a diamond-shaped pattern is cut or rolled into metal.
  36. 4 likes
    Recently I was interviewed by a Mechanical Engineering student on the importance of communications. I’m approaching 40 years in engineering practice so the examples began to flow and the student’s 15 minute time estimate for the meeting quickly turned into two hours. The meeting itself was a lesson in communications. My awareness of the root cause, that I will describe below, I believe made the information more valuable. The student and I covered many issues on the topic of communications, but the emphasis of his questioning was the difference between communicating with other engineers versus business majors or the sales personnel. The root issue of communications I believe goes deeper and must be identified to minimize the occurrence. There have been many occurrences of communication problems in my life and not all involved engineering. In the past, I viewed each incident as individual and isolated events. Of late, I have come to the conclusion there are common causes. Here I address one that I think is more common than realized. Communication problems are often dismissed as the language, generational, or cultural gaps. These all contribute to the issue but are not the root cause of a large portion of communication problems. If fact, obvious language issues often result in precautions being taken to avoid miscommunications. About 25 years ago I was among a group of technical people gathered for a seminar. While waiting for the speaker, conversations started within the group. Two people were carrying on an energetic conversation for 10-15 minutes consisting of acronyms -- just alphabet soup. Just prior to the speaker arriving, the two having the conversation realized each used a particular acronym for entirely different and unrelated meanings. Yet these two had conversed as if they were on the same subject. Imagine if the conversation had developed into a disagreement to the point of anger, and the instructor arrived before these two were able to define terms. Both would have left thinking badly of the other and maybe worse. In another situation I was just hired into a new position by a former coworker, now manager of a program. He asked that I do something which I immediately did. At our next meeting, the manger began to tell me how I should go about doing the task. I was fuming, to say the least. I was saying to myself, "what was wrong with the way I did it?" I fumed and fumed until I finally asked. The manager looked at me in astonishment and said “You did it? I am not use to anything getting done so fast around here.” One final example. A new VP of engineering admonished me for my poor design and release process causing many problems – no specifics were provided. I was shocked to the point of speechlessness, so I did not immediately ask for specifics that would have revealed the root cause of his dissatisfaction. I assumed my 2 + year old procedure had grown stale and caused problems. I printed a copy of my Design and Release Procedure and read it line for line, looking for something that was no longer correct. After failing to find any problems, I wrote in large red letters “Tell me what I need to change.” The boss was not at his desk, so I left it on his seat. Sometime later, a much more humble boss came to my office and asked if the release date on the procedure was correct – it was, and about 2 years old, so I said yes, and he left. All three examples have the same root cause. In each case one or both parties assumed implicitly that the other party knew something that in reality they did not. Case One: Each party assumed that a particular acronym meant the same to each of them. Case Two: I implicitly assumed the manger would know that I would quickly act on the simple assignment. We had worked together for 6 years prior, on a different program. Case Three: The VP had come to believe implicitly that there was no written process. In his mind, every problem that arose appeared to be a result of not having a process. I assumed he was talking directly to the written document that he did not know existed. As an independent Professional Engineer many of my clients are not engineers. What were once safe assumptions while working in an engineering office with other engineers, I learned quickly was no longer acceptable. Current technologies allow people from around the world to communicate with incredible ease. This has resulted in the root-cause I suggested above to run unchecked. When we write we need to be aware of generational, language, or cultural gaps as well as office jargon*. All can easily result in implicit assumptions of other people’s knowledge that are false. The first professional letter I wrote to be send outside the corporation was brought back to me by my supervisor. He called to my attention that office jargon has no place for a formal business letter. Here again, I was implicitly assuming the terms used every day in our group would be universally understood. It took me 40 years to “connect the dots.”** * Special words or expressions that are used by a particular profession or group and are difficult for others to understand. ** To understand the relationship between different ideas or experiences
  37. 4 likes
    well in except that both of them are Dassault Systèmes's products . there is a little difference between them. Basically , Solidworks is a CAD (computer aided design) software - the best of it's kind i assume - Simple to manipulate , easy to learn and used by almost every single industry in the world . CATIA is A CAM software , indeed it's better than solidworks in some modules such as surfacing and kinematics. But the main idea is that in CATIA you can not only create a mechanism , but a factory in which it will be produced, the machining processes required, and even you can simulate ergonomics studies as well, like weather the current layout of a plant will be comfortable for workers to work or not. So you can simulate the whole thing within a virtual reality, including, and of course, rendering. However CATIA is almost exclusively used in Aviation and Automotive industries. So there is no doubt you need to learn them both ... because let's say if you want to create an airplane Use CATIA to create the surface and to simulate the manufacturing process and Solidworks would easily handle the engines
  38. 4 likes
    One thing we know. We can’t use fuel in liquid form during compression, because liquids are incompressible. Now we have option to use diesel in vapour form. At atmospheric pressure, boiling point of diesel is 250°c to 300°c. And diesel in fuel tank have temperature around 40°c to 50°c. So it is not possible to make vapors (as in carburetor of petrol engine).So, how can we convert diesel into vapour form?There are three options: 1. If we put liquid diesel into a medium having pressure less than vapour pressure of diesel, it means we create vacuum inside the cylinder. During suction stroke we have vacuum and we can convert the diesel into vapors, but during compression stroke we must avoid auto ignition due to high compression ratio. The one and the only way to avoid the auto ignition in such case is to reduce the compression ratio. Which is not possible (2nd law of thermodynamics, higher is the pressure more is the power) if we want to get power from engine. Another important reason for using higher compression ratio is to get higher expansion ratio (more piston displacement) thus more power with same fuel consumption.Work done = pressure (mean effective pressure) × piston cross-sectional area × piston displacement. But still if someone manages this miracle, how he overcomes condensation of diesel during compression stroke where the pressure goes up again. So drop this option. 2. Increase the temperature of liquid diesel before putting into engine cylinder which is possible but not reliable. We have to use pre-heaters, which cost energy consumption and makes vehicles bulky. 3. Put liquid diesel into high temperature air (greater than saturation temperature of diesel) and provide some time for heat exchanging between them. In practical air standard engines third option is perfect as we produce high temperatures by compression. But still we can't use spark plug for ignition, since mixture present in the cylinder is heterogeneous (somewhere mixture within ignition limits and somewhere not). Ignition by spark plug required homogenous air fuel mixture. Now we have only 1 option to ignite the diesel, that is; compresses the air and raised the temperature of air up to ignition temperature of diesel and inject the diesel in cylinder.
  39. 4 likes
    saurabhjain

    turbofan engine

    From the album Engines

    The turbofan or fanjet is a type of airbreathing jet engine that finds wide use in aircraft propulsion. As all the air taken in by a turbojet passes through the turbine (through the combustion chamber), in a turbofan some of that air bypasses the turbine. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of those contributing to the thrust
  40. 4 likes
  41. 4 likes
    To protect the bolt hole, spread the load & forces evenly, as a spacer, protect the nut from crevice & galvanic corrosion.
  42. 4 likes
    Washers are used with mechanism for this, that forces on surface area spread evenly.
  43. 4 likes
  44. 4 likes
    What is Anti-lock braking system (ABS)? Anti-lock braking system (ABS) is an automobile safety system that allows the wheels on a motor vehicle to maintain tractive contact with the road surface according to driver inputs while braking, preventing the wheels from locking up and avoiding uncontrolled skidding. It is an automated system that uses the principles of threshold braking and cadence braking which were practiced by skillful drivers with previous generation braking systems. It does this at a much faster rate and with better control than a driver could manage. ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, ABS can significantly increase braking distance, although still improving vehicle control. How does ABS work? The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake). Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. 1. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second. Because of this, the wheels of cars equipped with ABS are practically impossible to lock even during panic braking in extreme conditions. 2. The ECU is programmed to disregard differences in wheel rotative speed below a critical threshold, because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all roadgoing vehicles. 3. If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel. What is Electronic brake-force distribution (EBFD)? You’re driving at a safe speed on a moderately busy highway. It has not been snowing for long, but already the pavement is dusted with snow and becoming slippery. Suddenly, another motorist signals to enter your lane and makes a sharp veering motion. You are forced to slam on the brakes to avoid hitting the encroaching vehicle. The weight of your car is thrust forward from the heavy braking, putting added pressure on the front wheels to stop the car. Meanwhile, the sudden shift in weight has significantly reduced the amount of traction available for the back wheels. After a few seconds, the back wheels lock completely. You feel the back end of your car start to fishtail into the lanes on either side of you. Finally, the back-and-forth motion of the rear of the car overcomes the braking power of the front wheels and you spin around, face-to-face with oncoming traffic. Situations like this are potentially very dangerous. Electronic brake-force distribution is a vehicle safety feature that can prevent this kind of event. How does EBFD work? 1. Electronic brake-force distribution is often installed with antilock braking systems (ABS). ABS installations that are supplemented with EBFD react more quickly and deliver more situation-specific braking commands than older ABS setups. 2. EBFD systems are usually made up of three subcomponents that are monitored and guided by an electronic control unit (ECU). These components include speed sensors for each wheel (sensors that monitor how fast the wheel is rotating), brake-force modulators (a mechanism that increases or decreases brake-force applied to a wheel), an acceleration / deceleration sensor that detects the vehicle’s forward and sideways acceleration/deceleration, and usually a yaw sensor (a sensor that monitors a vehicle’s movement along its vertical axis). 3. The electronic control unit interprets the information from the speed and yaw sensors, and then sends commands to the brake-force modulators. Similar to how ABS setups operate; the ECU in EBFD systems is attached to the hydraulic brake-force modulator. So, while the ECU and brake modulator serve different purposes, they are physically combined into one electro-hydraulic unit. 4. EBFD works by monitoring each wheel’s responsiveness to the brake, and then tailoring the amount of brake-force applied to each wheel. In vehicles without EBFD, when you apply the brakes the brake-force is evenly distributed across all four wheels. The danger here is that if, for example, one of your wheels is on ice and locks up, you lose 25% of your braking power. On a vehicle with EBFD, the system would sense that one of the wheels is not braking properly, and would redistribute the brake-force to the unaffected wheels to obtain optimal braking power. This way, you retain the maximum amount of braking power possible and reduce the risk of fishtailing or spinning around. 5. The yaw sensor installed with most EBFD systems also helps prevent oversteering and understeering. Oversteering occurs when a vehicle continues to turn beyond the steering input of the driver, while understeering refers to cases where the vehicle does not turn enough in response to driver commands. Both oversteering and understeering are the result of insufficient traction on the road. If you begin to oversteer or understeer, the yaw sensor will record unusual movement along the vehicle’s vertical axis, and your EBFD system will react by applying either the brakes on the inner wheel (to correct understeering) or the brakes on the outer wheel (to correct oversteering).
  45. 4 likes
    When we manufacture any product, usually we manufacture it by casting or forging process. To get a proper surface finish of that product we need a proper machining. At the time of maching a certain amount of material usually removed from the surface of the core product. For this reason a tolerance is needed over the designed dimension to maintain the actual dimension. Beside this reason, tolerances also kept to maintain the needed dimension after thermal expansion or contraction at the time of solidification during casting process.
  46. 4 likes
    Type Of Ignition: SI CI Cycle Of Operation Diesel Otto Dual Fuel Used Petrol Diesel Gas Electric Cooling method Air Water Oil Stokes 2 stoke 4 stroke No.Of Cylinders 1 2 3 4 6 8 12 16 Valve location L-head I-head F-Head T-head (Usually said as LIFT heads) Cylinder Nature V-type vertical opposed Radial Speed Low Medium High Lubrication method Wet sump Dry sump That's all folks, if found other than this, please leave a comment. I remember a type based on application, but it is not technical. So i left that type.
  47. 4 likes
    Diesel Engines we dont need the Spark Plug the Calorific value of the Diesel is more when compared with petrol Engine. For less colorific value we do not get more horse power. But diesel natually have more heat developed during combustion thus developing more power than petrol engines.
  48. 4 likes
    saurabhjain

    Worm drive

    From the album Engineering images

    A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm gear (which is similar in appearance to a spur gear, and is also called a worm wheel).Like other gear arrangements, a worm drive can reduce rotational speed or allow higher torque to be transmitted. Unlike with ordinary gear trains, the direction of transmission (input shaft vs output shaft) is not reversible when using large reduction ratios, due to the greater friction involved between the worm and worm-wheel, when usually a single start (one spiral) worm is used Worm drives are used in presses, in rolling mills, in conveying engineering, in mining industry machines, and on rudders. In addition, milling heads and rotary tables are positioned using high-precision duplex worm drives with adjustable backlash. Worm gears are used on many lift- (in US English known as elevator) and escalator-drive applications due to their compact size and the non-reversibility of the gear
  49. 3 likes
    Why tyres are made black in color? 1. You can answer this question 2. You can like the best answer 3. You can share the question.
  50. 3 likes
    To allow slip and creep chain drive is used over belt or rope drive. To get accurate rotational timing a chain drive is best replacement for belt drive. Pro's of chain drive over belt drive 1) It can be used for accurate rotational timing thus used in I.C. Engines as timing chain. 2) There is no loss of energy in the form of heat because no slip and creep occurs. 3) Better service than belt drive. Con's of chain drive over belt or rope drive 1) Initial cost is more than belt drive system 2) Require proper lubrication for smooth functioning. 3) Not silent as belt drive in absence of lubrication. 4) Catches rust easily.