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  1. 3 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
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    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.
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    Air cooled, liquid cooled, carburated or fuel injected, Direct injection, Air filter design, inlet roar, ohv or ohc, hydraulic valve adjustment, shimmed tapets manual tappet asjustment. How many more reasons for different engine sounds do you want
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    Following are the reasonable points that conclude the high torque and efficiency of diesel engine. Diesel engine uses simple mechanism for combustion unlike in gasoline engine. Removal of ignition system not only makes the mechanism simpler but also reduces the risk of improper combustion due to damage in ignition system. In short burning of the fuel is easy and always accessible. This results in higher efficiency diesel engine. Diesel fuel is a heavier hydrocarbon in which carbon and hydrogen are strongly bonded with each other. And when energy is supplied in form of heat it gets explode releasing much higher energy then gasoline. In short diesel fuel has higher energy density then gasoline which results in huge explosion. One more factor for higher efficiency in diesel engine is its property of lubrication. Although all fuel has property of lubrication but diesel fuel has much higher lubrication then gasoline fuel. The compression ratio is much higher in diesel as compared to gasoline because in diesel engine air is alone compressed inside the cylinder and it’s a known fact that gas easily compresses then liquid. This is not so in gasoline engine because air-fuel mixture is compressed inside the cylinder. This higher compression gives higher heat and simultaneously higher torque. We can’t use Carnot cycle to get 100% efficiency but can use its principle to attain maximize efficiency. In diesel engine heat is added at constant pressure which results in higher utilization of heat energy to get maximize work output. These were the advantageous features of diesel engine but it has some demerits as well like it releases highly toxic gases, noisy, higher maintenance cost and starting problem (now starting problem is eliminated by using a bulb nearby to the cylinder) to heat the engine before ignition. And it is costlierthan gasoline engine but with optimum operation and good maintenance resolve all these problems.
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    Very nice art work and short, simple explanations. Well done! DrD
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    why flywheel are used in punching machine: It decreases the variation of speed during each cycle of punching machine and it decreases the fluctuation of speed due to difference in output and input and It also stores energy during idle stroke and releases during working stroke.
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    If there were no flywheel, the punch would require a very large motor in order to provide the required power for the punch stroke. When not in the punch stroke, all that power would be essentially idle, waiting to be called upon for a brief period for the punch operation. By including the flywheel, you have a means to store up energy, and make it available as needed during the punch operation. Then, during the idle period, the motor pumps energy back into the flywheel to bring it back to full speed. DrD
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    Rankine cycle: transition from isobar to adiabatic process. Carnot cycle: transition from isothermal to adiabatic process.
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    A pipe is measured by Nominal Pipe Size (NPS) per Inch and Schedule number ( Thickness of pipe ) and tube is measures by Outside Diameter (OD) and BWG number ( Thickness of Tube) . The common Pipes size as ANSI are produced from size 1/8" to 48". Pipes are used for mass. fluid and gas transfer in different industrial. Tubes are manufactured from size 1/32" to 12". Tubes are used for heat transfer in Heat exchanges,boilers,vessels and also in fire burners ( size 2" and more) and as instruments tubes and also accessories tools in Turbines and Compressors.
  10. 2 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.
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    Dial Gauge is a measuring instrument used to measure small distances Slip Gauge is a piece of hardened steel which is machined in a standard size.This is used to accurately make gaps
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    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.
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    In welding two metals are melted together. In brazing two or more materials are joined by the use of a third, dissimilar material, such as braze alloy. brazing is not stronger as welding
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    Turbo charger and super charger increase the compression ratio in an engine without changing cylinder and piston dimensions. In other words we can say super charger or turbo charger increases air density at intake manifold of the engine. Difference between Turbocharger and supercharger. Both perform same function but their driving mechanism is different. Super charger utilizes engine power for operation by coupling with engine rotary source. While Turbo charger use waste exhaust gas pressure and flow in order to rotate and produce air charge to intake manifold.
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    Atmospheric pressure is the pressure applied by the air on the ground as a result of the fluid volume of air directly above.....it is roughly 14.7psi or 1 bar. Atmospheric pressure is constantly changing asa result of the eweathter...stormy is generally low pressure (about .96bar) whereas fine weather can be a result of high pressure (1.012 bar) as a result this is standardised as atmospheric pressure at 1 bar....a more useful unit is mBar, but can also be psi, mmHg etc. The variation above or below 1 bar of pressure as measured is generally known as "gauge" pressure as it does not take into account the surrounding atmospheric pressure (which is hydrostatic btw) therefore only measuring the difference between the "zero" which is in effect atmospheric and the vessel being measured. Similarly vacuum pressure is a measure of pressure below that of surrounding ambient....generally in Bar or Torr. Vacuum pressure is ALWAYS that below the surrounding medium (which is generally air although occasionally within the confines of a high pressure environ. ). Absolute pressure is a corrected pressure which takes into account the surrounding air pressure to read the true pressure. It is not always the case, but it can generally be read as pressure + 1bar as it completely negates the effects of the surrounding medium...comparing directly to a total vacuum.
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    Go through this link http://www.skf.com/in/products/bearings-units-housings/ball-bearings/principles/selecting-bearing-size/bearing-life/load-ratings/index.html
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    Darcy–Weisbach equation gives the value of head difference or in case of flow, loss of head in the turbulent flow through pipes due to frictional factors, this equation gives this in terms of all the measurable quantities and is derived from the equation of velocity profile. Head loss hf = ((P1 - P2)/(density x g)). Hence is of much importance in experimental works, dimensional analysis and model analysis of flows.
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    Because power to weight ratio is more important in gas turbines as compared to efficiency
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    A shaft is a power transmission device, connected to a gear or coupler on both ends. An axle may or may not transmit power. An axle may just be used for a center of rotation on non-driven wheels such as the front wheel of a motorcycle. An axle may or may not be a shaft.
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    Turbocharger : it is used as economizer in commercial vehicles and some passenger vehicle to boost up performance in lesser quantity of fuel.It have a compressor wheel and a turbine wheel attached to a common shaft and runs by the exhaust gases of engine.Firstly turbine wheel starts to rotate as it is pushed by the exhaust gases then the compressor connected to same shafts rotates and manage its function to sucks fresh air and sends it engine combustion chamber extra air means better rate combustion ultimately batters the performance of the whole unit. But the problem of turbo lag occurs, it's the time taken for turbocharger comes in action after exhaust gases reaches the turbine wheel Supercharger : Supercharger is installed for the same purpose in the vehicle, but with more adaptivity. it is installed in sports class vehicle used for racing purpose they are only performance oriented,that's why they are connected to directly the output shaft of the vehicle.It will successfully fulfill the need of sports vehicle of rapid change in velocities with high power and torque, by neglecting the need of giving emphasis to fuel economy upto some extent.There is one input geared shaft and output geared shaft in a properly meshed condition which rotates and other ultimately do its job.
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    I'm sorry I just forgot to mention that I've already corrected the mistake mentioned by @Alban Kronenberger. Thanks for pointing it out. P.S. ~ If you find any such mistakes, comment on the post, even if you're not fully sure. I'll verify it and edit it.
  22. 1 like
    Thank you Sir. The comments do inspire me to keep writing, and I wait for yours.
  23. 1 like
    Diesel or kerosene has no spark plug due to its higher volatility and flash point. The spark plug and voltage needed for ignition would be very large. So the atomized fuel-air mixture is ignited (adiabatic heating) by superheated, compressed air. The compression ratio for diesel is higher to ensure more complete combustion, which helps it have a much improved thermal efficiency over CI engines.
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    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.
  25. 1 like
    In diesel engines the compression ratio is much more than otto engines and it means that diesel engines burn more air and with less oil, and after ignition period we get higher pressure and temperature that provides more power that's why diesel engine efficiency is usually higher than otto engines, but when it comes high rpm values because of the ignition delay in diesel engines the combustion efficiency decreases at high rpm values because in diesel engines there is no spark plug as the diesel oil is ignited by itself at higher pressure and temperatures but in this peroid it needs some time even if it is very very little time and hence the required time for ignition decreases at higher rpm values and this causes lower combustion efficiency in diesel engines and this time the efficiency of diesel engine is lower than otto engines, that's why racing cars don't have diesel engines and heavier vehicles such as trucks and buses have diesel engines because they need more power with a higher efficiency but don't need higher velocity values.
  26. 1 like
    Because here ignition takes place at a very high compression ratio where the temperature is high enough for self ignition of the diesel(fire point) air mixture to takes place....
  27. 1 like
    When the belt moves over the pulley to transmit power, the tension in the tight side is more than than the tension in slack side. As the belt material is elastic, it elongates more on tight side than on slack side, resulting in unequal stretching on two sides of the drive. Therefore, the length of the belt received by the driving pulley is more than the length that moves of the driving pulley. Hence, belt must creep back slightly relative to driving pulley rim. On the other hand, the length of the belt received by the driven pulley is less than the length that moves of the driven pulley. Hence, the belt must creep forward slightly relative to driven pulley rim. This motion of belt relative to driving and driven pulley due to unequal stretching of the two sides of the drive is known as creep. The effect of creep back on the driving pulley is to slow down the speed of the belt with respect to driving pulley and the effect of creep forward on the driven pulley is to slow down the speed of driven pulley. Thus the net effect of creep is to reduce the speed ratio than the theoretical expected. Difference between slip and creep. Creep is due to the elastic property of belt whereas, the conventional slip is due to insufficient frictional grip between the belt and pulley. However, the effect of the creep as well as slip is to reduce the speed ratio, and hence power transmission.
  28. 1 like
    In welding, similar materials are used to melt together a seam creating a bond that is the same as the original material. In Brazing, it is akin to gluing, where a second material is melted and wets to the surface of the first, but not melting the original, creating a mechanical bond between the two. This is a quick description, because there are grey areas that can in fact melt and bond dissimilar materials with and without fluxes. Basically welding makes two parts into one, brazing is like gluing two parts together.
  29. 1 like
    1.tubes is used to the heat and mass transfer 2.pipes is used to the mass transfer
  30. 1 like
    In crown gear the pitch angle is 90 degree and in mitre gears the axes of gears are at 90 degree and gears are of same size.
  31. 1 like
    For cutting right hand helical gear right side of milling table is tilted up from normal position by helix angle. For cutting left hand helical gear,right side of table needs to be tilted down at helix angle,all other settings remaining unchanged.
  32. 1 like
    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.
  33. 1 like
    This is an easy to understand pdf on the topic. http://www.pages.drexel.edu/~rcc34/Files/Teaching/MEM201%20L6-Tolerance_RC.pdf
  34. 1 like
    generally tolerence are required for to control the quality of the product during mfg. GD & T is coontroll the dimension of the product during manufacturing .it mean it give the perticuler range of geometric parameters like surface finish,flatness,strigtness,...etc..., sometime tolerence are given for the purpose of the type of fit requirement between two meting parts, sometime tolerence stack up analysis is also required when more than 2 parts are assembled to each other..
  35. 1 like
    Leaf spring design is really intricate and it will act as shock absorber in vehicles (Medium -Heavy) Leaf spring load calculation can be done by applying UTM by fixing the leaf spring in the inverted direction and apply load on bolt area ( The fixing Bolt) we have to take the elongation and the how much or load it is carrying . for each vehicle the disgn will differ . If medum and thin deisng of leaf spring will give good cushioning effect. The camber and CRS of the leaf spring will decide its load carrying charcter ( camber is the distance measured vertically from the center line of The Eyes of the Leaf spring ) In vehicle Empty weight (No load condition) the CRS distance of the spring will be less than the loaded vehicle. suppose the CRS distance of the Front wheel and the rear wheel will differ after loading .The distance elongation will ease the vehicle to accomodate the Axels different location while the vehicle absorbs shock or sudden load.
  36. 1 like
    Difference in sound is observed because of following Reasons Type of Engine - Two Stroke/ Four Stroke Number of cylinders ( Normally 1 in all bikes but have more than 1 in some big brands) Design of exhaust Different Engine RPM Range Engine Geometry
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    In Shaper machine, tool is having reciprocating motion and w/p is clamped on table which is stationary. It is mostly suitable for light duty operation.In Shaping large cutting force is transferred to tool In Planer machine, tool is having stationary and w/p is clamped on table which is reciprocating moton. It is mostly suitable for Heavy duty operation.In planner large cutting force is transferred to table
  38. 1 like
    Tubes are used for both HEAT&MASS Transfer. Pipes are used for only MASS Transfer.
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    There are actually three efficiencies to be considered for a turbine. 1] The Carnot efficiency, which is the highest possible efficiency for any heat engine working across the given temperatures; Carnot eff = [Tin - Tout]/Tin 2] The mechanical efficiency, ie, how well the turbine does at approaching the Carnot efficiency; 3] The overall efficiency, power out/heat flux in [= work out/heat in] Overall efficiency = Carnot x mechanical
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    when a belt rotate through two pulleys, upper side of this drive will tight side and lower side will be slack side, now a certain portion of belt will pass through the area where it will change from tight side to slack side, then the length of that specific portion of the belt will expand and contract subsequently and a relative motion will happen between belt and pulley surface. This phenomenon is called creep of belt. This effects a slight reduction in velocity of follower pulley than driven one. proper selection of belt material and belt length can reduce this loss.
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    Hexagonal stands for head type. M for Metric. 12 mm diameter, 1.5 mm of thread pitch and 70 for the lenght (head thickness H, not couting)
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    ***Prior to reading, NOTE differing spellings of "Micrometer" and "micrometre".....the later being 1x10^-6, the former being the gauge*** A micrometer is used for measuring not only diameter, but width too, and is used where accuracy of measurement is needed (see vernier caliper comments). The graduations on a standard micrometer are in 0.01mm graduations, however - subject to certain constraints - a good metrologist can subgraduate these to get a reasonably acurate reading of about 2 micrometres. the certain constraints are numerous....temperature, anvil accuracy (and damage), calibration, softness of material being measured, speed of measurement..... At these scales, temperature becomes critical.....I used to work in a temperature/humidity controlled environment for tolerances of less than 15 micrometres....that was both challenging and - occasionally quite boring.....after every pass, the workpiece had to be left with the coolant running to return to ambient temperature before measuring. Measurement was also different. on tightening the screw on the micrometer, very very slow movements had to be undertaken in order to eliminate - as far as possible - the momentum of the gauge overtightening the workpiece against the anvil and giving a false reading....and then it was always measure 5 to 8 times to verify.
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    Example for Calculation of Least Count of Vernier Calipers: A vernier scale has the length of 9 main scale divisions and is divided in to 10 divisions. Calculate the Least Count of the Vernier Calipers. Solution: Since 9 divisions of the vernier scale coincide with 10 divisions of the main scale VSD = 9 / 10 mm = 0.9 mm MSD= 1 mm Least Count= 1 MSD- 1VSD = 1mm - 0.9mm = 0.1mm
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    Least count can calculated using the formula. Least Count = Length of 1 MSD – Length of I VSD Where MSD and VSD refer to Main Scale Division and Vernier Scale Division respectively Generally N divisions on main scale coincide with N-1 divisions on vernier scale 1 VSD is equivalent to (N-1)/N main scale divisions Using the formula for Least Count, we get LC = 1 MSD – 1VSD = 1 MSD – (N-1)/N MSD = 1/N MSD
  47. 1 like
    Least Count refers to the smallest distance that can be measured using an instrument. It indicates the degree of precision of an instrument. Most of the vernier Calipers have a least count of 0.1mm.
  48. 1 like
    Do see these 2 presentations for detail understanding of "theories of failure"
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    Governor regulates the speed by regulating the quantity of working agent of the prime mover. Flywheel function is to store the energy and gives up whenever required during a cycle.
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    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.