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  1. 1 point
    1. What are the differences between true stress, engineering stress, proof stress. 2. What do you men by factor of safety and what is its significance 3. What do you mean by Young’s modulus, modulus of rigidity and bulk modulus. 4. What do you mean by resilience. 5. What is pure torsion and what do you mean by flexural igidity. 6. What is the difference between endurance limit stree and endurance strength. 7. What do you understand by efficiency of riveted joint. 8. What is caulking and fullering in riveted joint. 9. What do you mean by stress conc. Factor and what are the methods to reduce stress conc. 10. Why stress conc. Is more serious in brittle materials. 11. What do you mean by fatigue . 12. Springs are subjected to which type of streses. 13. What are the difference between through bolt, tap bolt and stud. 14. What is check nut and what is the function of washer. 15. Cotter and knuckle joints take which type of load and where they are used. 16. What are the difference types of couplings and what is their function. 17. What is the function of key and which type of stress they are subjected to? 18. Generally shafts are subjected to which type of stress. 19. What are the difference types of mechanical drives and which is the best for different situations. 20. What is the function of a bush why it is phosphor bronze. 21. What are difference types of threads and which threads are used for power transmission and why. 22. Why the pulley arms are elliptical in cross section and it is made up of cast iron. 23. Why it is required to change the all V belt if one of them is broken. 24. Why V belts transmit more power than flat belts. 25. What is the meaning of 6*37 or 6*7 in a rope drive. 26. What do you mean by pinion sprocket and wheel sprocket and which one is used for driving shaft. 27. What is the function of flywheel and why its material is cast iron. 28. Why the leaf springs are laminated as reducing length. 29. What is the function of clutch and is the difference between uniform wear and uniform pressure. 30. Now a days which type of clutches are used in automobiles. 31. Why disc brake is more efficient than mechanical brake. 32. What is the function of bearings and what are the different types. 33. What is bearing characteristics number and bearing modulus. 34. What is the significance of the digits of a rolling contact bearing number 6304? 35. Which type of gear drive is used for perpendicular transmission of power? 36. Why helical gears transmit more power than spur gears. 37. What do you mean by different terms like back lash, pressure angle, circular pitch in a gear drive. 38. Why involute tooth profile is better than cycloid tooth profile? 39. What is interference in gear drive and how to avoid it? 40. What do you mean by law of gearing
  2. 1 point
    Even if I agree with your points, I don't think that they are decisively. I don't have an example either can't prove it, but I guess it's possible to achieve the same properties with changing the color. Maybe a simple answer is better to answer why this variable is always chosen: roads are dirty and the tire surface is submit to high attrition that makes easier to dirty. Black is the best color to not contrast the usual particles and try to make it appears that, even with some particles covering the surface, it is the same color when totally clean (but colors are not good to avoid this particles to reduce the brightness of the tire). Sure it is very convenient that black rubber has the better properties for this application.
  3. 1 point
    saurabhjain

    Jigs and fixtures

    From the album Engineering images 10

    What are Jigs? Jigs are the work holding device which holds, supports and locate the workpiece and guides tools to perform a specific operation. In other words we can say that, jigs are the device which is used for both purposes of holding the workpiece and guiding the tool. It is a tool which is used to control the location and motion of the tool during the operations. Jigs main purpose is to provide repeatability, accuracy and interchangeability in the manufacturing of products. It is used in the unidimensional machining i.e drilling, taping, reaming etc. Jigs are found to be light in weight and have complex designing. In jigs, gauge blocks are not necessary and the cost of jigs is higher. They are the special tools particularly used in drilling, reaming, tapping and boring Operations. Jigs are not fixed to the machine table until a big operation is not required to perform. What are Fixtures? Fixtures are the work holding device which holds, supports and locate the workpiece but not guides the cutting tool to perform a specific operation. In other words the fixtures are only the work holding device that holds, supports and locate the workpiece in desried position to perform any operation. The main purpose of the fixtures is to hold and locate the workpiece during any machining operation in the industries. And to provide repeatability, accuracy and interchangeability in the manufacturing of products. It is used in multidimensional machining i.e. milling, grinding, turning etc. Fixtures are found to be heavy in weight and have less complex designing. In fixtures, gauge blocks may be provided for effective handling and the cost of fixtures is not so high. Fixtures are specific tools used particularly in milling machine, shapers and slotting machine. Fixtures are fixed to the machine table. Difference Between Jigs and Fixtures in Tabular Form: The various difference between jigs and fixtures in the tabular form are given below: S.no Jigs Fixtures 1. It is a work holding device that holds, supports and locates the workpiece and guides the cutting tool for a specific operation. It is a work holding device that holds, supports and locates the workpiece for a specific operation but does not guide the cutting tool 2. jigs are used in unidimensional machining i.e. drilling,reaming, tapping, etc fixtures are used in multidimensional machining i.e. milling,turning,grinding,etc . 3. Jigs are light in weight. Fixtures are rigid and bulky. 4. Gauge blocks are not necessary. Gauge blocks may be provided for effective handling. 5. The jigs are special tools particularly used in drilling, reaming, tapping and boring operation. Fixtures are specific tools used particularly in milling machine, shapers and slotting machine 6. Usually it is not fixed to the machine table. It is fixed to the machine table. 7. Its cost is more. Its cost is less as compared with the jig. 8. Their designing is complex. Their designing is less complex. Summary of Difference Between Jigs and Fixtures Jigs are the device which is used to holds, supports and locate the workpiece and it guides the cutting tool for a specific operation. Fixtures are the device which is used to hold, support and locate the workpiece and they don’t guide the cutting tool. Jigs are used in unidimensional machining whereas fixtures are used in multidimensional machining. In jigs, gauge blocks is not necessary. In fixtures gauge blocks may provided for effective handling. Jigs are light in weight as compared with the fixtures. The cost of jigs is higher when it is compared with the fixtures. The jigs designing is complex where as fixtures designing is less complex. Jigs are not fitted to the machine table but fixtures are fitted.
  4. 1 point
    The purpose for a governor on at CI engine is the same as the purpose for a governor on any machine: to maintain constant speed under varying load conditions. DrD
  5. 1 point
    There is most definitely a difference. Accuracy is the closeness to the desired value. Precision is the closeness to each other. You can be precise in your measurements but be precisely wrong.
  6. 1 point
    Accuracy is closeness to the true value.Precision is degree of reproducibility of measured value.eg.If we measure 5cm distance by screw guage and its showing 4.99 then its accurate and if its showing 4.90 in 5-10 repeated observations then its precision
  7. 1 point
    Atanas Sechkov

    Why parabolic fins are preferred ?

    Because they provide a better stream by directing more of the mass that comes in contact with them.
  8. 1 point
    Lisho Thomas

    Why tyres are made black in color?

    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