Theory of machine/Dynamics of Machine | Gate Mechanical Basic Concepts

  1. A kinematics chain needs a minimum of 4 link and 4 turning pairs.
  2.   If the frequency of oscillation on earth is n then the frequency of oscillation on the moon will be n/√6.
  3.  The biflar suspension method is used to find out moment of inertia.
  4. The total number of instantaneous centers for a mechanism of n link is equal to n(n-1)/2.
  5. In case of an elliptical trammel two pairs turn and two pairs slide.
  6. A shaft revolving in a bearing forms a lower pair.
  7. For kinematic chains formed by lower pair the relation between the number of link L and the number of joint J is given by L = 2/3 (J+2).
  8.   The mechanism used to enlarge or reduce moments for reproducing drawings to different scales is called pantograph.
  9.  The number of links in a pantograph is to 4.
  10. If a practical of a link has a velocity that changes both in magnitude and direction at any instant, then it must have two components of acceleration e.g., centripetal. And tangential.
  11. The Klein’s method of construction for reciprocating engine mechanism utilities a quadrilateral similar to the diagram of mechanism for reciprocating engine.
  12. . In elliptical trammels have two pairs turning and two pairs sliding.
  13. Theory of machine/Dynamics of Machine
    Theory of machine/Dynamics of Machine
  14. When a ship travel in a sea, the effect of the pitching is more dangerous.
  15. If ф is angle of friction, the limiting value of tan ф will be µ.
  16. Multiple collars are provided on a flat collar pivot bearing to distribute the axial load due to limiting bearing pressure on a collar.
  17.   Slip in belt drive is different between the linear speed of the rim of pulley and the belt on it.
  18.   In case of flat belt drive the length of belt in case of gross belts depends on the sum of the diameters of pulleys.
  19. A pantograph is a mechanism having lower pairs.
  20. Kinematic pairs are those pairs that have two elements that allow relative motion.
  21.   A cam with a roller follower would constitute higher pair.
  22.   Peaucellier mechanism has eight links.
  23.   Hart mechanism has six links.
  24. For a kinematic chain to be considered as mechanism one link should be fixed.
  25. The cam angle is the angle of rotation of the cam for a definite displacement of the follower.
  26. Klein’s construction is used to find out acceleration of various parts.
  27. For a stable governor there is one radius of the governor weight for each equilibrium speed.
  28. In case of a governor isochronous is only one equilibrium which is constant for all radii of   rotation of the bells within the working range.
  29. Module can be expressed in mm.
  30. The bipolar suspension method I used to find out moment of inertia.
  31. Instantaneous centre of rotation of a link in a four bar mechanism lies on a point obtained by intersection of extending adjoining links.
  32. A reverted gear train is one in which the first and last gear are on the same shaft.
  33. In case of spur gears the flank of the tooth is the part of the tooth surface lying below the pitch surface.
  34. In case of cross helical worm the axes of two shafts are non parallel-non-interesting.
  35. In case of gears the addendum is given by one module.
  36. Gears for watches are generally manufactured by stamping.
  37. A cam where in the follower reciprocates or oscillates in plane parallel to the axis of the cam is called cylindrical cam.
  38. Rope break Dynamometers uses no lubricant.
  39. Tesla fluid friction dynameters used for power measurement when the speed is high and the viscous force is small.
  40. Hydraulic Dynamometers is widely used for absorption of wide range power at wide range of speed
  41.  The secondary disturbing force because of inertia of reciprocating mass is given by W/g ω2 r/n cos θ. 
  42. In a balancing machine the units for unbalance measurements are gm-cm.
  43. In a hartnell governor if the stiffness of spring is increased the governor will become less sensitive.
  44. The supply of working fluid to the engine to suit the load conditions can be controlled by governor.
  45. The governor used in gramophone is of pickening type.
  46. A porter governor could be classified as dead weight type governor.
  47. The function of a governor is to adjust variation of speed by varying the input to the engine.
  48. If D and T be the pitch circle diameter and no. of teeth of a gear, then its circular pitch p = π D/T.
  49. If D1 and T1 be the diameter and no. of teeth of gear 1 and D2 and T2 the corresponding value of other gear in mesh, then ratio N1/N2, will be equal to D2/D1.
  50. A scott-russel mechanism is made up of sliding and turning pairs.
  51. Ackerman steering gear is made up of turning pairs.
  52. A sliding crank chain is made up of three turning and one sliding pairs.
  53. A motor car takes a bend of certain radius in right hand direction when moving at some speed. If engine rotates in a clockwise direct when viewed from front, then because of centrifugal force reaction on outside wheel is increased and on inside wheels decreased.
  54. If δ be the static deflection of shaft under the gravity load, then natural frequency of the system in case of the longitudinal and transverse vibration is equal to 1/2 π   √g/δ.
  55. Cold working increased the fatigue strength.
  56. Coaxing is the procedure of increasing fatigue limit by overstressing the metal by successively increasing loadings.
  57. The notch angle of the Izod impact test specimen is 450.
  58. In vicker’s hardness testing, the pyramid indentor apex is 400.

Sachin Thorat

Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.

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