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Tuesday, 17 April 2012

Important basic concepts in Machine Design for GATE 2018 Part-1




This post gives some of the important basic concepts in Machine design (Design of Machine Elements) which can be helpful in GATE 2015 exam
  • In the majority of machine members, the damping capacity of the material should be zero.
  • At quite low temperatures (say -75°c) the notched bar impact value of steel decreases significantly.
  • The crest diameter of a screw thread is same as major diameter.
  • If d is the diameter of bolt hole then for a flanged pipe joint to be leak proof, the circumferential pitch of the bolts should be 20√d - 30√d.
  • Muntz metal contains copper-zinc.
  • A Babbitt is antimony bearing lead or tin alloy.
  • Steel balls for ball bearing are manufactured by cold heading.
  • The blow-off pressure of a safety value is 106% of boiler working pressure.
  • A foundation bolt with a circular end is secured to the floor by means of a steel cotter. If the pull on the bolt is 14000 kg, the diameter of the bolt should be 60 mm.
  • In case knuckle joint the pin is most likely to fail in double shear.
  • The key is cut is both shaft and hub is the case of the sunk key.
  • Splines are used when axial relative motion between shaft and hub is necessary.
  • Splined shafts are generally used in automobiles.
  • Universal coupling/Hook’s joint is used for non-collinear shafts.
  • In flange coupling, the weakest element should be key.
  • Turnbuckle has left-hand threads on one end and right-hand threads on other end.
  • The elastic nut is a locking device that has hard fiber or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip.
  • Treating the weld as a line, the moment of inertia about the center of gravity of a circular weld of diameter d, would be πd3/4.
  • A single ply leather belt running at a belt velocity of 300 ft/min is likely to transmit per inch of width 4.0 HP.
Important basic concepts in Machine Design for GATE 2015 Part-2

Important basic concepts in Machine Design for GATE 2015 Part-3

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