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Tuesday, 17 April 2012

Important basic concepts in Machine Design for GATE 2018 Part-3


The present article (Part-3) contains the important basic concepts in Machine design and related machine drafting technology in Mechanical Engineering. Note down each concept which might help in GATE 2018 Mechanical.



  • Spiral gears are suitable for transmitting small powers
  • As pump speed increases its NPSH (Net Positive Suction Head) requirement increases
  • If pump NPSH requirements are not satisfied, it will be cavitated
  • Bush roller chain is used in motorcycle.
  • The working load for a chain for crane application is expressed in terms of the diameter of the link in cm and given by 500 multiplied by the square of the diameter.
  • If a square key and shaft are to be of the same material and or of equal strength, the length of key would be 1.23d, d=diameter of shaft
  • In a standard coarse thread bolt, the stress concentration is maximum at the root.
  • Fatigue strength of a surface may be increased by polishing the surface
  • The maximum deflection allowed in gantry girders is L/1000
  • The maximum size of the fillet weld that can be used at 3 mm
  • The maximum size of fillet weld that can be made in single pass in 6 mm
  • A rolled steel flat designated as 50 ISF 8 means the flat is 50 mm wide and 8 mm thick.
  • The column splice is used for increasing length of column
  • The minimum thickness steel member exposed to weather and accessible for painting is 10 mm
  • For determination of allowable stress in axial compression, IS: 800-1962 has adopted secant formula
  • For accurately, cut gears operating at velocities up to 20 m/sec, the velocity factor v, is given by 6/6+v             
  • Zero axial thrust is experienced in herringbone gears
  • In order to realize the advantage of fluid friction, it is essential to have parallel oil film in bearing
  • A Shaft rotating in anti-clockwise direction at slow speed inside a bearing will be towards left side of bearing and making metal to metal contact
  • Bearing characteristics number relating Z-absolute viscosity of lubricant, N-speed of journal and p-bearing pressure on projected bearing area is ZN/p
Important basic concepts in Machine Design for GATE 2015 Part-1

Important basic concepts in Machine Design for GATE 2015 Part-2

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