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GATE 2020 ME (ME1) – Question 18

Theory of Machines · Displacement, velocity and acceleration analysis of plane mechanisms · 1 mark · Multiple choice

The shown four-bar mechanism has QR = 600 mm, RS = 300 mm and fixed PS = 400 mm. For a crank–rocker mechanism, link PQ can have length ______.

Diagram for GATE 2020 ME (ME1) question 18
  1. 80 mm
  2. 200 mm
  3. 300 mm
  4. 350 mm

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Show answer and explanation

Correct answer: (A) 80 mm

Explanation

A crank-rocker needs a Grashof chain with the shortest link adjacent to the fixed link. With PQ=80, s+l=80+600=680≤300+400=700, and PQ is adjacent to fixed PS. The other choices violate Grashof’s inequality. **Answer: A.**