Question

For one degree of freedom planer mechanism having links, which one of the following is the possible combination?

(a) Four binary links and two ternary links

(b) Four ternary links and two binary links

(c) Three ternary links and three binary links

(d) One ternary link and five binary links

I had been asked this question by my college professor while I was bunking the class.

My doubt is from Types of Kinematic Chains topic in section Simple Mechanisms of Machine Kinematics

Answer 1

Correct answer is (d) One ternary link and five binary links

Explanation: From Grubler’s criteria 1 = 3(l – 1) – 2j

or, j = 3/2l – 2 for six link

j = 3/2 x 6 – 2 = 7          1 ternary link = 2 binary link

a) j = 4 + 2 x 2 ≠ 7

b) j = 4 x 2 + 2 ≠ 7

c) j = 3 x 2 + 2 ≠ 7

d) j = 1 x 2 + 5 ≠ 7 the ans is d.