Question

Draw the linkage and graphically find all possible solutions (both open and closed) for angle 3 and 4. Determine the Grashof condition

L1 or a = 8

L2 or b = 5

L3 or c = 7

L4 or d = 6

theta2 = 25 degrees

all in cm.

Answer 1

SOLUTION

GIVEN DATA

L₁ = 8cm, L₂ = 5cm, L₃ = 7cm, L₄ = 6cm, theta2 = 25 degree.

To be a perfect 4bar mechanism with those link it should be satisfied with grashof's criterion

The law states that the summation of the smallest and largest link should be less than that of the sum of the other two links. i.e

S+L $\leq$ P+Q

where S = link 2, L = link 1, P = link3, Q = link4

putting the values S+L = 13 and P+Q = 13 hence it is satisfying grashof's criterion.

Now construction of the mechanism

Steps

• Draw a line of 8cm and name it O₂O₄ which is the link 1
• Draw O₂A = 5cm and the angle O₄O₂A = 25⁰
• From point A draw arc of 7cm as shown in the figure.
• Now draw another arc of length 6cm, where this arc intersect previous arc name that point as B and B'
• Finally, we got the complete mechanism.
• We will get two mechanisms one is open linkage and one is the closed linkage.
• All the angle measure are written in the figure attached.

Link LinX-2 25 Link-4 LinK-L Link-3 41