7/17/2019 4 Bar Linkage Assign (1)

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Name: Saad Munir Batch: ME-04A Registration No: 1922

Four Bar linkage:

A link is a rigid body which has at least two points of attachment (nodes) to make joints. A

binary link has two nodes. I have used four binary links to make a 4 bar linkage that has one

degree of freedom. The linkage has 4 components; the crank which is the driving bar to which

motor is connected, the rocker which is the driven bar, the coupler which is the connecting rod

between the crank and the rocker; and finally, the frame which is a fixed bar to which crank and

rocker are connected through pin joints. The original dimensions are  frame of length 460mm,

crank of L = 240mm, coupler of L = 420mm and rocker of L = 320mm.

Originally, the crank rotates complete 360 degree and rocker remains above the frame but

rotates less than 180 degree. All comparisions below are made with respect to original.

Observation of Doubling the original crank length ( L= 480mm): Crank and Rocker are

interchanged.

Frame

Rocker

Coupler

Crank

New

ocker

New crank

Original Design

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Observation of halving the original crank length ( L= 120mm): Crank and rocker remain the

same, but, rotation of rocker considerably decreased (swings less).

Observation of doubling the original coupler length ( L= 820mm): Original Crank and rocker

interchanged. Less than 180 degree rotation of crank and lesser rotation of rocker too.

Observation of halving the original coupler length ( L= 210mm): Original crank and rocker

remain the same. Rotation of crank less than 180 degree. Decreased rotation of rocker too

and now the angle of rotation for rocker lays downwards the frame.

Observation of doubling the original rocker length ( L= 640mm): Angle of rotation for rocker is

decreased and the minimum angle of rocker with frame becomes almost zero degree.

New

rocker

New crank

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Observation of halving the original rocker length ( L= 160mm): Original crank and rocker

interchanged. Lesser rotation of the new rocker compared to as was in original.

Observation of increasing the original frame length ( L= 800mm): Original crank and rocker

remain the same. Crank doesn’t rotate even 180 degrees. Considerable decrease in the

rotation of rocker as well. Rocker goes a little below the frame too.

Observation of halving the original frame length ( L= 230mm):Original crank and rocker

remain the same. Crank rotates little less than 360 degrees. There is an increase in the angle

of rotation for rocker. Rocker now goes considerably below the frame as well

New crank

New

ocker