Chapter 2_Basic Mechanisms

1.

Theory of Machines
Dr Sameeh Baqain
Adapted from Eng. Yanal Masarweh
American University of Madaba
Mechanical Engineering Department
American University of Madaba
10/28/2026
1

2.

Basic Mechanisms
(The Four Bar Linkage)
American University of Madaba
10/28/2026
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3. Four – Bar Mechanism

Four – link planar mechanism is the simplest
mechanism.
Four – bar mechanism is one of the most
useful and most common four – bar linkage.
◦ Link 1 is the frame (Fixed)
◦ Link 2 is the crank (driver) which makes a
complete rotation by an electric motor
◦ Link 3 is the coupler which is the intermediate
connecting link
◦ Link 4 is the rocker or follower (driven)
American University of Madaba
10/28/2026
3

4. Four – Bar Mechanism

B
3
A
Coupler
Output
Input
4
Follower
2 Crank
2
4