1. Introduction to Mechanisms
Ken Youssefi
UC Berkeley

2. Mechanism Mechanism consists of linkages and joints.
Machines are mechanical devices used to accomplish work. A mechanism is a heart of a machine. It is the mechanical portion of the machine that has the function of transferring motion and forces from a power source to an output.
Mechanism is a system of rigid elements (linkages) arranged and connected to transmit motion in a predetermined fashion.
Mechanism consists of linkages and joints.
Ken Youssefi
UC Berkeley

3. Example of Mechanism Can crusher Simple press Rear-window wiper
Ken Youssefi
UC Berkeley

4. Example of Mechanisms
Moves packages from an assembly bench to a conveyor
Microwave carrier to assist people on wheelchair
Lift platform
Ken Youssefi
UC Berkeley

5. Example of Mechanisms Lift platform Front loader
Device to close the top flap of boxes
Ken Youssefi
UC Berkeley

6. Example of Mechanisms Rowing type exercise machine
Conceptual design for an exercise machine
Rowing type exercise machine
Ken Youssefi
UC Berkeley

7. Example of Mechanisms Six-bar linkage prosthetic knee mechanism
Extension position
Flexed position
Six-bar linkage prosthetic knee mechanism
Ken Youssefi
UC Berkeley

8. Four-Bar Linkage
Ken Youssefi
UC Berkeley

9. Four-Bar Linkage Categories
Ken Youssefi
UC Berkeley

10. Four-Bar Linkage Categories
Ken Youssefi
UC Berkeley

11. 4-Bar mechanisms
Ken Youssefi
UC Berkeley

12. 4-Bar mechanisms S + l > p + q 4 double rocker mechanisms
Ken Youssefi
UC Berkeley

13. The Slider-Crank Mechanism
Ken Youssefi
UC Berkeley

14. Slider-Crank Mechanism
Offset slider-crank mechanism
Ken Youssefi
UC Berkeley

15. Slider-Crank Mechanism
The mechanism has a stroke B1B2 equal twice the crank length r2.
Locations B1 and B2 are called the extreme positions (limiting) of the slider
In-line slider crank mechanism
Ken Youssefi
UC Berkeley

16. The Slider-Crank Mechanism
Ken Youssefi
UC Berkeley

17. Slider-Crank Mechanism - Inversion
Ken Youssefi
UC Berkeley

18. Mechanism Categories Function Generation Mechanisms
A function generator is a linkage in which the relative motion between links connected to the ground is of interest.
A four-bar hand actuated wheelchair brake mechanism
Ken Youssefi
UC Berkeley

19. Mechanism Categories Function Generation Mechanisms
A four-bar drive linkage for a lawn sprinkler
Ken Youssefi
UC Berkeley

20. Mechanism Categories Motion Generation Mechanisms
In motion generation, the entire motion of the coupler link is of interest (rigid body guidance).
New Rollerblade brake system
Ken Youssefi
UC Berkeley

21. Mechanism Categories Motion Generation Mechanisms
Four-bar automobile hood linkage design
Ken Youssefi
UC Berkeley

22. Mechanism Categories Path Generation Mechanisms
In path generation, we are concerned only with the path of a tracer point and not with the motion (rotation) of the coupler link.
Crane – straight line motion
Ken Youssefi
UC Berkeley

23. Primary Joints
Ken Youssefi
UC Berkeley

24. Higher Order Joints
Ken Youssefi
UC Berkeley

25. Motion Generation Mechanisms
Rotating a monitor into a storage position
Moving a storage bin from an accessible position to a stored position
Ken Youssefi
UC Berkeley

26. Motion Generation Mechanisms
Moving a trash pan from the floor up over a trash bin and into a dump position
Lifting a boat out of water
Ken Youssefi
UC Berkeley

27. Straight line Mechanisms
Ken Youssefi
UC Berkeley

28. Straight line Mechanisms
Ken Youssefi
UC Berkeley

29. Straight Line Mechanism
Ken Youssefi
UC Berkeley

30. Scotch Yoke Mechanism
Ken Youssefi
UC Berkeley

31. Geneva Mechanism
Ken Youssefi
UC Berkeley

32. Linear Geneva Mechanism
Ken Youssefi
UC Berkeley

33. Ratchet Mechanism
Ken Youssefi
UC Berkeley

34. Straight Beam Walking Mechanism
Ken Youssefi
UC Berkeley

35. Ken Youssefi
UC Berkeley

36. Roller and Flat Follower Cams
Ken Youssefi
UC Berkeley

37. Cylindrical Cam Mechanism
Ken Youssefi
UC Berkeley

38. Gears – Rack and Pinion
Ken Youssefi
UC Berkeley

39. Gears Worm Gear Sets Bevel gears Planetary Gear set Ken Youssefi
UC Berkeley

40. V-8 Engine
Ken Youssefi
UC Berkeley

41. Type of Motion and Mechanisms
Most power sources that are readily available today are either of the pure rotational motion type, such as electric motor or hand crank, or of the pure translational type, such as pneumatic or hydraulic cylinder.
Translation to Translation
Ken Youssefi
UC Berkeley

42. Type of Motion and Mechanisms
Rotational to Rotational
Ken Youssefi
UC Berkeley

43. Type of Motion and Mechanisms
Rotation to Translation
Ken Youssefi
UC Berkeley

44. References
Mechanism Design, Analysis and Synthesis by Erdman and sander, fourth edition, Prentice-Hall, 2001,
Machines and Mechanisms by Uicker, Pennock and Shigley, third edition, Oxford, 2002.
Machines and Mechanisms by Myszka, Prentice-Hall, 1999
Ken Youssefi
UC Berkeley