1. Mechanical EngineeringST
EST
AST SE
Mechanical Engineering
Chapter 13
Observatory pp

2. What is Mechanical Engineering?
426
What is Mechanical Engineering?
Mechanical Engineering is the branch of engineering that focuses on the design, production, analysis, working and improvement of technical objects with moving parts.
Main Topics
Links
Guiding
Transmission
Transformation

3. 2. Linking in Technical Objects
427
2. Linking in Technical Objects
Linking is the mechanical function performed by any component that connects different parts of a technical object.

4. Characteristics of Links
You must know the main characteristics of links
Chart on p. 428 in textbook.

5. Links Direct OR Indirect Rigid OR Flexible Removable OR non-removable
Complete OR Partial

6. Degrees of Freedom of Movement
428
Degrees of Freedom of Movement
The Degrees of Freedom are the set of independent movements that are possible for a given part in a technical object.
E.g. A door can only rotate around the hinges – 1 degree freedom
E.g. A manual transmission gear shift moves forward/back and left/right – 2 degrees of freedom

7. Degrees of Freedom
Chart pg 429

8. 431
3. Guiding Controls
A Guiding Component or Control is a component whose mechanical function is to guide the motion of moving parts.

9. 431
Types of Guiding
Translational Guiding ensures the straight translational motion of a moving part. E.g. a vertical window groove
Rotational Guiding ensures the rotational motion of a moving part. E.g. a bicycle wheel hub
Helical Guiding ensures the translation motion of a moving part while it rotates about the same axis. E.g. threaded screw.

10. Six Symbols for Motion Types of Motion Symbols
Unidirectional Translation
Bi-directional Translation
Unidirectional rotation
Bi-directional rotation
Unidirectional helical motion
Bi-directional helical motion

11. Adhesion and Friction of Parts
433
Adhesion and Friction of Parts
Adhesion is the phenomenon by which two surfaces tend to remain in contact with each other without slipping.
In mechanics, Friction is a force that resists the slipping of one part over another.
Lubrication is the mechanical function performed by any component that reduces friction between two parts.

12. 5 Factors affecting friction
Nature of materials (eg: steel on asphalt vs. rubber on asphalt)
Presence of a lubricant like oil or wax
Temperature: the colder the temperature the less the adhesion
Surfaces (rough vs. smooth)
Mass of the object (a heavy object will have better adhesion, more friction)