1. Mechanical Engineering
Links and Degrees of Freedom
Grade 10 ST

2. What is Mechanical Engineering?
Engineering is a branch of science and technology that focuses on the analysis and execution of technological projects such as building bridges, roads, bicycles, cars and televisions.
Mechanical engineering is a branch of engineering that focuses on the design, production, analysis, working and improvement of technical objects

3. Linking in Technical Objects
When there are more than two parts in an object there needs to be a link to hold the two parts together.
Any part or fluid that holds together 2 pieces performs a mechanical function called linking

4. Characteristics of Links
Every link can have only 4 characteristics
Direct or Indirect
Rigid or flexible
Removable or non-removable
Complete or partial

5. Characteristics of Links

6. Practice The link between the tire and the wheel is: Direct Flexible
Removable
Complete

7. Practice Link between the wheel and the frame Indirect Rigid Removable
Partial

8. Degrees of Freedom of Movement
In a technical object linking limits the possibility of independent motion of one part in relation to another.
Ex: The link between the bicycle tire and the wheel.
The tire will always follow the wheel. Therefore, this is an example of a complete link.

9. Degrees of Freedom of Movement
Ex: The wheel and frame on a rollerblade.
The wheel can turn even if the frame is immobile. Therefore, this is an example of a partial link

10. Degrees of Freedom of Movement
There are 6 possibilities of independent motion
3 translational motions
3 rotational motions
A part may have a maximum of six degrees of freedom.

11. Degrees of Freedom of Movement

12. Guiding Controls
Guiding controls force moving parts to follow specific trajectory
There are 3 types of guiding
Translational guiding ensures the straight translational motion of a moving part
Rotational Guiding ensures the rotational motion of a moving part
Helical Guiding ensures both the translational motion of a moving part while it rotates about the same axis.

13. Examples
Examples:
The window has what kind of guiding? _____________________________
The axle on a bike provides what type of guiding? ____________________
The peanut butter lid has what type of guiding?_____________________

14. Adhesion and Friction
Adhesion is the phenomenon that enables two surfaces to remain in contact with each other without slipping.
Friction is a force that resists the slipping of one moving part over another
Lubrication is the mechanical function performed by any component that reduces friction between two parts.

15. Five Factors that affect the strength of adhesion between 2 Surfaces

16. How to reduce friction? Apply a lubricant
Polish the surface of the parts

17. Practice
For each of the following situations, determine whether the strength of adhesion between the surfaces described will increase or decrease, and identify the factor affecting the strength of adhesion. a) between the soles of a worker’s boots and the shingles on a roof as the temperature rises over the course of the day increase  decrease  Factor involved: _________________________________________ b) between a hockey puck and the ice as the period advances and the ice becomes rougher c) between the wheel of a wheelbarrow and the road after the wheelbarrow has been emptied Factor involved: _________________________________________

18. Practice