1. Basic Practical Mechanics
By Benjamin Kidd
Benjamin W. Kidd - ENGR-162/12

2. Benjamin W. Kidd - ENGR-162/12
Today’s Lesson
Gears
Belt Drives
Pulleys
Benjamin W. Kidd - ENGR-162/12

3. Benjamin W. Kidd - ENGR-162/12
What are they for?
Mechanical Advantage
Transmission of mechanical power
Change in rotational velocity
Change in direction of movement
Benjamin W. Kidd - ENGR-162/12

4. The Terminology of Gears
Gearset – Two (or more) gears used to translate rotational motion from one shaft to another.
Benjamin W. Kidd - ENGR-162/12

5. The Terminology of Gears
Mesh Point – Place where the teeth from individual gears come together.
Benjamin W. Kidd - ENGR-162/12

6. The Terminology of Gears
Pinion – The “driving” gear (usually the smaller of a pair).
Benjamin W. Kidd - ENGR-162/12

7. The Terminology of Gears
Pitch – A measure of compatibility of gears
Benjamin W. Kidd - ENGR-162/12

8. Different Types of Gears
Spur
Helical
Bevel
Worm
From
From
Benjamin W. Kidd - ENGR-162/12

9. Benjamin W. Kidd - ENGR-162/12
Speed of Gears
Rotational Velocity to Angular Velocity, ω
Example: 40 RPM
Benjamin W. Kidd - ENGR-162/12

10. Benjamin W. Kidd - ENGR-162/12
Velocity Transfer
r = Radius of gear
ω = Angular Velocity
N = Number of teeth on the gear
Remember, Pinion (subscript “p”) is the “input” or “driving” gear.
Benjamin W. Kidd - ENGR-162/12

11. Velocity Transfer Example
What’s the RPM of the gear pictured meshed with the All Electronics motor DCM-216?
DCM-216 RPM ≈ 1200 RPM
Benjamin W. Kidd - ENGR-162/12

12. Benjamin W. Kidd - ENGR-162/12
Answer?
240 RPM
Benjamin W. Kidd - ENGR-162/12

13. Benjamin W. Kidd - ENGR-162/12
Torque
Torque = Force x Radius of Lever
Torque Transfer Equation
From Previous Example
Benjamin W. Kidd - ENGR-162/12

14. Benjamin W. Kidd - ENGR-162/12
Belts and Chain Drives
What are some Examples of these?
Benjamin W. Kidd - ENGR-162/12

15. Benjamin W. Kidd - ENGR-162/12
Pulley Systems
What is a pulley?
Benjamin W. Kidd - ENGR-162/12

16. Pulley Systems Example
Benjamin W. Kidd - ENGR-162/12
Photos By Charles Mason

17. Benjamin W. Kidd - ENGR-162/12
Pulley Systems
Mechanical Advantage
Distance
Benjamin W. Kidd - ENGR-162/12