1. GEARS

2. Create Gear & Cam Mechanism Drawings
The Unit Organizer
The Big Picture
Various Devices are used to Transmit Power and Motion
LAST UNIT/ Experience
GDT
CURRENT UNIT
Create Gear & Cam Mechanism Drawings
NEXT UNIT/ Experience
Solid Modeling
UNIT SCHEDULE
Gear & Cam Mechanisms
Is about…
Pre-Test
Vocabulary
Drawings
Reading
Self-test questions
Goal Assessment
We must be able to identify
Requires that we understand…
Types of Gears
Cam Terms
Requires that we understand…
Gear Terms
Spur gear
Worm gear
Bevel gear
Rack gear
Root dia.
Pitch dia.
Outside dia.
Base circle
Pressure angle
Number of teeth
Involute profile
Addendum
Dedendum
Gear ratio
What purposes do gears serve and where are they used?
What are the features of a typical gear drawing?
What purpose do cams serve and where are they used?
What is the relationship between a cam profile and a displacement diagram?
UNIT SELF-TEST
QUESTIONS
UNIT RELATIONSHIPS

3. GEARS
GEARS ARE USED TO TRANSMIT POWER AND ROTATING MOTION FROM ONE MACHINE PART TO ANOTHER.
SPUR WORM BEVEL RACK

4. Objectives Identify and describe various gears and their applications.
Spur Gear
Worm Gear
Bevel Gear
Rack

5. Spur Gear Spur gears operate on axes which are parallel.
Click on the link below and view the gear in action.

6. Gear Ratio
In the simplest case, a set of gears results in the same rotation speed on both the input and the output axle.  This happens if both gears have the same number of teeth. 
However, in most cases gears are used to change the speed and mechanical advantage between axles. 
For simple gears calculating this gear ratio is simply a matter of counting the number of teeth on each gear and comparing by dividing the number of output teeth by the number of input teeth. 

7. Gear Ratio For example, if the input gear has 12 teeth
and the output gear has 24 teeth,
then the gear ratio is 24/12 = 2. 
The standard nomenclature for this is to use a colon and relate the gear ratio to one, for example 2:1.
INPUT GEAR
OUTPUT GEAR

8. Spur Gear i

9. Gear Nomenclature

10. Determining the Base Circle

13. Worm Gear Click on the link below and view the gear in action.

14. Worm Gear

15. Worm Gear

16. Worm Gear

17. Bevel Gear Click on the link below and view the gear in action

18. Bevel Gear

19. Bevel Gear

20. Rack Click on the link below and view the gear in action

22. Gear Applications
Subaru Transmission
LEGO Transmission

23. CAMS

24. Create Gear & Cam Mechanism Drawings
The Unit Organizer
The Big Picture
Various Devices are used to Transmit Power and Motion
LAST UNIT/ Experience
GDT
CURRENT UNIT
Create Gear & Cam Mechanism Drawings
NEXT UNIT/ Experience
Solid Modeling
UNIT SCHEDULE
Gear & Cam Mechanisms
Is about…
Pre-Test
Vocabulary
Drawings
Reading
Self-test questions
Goal Assessment
We must be able to identify
Requires that we understand…
Types of Gears
Cam Terms
Requires that we understand…
Gear Terms
Cam
Follower
Displacement diagram
Spur gear
Worm gear
Bevel gear
Rack gear
Root dia.
Pitch dia.
Outside dia.
Base circle
Pressure angle
Number of teeth
Involute profile
Addendum
Dedendum
Gear ratio
What purposes do gears serve and where are they used?
What are the features of a typical gear drawing?
What purpose do cams serve and where are they used?
What is the relationship between a cam profile and a displacement diagram?
UNIT SELF-TEST
QUESTIONS
UNIT RELATIONSHIPS

25. Objectives Identify and explain terms related to Cams. Cam Follower
Displacement diagram

26. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.
FOLLOWER
ROLLER
CAM
CAM SHAFT

27. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.

28. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.

29. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.

30. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.

31. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.

32. HOW CAMS WORK
A Cam is a rotating part that changes rotating motion into reciprocating motion.
Click on the camshaft below and view the cams in action.

36. CAM DESIGN PROBLEM Instructions:
Scale the drawing shown for all necessary dimensions. Then, using AutoCAD, create a cam that will move the Lever Arm roller to the position shown and then back to its original position in one 360 degree revolution.
Refer to Fig in ‘Technical Drawing’ textbook for sample.
Advanced: Create a solid model assembly of this mechanism.