the unit organizer last unit/ experience gdt current unit create gear & cam mechanism drawings...
TRANSCRIPT
GEARS
The Unit Organizer
LAST UNIT/ Experience
GDTCURRENT UNIT
Create Gear & Cam Mechanism DrawingsNEXT UNIT/ Experience
Solid Modeling
Pre-Test
Vocabulary
Drawings
Reading
Self-test questions
Goal Assessment
UNIT SCHEDULE
1. What purposes do gears serve and where are they used?2. What are the features of a typical gear drawing?3. What purpose do cams serve and where are they used?4. What is the relationship between a cam profile and a displacement
diagram?UN
IT S
ELF-
TEST
Q
UES
TIO
NS
UN
IT RELATIO
NSH
IPS
Gear & Cam Mechanisms
Is about…
Requires that we understand…
We must be able to identify
Types of Gears Gear
Terms
Cam Terms
•Spur gear•Worm gear•Bevel gear•Rack gear
• Root dia.• Pitch dia.• Outside dia.
• Base circle
• Pressure
angle
Various Devices are used to Transmit Power and Motion
The Big Picture
Requires that we understand…
• Number of teeth
• Involute profile• Addendum• Dedendum• Gear ratio
GEARS
GEARS ARE USED TO TRANSMIT POWER AND ROTATING MOTION FROM ONE MACHINE PART TO ANOTHER.
SPUR WORM BEVEL RACK
ObjectivesIdentify and describe various gears and their applications.
• Spur Gear
• Worm Gear
• Bevel Gear
• Rack
Spur Gear
http://www.ericalbrecht.com/technic/fundamentals.html
Click on the link below and view the gear in action.
Spur gears operate on axes which are parallel.
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.
Gear Ratio
Gear RatioFor 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
Spur Gear
i
Gear Nomenclature
Determining the Base Circle
Worm Gear
http://www.ericalbrecht.com/technic/fundamentals.html
Click on the link below and view the gear in action.
Worm Gear
Worm Gear
Worm Gear
Bevel Gear
http://www.ericalbrecht.com/technic/fundamentals.html
Click on the link below and view the gear in action
Bevel Gear
Bevel Gear
Rack
http://www.ericalbrecht.com/technic/fundamentals.html
Click on the link below and view the gear in action
Gear Applications
Subaru Transmission LEGO Transmission
CAMS
The Unit Organizer
LAST UNIT/ Experience
GDTCURRENT UNIT
Create Gear & Cam Mechanism DrawingsNEXT UNIT/ Experience
Solid Modeling
Pre-Test
Vocabulary
Drawings
Reading
Self-test questions
Goal Assessment
UNIT SCHEDULE
1. What purposes do gears serve and where are they used?2. What are the features of a typical gear drawing?3. What purpose do cams serve and where are they used?4. What is the relationship between a cam profile and a displacement
diagram?UN
IT S
ELF-
TEST
Q
UES
TIO
NS
UN
IT RELATIO
NSH
IPS
Gear & Cam Mechanisms
Is about…
Requires that we understand…
We must be able to identify
Types of Gears Gear
Terms
Cam Terms
• Cam• Follower• Displacement
diagram
Various Devices are used to Transmit Power and Motion
The Big Picture
Requires that we understand…
•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
ObjectivesIdentify and explain terms related to Cams.
• Cam
• Follower
• Displacement diagram
HOW CAMS WORK
FOLLOWER
ROLLER
CAM
CAM SHAFT
A Cam is a rotating part that changes rotating motion into reciprocating motion.
HOW CAMS WORKA Cam is a rotating part that changes rotating motion into reciprocating motion.
HOW CAMS WORKA Cam is a rotating part that changes rotating motion into reciprocating motion.
HOW CAMS WORKA Cam is a rotating part that changes rotating motion into reciprocating motion.
HOW CAMS WORKA Cam is a rotating part that changes rotating motion into reciprocating motion.
HOW CAMS WORKA Cam is a rotating part that changes rotating motion into reciprocating motion.
HOW CAMS WORKA Cam is a rotating part that changes rotating motion into reciprocating motion.
Click on the camshaft below and view the cams in action.
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. 20-19 in ‘Technical Drawing’ textbook for sample.Advanced: Create a solid model assembly of this mechanism.
CAM DESIGN PROBLEM
