1.1.1 Mechanisms

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1.1.1 Mechanisms
SIMPLE MACHINES
1 ST, 2 ND, & 3 RD C L A S S L E V E R S
WHEEL & AXLE
Quietly read and decide what type of learner you may be. Once you have
decided, privately write your choice on the sticky note provided.
 (1) I do it, build it, then I look at it to make it better.
 (2) I need to draw/write out my ideas before I start.
 (3) I work best talking about my ideas with others
and make a plan before I start.
 I then grouped them from their own number choice.
Your group’s challenge is to create a...
• 1st class lever system
• 2nd class lever system
• 3rd class lever system
–
with various FT parts & a scientific mass. Apply the scientific mass
(resistance force) to the lever and use a spring scale and/or a force
meter (measures force in Newtons) to determine static equilibrium.
~OR~
• wheel & axle system
–
–
utilizing the FT parts, a scientific mass, and string.
Attach one end of a string to the outside surface of the wheel.
Attach one end of a second string to the outside surface of the axle
(You’ll attach the scientific mass here later)
You want me to do WHAT????
 Build a simple machine…we’ll be testing it soon for
MA (AMA, IMA, and Efficiency…)
 Here’s some ideas to get you started…
Hints on how these
FTs go together?
(YOU WON’T USE ALL/MANY OF THESE FOR
THE SIMPLE MACHINES, BUT IT GIVES YOU
SOME IDEAS!)
Universal Joint
Transmits power when shafts are not in line
Spur Gears
Change speed, torque, and rotational speed
Idler Gear
No effect on speed and torque, but input and output shafts
turn in the same direction
Rack & Pinion
Rack (in red) & pinion (in black) converts rotary motion of
the pinion gear to linear motion of the rack
Reversible, positive drive with no slipping
Crown & Pinion
Mechanism reduces speed and increases torque
Output shaft is at a 90-degree angle to the input shaft
Gears rotate in opposite directions
Bevel Gears
Gears increase torque or speed
Output shaft is at a 90-degree angle to the input shaft
Gears rotate in opposite directions
Worm Gear
Gear increases torque and reduces speed
Output shaft is at a 90-degree angle to the input shaft
Direction of rotation can be reversed, but the output gear
cannot drive the worm gear
Cam
As a cam rotates the flat follower is raised and lowered,
converting rotary motion to linear motion
FOLLOWER
CAM
LOBE
Chain & Sprocket
Chain and sprocket apparatus increases speed or torque
Mechanism can run in reverse direction with no slipping
Input and output shafts rotate in the same direction
Pulley & Belt
Mechanism can increase torque or speed and can run in
reverse
Input and output shafts are parallel and rotate in the same
direction
Slipping of the belt may occur
Motor Driven Worm Gear
Gear reduces speed and increases torque
Output shaft is at a 90-degree angle to the input shaft
Direction of motion is reversible, but the output gear cannot
turn the worm gear
Motor Driven Pulley & Belt
Mechanism can increase torque or speed
Input and output shafts are parallel and rotate in the same
direction
Slipping of the belt may occur
Screw
Mechanism converts rotary motion to linear motion and
increases torque
Direction of rotation is reversible

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