1.1.1 Mechanisms

1 S T , 2 S I M P L E M A C H I N E S N D , & 3 R D C L A S S L E V E R S W H E E L & A X L E

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...

• • •

1 st 2 nd class lever system class lever system

–

3 rd 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?

( Y O U W O N ’ T U S E A L L / M A N Y O F T H E S E F O R T H E S I M P L E M A C H I N E S , B U T I T G I V E S Y O U S O M E I D E A S ! )

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