Understanding Simple Machines

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Understanding Simple Machines
Levers Inclined Plane Wedge Wheel and
Axle Screws Gears Pulleys Cams Machine
Elements Gadget Anatomy

• Assembled by Craig Tillmann
• from the following web sites
• Inventors Toolbox The Elements of Machines
• How Stuff Works
• Explore Science
• Beakman and Jax Levers
• Delightful Machines

Technology Education Home Page http//www.erols.co
m/te
Modified by the GA Agriculture Education
Curriculum Office July 2002
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Levers
All levers have 3 parts the fulcrum, the load,
and the effort.
The fulcrum is the pivot point. When it's right
in the middle of the lever, the amount of effort
you push down equals the amount of load you can
lift.
Learn more about levers
Water Powered Simple Machine
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Moving the Fulcrum
Here the fulcrum is closer to the load. The
distance from the effort end to the fulcrum is
twice the distance from the fulcrum to the load.
You only have to push down half as hard to lift
the same weight. The trade-off is you have to
push down a longer distance.
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Classes of Levers
First Class
Second Class
Third Class
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Inclined Plane
Examples of inclined planes Loading
ramp Stairs or wheelchair ramp Mountain
road Threaded screw. Inclined Plane Clocks
An inclined plane is a ramp used to reduce the
effort needed to raise or lower an object over a
vertical height.
Online Multimedia Activity Requires Shockwave
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Wedge
Nearly all cutting machines use the wedge.
A lifting machine may use a wedge to get under a
load.
A wedge converts motion in one direction into a
splitting motion that acts at right angles to the
blade.
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Wheel and Axle

• A wheel or spoke is locked to a central axle so
  that when one is turned the other must turn.
• A longer motion at the edge of the wheel is
  converted to a shorter more powerful motion at
  the axle.

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Screws
Archimedes screw
A screw is a central core with a thread or
groove(inclined plane) wrapped around it to form
a helix. While turning, a screw converts a rotary
motion into a forward or backward motion.
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Gears
Bevel Gear Rack and Pinion Worm Gear Learn more
about Gears

• Gears are toothed or pegged wheels meshed
  together to transmit motion and force.
• The larger gear will rotate more slowly than the
  smaller one, but will rotate with greater force.
• Each gear in a series reverses the direction of
  rotation of the previous gear.

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Bevel Gear

• Bevel Gears are Gears that mesh at an angle and
  change the direction rotation.

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Rack and Pinion

• A single gear, the pinion, meshes with a sliding
  toothed rack.
• This combination converts rotary motion to linear
  motion.
• Windshield wipers are powered by a rack and
  pinion gear.

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Worm Gear

• combination of a gear meshed with the threads of
  a screw.
• changes the direction of turning motion by ninety
  degrees.
• decreases the speed of turning from screw to gear
  and increase its force.

Click Image for animation
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Pulley System

• A single pulley reverses the direction of a
  force.
• When two pulleys are connected, they permit a
  heavy load to be lifted with less force.
• The trade-off is that the end of the rope must
  move a greater distance than the load.

Learn more about pulleys
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Pulleys in Action
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Cams

• A cam is a wheel with shaped bumps on it.
• Cams are often connected to rods, levers, or
  springs.

gravity trip hammer
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Cams at Work
A Crank Shaft changes the linear motion of the
piston to a rotary motion.
A Cam Shaft is connected to the Crank by gears,
belts or chains. It changes rotary motion to
linear motion to open and close valves.
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Other Elements of Machines
Crank and Rod
Ratchet
Chains and Belts

• Connects two separated wheels so that when one
  turns, the other will turn in the same direction.

• When the crank turns, the rod is pushed back and
  forth.

• Allows a wheel to turn in only one
  direction. A bar called the "pawl" is fixed above
  the ratchet wheel.

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Gadget Anatomy
1.
Name the simple machines that make up each
device.
2.
3.