Gears

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Forging new generations of engineers
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GEARS
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Presentation Objectives

• Identify parts of the gear trainer
• Identify gears
• Identify gear terminology
• Identify tooth terminology
• Identify gear purpose
• Determine RPM
• Determine torque

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Gear Trainer
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What is a Gear?

• A gear is a toothed wheel

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Spur Gear
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Worm Gear Drive
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Bevel Gears
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Crossed Helical Gear
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Harmonic Gear
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Planetary Gear Train
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Car Differential
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Car Differential
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Gear Terminology
Gear - A toothed wheel Drive Gear - The gear
which produces the input Driven Gear - The gear
which produces the output Chain Drive - Combines
the sprocket and chain that mesh together to
produce a positive mechanical force Gear Ratio -
The description of the mechanical advantage
obtained through the use of rotating
devices Mechanical Advantage - An output increase
determined by comparing the input revolutions per
minute (RPM) to the output revolutions per minute
(RPM)
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Gear Terminology
Pulley - A wheel used to transmit power by means
of a band, belt, cord, or rope Torque - The
turning effort that causes something to rotate.
If torque produces rotation, then work is
done Wheel - A lever that is rotated 360 degrees
around an axle Work - The ability of force to
travel through a distance Gear Train - A series
of two or more meshed gears used to increase or
decrease the RPM, torque, or direction of
rotation of the output gear.
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Gear Terminology
Compound Gear Train
Simple Gear Train
Worm Gear
Miter Gear
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Spur Gear Terminology
Involute Profile
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Spur Gear - Tooth Parts
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Gear Tooth Size Called Diametral Pitch
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Purpose of a Gear

• Energy Transmission
• In the proper combination can be used to increase
  or decrease speed and torque

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Gear Rotations
With two gears, the output of the driven gear
will rotate in the opposite direction of the
drive gear
With more than two gears, every other gear will
rotate in the same direction (ie. Gears 1, 3, 5
will rotate clockwise and gears 2, 4 will rotate
counter clockwise)
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Determining Gear Rpm
Driving Gear Teeth Driven Gear Teeth
X Driving Gear RPM RPM of Driven gear


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What Is Torque?

• The turning effort (measured in inch-pounds or
  foot-pounds) that causes something to rotate.
  When torque produces rotation, then work is done.

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Determining Torque
Power Out Power In
1HP at 100 rpm1/2 HP at 200 rpm 1 HP at 200 rpm
2 HP at 100 rpm
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Importance

• Modern Multi Speed Bicycles

• Automobiles

• Construction Equipment

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Also
Recreation (fishing)
Timing Gears
Efficient Transportation (sprocket system)
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Car 3 Speed Transmission
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Gear Facts

• The rpm of the larger gear is always slower than
  the rpm of the smaller gear.
• Mating gears always turn in the opposite
  direction.
• Gears locked together on the same shaft will
  always turn in the same direction and at the same
  rpm.
• Mating gears always have the same size teeth
  (diametral pitch).
• The gear ratio between mating gears is the ratio
  between the number of teeth, the pitch diameters
  and the rpms.

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Gear Review

• What is a gear?
• Name 4 different types of gears.
• What is torque and rpm?
• What is diametral pitch how is it shown?
• List 10 places where gears are used.