Pulleys, Sprockets, and Gears

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Forging new generations of engineers
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Pulleys, Sprockets, and Gears
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Pulleys, Sprockets Gears

• Pulleys, sprockets and gears are mechanisms used
  to transfer energy through rotary motion. These
  components can be used to
• change the speed of rotation
• change the direction of rotation
• change the amount of torque available to do work

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Applications
Sprockets
Pulleys
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Pulleys Sprockets
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Gears

• A gear train is another mechanism for
  transmitting rotary motion and torque.
• Gears transmit rotary motion through interlocking
  teeth.
• A gear train is made when two or more gears are
  meshed.

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Applications
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Gears
N number of teeth
Driver (in)
Driven (out)
Driver (in)
Driven (out)
Idler Gear
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Terms

• N Number of teeth
• D Diameter
• T Torque
• Angular velocity (?) - the time rate of change of
  angular position of a rotating body, usually
  expressed in radians per second or radians per
  minute.

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Formulas
Driven (out)
D out
1. Gear Ratio Input Rate (speed)
Output Rate 2. Angular velocity in N in
Angular Velocity out N out ?
in N in ? out N out 3. Gear Ratio ? in /
? out N out / N in 4. Gear Ratio ? in /
? out D out / D in 5. Torque in / Torque
out D in / D out N in / N out
Driver (in)
D in
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Example Find gear ratio and find the input
torque required so that the output torque is 100
ft-lb.
Driven
Driver
GR N out / N in 36/ 24 1.5 T in T
out N in / N out 100 24 / 36 66.7
ft-lb
24T
36T
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Example Find gear ratio and find the input
torque required so that the output torque is 100
ft-lb.
B
A
C
GR N B / N A N C / N B N C / N A
36/ 24 1.5 T in T out N in / N out
100 24 / 36 66.7 ft-lb Gear Ratio is
unchanged by the idler gear.
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Compound Gear Trains
60T
60T
What is the Gear Ratio?
Driven
Driver
C
A
D
15T
B
15T
GR N B / N A N D/ N C 60/ 15 60/15
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