Gears and Gear Trains: Student Learning Goal

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Gears and Gear Trains Student Learning Goal

• The student will be able to identify and
  describe, in quantitative and qualitative terms,
  the operation and applications of gears (C3.1).

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Gears and Gear Trains

• SPH4C

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Gears

• Gears are toothed wheels on axles and are
  therefore members of the lever family.
• The teeth prevent slippage.

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Purpose

• Gears are used to transfer or change rotational
  speed.
• Example
• The load gear will turn at 1/3 of the rotational
  speed of the effort gear (driver).

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Gear Ratio

• This ratio of the number of teeth of the effort
  gear to the number of teeth of the load gear is
  called the gear ratio.

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Gear Ratio

• This ratio of the number of teeth of the effort
  gear to the number of teeth of the load gear is
  called the gear ratio which is equal to the IMA.

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IMA

• Why would one want to use gears with an IMA of
  less than 1?

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IMA

• Why would one want to use gears with an IMA of
  less than 1?
• The trade-off is that when you reduce speed, you
  increase torque.

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Example

• What is the IMA of the following set of gears?

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Example

• What is the IMA of the following set of gears?
• IMA 4 (or the gear ratio 41)

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Gear Trains

• To create larger gear ratios, gears are often
  connected in gear trains, for example

Each gear turns at twice the speed of the one to
its left, which means that the red gear turns at
2 x 2 x 2 8 times the speed of the blue gear.
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Planetary Gear Trains

• Planetary gear trains allow the output shaft to
  be along the same axis as the input shaft

Such a gearing system would be used in a device
such as an electric screwdriver.
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More Practice

• Construction with Gears Lab Activity