Differential Dissection: Gears and Spline Shafts

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Differential Dissection Gears and Spline Shafts

• J. MacCaull
• To impart a basic understanding of differentials
  and a knowledge of gears and spline shafts in
  differentials

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What are differentials?

• Mechanical devices
• Used commonly in wheeled vehicles
• Provide power to the wheels
• Allow wheels to rotate at different speeds

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Why are differentials useful?

• When a car turns, the inside wheels spin more
  slowly than the outside wheels
• The driven wheels are linked
• Without a differential the wheels must spin at
  the same speed
• Turning is HARD without differentials

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How do differentials work?

• They use GEARS to split the engine torque
• GEARS are mounted on SPLINE SHAFTS

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Differential Gears

• Differential gears have two coaxial gears
  PINIONS and the TURNTABLE
• Pinions are mounted on shafts
• Shafts are connected to turntable

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Gear Types

• Spiral
• Pinion gears contact ring gear at its centreline
• Teeth are curved and oblique
• Transmit power to perpendicular shafts

• Hypoid
• Pinion gears contact ring gear below its
  centreline
• They operate on non-intersecting axes

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• THERE ARE MANY OTHER TYPES OF GEARS!

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Hypoid Gear
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SPLINES

• Unlike gears, they only apply transmission of
  power on the same axes
• Most splines are used for mounting gears
• Ends of shafts have teeth for the gears to fit
  between

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Summing Up

• Differentials allow driven wheels to rotate at
  different speeds
• This is done by using gears
• There are many gear types
• Splines are used to mount gears

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Conclusion

• Now you know what a differential is and what it
  does
• Now you know what gears do in a differential
• Now you know what spline shafts do in a
  differential

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More Information

• http//auto.howstuffworks.com/differential.htm
• http//en.wikipedia.org/wiki/Differential_gear
• http//www.gears-manufacturers.com/differential-ge
  ars.html
• http//www.arrowgear.com/products/custom_gearing.h
  tm