Crankshaft and Oil Film Journal Bearing

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Crankshaft and Oil Film Journal Bearing

• Presenter Aaron Ma
• Date Nov 8, 05

Objective To explain the role and function of
the crankshaft and the bearing in an engine.
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Purpose of Crankshaft

• Converts the piston's linear up and down motion
  into circular rotating motion.
• Connected to the piston by a connecting rod

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How is a Crankshaft Made?

• Forged or cast from either mild steel or high
  strength steel
• Machined out of a single billet of forged steel
• Cost mildltcastltforged/billet

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Why are so many of its dimensions critical?

• determines the piston stroke measurement, and
  engine displacement
• Ex. a common way to increase the power of an
  engine is to increase the stroke.
• increases the reciprocating vibration, however,
  limiting the high RPM capability of the engine

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Oil Film Bearings

• Carries load by sliding
• Sealed around the crankshaft

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How is the oil supplied to the film bearings?

• Crankshaft rotates
• Bearing is dipped into oil sump under crankshaft
• Fluid is swept into the bearing, forming a
  lubricating wedge under or around the shaft.
• Rely on an external pump to supply fluid

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References

• http//en.wikipedia.org/wiki/Crankshaft
• http//autorepair.about.com/library/glossary/bldef
  -100.htm
• http//auto.howstuffworks.com/engine7.htm