APP

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Department of Technical Education
Andhra Pradesh
Branch : Automobile Engineering
Institute : Govt. Polytechnic, Atmakur
Year/Semester : III Semester
Subject : Automobile Power Plants
Subject Code : A302
Topic : Engine Construction
Duration : 50 Minutes
Sub Topic : Crank Shaft
Teaching Aids : Images, Animations & Text

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Recap
In previous session you learnt about:
• Connecting Rod
• Functions of Connecting Rod
• Materials of connecting rod

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Objectives
On completion of this session, you would be able to
know:
• Crank shaft
• Materials and functions of crank shaft
• Bearings used on Crank shaft

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• Can you identify a crank shaft?
• Is it a shaft with uniform diameter?
NO, it is not

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Crankshaft
Fig:9

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Crankshaft
• The engine component from which the power
output is taken to drive wheels
• The crank shaft assembly includes:
• Main Journals
• Crank Pins
• Crank Webs
• Counter Weights
• Oil Holes.
• Flywheel mounting flange

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Function of A Crank Shaft
• The function of a crank shaft is to convert the
reciprocating motion of the piston into rotary motion.
• Should have high fatigue and creep strengths
• Should withstand the thrust of Piston
• It is free to revolve in the main bearings of the engine.
• Oil holes are provided in the crank shaft to carry
lubricating oil to main bearings
• The counter weights are to balance the rotary masses.

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Crankshaft
Main Journals, Crank Pins, Crank Webs, Counter
Weights, Oil Holes

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Crankshaft

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Crankshaft

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Materials used for Engine Components
Engine Component Material
Crankshaft
Forged Steel
Heat –treated Alloy
Steel
The crankshaft is manufactured by drop forging process or in
Some cases it is machined and then heat treated.

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Summary
In this session we have learnt about:
• Crank shaft functions and materials

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Quiz
1. Crank shaft is made of
a. Forged Steel
b. Cast Steel
c. Fabricated from steel components
d. Aluminium Alloy

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Frequently Asked Questions
1. State the functions of a Crank shaft.