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DESIGN MODIFICATION &

HARMONIC ANALYSIS OF ROCKER ARM

SYNOPSIS

In Automobile Components, Rocker Arm is one of the important

components, which is used to operate the engine movement. Generally

referred to within the internal combustion engine of automotive, marine,

motorcycle and reciprocating aviation engines, the rocker arm is a

reciprocating lever that conveys radial information from the cam lobe into

linear information at the poppet valve to open it. One end is raised and

lowered by the rotating lobes of the camshaft either directly or via a lifter

tappet! and pushrod! while the other end acts on the valve stem. "hen the

camshaft lobe raises the outside of the arm, the inside presses down on the

valve stem, opening the valve. "hen the outside of the arm is lowered by

the camshaft, the inside rises, allowing the valve spring to close.

#he effective leverage of the arm and thus the force it can e$ert on the

valve stem! is determined by the rocker arm ratio, the ratio of the distance

from the rocker arm%s center of rotation to the tip divided by the distance

from the center of rotation to the point acted on by the camshaft or pushrod.

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&or car engines the rocker arms are generally steel stampings,

providing a reasonable balance of strength, weight and economical cost.

'ecause the rocker arms are part of the reciprocating weight of the

engine, e$cessive mass limits the engine%s ability to reach high operating

speeds. It(s running whenever engine is working. )a*or problem in

Rocker Arm is early worn out. #o avoid this kind of problem, the design

parameters should be revised like geometry, material properties

)echanical + hysical!. #hese parameters should be decided along

with the previous e$perimental results or computational results. After that

the parameters has to be changed and verify the condition with the use

of Computer Aided -esign and ngineering softwares. #he pro*ect is

designed using /- modeling CA- packages, and all critical parts are

verified by theoretical calculations. A0121 results were taken for a

rocker arm. #hat the design is cost effective and it serves the purpose

more effectively.

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MODELING FOR ROCKER ARM