# The spring is generally made from plain carbon spring

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Unformatted text preview: arm is generally of I-section but for low speed engines, it can be of rectangular section. Due to the load on the valve, the rocker arm is subjected to bending moment. Let l = Effective length of each rocker arm, and σb = Permissible bending stress. We know that bending moment on the rocker arm, M = Fe × l ...(i) We also know that bending moment, M = σb × Z ...(ii) where Z = Section modulus. From equations (i) and (ii), the value of Z is obtained and thus the dimensions of the section are determined. 4. Design for tappet. The tappet end of the rocker arm is made circular to receive the tappet which is a stud with a lock nut. The compressive load acting on the tappet is the maximum load on the rocker arm for the exhaust valve (Fe). Let dc = Core diameter of the tappet, and σc = Permissible compressive stress for the material of the tappet which is made of mild steel. It may be taken as 50 MPa. We know that load on the tappet, π 2 Fe = (dc ) σc 4 From this expression, the core diameter of the tappet is determined. The outer or n...
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## This note was uploaded on 09/30/2012 for the course MECHANICAL 403 taught by Professor A.thirumoorthy during the Spring '11 term at Anna University Chennai - Regional Office, Coimbatore.

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