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Unformatted text preview: ker arm cross-section
Since the engine is a slow speed engine, therefore, a rectangular section may be selected for the
rocker arm. The cross-section of the rocker arm is obtained by considering the bending of the sections
just near the boss of fulcrum on both sides, such as section A–A and B– B.
l3 = l2 + 2 × Internal Combustion Engine Parts n 1207 Let t1 = Thickness of the rocker arm which is uniform throughout.
B = Width or depth of the rocker arm which varies from boss diameter
of fulcrum to outside diameter of the eye (for the forked end side)
and from boss diameter of fulcrum to thickness t3 (for the tappet or
stud end side).
Now bending moment on section A – A and B – B, 34 M = 885 150 −
= 117 705 N-mm
2 and section modulus at A – A and B – B,
Z = × t1 · B = × t1 ( D1 ) = × t1 (34)2 = 193 t1
...(At sections A–A and B–B, B = D) We know that bending stress (σb),
M 117 705
70 = Z = 193 t
...(Taking σb = 70 MPa or N/mm2)
t1 = 117 705 / 193 × 70 = 8.7 say 10 mm Ans.
4. Design for tappet screw
The adjustable tappet screw carries a comperssive load of Fe = 885 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.
- Spring '11