# 1194 let n a textbook of machine design d1 diameter

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Unformatted text preview: let valve of the same dimensions as that for exhaust valve. A typical rocker arm for operating the exhaust valve is shown in Fig. 32.24. The lever ratio a / b is generally decided by considering the space available for rocker arm. For moderate and low speed engines, a / b is equal to one. For high speed engines, the ratio a / b is taken as 1/ 1.3. The various force acting on the rocker arm of exhaust valve are the gas load, spring force and force due to valve acceleration. Fig. 32.24. Rocker arm for exhaust valve. Let mv dv h a pc ps = Mass of the valve, = Diameter of the valve head, = Lift of the valve, = Acceleration of the valve, = Cylinder pressure or back pressure when the exhust valve opens, and = Maximum suction pressure. We know that gas load, P = Area of valve × Cylinder pressure when the exhaust valve opens π (d )2 pc 4v Fs = Area of valve × Maximum suction pressure = Spring force, π (d )2 ps 4v and force due to valve acceleration, Fva = Mass of valve × Accleration of valve = mv × a ∴ Maximum...
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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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