1166 n a textbook of machine design 2 when the crank

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Unformatted text preview: bending moment due to the weight of flywheel, MW = V3 . c1 and bending moment due to belt tension, MT = H3′ . c1 These two bending moments act at right angles to each other. Therefore, the resultant bending moment at the flywheel location, ... (i) M S = ( M W ) 2 + ( M T ) 2 = (V3 · c1 ) 2 + ( H 3 · c1 ) 2 We also know that the bending moment at the shaft, π ( d ) 3 σb Ms = ... (ii) 32 s where σ b = Allowable bending stress in N/mm2. From equations (i) and (ii), we may determine the shaft diameter (ds). 1166 n A Textbook of Machine Design 2. When the crank is at an angle of maximum twisting moment The twisting moment on the crankshaft will be maximum when the tangential force on the crank (FT) is maximum. The maximum value of tangential force lies when the crank is at angle of 25° to 30º from the dead centre for a constant volume combustion (i.e petrol engines) and 30º to 40º for constant pressure combustion engines engines (i.e. diesel engines). Consider a position of the crank at angle of maximum twisting moment as shown in Fig. 32.17 (a). If p′ is the intensity of pressure on the piston at this instant, t...
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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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