CH-32

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Unformatted text preview: etermined. The direct compressive stress is given by, where FR σd = 2 w. t The maximum compressive stress (σc) will occur at the upper left corner of the cross-section of the crank. ∴ σc = σbR + σbT + σd Now, the twisting moment on the arm, lc lc l2 T = HT1 b2 + 2 − FT × 2 = HT2 b1 − 2 We know that shear stress on the arm, 4.5 T T = τ= ZP w .t 2 w .t 2 where ZP = Polar section modulus = 4.5 ∴ Maximum or total combined stress, (σc)max = σc 1 + 2 2 ( σ c ) 2 + 4τ 2 Snow blower on a railway track 1170 n A Textbook of Machine Design The value of (σc)max should be within safe limits. If it exceeds the safe value, then the dimension w may be increased because it does not affect other dimensions. (e) Design of left hand crank web Since the left hand crank web is not stressed to the extent as the right hand crank web, therefore, the dimensions for the left hand crank web may be made same as for right hand crank web. ( f ) Design of crankshaft bearings The bearing 2 is the most heavily loaded and...
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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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