3 nmm2 or mpa z 2927 fig 3230 the induced bending

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Unformatted text preview: onsidering the weight of the valve, We know that s =u.t+ 3 × 45.274 + 3 = 16.84 N ... (∵ m = w/g) 9.81 We know that the maximum load on the rocker arm for exhaust valve, Fe = P + Fs + Fa = 820 + 48 + 16.84 = 884.84 say 885 N Since the length of the two arms of the rocker are equal, therefore, load at the two ends of the arm are equal, i.e. Fe = Fc = 885 N. We know that reaction at the fulcrum pin F, Fa = m · a + w = 1204 n A Textbook of Machine Design RF = = ( Fe ) 2 + ( Fc ) 2 − 2Fe × Fc × cos θ (885) 2 + (885) 2 − 2 × 885 × 885 × cos 160º = 1743 N The rocker arm is shown in Fig. 32.29. We shall now design the various parts of rocker arm as discussed below: Fig. 32.29 1. Design of fulcrum pin Let d1 = Diameter of the fulcrum pin, and l1 = Length of the fulcrum pin = 1.25 d1 ... (Assume) Considering the bearing of the fulcrum pin. We know that load on the fulcrum pin (RF), 1743 = d1 × l1 × pb = d1 × 1.25 d1 × 5 = 6.25 (d1)2 ∴ ... (For ordinary lubrication, pb is taken as 5 N/mm2) = 1...
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