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Unformatted text preview: der W2 = 250 N is 25 mm (i.e. equal to full valve lift),
therefore, maximum compression produced ( δ max) under the maximum load of W = 346.6 N is 25
× 346.6 = 34.66 mm
We know that free length of the spring,
LF = n′ · d + δmax + 0.15 δmax
= 12 × 4.47 + 34.66 + 0.15 × 34.66 = 93.5 mm Ans.
(d) Pitch of the coil
We know that pitch of the coil
δmax = Free length
= 8.5 mm Ans.
n' − 1
12 − 1
Example 32. 8. Design the various components of the valve gear machanism for a horizontal
diesel engine for the following data: = Bore = 140 mm ; Stroke = 270 mm ; Power = 8.25 kW ; Speed = 475 r.p.m. ; Maximum gas
pressure = 3.5 N/mm2 1202 n A Textbook of Machine Design The valve opens 33º before outer dead cerntre and closes 1º after inner dead centre. It opens
and closes with constant acceleration and decleration for each half of the lift. The length of the
rocker arm on either side of the fulcrum is 150 mm and the included angle is 160º. The weight of the
valve is 3 N.
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- Spring '11