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Unformatted text preview: ominal diameter
of the tappet (dn) is given as Internal Combustion Engine Parts n 1195 dn = dc / 0.84
The diameter of the circular end of the rocker arm (D3) and its depth (t4) is taken as twice the
nominal diameter of the tappet (dn), i.e.
D3 = 2 dn ; and t4 = 2 dn
5. Design for valve spring.The valve spring is used to provide sufficient force during the valve
lifting process in order to overcome the inertia of valve gear and to keep it with the cam without
bouncing. The spring is generally made from plain carbon spring steel. The total load for which the
spring is designed is equal to the sum of initial load and load at full lift.
W1 = Initial load on the spring
= Force on the valve tending to draw it into the cylinder on suction
W2 = Load at full lift
= Full lift × Stiffness of spring
∴ Total load on the spring,
W = W1 + W2
Note : Here we are only interested in calculating the total load on the spring. The design of the valve spring is
done in the similar ways as discussed for compression springs in Chapter 23 on Spr...
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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.
- Spring '11