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Unformatted text preview: rum is usually taken twice the diameter of the fulcrum pin.
2. Design for forked end. The forked end of the rocker arm carries a roller by means of a pin.
For uniform wear, the roller should revolve in the eyes. The load acting on the roller pin is Fc.
d2 = Diameter of the roller pin, and
l2 = Length of the roller pin.
Consiering the bearing of the roller pin. We know that load on the roller pin,
Fc = d2 · l2 · pb
The ratio of l2 / d2 may be taken as 1.25. The roller pin should be checked for induced shear
The roller pin is fixed in eye and the thickness of each eye is taken as half the length of the
∴ Thickness of each eye = l2 / 2
The radial thickness of eye (t3) is taken as d1 / 2 . Therefore overall diameter of the eye,
D1 = 2 d1
The outer diameter of the roller is taken slightly larger (atleast 3 mm more) than the outer
diameter of the eye.
A clearance of 1.5 mm between the roller and the fork on either side of the roller is provided.
3. Design for rocker arm cross-section. The rocker arm may be treated as a simply supported
beam and loaded at the fulcrum point. We have already discussed that the rocker...
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- Spring '11