Unformatted text preview: oil level Crankshaft turns the
piston action into rotation Piston Sump is filled with oil to
Oil is pumped up into
cylinders to lubricate pistons The above picture shows crankshaft, pistons and cylinder of a 4-stroke petrol engine. 1128 n A Textbook of Machine Design Since these two stressess act at right angles to each other, therefore, the net stress in each
direction is reduced.
The piston side thrust tends to bend the cylinder wall, but the stress in the wall due to side thrust
is very small and hence it may be neglected.
D0 = Outside diameter of the cylinder in mm,
D = Inside diameter of the cylinder in mm,
p = Maximum pressure inside the engine cylinder in N/mm2,
t = Thickness of the cylinder wall in mm, and
1/m = Poisson’s ratio. It is usually taken as 0.25.
The apparent longitudinal stress is given by
× D2 × p
D2 . p
[( D0 ) 2 − D 2 ] ( D0 ) − D
and the apparent circumferential stresss is given by
σc = Force D × l × p D × p
2t × l
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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