Unformatted text preview: pressure is less than the safe limit of 5 to 8 N/mm2, therefore, the design is safe.
Example 32.5. Design a side or overhung crankshaft for a 250 mm × 300 mm gas engine. The
weight of the flywheel is 30 kN and the explosion pressure is 2.1 N/mm2. The gas pressure at the
maximum torque is 0.9 N/mm2, when the crank angle is 35° from I. D. C. The connecting rod is 4.5
times the crank radius.
Solution. Given : D = 250 mm ; L = 300 mm or r = L / 2 = 300 / 2 = 150 mm ; W = 30 kN
= 30 × 103 N ; p = 2.1 N/mm2, P′ = 0.9 N/mm2 ; l = 4.5 r or l / r = 4.5
We shall design the crankshaft for the
two positions of the crank, i.e. firstly when
the crank is at the dead centre and secondly
when the crank is at an angle of maximum
1. Design of crankshaft when the crank is
at the dead centre (See Fig. 32.18)
We know that piston gas load,
× D2 × p
= (250)2 2.1 = 103 × 103 N
Now the various parts of the crankshaft
are designed as discussed below:
Valve guides of an IC engine
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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