CH-32 - CONTENTS CONTENTS Internal Combustion Engine Parts...

Internal Combustion
Engine Parts
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1. Introduction.
2. Principal Parts of an I. C.
Engine.
3. Cylinder and Cylinder
Liner.
4. Design of a Cylinder.
5. Piston.
6. Design Considerations for
a Piston.
7. Material for Pistons.
8. Piston Head or Crown .
9. Piston Rings.
10. Piston Barrel.
11. Piston skirt.
12. Piston Pin.
13. Connecting Rod.
14. Forces Acting on the
Connecting Rod.
15. Design of Connecting Rod.
16. Crankshaft.
17. Material and Manufacture
of Crankshafts.
18. Bearing Pressures and
Stresses in Crankshafts.
19. Design Procedure for
Crankshaft.
20. Design for Centre
Crankshaft.
21. Side or Overhung
Crankshaft.
22. Valve Gear Mechanism.
23. Valves.
24. Rocker Arm .
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32.1 32.1
32.1 32.1
32.1 Introduction Introduction
Introduction Introduction
Introduction
As the name implies, the internal combustion engines
(briefly written as I. C. engines) are those engines in which
the combustion of fuel takes place inside the engine cylinder.
The I.C. engines use either petrol or diesel as their fuel. In
petrol engines (also called spark ignition engines or S.I
engines ), the correct proportion of air and petrol is mixed
in the carburettor and fed to engine cylinder where it is
ignited by means of a spark produced at the spark plug. In
diesel engines (also called compression ignition engines
or C.I engines ), only air is supplied to the engine cylinder
during suction stroke and it is compressed to a very high
pressure, thereby raising its temperature from 600°C to
1000°C. The desired quantity of fuel (diesel) is now injected
into the engine cylinder in the form of a very fine spray and
gets ignited when comes in contact with the hot air.
The operating cycle of an I.C. engine may be
completed either by the two strokes or four strokes of the

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piston. Thus, an engine which requires two strokes of the piston or one complete revolution of the
crankshaft to complete the cycle, is known as two stroke engine. An engine which requires four
strokes of the piston or two complete revolutions of the crankshaft to complete the cycle, is known as
four stroke engine.
The two stroke petrol engines are generally employed in very light vehicles such as scooters,
motor cycles and three wheelers. The two stroke diesel engines are generally employed in marine
propulsion.
The four stroke petrol engines are generally employed in light vehicles such as cars, jeeps and
also in aeroplanes. The four stroke diesel engines are generally employed in heavy duty vehicles such
as buses, trucks, tractors, diesel locomotive and in the earth moving machinery.
32.2 Principal Parts of an Engine Principal Parts of an Engine
The principal parts of an I.C engine, as shown in Fig. 32.1 are as follows :
1. Cylinder and cylinder liner, 2. Piston, piston rings and piston pin or gudgeon pin, 3. Connecting
rod with small and big end bearing, 4. Crank, crankshaft and crank pin, and 5. Valve gear mechanism.