MAIN  PARTS  OF  THE  ENGINE  :

Main parts of the engines are given below  ;

PISTON  :

Inside the cylinder of the engine there is a box – shaped device which is called as piston . The movement of the piston is between two positions called as ‘TOP DEAD CENTRE’ and ‘BOTTOM DEAD CENTRE ‘ or INNER DEAD CENTRE and OUTTER DEAD CENTER . One time movement between these two extreme positions are called stroke . This provides the basic information of 2-stroke and 4-stroke engine pistons are usually made of aluminium but in some murcidies and other luxuary vehicals they may be of steel.

. CONNECTING  ROD  :

In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion.Connecting rods may also convert rotating motion into linear motion. Historically, before the development of engines, they were first used in this way.As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank through both halves of a revolution, i.e. piston pushing and piston pulling. Earlier mechanisms, such as chains, could only pull. In a few two-stroke engines, the connecting rod is only required to push. Connecting rods are best known through their use in internal combustion piston engines, such as car engines. These are of a distinctly different design from earlier forms of connecting rods, used in steam engines and steam locomotives.

SPARK  PLUG  :

.A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.Spark plugs have an insulated central electrode which is connected by a heavily insulated wire to an ignition coil or magneto circuit on the outside, forming, with a grounded terminal on the base of the plug, a spark gap inside the cylinder. Normally , for combustion (10,000 – 90,000) volts are required . in case of bike it may  be (30,000-35,000) volts .As we know in the desiel engine the ignition takes place due to compression and spark is not required so it is not used

RINGS  OF  PISTON  :

A piston ring is an open-ended ring that fits into a groove on the outer diameter of a piston in a reciprocating engine such as an internal combustion engine or steam engine .The three main functions of piston rings in reciprocating engines are:

1 . Sealing the combustion/expansion chamber.

2 . Supporting heat transfer from the piston to the cylinder wall.

3. Regulating engine oil consumption.

The gap in the piston ring compresses to a few thousandths of an inch when inside the cylinder bore

ENGINE  FINS  :

The engine fins are the section of engines which are used for cooling of different parts of engine . They are of different sizes . The reason behind that is the different cooling required by engine at different points. The fins are larger where larger cooling is required and small fins where less cooling is required .

ROCKER  ARM  :

The rocker arm is a reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it. One end is raised and lowered by the rotating lobes of the camshaft (either directly or via a tappet  and pushrod) while the other end acts on the valve stem. When the camshaft lobe raises the outside of the arm, the inside presses down on the valve stem, opening the valve. When the outside of the arm is permitted to return due to the camshafts rotation, the inside rises, allowing the valve spring to close the giver.It is the essential part for the efficiency of the engine . Cam shaft delivers it’s motion through push rods .

TAPPET  :

A tappet is the only part of a rocker arm that makes contact with an intake or exhaust valve stem above the cylinder head of an internal combustion engine. As the cam rotates, it creates both a sideways and a downward force on the tappet. Without a tappet (and with the cam acting directly on the valve), the sideways force would cause the valve stem to bend. With a tappet, the sideways force is transferred to the cylinder head so only the downward force acts on the valve stem. It plays a very important role in opening and closing of the valves. Thus connecting the intake and exhaust stroke . They move side ways and downward .In  IC  engines the sideways movements make the valves stem to bed . While the downward force is used in opening and closing of valves .

CRANK   SHAFT  :

Crank shaft  is the part of an engine which translates reciprocating linear piston motion into rotation. To convert the reciprocating motion into rotation, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to which the "big ends" of the connecting rods from each cylinder attach.It typically connects to a flywheel, to reduce the pulsation characteristic of the four-stroke cycle, and sometimes a vibrational damper at the opposite end, to reduce the torsion vibrations often caused along the length of the crankshaft by the cylinders farthest from the output end acting on the torsional elasticity of the metal.During one half revolution of piston from TDC to BDC or from BDC to TDC , the crank angle is 180 degree. Crank transmitts power to cam shaft .Crank shaft is connected o piston through crank pin. Which is sometimes callad as judgen pin . All the apparatus is enclosedin crankcase.

CAM  SHAFT  :

A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part. In internal combustion engines with pistons, the camshaft is used to operate poppet valves. It then consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes protruding from it, one for each valve. The cams force the valves open by pressing on the valve, or on some intermediate mechanism as they rotate.The ratio between the movement of cam shaft and crank shaft is 2 : 1. This means in one revolution of crank , cam rotates twice .