Unit III Main Parts of an Engine

8/9/2019 Unit III Main Parts of an Engine

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UNIT III

MACHINERY

MAIN PARTS OF ENGINE


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STATIONARY PART

SSTATIONARY PART

S

The stationary parts of an engineare;

b edplate,engine framemain b earingscylinder b lockcylinder head

crankcase .


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RUNNING PARTS

The running parts of engine arepiston,crosshead,

connecting rodcrankshaft


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ENGINE FRAME

Engine frame houses all therunning parts of the diesel

engine.


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Engine frame links theb edplate with thecylinder b lock.


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BEDPLATE

Bedplate is seated on thefoundation.


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I t supports the enginecolumns and thecrankshaft bearings .


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I t has two sections and eachsection consists of two

longitudinal girdersconnected with transversegirders.

The transverse girders carrythe main bearings .


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MAINB

EARINGS

M ain bearings are usuallymade of cast iron, steel oraluminium alloy .

They consist of bearing capsand shells.


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CYLINDERB

LOCK

The engine has two b asicassem b lies;cylinder b lock

cylinder heads .


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The cylinder b lock is castfrom iron or iron alloyed

with other metals.


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C ylinder b lock supports the

cylinder liners and heads.The cylinder b lock alsosupports camshaft, and oiland air passages, and

jacket water cooling.


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CYLINDERS

The cylinders may b e "inline," or may b e in a "V"

configuration.


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The top of each cylinder isclosed b y a cover.The cover is tightened againstliner and cooling jacket withstuds. It forms the com b ustioncham b er of the engine togetherwith the piston crown and theliner.


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The cylinders of a liquid-cooledengine are surrounded b y jacketsthrough which the coolantcirculates.

The coolant maintains enginetemperature.


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Lu b ricating oil is distri b uted

through oil passages in thecylinder b lock.Lu b ricator feeds the

lu b ricating oil nozzles with oil.


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LINERS

The liners are inserted into ahole in the b lock and designatedas either a WET-TYPE or DRY-TYPE.


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The wet-type liner comes in

direct contact with the coolantand is sealed at the top and atthe b ottom b y O-rings.

The dry-type liner does notcontact the coolant


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CRANKS

HAFT

The crankshaft convertsthe reciprocating motion of the piston and connectingrod to rotary motion .


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C rankshaft comprises connectingrod and crankshaft with the trunkpiston engines; piston, crosshead,connecting rod and crankshaft withcrosshead engines.


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C rankshaft is made of castiron or forged from steel.


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The crankshaft consists of main b earing journals, crankwe b s and crank pins.


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CRANKCAS

E

The crankcase is b elow the

cylinders and has twosections as upper and lower.It encloses the crankshaft

and provides a reservoir forthe lu b ricating oil.


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CONNECTING ROD

The connecting rod serves as alink b etween the crankshaft andthe piston.


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The upper end of theconnecting rod is connected tothe piston. As the lower end of the connecting rod revolves withthe crankshaft, the upper end isforced to turn b ack and forth onthe piston pin.


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PIS

TON

Piston transmits theforce of com b ustion to thecrankshaft through theconnecting rod.


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Most diesel engines use a trunk

type piston.Engines with crosshead useb arrel type piston.

Barrel type piston is attached tothe crosshead with studs.


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The components of thepiston are the head, skirt,rings and pins.


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The piston is attached tothe connecting rod b y the

piston pin.


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Piston rings are used tomaintain gastight seal s b etweenthe pistons and cylinders, to aidin cooling the piston, and tocontrol cylinder-wall lu b rication.


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Piston rings are two main

types:compression rings

oil control rings.


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CAMS

HAFTC amshaft has cams, and

the parts on the cams arecam followers.

The cam followers are

raised and lowered b y thecams when the camshaftrotates.


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The camshaft is driven b y acam gear.

The camshaft is in camb

earings supportedb

y the cam journals.


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There are three cams for

each cylinder of four strokecycle engine; one for theintake and one for the

exhaust valve and one forthe fuel pump.


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CROSS

HEAD

Crosshead acts as the connectionb etween piston and connecting

rod and transfers the normalforce to the guide b ars, whichare attached to the frame.


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The crosshead consists of a b odyinto which the piston rod isscrewed and secured b y a nut.


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1- What are the fixed partsof an engine?


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2 - Where is the b edplate isseated on?


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3 - What are the componentsof;-piston-camshaft


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5 - What is/are the

function(s) of;- b edplate-lu b ricator-crankshaft-connecting rod


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Etymology

C ylinder < French,cylinder, < Latin, cylindrus,

< Greek, kylindein, to rollL ubricate < Latin,lubricare, to make slippery

and smooth < lubricus,slippery < Indo-European,sleub, to slip, slide


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S OME WORD S

A lloy (n) - A mixture of metallicelements.


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A ssembly (n) - A group of machine parts forming a self-contained unit.


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C ast (n) - Formed b y pressing orpouring into a mould.


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L ink (v) - To make a connection.


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S eal (v) - To make tight againstleakage.

Transverse (adj.) - C ross, lyingacross


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Change the following sentencesinto passive.

AC T IVE:

1- The fixed parts furnish theframework of engine.

PASSIVE:

Th e frame work of engine isfurnis h ed by t h e fixed parts


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2 - Engine frame links the b edplate withthe cylinder b lock


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3 - The transverse girders carry themain b earing seats


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4 - C ylinder b lock supports thecylinder liners and heads.


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5 - The coolant maintains enginetemperature.


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6 -The crankcase encloses thecrankshaft.


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Complete the passage withwords given below .

R ings / pin / h ead / temperature /cast / combustion / ring

The piston is made of ....... iron suita b lefor high .. and high pressure. Thepiston is so shaped as to secure agood There are four piston. at the upper part of the piston.The piston is inserted at itscentre and an oil . on its upper andlower side


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M atch the two columns.

C olumn A C olumnBh 1- frame a-piston

2 - pin b -connecting

3

-b

lock c-crank 4 - shaft d-lu b ricating 5 - follower e-air 6- case f-reciprocating

7- oil g-crank 8- rod h- engine 9 - passage I-cylinder 10 -motion j-cam


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W hat links the cylinder blockand bedplate?

a. crank pin

b. crankcasec. connecting rodd. engine framee. camshaft


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W hat links the cylinder blockand bedplate?

d. engine frame


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W hich one is a moving part?

a. crankcase

b. cylinder b lockc. engine frame

d. connecting rode. b edplate


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W hich one is a moving part?

d. connecting rod


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W hat is the function of bedplate?

a. houses all components of

engineb. links piston with crankshaftc. supports engine columns

d. supports linerse. drives camshaft


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W hat is the function of bedplate?

c. supports engine columns


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R otary motion is provided by

a. piston

b. camshaftc. connecting rodd. crankshafte. crosshead


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R otary motion is provided by

d. crankshaft


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W hat kind of motion does pistonhave?

a. circulating

b. reciprocatingc. rotary

d. twistinge. b ending


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W hat kind of motion does pistonhave?

b. reciprocating


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16-P iston rings can be either .. or.............

a. dry-type / wet-typeb. in line / V configurationc. running /stationary

d. trunk / b arrel typee. compression / oil control

type


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16-P iston rings can be either .. or.............

e. compression / oil controltype


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18-W hat is the function of connecting rod?

a. It connects the piston andcrankcase

b. It raises cam followers.c. It converts rotary motion into

reciprocating motion.

d. It links the piston and crankshafte. It supports the main b earing journals


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18-W hat is the function of connecting rod?

d. It links the piston and crankshaft

Unit III Main Parts of an Engine

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