Yangdong Co. Y90 Series Spécifications télécharger pdf (Page 26)

the

diesel

engine,tlush

all lube oil passages"and be

sure

that

they

are

clean

and

unb

locked. All

passage plugs

should

be

sealed reliably

and

leakproof.

·-rhe

tnain

bearing:~\

are

of

cornplete

suspension-

support

type"Since

the

main

bearing

caps

and cylinder block are rnatched to bore.Jhe

matching

marks

are

both

on

the

bolck

and

main

bearing

~aps.Misplaccnlent

or

inverted installation,when

assembling,are

prohibited.The

Inain

bearing

shells

are

made

of

high-

tin

aluminiurn-base

alloy.When

dismantling

for

cleaninR,be

sure

that the

upper

and

lower

bearing

shells

are

in right

places(the

upper

shell \vith

an

oil

groove).The

crankshaft

thrust

plates are assetnbled

on

the

last

main

bearing with

an

upper

piece

and

a

lower

piece

on

each

side.l~he

thrust plates

bear

the

axial force from

the

crankshaft.There

are

oil

channels

on

its

operatin~

surJacewhich

should

be

located

against

the

thrust

planes

on

the

crank,

and

its

back

surface

is

smooth.Never

locate thenl in reverse.

When

tightening

the

tnain bearing

blots~tw()

bolts

on

the bearing

cap

should

he

tightened

several tilnes in

turn.Before

tIghtening

the

main bearirlg

cap~strjkc

the crankshafttof\Vard and back\vard in

order

to

keep

the

upper

and

lo\ver thrust plates

in

th(~

sanle plane."fhen tighten

the

bolts until t'hey reach

the

sp-ecified

tightening

torque.When

completing

the

crankshaft

assembly,turn

it

at

the

flywheel

end

by

hand

to

check

whether

it

can

be

rnoved freely.

T'he liner is slipped into

the

cylinder

bore

vertically

so

that

deformation

of

the

liner may

be

avoided.'I'he liner flange

plane

should protrude

out

the

top

plane

of

cylinder

block

by

0.07---

0.15

mnl

to

keep

an

excellant

sealing

bet\veen

the

cylinder

liner.and

cylinder

head,as

sho\vn

in Fig6.

ill . Piston

and

Connectin2-rod

.

The piston

and

connecting- rod

assembly

c.omprises

the

piston,piston

rin~s,piston

pin, re-

taining

rings.~connecting-rod

..

connecting

rod cap,connecting-rod

bolts

and

connecting-rod

bearing

sh.ells and

bush,ctc:rhe

mass difference

of

piston

and

connecting-

rod

assenlblies

in

the

same

engine should

be

within 20g.

,£\11

of

the

compression

rings

are

lnade

of

alloy

cast

iron.The

outer

circle

surface

of

the

first

ring

is

plated \vith

porous

chrome

in

order

to

decrease

the

wear

between

the

cylinder

liner and

piston ring.The

second

ring

has

a conical surface.

When

assembling,the

surface

marked

with a

sign lfUp"

should

be

keptagainst

the

top

of

piston

and

be careful

to

avoid

assemblin~

in reverse.

'[he

oil,.control ring is

of

tensioning

ring type:rhe radial force

of

oil ring is still kept while

decreasing

the

elasticity

due

to \vear.'Thus the service life

of

oil ring is prolonged.

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