Crankcase - Mitsubishi S4E Manual

CONSTRUCTION AND FUNCTION
Crankcase
- - 1
a
4
l-Cran kCiU.e 3 · Side $.,1
2 · ~
II nde r $Ieeve
4 ~ ~iI'
i ng CillJS
Crankcase and cylinder block
Cmnkcase
The
crankcm
and cylinder block are in one, shaped as
a singJe caslmg. into which Ihe cylinder slee ves made of
16
a special cast iron are press-fitted. The sleeves are of
"dry" type: they are. not
in
direct
cOntact
with engine
c.oolant .
The cTank"", as , whole is designed fOT high rigidily;
the strength built into it is. calculated to withstand
l
with
an ample margin, the soevere
cydic~t ress.
of complex
nature imparted by the internal running parts.
These stresses
~ry
from one part of the crankcase to
another as jn any diesel engine;
lhe
needed rigi dity and
durability are secllred by th e skin section. which is stud
more substantiaJ and extending far below the level at
which
con ventiona l·desisn crankca.s.€s are te rmLI)ued
[ 0
mote with the oil pan .
Eoch main bealing ca p is filted inlo and held by the
crankcase, thu s proyjding a more reliable support for the
cran kshaft at five pl.ces along ils length .
Main, thrust and big-<md bearings
The five main bearings are of shell type , each consisting
of Iwo half shells, there being no dis tinclion between
lhe two: each may be located on top or bottOn) at the
lime of hearing installati on in engine reassembly .
Crankshaft thrust is taken up al No. 5 journal . Three
bearing pJates
l
each in the form o f half-ring) ate used:
t\Vo on the
teat
and one on the bottom front side of
No. 5 bearing. The", U ,rust plales are held in place by
spring p ins_
Connecting-rod bearings too or. of ,heU Iype, each shell
being of tli-melal design . Tho sheU is essent ially a kelmel
metal fused 10 a steel backing base .nd co vered
by
an
overlay of a lead-tin alloy deposited by plaling.
l ·Main bearing
2·T"hrust bearing