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When installing the cylinder.s on
the
pistorJs, turn the compres-
siOn rin.gs so that their
locks
are set apart in order to
reduce
the
gas
leakage.
The
pis•
ton is linked with the connecting rod through floating pin
16, which is prevented from axia,J displacement by two circlips 17
(Fig. 7), inserted into the ring grooves of the piston bosses.
Crankcase
Crankcase 3
(Fig. 5),
cast
from
aluminium alloy,
is
the basic
structural component of the engine.
Installed
on and secured .to the -crankcase are the cylinders
with
the
heads
and auxiliary
mechanisms. I
n addition, the crankcase
ser-
ves as an oil
reservoir.
Rotating inside
the
crankcase are the
crank-
shaft and camshaft, at the front of it
is
a
timing
gear
box,
the gene-
rator is
located a.t the top.
The bottom of the
•
crankcase is closed
w
ith
a stamped sump
10.
Inserted
between the crankcase and the sump is sealing gasket 11.
During
engine operation, pa-rt of
the
gas mixture and of exhaus
t
gases burst
into
the crankcase through
the clearances
of piston rings;
also, as the pistons move to the bottom
dead centre,
the V ·O lume
of
the crankcase decreases, the gases
filling
the crank chamber
beco-
me compressed and force the oil outwards
through
the
packi
ng
gland,s and
crankcase-and-•
cover
joints. To
avoid
this,
the
crankcase is
provided with a fopced air
suppt
l y.
To open the crank
chamber
to the
atmosphere,
when the pistons move down, or t
o
shut it off,
.when
the pistons move up, breather
15
(Fig.
6) is provided in the
central
hole of the distribution box cover
40.
The gases
escaping
from the
•
crankcase
th
rough
the
breather a
l-
ways contain
some
water
va·
p our.
Therefo
re, during operation
in
the
winter time, an
ice
lock may form in the rubb
er
tube
of the brea-
ther, thus obstruCting .the gas outlet
and
causing oil leakage
th rough
the packing glands.
To prevent this from happening, it
is
advisai
b le
to
remove the
rubber
tube
when
operating
the
vehicle
in
winter
time at
a
tempe-
rature
0
°C
and
below.
Cylinders
Engine cylinders
6
(Fig. 7) are
similar
in design, interch
ange-
able,
(bimetallic aluminium jacket
with
a
cast
iron
liner).
The
lower
part of the
cy1
l inder has a flange with holes passing through
all the
fins. These holes are intended for anchor studs
to secure the
cyli
n-
ders
and
the cylinder heads .to the ·crankcase. The upper
pa.
r t
of
the
cylinder is fitted with a
collar
•
w hich
·
e nters the groove of the
head
.
Placed between the cylinder
and the
head is sealing gasket
4.
24
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