4-2
CRANKCASE
All parts related with crankcase assy are aluminium alloy diecastings, which removed all unnecessary excess thickness for
extreme lightness, consist
of
split-type front crankcase, rear crankcase and crankcase cover (for Model
D)
or reduction cover
(for Model B) depending upon the model as per the following table,
Model
Reduction
Cover
Crankcase Cover Rear Crankcase
Front Crankcase
EC05-2
D
B
B
Exclusive for
D
D
Exclusive for
B
Exclusive for
B
for
D
type
~
EC07-2
for
D
type
Exclusive for
B
Exclusive for
B
D
Exclusive for
D
Exclusive for
D
-
EC10 for
D
type Exclusive for
B
B
~
v
Exclusive for
D
Exclusive for
D
D
Exclusive for
D
Exclusive for
V
~-
EC17
for
D
type Exclusive for
B
/
Exclusive for
B
B
v
Exclusive for
D
Exclusive for
V
I
EC25-2
D
for
DS
type
DS
for
D
type
Exclusive for
D
Exclusive for
D.DS
Model EClOD,
V.
EC17D,
V.
EC25-2D.
DS:
The rear crankcase forms a governor chamber and provided with crankcase cover. As front, rear crankcase cover hasone ball bearing respective-
ly,
the crankshaft
is
supported by
3
ball bearings.
Model
EClOB,
EC17B
The rear crankcase forms
a
part of the reduction gear chamber and after installing the reduction gear and governor, reduction cover
is
to
be
fitted.
The
reduction cover has two ball bearings, one
is
supporting the crankshaft and the other one
is
supporting the driving shaft.
4-3
BASE PLATE
The base plate made
of
aluminum alloy diecasting is to be attached
to
the front and rear crankcase .with
4
bolts.
4-4
CRANKSHAFT
and
CONNECTING ROD ASSY.
The crankshaft is separable into the front crankshaft, rear crankshaft and crank pin.
Crankshaft is made
of
forged carbon steel; Crank pin is made
of
chromium-molybdenum steel, hardened and
precision machined.
Connecting rod is a forged chromium-molybdenum piece which is equipped with needle-bearings at both large and
small ends. Both rod ends has an oil grooves
to
deliver lubricant to prevent burning and wearing.
The front, rear crankshafts and the crank pin are assembled together and force fitted in exact alignment with the
special assembling fixture after fitted the needle-bearing and connecting rod on the crank pin. Generally, they can
not disassembled. In case
of
replacing the crankshaft, it is requested
to
replace crankshaft and connecting rod in
assembled manner.
4-5
PISTON
The piston is made of precision-casted heat-resistant aluminum alloy which machined precisely into oval section in order to
prevent from burning and slapping. It is attached to the connecting rod small end by means
of
a piston and a needle bearing.
Near the top of the piston, there are two grooves for compression rings. In order to prevent the rotating the rings during the
operation and damaging the cylinder port, lock-pins are inserted.
-
14-
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