SOHC ENGINE MECANICAL 1B – 3
parts are installed in the cross flow arrangement. The
rocker arm (i) operates in seesaw motion to close and
open the intake and exhaust valves (j) with camshaft by
turning the rocker arm shaft of each intake and exhaust
part.
ENGINE BLOCK
As the largest part of the engine components. the block
(l) has all the necessary parts attached to outer surface
of it.
On the inside surface of block, there are bore surfaces
by horning, which are cylinders, and on the periphery of
the cylinders, there are the passages to prevent the
over-heated and to lubricate the engine block.
CRANKSHAFT
The crankshaft (m) is to convert the rectilinear motion
into the rotation motion through the connecting rod (n)
which transmits the power generated by combustion.
On the one side of it, oil pump, crankshaft pulley and
timing belt pulley are attached, and oil seal housing and
flywheel are on the other side.
A special steel of high grade cast iron is used for the ma-
terial to stand the bending load and distortion. The mate-
rial of the main bearing (o) is aluminum alloy. The split
thrust bearings (p) are inserted in the journal bearing
part (No.3).
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CONNECTING ROD
The connecting rods (n) are made of forged steel, and
its section is typed “I” with its big end connected to
crankshaft (m) and its small end to piston pin to transmit
the power.
The big end is detachable, and its upper and lower parts
are fastened by bolting after the metal bearings (q) are
inserted.
PISTON, PISTON RING AND PISTON
PIN
Piston
The piston (r) is of the open skirt type and its crown is
exposed in the combustion chamber to generate power.
Its land and skirt parts are made of coat aluminum alloy
which is light and has excellent heat conductivity in order
to meet its continuous and high speed reciprocation
movement.
Piston Ring
It is composed of two compression rings (s) and one oil
ring (t) and installed between the grooves of the piston
to make the high speed reciprocating movement main-
taining a remarkable air tightness as well as cylinders. It
is a critical parts to affect the compression pressure, oil
consumption, compression, blow by pressure and en-
gine performance.
Piston Pin
The pin (u) is not fixed to the piston or connecting rod
and its both ends are assembled by the circlip (v) in the
full floating type. The pin is used to transmit the power
from the crown part of piston to connecting rod.
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