GENERAL
DESCRIPTION
PISTON
AND
PISTON
RINGS
This engine employs the E-TVCS VERSION-II
so
that
the improved combustion surface at the
top
of
the piston enables more complete com-
bustion efficiency than the conventional
models.
The profile and the offset
of
the piston are
optimized
to
reduce piston slap. The oil
jet
at
the
small end
of
the connecting rod reduces the
heat
load of the piston.
TOP
RING
I I \
~~~G
r;
I \ -
....
;:.
OILRING
~
PISTON
Three rings are installed
in
grooves
in
the
piston. The top ring is made
of
nitrizing steel to
get
more reliability than the chrome plated ring.
It
is
a keystone type ring to provide durability
against heavy load. At the Sliding part, a
special piston ring which is conformable to the
cylinder wall is employed. The second ring is
chrome-plated on the
peripheral surface and it
is
an undercut ring to prevent the holding
of
oil.
DEPRESSION
~~~_77GROOVES
The oil ring (3) has chamfered contact faces
and an expander ring, which increase the
pressure
of
the oil ring against the cylinder
wall.
Several
grooves are cut
on
the topland to
help heat dissipate and to prevent scuffing.
DYNAMIC
BALANCER
Engines are sure to vibrate due to the
reciprocation
of
the pistons. theoretically, three
cylinder engines are much less prone to cause
vibration than four
cylinder engines. However,
any engine has many moving parts
in
addition
to its pistons and cannot be
completely free
from vibration.
The
four
cylinder engine is fitted with
balanced weight
on
the crankcase to absorb the
second inertia mentioned above and reduce
vibration.
-.v
WESTERBEKE
Engines &
Generators
9
PISTON
TOPLAND
BALANCER
SHAFT
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