Chapter 7 Reduction
and
Reversing Gear
1. Construction
4LHA Serie:
Marine
Gear
Model
KM
5
A
1.
Construction
1-1
Construction
The
clutch is a cone-type, mechanically operated clutch.
When
the drive cone (which is connected to the clutch shaft
by the lead spline) is moved forward or backward, its taper
contacts
with
the clutch gear and transfers power to the
output
shaft.
The
construction is simple when compared
with
other types
of clutch and it serves to reduces the number of compo-
nents,
making for a lighter, more compact unitwhich can be
operated smoothly. Although it is
small,
the power trans-
mission
efficiency is high even under a heavy
load.
It is
also
durable and reliable because high grade materials are
used
for the shaft and gear, and a taper roller bearing is
incorporated. Power transmission is smooth because
connection
with
the engine is made through the damper
disc.
• The drive cone is made
from
special aluminum bronze
which has high wear-resistance and durability. The
drive cone is connected
with
the clutch shaft. The taper
angle,
diameter of the drive cone,
twist
angle, and
dia-
meter of the involute spline, are designed to give the
greatest efficiency, thus ensuring
that
the drive cone can
be
readily engaged or
disengaged.
•
Helical
gears are used for greater strength. The
inter-
mediate shaft is supported at 2 points to reduce deflec-
tion
and gear noise.
• The clutch
case
and mounting flange are made
from
an
aluminum alloy of special composition to reduce weight.
This
is non-corrosive in seawater.
• The damper disc is
fitted
to the
input
shaft, so power
can
be transmitted smoothly. Springs of
different
streng-
ths are used for the damper disc so
that
two stages of
torque and
twist
angle are applied. That is, in the
first
stage,
only the weak spring is
used,
and the strong spring
comes
into
action for a torque higher than a predetermin-
ed
value.
This
prevents gear noise due to torsional vibration, as
well as absorbing shock when engaging.
Stage
arrangement
Absorbs
shock
when engaging
Twist angle 6
There
is a small clearance between the dipstick and the
inside
of the dipstick tube. A small hole in the dipstick
works
as
a breather.
•
When
the load on the propeller is removed, the engage-
ment of the drive cone and the clutch gear is maintained by
the shifter and V-groove of the drive cone.
Even
when the
drive cone's tapered area and V-groove are worn, this
engagement is maintained by the
shift
lever device.
Accordingly
no adjustment of the remote control cable is
required.
• The cup spring on the rear of the clutch gear absorbs
rotational fluctuations and stabilizes the engagement of
the drive cone and the clutch gear. Thus, the durability
of the cone against wear is enhanced.
7-1-1
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