Gravely 424 - Governor System

GOVERNOR
SYSTEM
The
governor
gear
-
flyweight mechanism
is mounted
rvithin the crankcase
and driven
ofi il
gear
on
the
camshaft.
In operation, centrifugal
force
causes
the
fyweights
to move
orrtrvirrd with
increase in speed
and
inward
rvith decreasing
speed.
As the flyweights
move outward,
tlrey force the rod
portion of the rrssembly
to
pr:sl.r
out-
wnrd. Tension
of the
governor
spring
pulls
the flyrveights
bnc'k inrvrrrd
rvith decrease
in engine s1:eed.
T1:e
rod,
in turn,
contacts a tirb
on
the
governor
cross
shaft ctrusing
it to rotirte
rvith
changing
speed. One end
of the
cross
sh:rft
protrudes
through
the side of
the crankcase.
Through
externirl
linkirge,
the
action of
the
cross
shaft
is trans-
mitted to the throttle
(or
butterfy)
valve in the carbruc.tor.
\\{ren the
engine
is irt
rest, the tension of the
governor
spring
should
hold the
tlrrottle valve in open
position.
When
a normal load
is
applied
and
engine
(and
governor)
speed
tends to decrease,
the
resulting
rotation
of
the cross
sh:rft acts against
the
governor
spring
to open the
tlrrottle valve
rvider which,
in tttrn,
admits more
fuel
and restores engine speed.
With
governor properly
adiusted,
this lction
takes
place
so
rapidly
that a reduction
in
speed
is bardly
noticed.
As speed again reaches
governed
setting,
the shaft rotates
to either
open or
close
the
throttle
vtlve
to maintain
speed at a relatively
constant
level.
ADIUSTMENI: Covernors
are
adjusted
at
the factory
and further adiustment should
not
be necessary
unless
governor
arrn or
linkage
rvorks loose and becomes disconnected.
Covernor
readiustment
miry be indicated
if
en-
gine
speed
surges
or
huats
rvith changing
load
or
if speed
drops considerably
rvhen normal load
is applied.
Initial
Adiustment:
Tlre following
procedure
can
be used on all models
for
the initirrl setting.
Make this setting
with
engine stopped.
STEP
l.
Loosen
(do
not remove) nut which
holds
governor
arm to
the
governor
cross
shaIt.
STEP
2: Crasp
end
of cross
shaft
with
pliers
and
turn in counterclockrvise
direetion
as far
as
possible
(tatr
on
cross sha{t rvill
stop
against
rod on
governor
gear
assembly),
STEP
3: Pull
governor
arm all
the
way from
carburetor
then:etighten
nut
holding
governor
arm to
shaft.
With
updraft
type
carburetor,
Iift arm
as far as it
will
go
then
retighten arm nut.
SPEED
ADJUSTMENI
After
making
initial adjustment
and hooking up
throttle
wire, start engine
aad check
opetating
speed
with
hand
tachometer. Maximum allowable
speed for K241,
K301 and K321 models
is
3600 RPlvI. Do
not exceed
this
speed.
Loosen capscreri/
and
move high speed stop
bracket
until
eorrect
speed
is attained
then retighten
capscrew.
SENSITIV:IY
ADJUST'I'IENT
Goyernor
sensitivity
can be adiusted by
repositioning
the
governor
spring in the
holes
on tle
governor arm
and
speed
control brackets.
If set too sensitive, speed
surging
will
occur with
change
of
load. If a big d:op
in
speed occurs
when
normal
load is applied,
the
governor
should
be
set for
greater
sensitivity.
Normally,
the
governor
spring is
placed
in the third
hole
from bottom on
the
governor
arm
bracket
and in
dre
second
hole from top on speed control braeket.
To make
governor
control
more sensitive,
increase
tension
on
spring
by
moving
spring
into holes
spaced further apart.
Conversely decreasing
spring tension
allows
broader
governor
coritrol
but less sensitivity.