TRANSMISSION
(GEARBOX)
SECTION
09
INSPECTION
OF
THE
TRANMISSION
(GEARBOX)
COMPONENTS
D
Thoroughly
dean
all
parts
In
kerosene
(paraffin) and
check
them
for
wear
and fatigue,
as
follows:-
(1)
Inspect
the
housing and
Inner
cover
for signs
of
cracking and damage
to
the
Joint faces.
Check
that
the
location dowels
are
in
their
correce positions
In
the
gearbox
and Inner
cover (2 dowels each).
In
preparation
for
re-
assembly,
dean
all
the
Joint faces.
..
(2)
Examine
both
the
malnshaft and layshaft for
signs
of
fatigue, damaged
threads,
and badly
worn
splines. Check
the
extent
of
wear
to
the
bearing
diameters
of
both
shafts by comparing
them
with
the
figures given
In
"General
Data".
Examine
the
shafts carefully for signs
of
seizure.
Excessive
frictional resl!.tance
and
seizure will
be Indicated
by
local coloring
on
the
shaft.
(3)
Check
the
layshaft needle
roller
bearing
by
inserting
the
layshaft and feeling
the
amount
of
play.
(4)
Inspect
the
malnshaft bearings
for
roughness
due
to
pitting
or
Indentation
of
the
bali/roller
tracks.
Note
that
the
high
gear
bearing
operates
directly
In
a
roller
bearing
pressed Into
the
left side crankcase half.
If
wear
Is
apparent
at
the
high
gear
bearings (check general
data
for high
gear
spigot dimensions), It will be
necessary
to
replace
the
roller
bearing
and
the
high gear.
Under
no.
circumstances
should
the
bearing
or
the
high
gear
be
replaced
independently.
Check
the
Inner
cover
bearing by feeling
the
amount
of
side play
of
the
centre
track.
It
should
not
be possible
to
detect
any
movement
by
hand
If
the bearing
Is
In
good condition.
The mainshaft should be a push fit
In
the
Inner
cover bear! ng.
(5)
Examine
the
gears thoroughly, for chipped,
fractured or worn
teeth.
Check
the
Internal
splines, dogs and bushes. Make sure
that
the
splines are free on their respective shafts wlth-
DUt
any tendency
to
bind, and
that
the
bushes
In
the
malnshaft
third
gear, layshaft second gear,
and
layshaft first gear, are
not
loose,
or
excessiv-
ely
worn.
Again, reference should be made
to
the
dimensions given
In
uGeneral Data".
(6)
Check
that
the
selector
fork
rod
Is
not
grooved,
and
that
it
Is
a good fit
In
the
casing and
the
Inner cover. Inspect
the
selector fork running
faces for wear. This will have
occurred
only
If
the
gearbox
Is
being continually used
with
a
badly
worn
malnshaft bearing.
(7)
The
gear
selector camplate should be Inspected
for signs
of
wear
In
the
selector
tracks. Exces-
sive
wear
will occur
If
the
mainshaft bearing
has
worn badly. Check
the
fit
of
the
camplate
spindle
In
Its
housing. Examine
the
camplate
gear
wheel for excessive
wear.
Difficulty
will be
encountered
In
gear
selection
If
this
gear
Is
badly
worn,
causing
subsequent
damage
to
the
gears.
(8)
Inspect
the
malnshaft high
gear
needle
roller
bearings for roughness
or
fracture.
Check
the
malnshaft diameter
with
the
"General
Data",
and check for surface pitting
or
damage
due
to
scoring.
SECTION
010
RENEWING
MAINSHAFT.AND
LAYS
HAFT
BEARINGS
MAINSHAFT
The bearings
are
a press fit
In
their
respective
housings and
that
on
the
right
side
Is
retained
by
a
spring
cirdlp
to
prevent
sideways
movement
due
to
end
thrust.
To
remove
this
bearing,
first
lever
oUt
the
cirdlp.
then
heat
the
cover
to
apprOXimately
100'C. (boiling water), and drive
out
the
bearing,
using a sUitably
shouldered
drift.
The
new
bearing
should be pressed
or
drifted
In
whilst
the
cover
Is
stili hot, using a suitable
tubular
drift
onto
the
outer
race. Do
not
forget
to
refit
the
cirdip.
To remove
the
high
gear
bearing on
the
left
of
the
machine, first remove
the
screws
and
011
seal holder.
Carefully
heat
the
casing locally
to
apprOXimately
100'c..
then
drive oUt
the
bearing from
the
Inside
of
011
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