filter incorporated
in
it, should be
washed in petrol and drained on each
occasion when the engine oil is
changed.
2.
ENGINE
LUBRICATION
(Figs.
12
and
13)
Description
Lubrication of the engine is by a Hobourn-
Faton pump. The pump is driven by a
shaft which is mounted in a bush pressed
into the cylinder block, and is provided
with a helical gear which engages with a
similar gear on the camshaft.
Oil is drawn into the pump through
a
primary gauze tilter and passes through a
channel in the pump casting to
an
annular
space around the oil pump shaft. The
annular space round the drive shaft is
closed by the bush, and the oil thus forced
through a hole in the cylinder block into the
head of the external oil
filter where some of
this oil passes directly into the oil gallery
which
extends the length of the cylinder
block
;
the remainder of the oil passes into
the bowl of the oil filter under the pressure
of the oil pump. When the oil pressure
exceeds
70
to
80
Ibs. per sq. inch it opens
a
spring loaded
ball
valve and passes into the
sump. The oil
on
its way to the base of the
filter is forced
through
the filtering media
and
passor
up
an
annular
space around the
bowl holdmg bolt
through
a restriaor into
the sq.
The oil passes
from
the gallery to the three
main
bearings,
through
ddhngs
in the
crankshaft
to
the big end
bearing;
then
through further drillings
in
the connecting
rods to the small end bushes and gudgeon
pins. Splash lubrication is further assisted
by a drilling into the oil passage between
the small end and big end just below the
piston skirt on each connecting rod.
By
drillings from the channels leading to
the
main
bearing
oil is conveyed to the
front, second and rear
camshaft
bearings.
In the case of the third camshaft bearing
this is fed
direct
from the oil gallery through
a metering hole.
A
by-pass from the rear
camshaft
bearing
conveys oil upwards
through a drilling
in
the combustion head
and rearmost rocker pedestal to the rocker
shaft.
Oil
passes along the hollow shaft and
through
radial
holes to the rockers, leaving
each rocker by a hole
drilled
vertically to
each
tappet
ball
pin.
ENGINE
13
The oil is prevented from escaping by the
rocker cover and after lubricating the
valve springs and ball pins, returns down-
wards through the push rod tubes lubri-
cating the push rod tappets before entering
the sump.
Oil
from the front camshaft bearing lubri-
cates the
timing
chain where four slots cut
at
90"
to each other on the face of the
flange adjacent :o the camshaft timing
wheel allow oil to escape on to the timing
wheel. The oil is thrown out by
centrifugal
force on to the underside of the flanged
portion of the wheel on which the teeth are
cut.
Six
holes are drilled obliquely, alternatey,
from the back and the front of the wheell
at equal
intervals from the underside of the
flange into the s pace between the rwo toothed
rings. These holes allow the oil to be thrown
on to the underside of the timing chain,
ensuring its lubrication.
3.
OIL
PUW
The oil pump is
d
the double rotor type as
shown in Fig.
14.
The smaller centre rotor is driven by a
short shaft on which it is pressed and pegged
in position. The two
romrs are contained
in
a
housing at the
base
of the oil pump
casting, which is provided with a cover
piatc
having
a ground face, allowing only
sufficient
clearance
on
the
two rotors to
provide for lubrication. The centres of the
rotors are offset.
The rotor shaft has at its upper extremity
a recess
which engages a tongue on the
lower end of the drive shaft. The driving
shaft is mounted in a phosphor bronze
bush which is pressed into the cylinder
block, and at its upper end a helical gear
is secured by
mans of a Woodruffe key.
The helical gear on this shaft engages with
a similar gear which is an integral part of
the camshaft.
The centre rotor, by its engagement
with
the outer rotor, drives the !atter at
a
slightly lower speed owing to the difference
in
sizes.
Owing to the relative movement of the
outer rotor around the inner
rotor) and the
close fit of the cover plate, oil is forced
round
between
the lobes of the rotor and
forced out of a hole in the top of the rotor
casing
and
upward through a drilled pas-
sage
tn
The
annldar
space
arn1md
fie
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