ELECTRICAL
EQUIPMENT
Porous bronze bushes must not
be opened out after fitting or the
porosity of the bush may be
impaired.
NOTE:
Before fitting a new
porous bronze bearing bush it
should be completely immersed
for
24
hours in clean,
thin
engine oil. In cases of extreme
urgency this period may be
shortened by heating the oil to
100°C.
for
2
hours, then allow-
ing to cool before removing the
bearing bush.
Re-assembly
This is,
in
the main, a reversal of the
procedure given in Para.
4
(c) for
dismantling.
Commutator end bracket replacement
:
The starting motor is designed for
clockwise rotation, indicated by the
arrow on the yoke. Press out the
through bolt indentations marked
"
C
"
on the replacement bracket.
Press the locating dowel into the
appropriate hole marked
"
C."
Insert the through bolts into the holes
made in the bracket and tighten the
bracket to the yoke.
STARTING MOTOR
DRIVE
I.
GENERAL
The drive embodies a combination of
rubber torsion member
and
friction clutch
in
order to control the torque transmitted
from the starter to the engine flywheel and
to dissipate the energy in the rotating
armature of the starter at the moment when
the pinion engages with the flywheel.
It also embodies an overload release
mechanism which functions in the event of
extreme stress, such as may occur in the
event of a very heavy backfire, or if the
starter is inadvertently meshed into a fly-
wheel, rotating in the reverse direction.
When the starter is energised, the torque is
transmitted by
two paths, one via the outer
sleeve of the rubber coupling and
through the friction washer to the screwed
sleeve, while the other path is from the
outer to the inner sleeve through the rubber
coupling
and
then directly to the screwed
sleeve.
The torque through the rubber limits the
total torque which the drive transmits and
since the rubber is bonded to the inner
sleeve, under overload conditions slipping
will
occur between the rubber bush and the
outer sleeve of the coupling. Slipping does
not take place under normal engagement
conditions, when the rubber acts merely as
a spring with a limiting relative twist on the
two members of approximately
30".
Under conditions of unduly severe overload
'which might cause damage to the drive or
its mounting, the rubber slips in its housing
so that a definite upper limit is set to the
torque transmitted and to the stresses
which may occur.
2.
ROUTINE
MAINTENANCE
If any
difficulty
is experienced with the
starting motor not meshing correctly with
the flywheel, it may be that the drive
requires cleaning. The pinion should move
freely on the screwed sleeve
;
if there is any
dirt
or other foreign matter on the sleeve it
must be washed off
with
paratfin.
In the event of the pinion becoming jammed
in mesh with the flywheel, it
can
usually be
freed by turning the starter motor armature
by means of a spanner applied to the shaft
extension at the commutator end. This is
accessible by removing the cap which is a
push fit.
3.
CONSTRUCTION
The construction of the drive will be clear
from the illustration. The pinion is carried
on a barrel type assembly which is mounted
on a screwed sleeve.
The screwed sleeve is secured to the
armature shaft by means
of
a location nut
and is also keyed to the inner sleeve of the
rubber coupling by a centre coupling plate.
A
friction washer is fitted between the
coupling plate and rubber assembly and the
outer sleeve of the rubber
coupling is keyed
at the armature end of the starter by means
of a transmission plate.
A
pinion restraining spring is fitted in the
barrel assembly to prevent the pinion
vibrating into mesh when the engine is
running.
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