PIPER
COMANCHE
SERVICE
MANUAL
9-62,
Cranking
Motors.
(Delco-Remy)
9-63,
General.
When
the
cranking
mOlOr switch
is
closed.
the
armature
begins
to
rotate
The
dri\'e
pinion.
being a loose fit
on
the drive sleeve located
on
the
armature
shaft.
does
not
pick up speed
as
fast as
the
armature
Therefore.
the
drive
pinion.
ha,ing
internally
matched
splines with respect
to
the splines
dri,e
sleeve.
moves
endwise
on
the
shaft
and
into mesh with
the
nywheel As the pinion hits the pinion
stop.
it
begins
10
rotate
with
the
armature
and
cranks
the engine,
When
the engine
starts.
the nywheel begins
10
spin the pinion
faster
than
the
armature
Again. because
of
the
splined
action
of
the
pinion
and
drive sleeve assembly. the
pinion
backs
out
of
mesh with the
n~
wheel
ring
gear
protecting
the
armature
from
excessi,'e speeds,
Some
Bendix drives
incorporate
a small
anti-drift
spring between the drive
pinion
and
the
pinion
,top
which
pr"ents
the
pinion
from
drifting
into
mesh when the engine
is
running.
Others
use a small anti-drift pin
and
spring
inside
the
pinion
which
pro"ides
enough
friction
10
keep the pinion
from
drifting
inlO mesh
'"er
operate
the
motor
for
more
than
30
seconds
without
pausing
for
two
minutes
to
allow
it
to
cool
9-64
Checking
'::ranking
Motor.
Se"ral
checks.
both
,isual
and
electrical. should be made
in
a
defecti\e
cranking
circuit
10
isolate
trouble
before removing
any
unit
Many
times a
component
IS
remO\ed from the
aircraft
only
10 find
it
is
not
defecti"
after reliable tests,
Therefore.
before remO\'ing a
Unit
in
a
defecti\e
cranking
system.
the
following
checks
should be
made
a
Determine
the
condition
of
the
bal\ery
b Inspect
the
wiring for frayed insulation
or
other
damage
Replace
any
wiring
that
is
damaged
Inspect all
connections
10
the
cranking
mOlOr. solenoid
or
magnetic
switch. ignition switch
or
am
other
control
switch.
and
bal\ery.
including all
ground
connections
Clean
and
tighten all
connection-
and wIfing
as
re4uired
Man~
engine
manufacturers
specif~
allowable,
oltage
drops
in
the
cranking
circuit
For
thi_'
information.
refer
to
the
engine
manufacturers
shop
manual
c I nspect all
control
sw
itches
and
the ignition switch.
to
determine
their
cond
ition,
Connect
ajumpe
lead a
round
any
switch suspected
of
being defective If t
he
system
functions
propcrl~
using this
method.
repair
or
replace the bypassed switch
d, If specified
battery
voltage
can
be
measured
at
the
motor
terminal
of
the
cranking
motor.
allowing
for
some
voltage
drop
in the circuit
and
the engine
is
known
to
be
functioning
properly.
remo'e
the
motor
and
follow
the
test
procedures
9-/>5
Test
And
Maintenance
or
Cranking
Motor.
(Delco-Remy)
9-/>1>
Inspection.
With the
cranking
mOlOr
removed
from the engine. the pinion should be checked for
freedom
of
operation
by
turning
it
on
the screw shaft
The
armature
should
be checked for freedom
of
operation
b,
turning
the
pinion
Tight.
diny,
or
worn
bearings.
bent
armature
shaft.
or
loose pole shoe screw
will
cause
the
armature
to
drag
and
it
will not
turn
freely
If
the
armalUre
does not
turn
freel~
the
motorshould
be
disassembled
immediately,
How,,'er.
if
the
armature
does
operate
freel,'. the
motor
should
be
gi\en
electrical tests before disassembly
(Refer
to
Paragraph
9-73 )
9-67
Checks.
3CIO
ELECTRICAL
SYSTE_
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