Piper Cherokee Six - Page 580

PIPER
CHEROKEE
SIX
SERVICE
MANUAL
10-33.
CRANKING
MOTORS.
(Delco
Remy)
10-34.
GENERAL.
When
the
cranking
motor
switch
is closed,
the
armature
begins
to rotate.
The
drive
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
pin-
ion,
having
internally
matched
splines
with
respect
to
the
splines
drive
sleeve,
moves
endwise
on
the
shaft
and
into
mesh
with
the
flywheel.
As
the
pinion
hits
the
pinion
stop,
it begins
to
rotate
with
the
armature
and
cranks
the
engine.
When
the
engine
starts,
the
flywheel
begins
to
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
flywheel
ring
gear
protecting
the
armature
from
excessive
speeds.
Some
Bendix
drives
incorporate
a small
anti-drift
spring
between
the drive
pinion
and
the
pinion
stop
which
prevents
the
pinion
from
drifting
into
mesh
when
the
engine
is running.
Others
use
a small
anti-drift
pin
and
spring
inside
the
pinion
which
provides
enough
friction
to
keep
the
pinion
from
drifting
into
mesh.
Never
operate
the
motor
for
more
than
30
seconds
without
pausing
for
two
minutes
to
allow
it
to cool.
10-35.
CHECKING
CRANKING
MOTOR.
Several
checks,
both
visual
and
elec-
trical,
should
be
made
in
a defective
cranking
circuit
to
isolate
trouble
before
removing
any
unit.
Many
times
a
component
is
removed
from
the
aircraft
only
to find
it is
not
defective
after
reliable
tests.
Therefore,
before
removing
a
unit
in a
defective
cranking
system,
the
following
checks
should
be
made:
a.
Determine
the
condition
of
the
battery.
b.
Inspect
the
wiring
for
frayed
insulation
or
other
damage.
Replace
any
wir-
ing
that
is damaged.
Inspect
all
connections
to the
cranking
motor,
solenoid
or
magnetic
switch,
ignition
switch
or
any
other
control
switch,
and
battery,
includ-
ing
all ground
connections.
Clean
and
tighten
all connections
and
wiring
as
required.
Many
engine
manufacturers
specify
allowable
voltage
drops
in the
cranking
circuit.
For
this
infor-
mation,
refer
to
the
engine
manufacturer's
shop
manual.
ELECTRICAL
SYSTEM
Revised:
8/14/73
3C4