28
MOUNTING-ALIGNMENT
: Make sure the special mounting bolts (and lock washers) are used when
reinstalling starter. In addition to securing the starter to the machined surface on the crankcase, these
special bolts provide proper alignment of the Bendix drive gear to the ring gear on the engine. Use of
ordinary bolts will allow the starter to shift which could result in clashing and damage to the gears.
Trouble Analysis:
Problems that can occur during normal usage are listed in the accompanying chart. The
symptom, possible cause and the suggested remedy are stated. If these steps do not solve the problem, the
starting motor should be replaced. Replacement of the end cap assembly, which includes the negative
brush and spring, is the only recommended field service that requires partial disassembly of the motor -
complete disassembly must not be attempted in the field.
TEST PROCEDURE - STARTER ON ENGINE
CONDITION
POSSIBLE FAULT AND CORRECTION
A.
STARTER FAILS TO ENERGIZE
A-1 Wiring: Check for badly corroded or loose
connections, also broken or frayed insulation.
Clean and tighten connections, replace wires in
poor condition.
A-2 Starting Switch or Solenoid: Bypass the switch or
solenoid with jumper wire - if starter cranks
normally, replace defective part.
A-3 Battery: Check specific gravity of battery - if low,
recharge or replace battery as necessary.
B.
STARTER ENERGIZES BUT TURNS TOO SLOWLY B-1 Battery: Check condition of battery (See A-3).
B-2 Brushes: Remove end cap, check for unevenly worn
or dirty brushes and commutator. Use a coarse
cloth (not emery paper) to clean. Replace brushes
if excessively or unevenly worn. See brush
replacement procedure.
PERMANENT MAGNET TYPE STARTING MOTORS (Late C-10A and Late C-12
)
The permanent Magnet (PM) starting motors, now used on the 10, and 12 HP engines, weigh less
than conventional starters and require less current to operate. The PM starters weigh less due to the fact
that field coils are eliminated. On conventional starters, a relatively heavy current is directed thru the field
coils to build up the strong magnetic field necessary to start the armature turning. On PM starters, the
permanent magnets provide this strong field, and only a small current is needed in the armature to start it
turning.
DRIVE UNIT
The PM starters use a drive very similar in appearance and function to a Bendix drive arrangement.
There are, however, design differences which excluded it from being classified as a Bendix drive. On the
PM starter drive, for example, the inertia absorbing cushion is part of the pinion, not separate, as on the
Bendix drives. With the one piece unit, the greater mass provides more inertia for positive engagement
plus it permits use of a heavier duty anti-drift spring for quicker, cleaner disengagement. When the
armature starts to turn, the drive pinion moves laterally on the splined portion of the armature shaft into
mesh with the ring gear on the flywheel of the engine. As the -pinion butts against the stop or spacer, it
locks in positive engagement with the armature to turn the engine. When the engine fires and attains the
speed where the flywheel begins to "override" the armature, the greater momentum of the flywheel throws
the pinion out of mesh. The antispring holds the pinion in the retracted position as the armature coasts to a
halt.
PRECAUTIONS
In the event of a "false start", that is, if the engine gets up sufficient speed to disengage the starter but
then fails to continue running, the engine must be allowed to come to a complete halt before a restart
attempt is made. If the flywheel is still rotating when the starter is engaged, the pinion and ring gear may
clash and damage the teeth.
Even with PM starters which can crank for long periods without overheating, the cranking time
should be limited to 60 seconds. If an engine fails to start after this length of time, there is probably
something wrong with the engine or it may be out of fuel, flooded, or there may be poor ignition or some
other condition preventing it from starting.
Make sure the special shouldered capscrews (and lock washers) are used when installing starter. In
addition to securing the starter to the machined surface on the crankcase, these special capscrews properly
align the pinion to the ring gear on the engine. Use of ordinary capscrews will allow the starter to shift
which could result in clashing of the gears.
