TM 5-3895-359-14&P
2. Disconnect field coil connector from solenoid motor
Interpreting Results of Tests
terminal, and lead from solenoid ground terminal.
1. Rated current draw and no-load speed indicates
normal condition of the starting motor.
3. Remove the brush inspection plugs and then remove
the brush lead screws. This will disconnect the field
2. Low free speed and high current draw indicate:
leads from the brush holders.
4.
Remove the attaching bolts and separate the
bent armature shaft or loose pole shoes allowing
commutator end frame from the field frame.
armature to drag.
5. Separate the nose housing and field frame from
b. Shorted armature. This can be further checked
lever housing by removing attaching bolts.
on a growler after disassembly.
6. Remove armature and clutch assembly from lever
c. Grounded armature or fields.
Check further
housing.
after disassembly.
7. Separate solenoid from lever housing by pulling
3. Failure to operate with high current draw indicates:
apart.
a. A direct ground in the terminal or fields.
Cleaning
b. "Frozen" bearings (this should have been
The drive, armature and fields should not be cleaned in
determined by turning the armature by hand).
any degreasing tank, or with grease dissolving solvents,
since these would dissolve the lubricant in the drive and
4. Failure to operate with no current draw indicates:
damage the insulation in the armature and field coils.
a. Open field circuit. This can be checked after
All parts except the drive should be cleaned with mineral
disassembly by inspecting internal connections
spirits and a brush. The drive can be wiped with a clean
and tracing circuit with a test lamp.
cloth.
b. Open armature coils. Inspect the commutator
If the commutator is dirty it may be cleaned with No. 00
for badly burned bars after disassembly.
sandpaper. NEVER USE EMERY CLOTH TO CLEAN
COMMUTATOR.
c. Broken brush springs, worn brushes, high
insulation between the commutator bars or other
Brushes and Holders
causes which would prevent good contact
Inspect the brushes for wear.
If they are worn
between the brushes and commutator.
excessively when compared with a new brush, they
5. Low no-load speed and low current draw indicate:
should be replaced. Make sure the brush holders are
clean and the brushes are not binding in the holders.
a. High internal resistance due to poor
The full brush surface should ride on the commutator to
connections, defective leads, dirty commutator
give proper performance. Check by hand to insure that
and causes listed under Number 4.
the brush springs are giving firm contact between the
6. High free speed and high current draw indicate
brushes and commutator. If the springs are distorted or
shorted fields. If shorted fields are suspected, replace
discolored, they should be replaced.
the field coil assembly and check for improved
ARMATURE SERVICING
performance.
If the armature commutator is worn, dirty, out of round,
DISASSEMBLY
or has high insulation, the armature should be put in a
Normally the starting motor should be disassembled
lathe so the commutator can be turned down. The
only so far as is necessary to make repair or
insulation should then be undercut 1/32 of an inch wide
replacement of the defective parts. As a precaution, it is
and 1/32 of an inch deep, and the slots cleaned out to
suggested that safety glasses be worn when
remove any trace of dirt or copper dust. As a final step
disassembling or assembling the starting motor.
in this procedure, the commutator should be sanded
lightly with No. 00 sandpaper to remove any burrs left
1. Note the relative position of the solenoid, lever
as a result of the undercutting procedure.
housing, and nose housing so the motor can be
reassembled in the same manner.
The armature should be checked for opens, short
circuits and grounds as follows:
1. Opens-Opens are usually caused by excessively
long cranking periods. The most likely place for an
open to occur is at the commutator riser bars. Inspect
the points where the conductors are joined to the
1-8-14
