MOTOR (MODEL EJ4-4001 AND EJ8-4001A)
Motor Component Testing and Inspection
18
MOTOR FRAME AND FIELD WINDINGS INSPECTION
1.
Remove the motor from the vehicle.
See Motor Removal on page 18-3.
2.
Remove the and cap and armature by performing steps 1 through 7 of Motor Disassembly on page 18-4.
3.
Burned or scorched insulation on the field windings indicates the motor has overheated due to overloads or
grounded or shorted coil windings. If the insulation on the field windings is scorched, replace the motor or
the stator shell assembly.
MOTOR BRUSH, SPRING, AND TERMINAL INSULATOR INSPECTION
Brush Spring Tension Test
1.
Remove the motor from the vehicle.
See Motor Removal on page 18-3.
2.
Remove the end cap and armature by performing steps 1 through 7 of Motor Disassembly on page 18-4.
3.
Inspect the brush springs (14)
(Figure 18-15, Page 18-11)
. Replace springs that are discolored from heat
(light gold or blue tinted).
4.
Test the brush springs for proper tension.
4.1. Place a C-shaped steel plate on a scale.
4.2. Place the end of the C-shaped plate so that it is between the spring and the brush as shown
(Figure
18-13, Page 18-10)
.
4.3. Gently pull the scale to obtain the spring tension reading.
See following CAUTION.
CAUTION
• When checking brush spring tension, do not over-extend the spring. Using excessive force will
damage the spring.
4.4. Replace springs which require a force of less than 35 oz. (990 grams)
(Figure 18-13, Page 18-10)
.
See
following NOTE.
NOTE:
When installing new brushes, remove and replace brushes one at a time. This method ensures the terminals
and brushes will be properly positioned in the rigging. Refer to
Motor Assembly on page 18-12
for brush
installation.
When replacing brushes, replace all four brushes. Never replace only two.
Install the brushes in the same rigging 180° apart from each other.
Brush Inspection
1.
Remove the motor from the vehicle.
See Motor Removal on page 18-3.
2.
Remove the end cap and armature by performing steps 1 through 7 of Motor Disassembly on page 18-4.
3.
Inspect the brushes (13) for damage or excessive wear
(Figure 18-15, Page 18-11)
. Replace brushes if required.
See preceding NOTE.
4.
Use dial calipers or a micrometer to measure the brush length. The minimum-allowable brush length is 0.62
inches (16 mm). Replace the set of brushes as required.
See preceding NOTE.
Terminal Insulator Inspection
1.
Remove the motor from the vehicle.
See Motor Removal on page 18-3.
2.
Remove the terminal insulators by performing steps 1 through 12 of Motor Disassembly on page 18-4.
3.
Inspect the insulators (4 and 6) for cracks or other damage
(Figure 18-15, Page 18-11)
. Replace insulators
as required.
2009 Electric Precedent Maintenance and Service Manual
Page 18-9
