Snorkel A38E Parts And Service Manual page 117

4.10 Traction Motor Maintenance
-512944-000 ( See 7-21)
Figure 1. Exploded view of Drive End Locked Motor
1. Pull back the brush springs and latch them on the
holders in the open position (or if the brush box
assembley has no holders, pull the springs out,
pull the brush back and rest the springs on the
side of the brush). See Figure 1. The brushes
should move freely within the holders.
2. Check the brush springs for correct alignment on
the back of the brush. A brush spring that does
not apply equal pressure on the center of the
brush will cause the brush to wear unevenly.
Check for correct clearence and freedom of brush
movement in the holder.
3. Replace brushes that are worn below their usable
length, show signs of uneven wear or signs of over
heating, such as discoloured brush shunts and
brush springs.
4. Make sure the brush box assembley is tight on the
commutator end head. Replace brush box
assemblies in the commutator end head if they are
physically damaged or brush holders are loose on
on the brush plate.
5. Brushes should always be replaced in complete
sets of four or eight. Use identical replacement
parts; do not substitute brush grades as the
are matched to the motor type and application to
provide the best service. Substituting brushes of
the wrong grade can cause premature
commutator failure and excessive brush wear.
6. Carefully release the brush springs allowing the
brushes to contact the commutator.
Brushes should be checked for proper tention
using the following procedure:
a. Place paper strip between brush face and
commutators. See Figure 8.
A38E Work Platform
Maintenance Process
b. Hook spring scale as shown.
c. Pull spring scale on a line directly opposite the line of
force exerted. When the paper strip begins to move
freely read the spring tention on the scale.
Figure 8.
Motor Diameter
5.5 inch
6.7 Inch
8.0 inch
9.0 Inch
Table 2. Brush Tension Values
Every 500 working hours, or annually
Brushes -
Springs -
Commutator - The surface must be clean and
General -
Every 1000 working hours, or every two years
Bearings-
Screws -
Brush Tension Testing
New Brush
Worn Brush
New Brush
Worn Brush
Check the wear, the correct seating,
and the regularity of the working
surface.
They should not be burned or
damaged, and they must apply a
constant and equal pressure on the
brushes.
regular without grooving or burning.
Check that foreign bodies or dirt
have not entered the motor.
Check that the ventilation holes are
clean and not obstructed.
All the bearings are fitted with a
double shield and lubricated with
high temperature grease.
Check for leaks, vibration and noise.
If necessary replace with bearings
of identical type.
Check that all nuts, particularly the
cable nuts and screws are tight.
Section
4.10
Ounce Gram
55 1540
35 980
65 1820
40 1120
4-13