4-17
Section
4.13 Electric Motor (Figure 4-17)
Before carrying out any maintenance procedures
on the electric motor ensure that the electric
circuit is disconnected i.e. disconnect the batteries
and unplug the charger!
TROUBLESHOOTING
1. Read the nameplate to become familiar with the motor,
especially the rated voltage.
2. Try to turn the shaft by hand. Keep motor leads
seperated while doing this. If the shaft turns freely go
to step 3. If the shaft won't tun, proceed to step 2A.
2A.The shaft could be tight for a number of reasons , this
check is to determine if the tightness is of a temporary
nature only. Obtain power to produce the nameplate
voltage. Do not make a permanent connection.
First touch the motor leads quickly to the power supply
just long enough to observe if the shaft runs. If it does
turn, then hold the motor leads on the power supply for
a longer time. If the motor sounds normal , go to step 3.
If the motor is noisy it should be taken apart as
described in the disassembly section.
3. If the motor turned freely, connect an ammeter in the
circuit as shown in Figure 4-16. With rated voltage
applied and the shaft running free, the ammeter should
read less than 20% of the nameplate full load current. If
the motor meets the above conditions then it can be
assumed the original problem is external to the motor.
Figure 4-16: Electrical Test Circuit
DISASSEMBLY
1. Remove through bolts.
2. Remove pulley end cover
3. Pull the armature out of the assembly in one swift
motion.
4. Remove commutator end cover.
NOTE: Do not place the stator ring in any mechanical
holding device during the disassembly or
assembly operation. Permanent distortion or other
damage will result.
INSPECTION
Once the motor has been disassembled, go through the
following check list steps to determine where the problem
lies.
1. Bearings should spin smoothly and easily and have
ample lubrication and be free of corrosion.
2. Armature should be checked for grounds and shorted
turns. Refinish commutator surface if pitted or
excessively worn.
3. Brushes should be checked for wear and to ensure that
they are free in the brush holders.
NOTE: Observe how the brushes are assembled in brush
holders and position of brush lead. New brushes must be
installed in same manner. Brushes should be removed as
follows:
• Remove brush spring clip from its mounting
on brush assembly.
• Lift brush assembly from the brush holder
• Disconnect brush assembly lead.
• New brush assembly to be installed by
reversing the above procedure.
4. Inspect wire harnesss and all connections for signs of
damage due to overheating.
5. Check stator to see if it is securely mounted.
WARNING
AMMETER
D.C.
MOTOR
VOLTMETER
D.C.
POWER
SUPPLY
V
A
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