Upright 503502-000, Service & Parts Manual

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Page 3-26
Maintenance 3.18 - Electric Motor
TL50 Service & Parts
3.18 E
LECTRIC
M
OTOR
T
ROUBLESHOOTING
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 separated while doing this. If the shaft turns
freely, go to step 3. If the shaft won’t turn, proceed to step A.
a. 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 sounds
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 3-9A. 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 3-9: Electric Motor
D
ISASSEMBLY
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.
1. Remove three bolts.
2. Remove pulley end cover.
3. Pull the armature out of the assembly in one
swift motion.
4. Remove commutator end cover.
I
NSPECTION
1. Once the motor has been disassembled, go
through the following check list steps to deter-
mine where the problem lies.
2. Bearings should spin smoothly and easily and
have ample lubrication and be free of corrosion.
3. Armature should be checked for grounds and
shorted turns. Refinish commutator surface if
pitted or excessively worn.
4. Brushes should be checked for wear and to
ensure that they are free in the brush holders.
DC
Power
Supply
V
A
Voltage Meter
Ammeter
Brushes and
springs in their
final position Brushes raised with
the springs in locked
position on the side
of the brush
A
B
C
Keep fingers
clear of this
space.
DC
Motor