Taylor-Dunn ET-015-00 Operation, T Roubleshooting And Replacement Parts Manual page 75

Inspection
1. Measure the length of each motor brush.
• If any one brush is less than or equal to the
service limit specified in section
Limits
, then all four brushes should be
replaced. Refer to
section for information regarding replacing the
motor brushes.
2. Measure the diameter of the commutator.
• If the commutator is less than the minimum
diameter specified in section
then the motor must be replaced.
3. Measure the commutator undercut depth in 5-
places around the commutator.
• If any one of the measurements is less than the
minimum undercut depth specified in
Limits
above, then the commutator must be
undercut. Refer to
section for information regarding undercutting
the commutator.
Hacksaw blade
Incorrect
Correct
4. Inspect the commutator for grooves.
• If the commutator is groved then it must be
machined on a lathe. Do not machine the
commutator past the minimum diameter
Service Limits
specified in
Repair Commutator
regarding machining the commutator.
Service
Replacing the Brushes
Service Limits
Service
Repair Commutator
Undercut
Armature
Insulation
Min. OD
Commutator
section. Refer to
section for information
5. Inspect the commutator for burn marks.
• Burn marks and/or raised commutator segments
90 or 180 degrees apart is evidence of a shorted
armature. A tool called a growler is required to
reliably test for a shorted armature.
,
Typical burn mark on a shorted armature
6. Inspect the commutator for raised segments.
Raised segments could be a result of a stalled
motor or shorted armature. A tool called a growler
is required to reliably test for a shorted armature.
• If the armature is not shorted then the raised
segments can be removed by machining the
commutator. Do not machine the commutator
past the minimum diameter specified in
Service Limits
Commutator
machining the commutator.
7. Visually inspect the armature windings for burnt
insulation. Burnt insulation is a direct result of
motor overheating and could lead to a shorted
armature.
• If the insulation is cracked or burnt, then it is
recommend that the armature or motor be
replaced.
NOTE: If the armature has been burnt then there is a
good possibility that the field windings may
also be burnt. Symptoms indicating a shorted
field include high motor current, lack of power
and possibly excessive speed.
8. Using a growler, test the armature for shorts.
• If the armature is shorted, then we recommend
that the armature or motor be replaced.
9. Using the continuity function of digital multi meter,
check the continuity around the entire commutator
by placing one test lead against one of the
commutator segments and the other test lead
against all of the other segments one at a time.
There should be continuity around the entire
commutator. If any segment indicates an open
circuit, then the motor must be replaced.
Motor Service
Repair
section. Refer to
section for information regarding
Motor
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