Taylor-Dunn RE-380-36, Service And Replacement Parts Manual

Page: 79 / 150

Motor SEM
Page 79
MR-380-05
RE-380-36 & RE-380-48
INSPECT
Brushes
Measure the length of each motor brush.
• If any one brush is less than or equal to the
service limit specified in section Service Limits,
then all four brushes should be replaced. Refer
to Replacing the Brushes section for information
regarding replacing the motor brushes.
• A burnt brush lead is an indication of excessive
motor current or another brush was stuck in the
brush holder, not in contact with the commutator.
Bearing
A faulty or worn bearing is typical a accompanied with
a report of noise from the motor that could be called a
growl or grinding noise and is best diagnosed while in
the vehicle using a mechanics stethoscope.
Since disassembly of the motor typical damages the
bearing, the bearing should be replaced whenever the
motor is disassembled.
Commutator
Measure the diameter of the commutator.
• If the commutator is less than the minimum
diameter specified in section Service Limits, then
the motor must be replaced.
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 Service
Limits at the end of this section, then the
commutator must be undercut. Refer to Repair
Commutator section for information regarding
undercutting the commutator.
This section is one section of a complete service
manual. Before starting any procedure, read all
warnings and instructions that are located in the
Service Guidelines chapter.
WARNING
Inspect the commutator for groves.
• If the commutator is grooved then it must be
machined on a lathe. Do not machine the
commutator past the minimum diameter specified
in Service Limits section. Refer to Repair
Commutator section for information regarding
machining the commutator.
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.
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 at the end of this section. Refer to Repair
Commutator section for information regarding
machining the commutator.
Armature Windings
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.