MATTHIESEN Magic Finger Bagger, Owner'S Manual

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3-4 Maintenance & Troubleshooting MN605
Brush Replacement
Do not change brush grades or suppliers without first contacting Baldor for
technical assistance.
Brush life will vary greatly due to motor load conditions and the operating environment.
The brush pigtail leads should be checked for secure connection to the brush support
stud. Brushes should be replaced when their pigtails touch the top of the brush holder.
When replacing brushes, proper seating is important!
1. Wrap a strip of coarse grit (60#) sandpaper, rough side out, around the
commutator and under the brush holder. (Do not use metal oxide based
sandpaper or emery cloth that contains electrically conductive materials).
2. Slide the new brush into the holder and snap the spring clip in place.
3. Rotate the armature slowly in the direction of normal motor rotation.
4. Remove the brush and inspect the face. The brush should be seated over 90%
of the face area and completely seated from leading to trailing edge.
Brushes should move freely in their holders. If brushes stick, it is usually due to built up
dirt and oil. Brushes should be inspected on occasion to see that they are long enough to
press firmly against the commutator. Brush springs should have equal tension. Only
brushes of the same size, grade and shape as those originally supplied should be used.
All motors have their brushes set on neutral before leaving Baldor’s factory. After
replacing the brush holder, realign it to the factory neutral mark.
When replacing a turned-down commutator in the motor with a new commutator, the
brush holder assembly must be adjusted. Keep 1/16
″
clearance between the bottom of
the brush holder and commutator. The brush holder assembly is designed with a nut/bolt
guide assembly for ease in positioning of the brush-box.
During periodic inspections, check that electrical connections are tight and properly
insulated.
Brush Springs
Brush springs should be inspected for proper tension during brush replacement. If the
spring shows a loss in tension, it should be replaced. Routine replacement of brush
springs is recommended with every third set of brushes.
Poor Brush Life
Poor brush life may be caused by overloading, brushes operating at higher than their
rated speed, or very light electrical loads. These can be corrected by using a brush with
greater current-carrying capacity for overloads. Friction-reducing treatments reduce wear
on high speed applications. Where light loading is the cause, the answer may be to
remove some brushes from the motor (with multiple brushes per pole). Another is to
install brushes with a higher content of graphite that can handle the lower current and still
film properly. Poor brush life is generally not related to the “softness” or “hardness” of the
brush.
Do not change brush grades or the number of brushes per pole. Doing so may void the
warranty and make the motor unsafe to operate. Contact your local Baldor district office
or an authorized Baldor service center for technical assistance.
Brush Chatter or Bounce
Brush chatter or bouncing can be caused by vibration from an external source. This may
be a bad gearbox coupling or condition, or insecure mounting of the motor. Stronger
carbon grades are available that provide more capacity for the brush to resist vibration. It
is always best to fix the cause of the problem.
Brush Sparking
Excessive sparking of brushes may be due to electrical causes such as an overload or a
very unstable DC power supply. Mechanical causes include a flat spot on the commutator
or external vibration. Changing to a better brush grade, or a split-brush design may be
required.
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