Rockwell Automation 1325L DC Motors, Frames C210ATZ - C440ATZ - Manual (Page 19)

DC Motors 19
Most commonly used bearings are:
•
Single row, open ball bearings for coupled and belted duty for
frames C210ATZ - C250ATZ.
• Single row, open ball bearings for coupled duty for frames
C280ATZ - C440ATZ.
• Cylindrical roller bearings at drive end for belted duty on frames
UC280ATZ - UC440ATZ
Frequent bearing checks are recommended. If temperatures become
excessive, investigate immediately for the cause. Total bearing
temperatures should not exceed 90 degrees C (194 degrees F). Causes
for high bearing temperature are:
•
Contaminated grease.
• Insufficient grease or excessive amount.
• Incorrect grease.
• Excessive load or thrust due to misalignment or motor overload.
• Loose bearings.
• Bearing failure.
• Excessive ambient temperature.
Replacement bearings should be ordered from Allen-Bradley in order
to obtain the same carefully selected bearing as the original. Bearings
should never be exposed by disassembly of the motor unless
absolutely necessary for inspection or replacement of the bearing or
maintenance in other parts of the machine. Protect good bearings
from dirt and contamination at all times. Most bearing failures are
caused by dirt.
The open ball bearings for motor frames C210ATZ - C250ATZ are
the same regardless of whether application is coupled or belted.
Belted duty for frames UC280ATZ - UC440ATZ requires the use of
roller bearings. Coupled duty uses ball bearings.
Brushes
Brush pressure is correctly established at the factory and maintained
at the correct value throughout the life of the brush by means of a
constant pressure design. Brushes and brush-holders should be clean
so that the brushes are free to move in the holders. Replace brushes
with new brushes of the same grade before wear permits the rivet or
tamped pigtail to score the commutator. It is best to change out
complete set.
Brush Changing Procedure
1. Remove hand hole covers from each side of the commutator end
bracket.
2. Loosen four (4) hex head cap bolts which hold the rocker ring
assembly to the bracket.
3. Brushes are removed from the holder by lifting the brush finger
and removing the hex head cap bolt which secures the brush lead
to the holder. New brushes are installed by following the reverse
procedure.