Rockwell Automation 1325L DC Motors User Manual - Manual (Page 19)

DC Motors 19
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 C180ATZ are the same regardless
of whether application is coupled or belted.
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.
Fit the face of new brushes to the contour of the commutator with sandpaper
only, no emery abrasive. Keep brush lead (pigtail) connections tight.
Replacement brushes should have sleeved pigtails.
Commutator
A commutator in good condition is clean and smooth with a medium polish
and a light brown color. Keep clean by occasionally wiping with a canvas
pad. Use no lubricant or emery abrasive. If a commutator becomes rough, it
needs to be resurfaced. Roughness can be easily detected with the machine
running by resting a pencil-like rod of insulating material (dry wood) on
one of the brushes. In mild cases, a commutator dressing stone can be used.
Very rough or out of round commutators require turning in a lathe. In every
case, maintain concentricity and remove the minimum material required for
proper cleanup. Undercut the mica approximately l/16” and polish. Adjust
brush holders for approximately 1/8” clearance to commutator.
The finished diameter and the minimum diameter of the commutator for the
various frames sizes are as follows:
The commutator should be replaced if the final diameter would have to be
turned down to a value less than minimum limits.
!
ATTENTION: To guard against personal injury or death, ensure
that all power to the motor has been removed and the motor shaft
is stationary. Brushes must not be touched or replaced while
motor is energized or rotating.
Frame
New Diameter Minimum Diameter
Inches Millimeters Inches Millimeters
DC180ATZ &
DC210ATZ 3.01 76.5 2.62 66.5
C180ATZ 4.12 104.8 3.66 93.0