Sorvall RT/T6000D - Page 70

SORVALL®
Centrifuges
Repair
&
Replacement
5-31. Motor Brush
Replacement
1.
Unplug
the
centrifuge
power
cord
and
remove
the
access panel (paragraph
5-33).
NOTE
Remove
the
motor
if
necessary
to
access
the brushes
(see
paragraph
5-30).
2.
Remove
the
plastic
brush
caps
from the
motor
with
a
stubby
screwdriver,
and
pull
the
brushes
from
their
holders,
noting
orientation (also shown
in
figure
5-15).
a.
If
the
brushes
are longer
than
6
mm
(1/4
inch),
return
brushes to
their
original
brush
holders,
retaining
the
same
orientation.
b.
If
the
brushes
are
shorter than
6
mm
(1/4
inch),
the
brushes
must
be
replaced.
c.
If
these
are
not
the
original
set
of
brushes and
they are
shorter than
6
mm
(1/4
inch),
replace
and recondition
the
armature.
3.
Remove
any
carbon accumulation
from
the brush
holders.
CAUTION
Do not stone
or
burnish the
commutator
as
this
will
increase
brush
wear
and
may
result in
smear
metal
on
the
surface
of the
commutator.
Do
not
allow the brushes
to
wear
to the
point
where they
no longer
meet
the
commutator.
This
condition
causes
severe arcing
which
results
in
excessive
brush and
commutator
wear.
To
replace
motor
brushes:
1.
If
brushes need
to
be
replaced,
insert
new
brushes into
the
brush
holders
on
opposite
side
of the
motor.
2.
Press
down
on
the
brush
spring
retainer
and install the
plastic
brush
caps,
making
sure
the
brush
spring
retainer
"ears"
are seated
in
the
brush holder
slots
(see
figure
5-15).
3.
Replace
the
access panel
(paragraph
5-33) and
plug
in the
centrifuge
power
cord.
4.
If
a
new armature and/or new brushes have been installed,
run
the
centrifuge
at
2000
rpm
with
no rotor
for
thirty
minutes to seat
the
brushes.
Failure
to
do
this will
result
in immediate brush bum and
commutator
pitting
and
will
severely
limit
the
life
of the
new
parts.
CAUTION
Under
normal
operating
conditions,
the
centrifuge must not
be
operated
without
a rotor
properly
installed
and balanced.
Brush
seating procedures
are
the
only
exception
to
this
rule.
5-27