Du Pont SORVALL RC-5 Service Manual page 147

Sorva
II ^CentrifugesMaintenance
&
Repair16
mm'(5/8
in.)Sipi^^i'^at^14
mm"(9/16
in.)7/79RCS/57BE
SURE
BEVELLEDEND
OF EACH
BRUSHMATCHES
CURVATUREOF
COMMUTATOR.7/79RCS/58Figure
6-10.Drive
Motor Brush
DimensionsFigure
6-11.Proper
Insertion
of
Brushes2.
Position the brush lead
along
the
top
of the brush to the brush
spring
and
fromthere
out along
the
spring
in
a flat. easy curve
to the terminal
screw. Keep
thebrush
leads flat and well within the outer confines of the motor.
If
the lead
isbrought
out directly over
the
top
of the brush holder, the brush
will "hang up"
aftera
short
period
of
operation
(see figure 6-12). Adjust brush tension
with
Alienwrench
to 6
N
± 0.56
N
(18-22
oz.).3.
To
reassemble, reverse
the above
procedure.
Make
sure
when
replacing
motor
thatthe
guide pin
of the
centering assembly
is aligned with the
guide pin
hole.c.
Brush Break-in
ProcedureUsing
an
SS-34
rotor:1.
Run the rotor at 5
000
rpm
for 30
minutes.2.
Increase the
speed
to 10 000
rpm
for an additional 30
minutes.6-8.
Drive Motor Brush
Replacement,
RC-5BTo
eliminate
periodic motor
brush
inspection, a
BRUSHES
lamp warns when
thebrushes
are worn to minimum operating length. When
the
lamp flashes, the
brushesstill
have
about
an
8-hour
operational
life.
However, to prevent motor
commutatordamage,
a
lock-out
system
is
included.
When the
lamp starts flashing, no
additionalruns
can
be made after the motor turns
off, except as
specified in Section
4,
paragraph4-13.
Replace
the brushes
as
follows:1.
Remove drive motor and gyro-assembly
(paragraph
6-4).NOTEStep
(b)
applies
only when optional automatic rate controller is
installed.6-9