Rolls-Rovce Silver Shadow
&
Bentley
T
Series
Workshop
Manual
Brushgear-To inspect (see Fig.
M
26)
The brush length when new is 12,7 mm.
(0.5
in.).
The serviceability of a brush may be determined by
measuring the amount by which it protrudes
I~eyond
the brush
box
moulding when in [he frre position.
Replace the brush
if
there is less than
.5
mm.
(0.2 in.) protruding. If brushes are changed, take
care not to lose the leaf spring fitted at the
sidc of
the inner brush.
Check the brush spring pressure using a push
type spring gauge. This should indicate
0,255 kg
-
0,368 kg
(9
-
13
or)
when the brush face
is flush with the housing. Sticking
l)rnshes may be
cleaned with a petrol moistened cloth.
Sliprings-To inspect
The surfaces of the sliprings should be smooth and
uncontaminated by oil or other foreign matter.
Clean the surfaces with a petrol moistened cloth,
or if there is evidence of burning, very fine glass
paper. On no account must emery paper or similar
abrasive be used.
Rotor-To test
For clarity, the illustrations of the electrical testing
of the rotor and stator shows these components
isolated from the
remainder of the alternaio~.
Chapter
M
FIG. M27 MEASURING ROTOR WINDING RESISTANCE
WITH BATTERY
&
AMMETER
Test the rotor winding by connecting either an
0407
ohmmeter or a 12 volt battery and ammeter betwecn
the sliprings
(see
Fig.
M27).
The resistance :should
be 3.6 o'hms at 20
OC
or the current approximately
3 amps. Test for defective insulation between one
FIG.
M28
INSULATION TEST OF ROTOR w~~D~NG
of the sliprings and one of the rotor poles using a
0
110 volt A.C. mains supply and a
15
watt test lamp.
I
110
volts
AC
(see
Fig.
M28).
If
the lamp illuminates the coil is
2
15
watt lamp
earthed to the rotor core and a replacement
rotor/
3
Slipring
slipring assembly must he fitted.
4
Rotor poles
Stator-To test
W
Connect any two of the three stator windings in
t
series with
a
12
volt battery and
1.5
watt test lamp
6
V:
(see
Fig.
M29).
Replace one winding with the third
i
winding and repeat the test.
If
the test lamp does
not
illuminate on either occasion, the stator winding
is open circuit and a replacemrnt stator must he
C'
.I
ttpd.
Test for defective insulation between the stator
coils and the lamination pack with the mains test
K
697
lamp. Connect the test probes between any of the
three cable ends and
the laniination pack
(s~e
Fig.
hi'30).
If
the lamp illuminatrs, the stator coils
0
at-e earthing and a replacenwst stator must be fitted.
FIG. M29 STATOR WINDING CONTINUITY TEST
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