Workshop
Manual
Rolls- Royce Silver Shadow
&
Bentley
T
Series
Chapter
M
FIG. M30 INSULATION TEST
diode.
FIG. M31 TESTING DIODES
Diodes-To test
If
a fault in a diode is indicated, remove the
rectifier/heatsinks cotnplete. Unscrew the three
stator winding connections at each diode heatsink.
Remove the four screws which pass through the
nylon insulating washers and also the small
screw
which secures the earthing strip to the bracket and
remove the complete assembly.
Connect the pin of a diode
in
series with a 1.5
watt test lamp and one
terminal
of
a 12 volt
battery, connect the other
battery terminal to the
diode
heatsink
(see
Fig.
12131).
Observe the test
lamp.
Reverse the connections to the diode and again
observe the test lamp.
If
the lamp illuminates in
both tests or remains unlit in both tests then the
diode is faulty and
a
new rectifier./heatsink
assembly must be fitted. Repeat the tests for each
FIG. M32 USE OF THERMAL SHUNT
Note:
When unsoldering any link wlres
connected to the diodes always use
a
thermal shunt
(see
FIR.
,2132).
Alternator-Further dismantling
a
Remove the
heatsink/terminal block assembly.
b. Withdraw the three through bolts.
c. Separate the slip ring end bracket and stator
assembly from the
gotor and drive-end bracket by
inserting a lever between the stator and drive-end
bracket and carefully prise the two apart until the
slip ring end bearing is clear of its housing.
If necessary, the rotor shaft can
be
pressed out
from the drive-end bracket having first removed the
shaft nut, washers, pulley, fan
&
shaft key.
d. Drive-end bearing
Dismantle the alternator and separate the rotor
from the drive-end bracket. Unscrew the three
countersunk screws securing the bearing retaining
plate, remove the plate and withdraw the drive-end
bearing assembly.
e. Slip ring end bearing
Dismantle the alternator.
Unsolder the field
winding connections to the slip ring moulding
assembly and withdraw the assembly from the rotor
shaft. Extract the bearing from the shaft. Fit the new
bearing and engage the slip ring moulding with the
slot in the motor shaft. Finally, remake the field
to slip ring connections using Fry's
H.T.
3
solder
(or any high melting point solder).
When required, the alternator bearing may be
lubricated with Shell
'
Alvania'
'
R4'.
3
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