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If the dynamo is in good order, leave the temporary link in position between the terminals and restore
the original connections, taking care to connect the dynamo terminal 'D' to the control box terminal 'D'
and the dynamo terminal 'F' to the control box terminal 'F'. Remove the lead from the 'D' terminal on
the control box and connect the voltmeter between this cable and a good earthing point on the vehicle.
Run the engine as before. The reading should be the same as that measured directly at the dynamo.
No reading on the voltmeter indicates a break in the cable to the dynamo. Carry out the same
procedure for the "F terminal, connecting the voltmeter between cable and earth. Finally remove the
link from the dynamo. If the reading is correct test the control box (Section N.9).
Fig. N.2 The correct method of undercutting the dynamo
N.3 REMOVING AND REPLACING THE DYNAMO
To remove the dynamo, disconnect the dynamo leads from the dynamo terminals.
Slacken all four attachment bolts and pivot the dynamo towards the cylinder block to enable the fan
belt to be removed from the dynamo pulley. The dynamo can then be removed by completely
removing the two upper and one lower attachment bolts.
Replacement of the dynamo is an exact reversal of this procedure.
N.4 DISMANTLING THE DYNAMO
Take off the dynamo pulley. Remove the cover band, hold back the brush springs and remove the
brushes from their holders.
Unscrew the locknuts from the through-bolts at the commutator end. Withdraw the two through-bolts
from the driving end.
Remove the nut, spring washer and flat washer from the smaller terminal (i.e. field terminal) on the
commutator end bracket and remove the bracket from the dynamo yoke.
The driving end bracket, together with the armature, can now be lifted out of the yoke.
The driving end bracket which, on removal from the yoke, has withdrawn with it the armature and
armature shaft ball bearing, need not be separated from the shaft unless the bearing is suspected and
requires examination, in which event the armature should be removed from the end bracket by means
of a hand press.
N.5 SERVICING THE DYNAMO
Brushes
Test if the brushes are sticking. Clean them with petrol and, if necessary, ease the sides by lightly
polishing with a smooth file. Replace the brushes in their original positions.
Test the brush spring tension with a spring scale if available. The correct tension is 20.5 oz. (567-709
gm.). Fit a new spring if the tension is low.
lf the brushes are worn so that the flexible lead is exposed on the running face, new brushes must be
fitted. Brushes are pre-formed so that bedding to the commutator is unnecessary.
Commutator
A commutator in good condition will be smooth and free from pits or burned spots. Clean the
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