ELECTRICAL EQUIPMENT—Q.6
2.
Check the connections on the commutator end
bracket. The larger connector carries the main
dynamo output, the smaller connector the field
current.
3.
Switch off all lights and accessories, take off the
cables from the terminals of the dynamo and
connect the two terminals with a short length of
wire.
4.
Start the engine and set to run at normal idling
speed.
5.
Clip the negative lead of a moving coil type
voltmeter, calibrated 0 - 20 volts, to one dynamo
terminal and the positive lead to a good earthing
point on the yoke.
6.
Gradually increase the engine speed, when the
voltmeter reading should rise rapidly and without
fluctuation. Do not allow the volt meter reading
to reach 20 volts, and do not race the engine in
an attempt to increase the voltage. It is
sufficient to run the dynamo up to a speed of
1,000 rev/min. If the voltage does not rise
rapidly and without fluctuation the unit must be
dismantled for internal examination, see Para
4(b). Excessive sparking at the commutator in
the above test indicates a defective armature
which should be replaced.
(b)
To Dismantle
1.
Take off the driving pulley.
2.
Unscrew and withdraw the two through bolts.
3.
Withdraw the commutator end bracket from the
yoke.
4.
Lift the driving end bracket and armature
assembly from the yoke. Take care not to lose
the fibre thrust washer from the commutator end
of the shaft.
5.
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the yoke has withdrawn with it the armature and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, or the
armature is to be replaced; in this event the
armature should be removed from the end
bracket by means of a hand press, having first
removed the shaft key.
(c)
Brush Gear (Checking with yoke removed)
1.
Lift the brushes up into the brush boxes and
secure them in that position by positioning the
brush springs at the sides of the brushes.
Fig. Q.2.
Dynamo Dismantled.
