A.J.S. 16 Instruction Book - page 82
Remove the cover band to inspect commutator and brush gear.
The brushes are held in contact with the commutator by means of springs. Move each
brush, see they are free to slide in their holders, if dirty, or if sticking, remove and clean
with a cloth moistened with petrol. Take care to replace brushes in their original
positions, otherwise they will not "bed" properly on the commutator.
If, after long service, the brushes have become worn to such an extent that the brush
flexible wire is exposed on the running face, or if the brushes do not make good contact
with the commutator, they must be replaced by genuine LUCAS brushes.
The commutator must be free from any trace of oil or dirt and should have a highly
polished appearance. Clean a dirty, or blackened, commutator by pressing a fine dry
cloth against it while the engine is slowly turned over by means of the kick-starter.
(It is an advantage to remove the sparking plugs before doing this.) If the commutator
is very dirty, moisten the cloth with petrol.
At every 10,000 miles, the complete dynamo should be handed to a Lucas Service
Station for dismantling, replacement of worn parts, cleaning and lubrication.
Electrical breakdown of the dynamo is most unusual and therefore before assuming this
unit is defective, it should be tested as follows:
Check that the dynamo, regulator and battery are correctly connected.
Test Dynamo in position by:
(a) Remove the two wires from the dynamo terminals and connect the two terminals
with a short length of wire.
(b) Start the engine and set to run at normal idling speed.
(c) Connect the negative lead of a moving coil voltmeter (calibrated not less than 0 to
10 volts) to either of the two dynamo terminals and connect the positive lead to a
good earth point on the dynamo or engine.
(d) Gradually increase the engine speed, when the voltmeter reading should rapidly rise
and without fluctuation.
Do not allow the voltmeter reading to rise above 10 volts.
Do not race the engine in an attempt to increase the voltage. It is sufficient to run
up the engine to a speed of 1,000 r.p.m.
If the above reading is obtained the dynamo is in order.
If there is no reading, check the brush gear.
If there is a low reading of approximately ½ volt, the field winding may be at fault.
If there is a low reading of approximately 1½ to 2 volts, the armature winding may
be at fault.
if the tests, mentioned above, clearly indicate the dynamo is not charging, it is then
desirable to remove the dynamo from the machine in order to make further tests and
repairs or replacements.
To remove and re-fit dynamo
The dynamo rests on a cradle forming part of the crankcase and is retained by a band
having an adjustable clamping action and one stud passing through timing gear case.
It is rotated by a gear meshing with the timing gear wheel on the exhaust cam shaft.
Upon merely slackening the clamping strap and removing the sleeve nut on the outside
of timing cover, the dynamo, complete with its driving gear, can be withdrawn from the
crankcase. The two wires from dynamo to regulator unit are retained by an insulated
bridge secured by one screw and, upon removing that screw, the bridge, with the two
cables, can be taken away from the dynamo.
C O N T R O L B O X
The regulator is set to maintain a pre-determined dynamo voltage at all speeds and
regulate the output of the dynamo to the battery according to the state of charge of the
battery. The charge rate is at its maximum when the battery is discharged, automatically
tapering off to a minimum as the battery becomes charged and its voltage rises.
Inspect commutator and brush gear every 5,000 to 6,000 miles
(Maker's
Recommendation.)
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