ELECTRICAL EQUIPMENT—Q.5
DYNAMO
1. General
The following information concerns the dynamo fitted
as standard equipment to the earlier 4.236 marine
engine, namely, the Lucas C40A model. If information
concerning another type of dynamo is required, the
relevant manufacturer should be contacted.
The C40A is a non-ventilated, shunt-wound two-pole
two-brush machine arranged to work in conjunction with
a compensated voltage control regulator unit. A hall
bearing supports the armature at the driving end and a
porous bronze bush at the rear supports the commutator
end.
The output of the dynamo is controlled by the regulator
unit and is dependent on the state of charge of the
battery and the loading of the electrical equipment in
use. When the battery is in a low state of charge, the
dynamo gives a high output, whereas if the battery is
fully charged, the dynamo gives only sufficient output to
keep the battery in good condition without any possibility
of overcharging. An increase in output is given to
balance the current taken by lamps and other
accessories when in use.
When fitting a new control box, it is important to use
only
an
authorized
replacement.
An
incorrect
replacement can result in damage to the dynamo.
2. Routine Maintenance
(a)
Lubrication
Every 250 running hours, inject a few drops of
high quality S.A.E. 30 engine oil into the hole
marked "OIL" at the commutator end bearing
housing.
(b)
Inspection of Brushgear
Every 2,500 running hours, the dynamo should
be removed from the engine and the brushgear
inspected by a competent electrician.
(c)
Belt Adjustment
Occasionally inspect the dynamo driving belt,
and if necessary, adjust to take up any
slackness by turning the dynamo on its
Fig. Q.1.
Lubricator in Commutator End Bracket.
mounting. Care should be taken to avoid
overtightening the belt (see Page M.1).
3. Performance Data
The cutting in and maximum output speeds quoted
below are production test figures and refer to cold
machines with brushes only partly bedded.
Model C40A
Cutting-in Speed
1,100 rev/min (max.) at 13.0 dynamo volts.
Maximum Output:
11 amperes at 1,700 rev/min (max.) at 13.5
dynamo volts and a resistance load of 1.23
ohms.
Field Resistance:
6.0 ohms.
4. Servicing
(a)
Testing in Position to Locate Fault in
Charging Circuit
1.
Inspect the driving belt and adjust if necessary.
