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TECHNECAT SERYICE

GENERATOR
OUTPUT CONTROI.
UNITS
OPERATI ON-CONSTRUCTI O N_SERYI CI N G
 INTRODUCTION

Both the Lucas Compensated Voltage and Current Voltage regulating

systems are covered in the accompanying pages of this publication.

In the explanation of the working of Lucas generator output

control units, certain abstruse technical considerations have been
deliberately omitted, but these factors do, of course, have to be
considered by Lucas engineers when designing the equipment. It
should also be emphasised that our recommendations in regard to
regulator open-circuit voltage settings should always be strictly
adhered to if satisfactory working of the equipment is to be obtained.

Regulators are designed to snit the electrical equipment of each

individual vehicle, i.e., type of generator, lamp and accessory load,
etc., and for this reason are not interchangeable as a whole. Always
refer to a Lucas Interchangeability List before fitting a replacement.

The mention of any unit, or parts of a unit does not imply the
availability of either the complete unit or spare parts for service
purposes.

Page 3
 C0NTEf.ITS

PART 1.
Why control of the generator outpttt is necessary.
The Principles of Voltage Control.
The construction of the control unit.
Voltage control in practice the voltage regulator.
The cutout. -
A theoretical constant voltage control charging circuit.
Compensated Voltage Control.
Why compensation is necessary.
The regulator series and load uindings.
The charging circuit employing the Lucas C.V.C. system'
Temperature com pensation.
Auxiliary circuits the complete colrtrol box.
-
PART 2.
Control Boxes: S1'mbols. T1'pcs :lnd Applications, Service Adjustments.
Symbols.
Features or tl:e R F.95 . 9(r, 97, RB. I 07, RB. I 08, RB. 1 06/ l. RB. I 06/2 control
boxes.
Reguletor nrc'chattical settings and contact cleaning.
Cut-,rri1 tnechanrcul settings and contact sets.
T llc ru'rlulrtlor poirit: resistor.
Frusr,' unils. FS5 -5lF and 4JF.

PAIIT 3.
Chccking the Charging System.
Conrplete test procedure for the charging system, comprising battery and
generirror tests. checking of the regulator, electrical setting; checking
crit-out operation. warning light, ammeter. Possible faults are indicated
at each stage.

I'AiiT ;1

Currcnt Voltage Regulators.

Reasons for the introduction of the current/voltage system.
Charging characteristics of the compensated voltage and current/voltage
systems.
The RB.3l0 and 6GC current-voltage regulator build-up of the unit.
Circuits of the Lucas current/voltage regulator; -method of operation.
Construction details of the RB.310,6GC and RB.340 control boxes.
Charging troubles Checking and adjusting current voltage regulators.
-

@ Printed in England.

JOSEPH LUCAS (SALES & SERVICE) LTD., BIRMINGHAIVI 18, ENCLAND.

Page 4
 PART ONE
Working Principles

GENERATOR OUTPUT CONTROL

The generator with which we are concerned is a
plain, shunt-connected machine. The main charac-
teristic of this type of generator is that its output rises APPROXIMATE EATTERY VOLTAGE: DISCHARGED
r.vith increasing speed and is by itself totally unsuitable ; FULLY CHANGED nI
that on modern vehicles GENEPATOR VOLTAGE CONTROLLEO AT 16V,

is therelore necessary, when it is applied to a vehicle as

the source of the battery charging current, if it is to
function efficientll, at all road speeds. To function GENERATOP PPESSUPE BATTERY BACK PRESSURE
efficiently i1 6ust not only be controlled over the
speed range but also give an output which varies
according tc th- load on the battery and its state of
charge.

CONSTANT VOLTAGE CONTROL

The answer to the problem of how to control the state of charge. The difference between the battery
generator output, so that at all times the battery is terminal voltage and the generator terminal voltage
being correctly charged and the generator kept would be appreciable when the battery was in a low
within its rated output, is the fact that the battery state ofcharge, getting progressively less as the battery
voltage (and consequently the back E.N{.F.) varies reached its fully-charged state. lf the pre-determined
according to its state of charge. If now we could voltage at the generator terminals has been correctly
control the generator terminal volta_qe at a pre-set set. in theory rve shall arrive at a state where the
figure over a wide speed range, we should have a battery terminal voltage in its fully charged condition
variable voltage at one end of our charging system and will exactly equal the generator terminal voltage. At
a constant voltage at the other. The current florving this point, no current will flow through the charging
in this charging circuit would therefore vary rvith the circuit, as the back E.M.F. of the battery will equal
varying terminal voltage of the battery, i.e.. rvith its the terminal voltage of the generator.

CHARGI NG CHARACTERISTICS THE CONSTRUCTION OF:THE CONTROL

The graph below shows how the charging rate UNIT
falls as the battery reaches its fully-charged state, As shown in the illustration below, the voltage
becoming a trickle charge, in this case of I or 2 amps., control unit comprises an iron frame or "Yoke" (1)
after 10 hours. on which is mounted two iron bobbin cores (2)
It is also clear that with this system of regulation one (left) the voltage regulator and the other (right)
"Voltage Control" the battery receives a high charge the cut-out switch.
from the generator when it needs it most. Consider the voltage regulator unit: a pivoted
(bell-crank) armature (3) is attached by means of a
spring blade (4) to the top of the iron frame. The
horizontal member (5) lies immediately over the
bobbin core and when this core is magnetised the
flat member will be drawn down to it. In order to
prevent it clinging to the core by residual magnetism
a brass plate (6) or a copper button prevents iron to
iron contact. (Continued on next page).

o
2

Page 5
THE CONSTRUCTION OF THE CONTROL
UNIT (continued) terminal F connects to the insulated contact point (8).
On the vertical member of this armature a contact When at rest the two contact points will be closed,
point (7) is fixed to line up with a stationary contact thus completing the circuit between the generator
(8) insulated from the main bracket. Also on the armature and field.
vertical member of the armature is a spring blade The contact point assembly of the automatic cut-out
(9) and this blade lines up with an adjusting screw (10). switch (12) is of a generally similqr constructiori but
By means of this adjusting screw the pressure between a single opening and closing operation disconnects and
the two contact points may be varied. connects the generator from the battery. In the rest
The main D terminal of the generator connects position the cut-out points are open whereas the field
to the bracket as shown (11) and the generator field regulator points are closed.

THE GENERATOR FIELD CIRCUIT

The output of the shunt-wound generator is only
obtained when the field circuit is joined in parallel
with the armature circuit, i.e., when terminals D and
F are connected together. By breaking this DiF
connexion, that is, breaking the field circuit, the
generator output will immediately fall off.
The illustration on the right shows the regulator
frame and its connexion to the generator. By
following the circuit from the generator D terminal,
through the right-angle frame and moving contact to
the fixed contact, and back to F at the generator.
it can be seen that D is effectivelyjoined to F through a
pair of contacts. Spring tension holds the contacts
iogether, thus keeping the D/F circuit closed.

REGULATOR SHUNT COIL

The breaking of the contacts is controlled by an
electro-magnetic relay whose winding is connected
across the generator between terminal D and earth,
that is, in parallel with the generator armature. Thus,
as the generator voltage rises, this shunt winding
will be energised, magnetising the core, and a point
will be reached when the magnetic pull of the core is
strong enough to overcome the spring tension and
separate the contacts.
Immediately the contacts separate, breaking the
field circuit, the voltage of the generator falls. In
turn, the bobbin will lose its magnetic pull, release
the moving contact and, with the field circuit again
completed, the generator output will rise.
When in operation this becomes an alternate rapid ll
opening and closing of the contacts at a frequency ofll
between 15 and 30 times per second enabling a very l!
fine regulation of the generator voltage to be obtained. ,l I
The voltage necessary to create sufficient magnetic
effect to separate the contacts can now be controlled
by the spring tension on the contacts themselves.
Thus we can control our generator voltage at a pre-set
figure by adjustment of the spring tension. And
what is more, this control is independent of the speed
at which the generator is being driven.

Page 6
THE REGULATOR POINTS RESISTANCE THE CHARGING CIRCUIT
Unfortunately, however, to break the field circuit Let us now build-up a charging circuit from what
when a fairly heavy current is passing causes con- we have discussed so far. Al1 we need is an ammeter
siderable arcing across the contacts. Therefore a in series with our battery, and some sort of switch to
resistor must be placed in parallel with the contacts disconnect the battery from the generator when
to protect them against the heavy inductive surges charging stops. Otherwise the battery would dis-
which occur as they open. t charge itself through the generator windings.
When the regulator contacts are closed the resistance The switch is represented here by a pair of contacts,
is short circuited; it provides however an alternative on the right of the illustration below.
path between D and F when the contacts are open, Follow the circuit from the generator D terminal,
thus quickly limiting the induced field current. along the extended regulator frame, through the
switch and then through the ammeter to the battery.
The circuit is completed via the battery and generator
earths.

trr
GENERATOR FrELp CIRCU1I
VIA RESISTANCE

THE CUT.OUT assists the magnetic pull of the shunt winding,

preventing the cut-out contacts from chattering once
In practice of course all this switching is done they have closed.
automatically by another electro-magnetic relay called
a 'ocut-out". The winding for this cut-out is wound Also, when the generator stops charging, the
on a separate bobbin on the frame and connected momentary reverse current from the battery flows
across the generator between terminal D and earth. through this series winding, creating a magnetic fleld
It is, then, a shunt or voltage winding as was the which opposes and therefore cancels the existing field,
regulator shunt winding but we that the thus accelerating the opening of the contacts.
- separate stress
regulator and cut-out are two units.
You will notice that the entire regulator frame is at
generator potential; in more practical terms, the
connexion from D of the generator is actually attached
to the frame.
When the generator voltage rises sufficiently, the
cut-out contacts are closed against spring tension by
the magnetic pull from the cut-out bobbin and the
circuit between the generator and the battery is thus
closed.
When the generator speed or voltage is low or the
engine stationary, the contacts will break, thus
preventing current from the battery flowing back
xtrrl
through the generator armature windings.
There is one important point to remember: all the
charging current from the generator passes through
the cut-out contacts and through a heavy "series" or
current winding on the cut-out bobbin. This current CUTOUT

P.age 7
CHARGING CIRCUIT: "CONSTANT
VOLTAGE CONTROL"
The regulator and cut-out assembly, that is, the
control box, would now look like this. Follow the
circuit through, starting at the D terminal of the
generator, from there to the D terminal of the box
and then to the regulator frame, through the cut-out
when the contacts close, through the heavy series
winding on the cut-out and across to terminal A.
This telminal is connected via the ammeter to the
battery. The circuit is completed by the battery and
generator earths.
Unfortunately, this simple "constant voltage con'
lrol" system has one snag: it presupposes the use
of a generator of very great generating capacity.
Consider the case of a battery in a low state of charge,
its terminal voltage will be low. If, in addition, a
load is put on the battery, switch the headlamps on
for instance, the voltage will fall still lower. Under
such conditions, the generator will still endeavour to
maintain the pre-determined voltage set by the
regulator and consequently an extremely heavy
cuirent will flow in the charging circuit, owing to the
substantial difference between the battery and genera-
tor voltages. In practice this current would be
sufficient to burn out the armature of a standard
automobile generator.

..COMPENSATED VOLTAGE CONTROL''

The Lucas "COMPENSATED Voltage Control
System" overcomes this difficulty by automatically
varying the OPERATIONAL voltage setting of the
regulator, so that the difference between the generator
and battery terminal voltages is never great enough to
cause such a heavy current to flow that the generator
would be damaged.

THE REGULATOR SERIES WINDING

In practice, this variation in the operating voltage
of the regulator is brought about by adding another
winding to the regulator bobbin. In other words, the
charging circuit now continues from the cut-out
series winding, not direct to terminal A, but through
an additional "Series" winding on the regulator
bobbin. This winding thus carries all charging current
flowing from the generator to the battery and is wound
so that its magnetic field assists that of the voltage or
shunt coil ofthe regulator in pulling apart the regulator
contacts. The heavier the current flowing, the greater
will be the magnetic pull of the bobbin, and the sooner
the contacts will open. Thus in effect we have lowered
the voltage at which regulation occurs: our generator
will then be working at an operational voltage which
is varied according to the current flowing into the
battery.
As the battery becomes discharged and its voltage
falls the charging circuit voltage or "LINE VOLT-
AGE" will also fall. The action of the COM-
PENSATING or SERIES winding on the regulator
is thus to limit the charging current to the maximum
safe output of the generator.

Page 8
THE REGULATOR "LOAD TURNS"
If, when the battery is discharged, all the lights,
etc., are switched on, a further drop in the line voltage
will take place. To compensate for this. one or more
additional turns will be added to the series u'inding
and taken to a terminal marked A1 as shown. These
are called LOAD TURNS and only'become effective
rvhen the lights and any other external load are
switched on.
In appearance all the regulator units are similar and
mechanically this is so. Also with a very few excep-
tions the regulator settings are the sanle.
So, in order to make this standard unit universally
applicable to all types of generators and all models of
vehicles it is necessary to vary the number of turns
in the compensating and load windings. The com-
pensator windings must be made to suit the generator
and the load winding to suit the external loads, that is,
the lighting, etc., for different vehicle layouts.
Thus each type of control box has an identification
number which relates it to the correct generator and REGULATOR SPLIT SERIES WINDING
also the vehicle application. For this reason the
control units must not be interchanged except as
recommended in Lucas Interchangeability Lists.

CHARGING CIRCUIT: COMPENSATED

VOLTAGE CONTROL
The illustration on the left shows the complete
charging circuit incorporating a compensated voltage
control regulator.
To trace the circuit start at the generator armature
which is connected to the D terminal on the generator.
This terminal is connected to the D terminal at the
control box and a metal connecting strip joins the D
terminal to the regulator frame, causing the frame to
be at generator potential. Follow the arrows from
this point, along the frame, through the moving
contact, then to the fixed contact when the cut-out
points close. The current is then able to flow through
ihe series winding of the cut-out and through the main
regulator series winding, being taken off at the tapping
to the A terminal. The circuit then continues to the
battery by way of the ammeter.
The circuit is completed through the vehicle chassis
CHAPGING aNo uolo crpcurrs (sxovt rn xeew lrxes) and so to the earthed brush of the generator.
The current for the load circuit is taken from the
very bottom of the regulator series winding to the
terminal Al and from there to the main lighting and
ignition switch.

Page 9
TEMPERATU RE COMPENSATION
The regulators themselves, in addition to having
compensating and load turns, are also TEMPERA-
TURE compensated. This, like the regulator setting,
is common to them all, but is not in any way adjustable.
Put in its simplest form, this temperature com-
pensation aims primarily to make the generator
voltage-setting follow the comparative battery voltage
BI.M EIAL
as it rises and falls due to marked temperature changes. srRr P,
As the charge proceeds, the generator will heat up
quickly. The temperature compensating feature
enables an extra high charge rate to be applied to the BI.METAL STRIP FITTED BEHIND
battery with a cold generator and be maintained until CONTACT TENSIONING SPRING
the generator reaches its maximum working tempera-
ture, when the generator voltage is automatically
reduced by the compensator and the charge proceeds the temperature falls. Having then applied such a
at a normal rate. combination of metals to the regulator adjusting
To this end, as shown in the illustration, a bi-metal spring, a spring tension is obtained which will vary
strip is fitted behind the contact tensioning spring. automatically with the temperature of the equipment.
This consists of two strips of metal with different The controlling voltage of the regulator will thus be
co-efficients of expansion welded together and the higher when it is cold than when it is hot.
combination, when heated, will give a differing degree Like the regulator, operation of the cut-out is
of expansion, causing the combination to bend as the temperature-controlled by means of a bi-metallic
temperature rises and resume its normal shape when tensioning spring.

AUXILIARY CIRCUITS
The regulator unit itself is now complete, but there
are other features of the control box which must be
considered.
On some control boxes, additional terminals are
provided to cater for accessories fltted on the vehicle,
such as trafficators, windscreen wipers, etc.
Extra terminals on this type of box are, flrst: the
A2 terminal. This, as you can see, is connected
from the Al terminal through a fuse marked "AUX"
(auxiliary). Any accessories connected to this ter-
minal will be fed from the battery via the ammeter
through the load turns on the regulator bobbin, with
a fuse in circuit.
Next, the ,A.3 and ,A.4 terminals. The A3 terminal is
fed from the ignition switch, and is thus "live"
only when the ignition switch is on. Both A4 terminals
are then fed through a fuse from A3. Thus auxiliaries
AUXILIARY IGNITION AND ACCESSORIES CIRCUIT connected to ,A.4 will only operate when the ignition
is switched on. The feed to the ignition switch itself
is from A1, i.e., through the LOAD turns.

REGULATOR LOCKNUT
ADJUSTING SCREW

SCREWS SECURING THE COMPLETE CONTROL BOX

FIXED CONTACT PLATE
Most of the features discussed are indicated in this
illustration, which shows the two auxiliary fuses, and
the right angle bracket or yoke on which both regulator
SPLIT SERIES and cut-out are mounted, regulator left, cut-oui right.
WINDING
The regulator split-series winding is pointed out;
and the screws for adjusting the spring tension on the
regulator and cut-out.

FUSES
COMPENSATED VOLTAGE CONTROL REGULATOR

Page l0
 PART TWO
Control Boxe Symbols, Types and Application

IDENTIFICATION SYMBOLS RB340 Current Voltage Control Box, 5 terminals

(E, D, WL, F, B). Toothed adjustment
RBl06/1 Regulator Box, incorporatin_e LRTg 12 regu- cams.
lator. Shrouded terminals. RF95/2 Regulator Box. incorporating LRT9 l2 regu-
RB106/2 As RB106/1, but wirh built-in regulator. lator. External fuses.
RBl07 Regulator Box, incorporating built-in regu-
Xnpss/: As RF95/2, but incorporates built-in regu-
lator sealed cover. lator.
RB108 As RBl07, but with riveted cover. Some RF96/2 Regulator Box, incorporating LRT9 l2 regu-
versions have rubber mounting studs. lator. No fuses.
RB3l0 Current Voltage Control Box, 3 terminals RF97 Regulator Box, incorporating LRT9 l2 regu-
(B, F, D). lator. Sealed cover.

!F952 95' RBt07' RB108, RB105/1 AND R8106/2 THE RF96 CONTROL BOX
CONTROL BOXES This control box also has a moulded base assembly
We can now review the Control Boxes themselves. upon rvhich is mounted a similar LRT9 regulator and
In this particular section we will deal r.vith compensated cut-out. Again various split-series windings are
voltage control units only. employed.
To begin with, what are their characteristic features ? The 96 is a more recent design than the 95 and is
With the exception of the RF95/3, RBl07, RB108 and primarily intended for use with the heavier output
RB106i2 the LRT9 regulator is used with a variety of generators, in particular the RA5.
series windings, but the voltage settings are sometimes
The split-series winding generally has fewer turns
special for particular applications.
when used with the heavier output generators.
THE RF95 CONTROL BOX The simplified terminal board of the box is at once
noticeable. (See illustration below).
This control box comprises of a bakelite rnoulding
upon which is mounted the LRTS regulator and the Only terminals required by the regulator and cut-out
cut-out assenrbly. The heavy series turns on the are provided; commencing from the left.
regulator are divided into the main and load com- Al The supply for all external load; comes from
pensating windings. the load turns of the split-series winding.
Two 35 amp. fuses are provided lor the accessory A Comes from the main compensating turns of the
circuits. The one fuse (right) is fed through the ignition series winding.
switch. The second (left) has a direcr supply through F Wired to the generator f,eld terminal.
the load winding ol the regulator. D Wired to the generator main terminal.
The fleld points resistance are in the form of a E For the earth connexion from the LRT9
cartridge placed on the underside of the base.
assembly.
The terminal layout is indicated in the picture.
One or more independent fuse boxes can be fed
Later units of this type incorporate the RB built-in from the Al terminal according to car ffianufacturers'
regulator and are known as the RF95/3. requirements.

Page 11
THE REGULATOR SPLIT.SERIES WINDING
You may have noticed that the number of series
turns on the regulator bobbin varies considerably,
generally, the higher the output rating of the generator'
ihe fewer the series turns required. S'ith the RA5
for instance, the high output generator which was
used by Rolls Royce and Bentley. the regr-rlator split-
series winding has only I main turn. and 1 load turn.
At the other extreme, the regr'rlator used with the
fully enclosed, low output generator on the "Ford-
son" tractor has 6 main and 3 load turns.

THE RF97 CONTROL BOX

This is a fully enclosed metal box asser.nbly. and tvas
designed expressly for use in exposed. working con-
ditions. It was thus well suited for marine and tractor
work.
The LRTS regulator-cut-out assernbly used is fitted
with a "Pellet" type resistance mounted on the back
of the regulator frame and irtside the box. Connexions
to the box are made by means of "plug-in" ternlinals.
thus keeping the unit watertight and dustproof.
The regulator series winding, you will notice' is not
a split winding. In other words, the box is not designed
to provide cotnpensation for a lighting and accessory
load, but for use where the generator output is rnostly
required for charging the battery only.
The unit is sealed by nteans of a Langite Gasket
visible in the picture and the cover is riveted down.
In the event ofit being necessary to open the box the
rivets have to be drilled out and the cover re-assembled
and properly re-tightened by means of 2BA or similar included within the sealed cover and thus prevetit
screws and nuts. corrosion and damage from exposure.
The change from a cartridge to a pellet type resis- The unit is produced in both 12 volt and 6 volt
tance was introduced to enable the resistance to be and mostly applied to tractors.

REGULATOR AOJUSTMENT CUTOUT AOJUSTMENT

lscRew
THE RB1O7 CONTROL BOX
Frx€o This control box was designed to replace the RF97.
TACT
It was designed to give greater ease of adjustment and
maintenance when fltted to tractors and motor cycles
and is specially applicable to marine work. Its
electrical operation is the same as other compensated
voltage control regulators.
STOP PLATE The main constructional changes concerned the
cut-out and regulator. Both were redesigned and the
contacts positioned above the bobbins.

Page 12
THE RBt06/1 CONTROL BOX
This control box is similar to tlie RF96, but was
designed for use with the higher output generators
C45PV5 and C39PV2. It may have a series com-
pensating u,inding consisting of only one main turn
and one load turn.
Neither the RBl06i I nor the RF96 are suitable for
use rvith tl.re lorver output, fully enclosed generators, as
the latter. in trying to maintain the regulation voltage
uith little series compensation. would be working out-
side their rated output and rvould thus over-heat.
On the other hand. if the older RF95 with more
series turns u,ere used with the high output generators,
their maxirnurn output would never be available.
This unit is mostly used for 12 volt u,orking but
u'as also available for special 6 volt applications. No
fuse positions are provided.

THE
REGULATOR
R8106/2
- CONTROL BOX
The illustration on the left shows the Iatest pattern
CUT_OUT AAJUSTING
A DJUSTING SCREW R8106/2 which is used on the majority of preserrt-day
SCREW cars. It has the same electrical operation as the
RB106/1.
The rnain difference lies in the mechanical arrange-
n-rentof the cutout and the voltage regulator. The
contacts are now fixed above the bobbins.
As shown, "Lucar" tenr-rinal blades are being
fitted in place of the grub screw type terminals
previously employed.
In addition, the regulator and cut-out electrical
setting adjusters are locked with a compression
spring located behind the head instead of with a
locking nut.
*Al One 17.5 amp. and one 35 amp. blade.
xA As for A1.
F One 17.5 amp. blade.
*D As for A1. The 17.5 amp. is for W/Light corlnex-
ion, the 35 amp. for main generator lead.
E One 17.5 amp. blade.
*Inhibitor tags are fitted in order to prevent crossed
AI AFDE connexions at these terminals. The inhibitor is
attached to the female portion on the wiring harness.

Page 13
CONTROL BOX MODEL RB1O8 On earlier units the cover was secured to the base by
This unit is fitted to tractors, motor cycles and means of four rivets and rolling over of the edge of the
stationary engines. Internally, it is identical with cover. On present day units the cover is rolled over the
control box model RF97 but externally, there are base edges.
differences in the methods of securing the cover and Because of the "rolled over" cover a new method of
of the mounting of the unit. Some units are fitted checking the O.C.V. was devised, see illustration
with the moulded rubber shockproof mounting studs. belou'.
Others are arranged for foot or bracket mounting, see
illustrations below.
FIEGULATOR REGULATOR CUT-OUT AAJUSIING FIXED CONTACT
SERIESWINOINGS ADJUSTING SCREW BLAOE

REGULATOR REGULATOR SiIOPTARM

I,(OVING CONTAC? FIXED @NTACT SCREW

FROM BA-ITERY
AMMETER OR
LIGHTING SWITCH

TO
EARTH If the positive lead of test voltmeter can be fitted
with a suitable probe to enable it to be inserted into
the "A" terminal socket, then the open-circuit
voltage can be checked without having to remove the
cover, see illustration on left.
TO GENERATOR
If, of course, any mechanical or electrical adjustment
TERMINAL,D.
is necessary the cover will have to be removed.

LATER RB'08 REGULATOR ADJUSTMENTS

We must add, however, that the latest RBl08
Control Boxes have two holes in the cover. So that it
is unnecessary to remove the cover to adjust the
regulator and cutout assemblies.
However, when the Control Box is in position on the
vehicle, the two holes are sealed with rubber bungs to
prevent the entry of dust and moisture.

Page 14
ADJUSTMENTS IN SERVICE
There is only a limited amount of service work (2) Oxidation of the points due to nortnal usage.
possible for the motor engineer who will usually (3) Incorrect air gaps invariably due to interference.
require to work with the components in situ. These faults can usually be corrected quite easily.
The perforn,ance of the regulator may be affected The voltage can be set with the aid of a good Moving
by three factors: Coil Voltmeter as detailed in Part 3. The air gaps
(1) Maladjustment of electrical setting, usually the can be checked and the regulator points cleaned, as
result of tinkering adjustments. detailed in the following paragraphs.

LRT9_ REGULATOR CONTACTS SET LRT9 _ CUT-OUT CONTACTS SET

A word now about the Regulator Contact Sets And here is the standard contact set for the Cut-out
then.rselves. There is only this one standard set used ol the LRT9 unir.
for the Voltage Regulator on all the LRT9 Regulator
units.

n1
ffi,1*
&#u:e ffi
#B

*p

Note. The "E" shims shorvn in the above photo-

graph are- not used on later models of the LRT9, for
adjusting the contacts gap. The correct gap being
obtained by bending the fixed contact carrier uith the
aid of a suitably slotted bending tool.

RB_ REGULATOR CONTACTS

- CUT.OUT CONTACTS SET
SET RB
The contact set shorvn belorv is used on tlie latest And this is the contact set for the cut-out of this unit.
type regulator fitted to the RF95/3. RBi07. RB108
and RBl06/2.
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i@l
ffi WW
-# 'w
.5s#
ffiffi
Hffi

Page 15
THE REGULATOR VOLTAGE SETTING
Adjustment of the voltage setting is very easily
carried out by means of an adjusting screw, A, atrd
lock nut, B, on earlier units. (A spring loaded screw
is used on later production units).
This dangerously simple adjustment can only be
safely made with the control box connected to a
generator. A good quality moving coil voltmeter
should be used.
The operation as carried out in service is fully
dealt with in "Testing the Charging Systeur".
The regulator settings should always be checked
before any interference with the contact points and
alr gaps.
There are standard settings for all conditions of
working which will be outlined later.
CLEANING THE CONTACTS
L RT9 The contacts on the latest type ol control bor are
easily accessible, so that it is not necessary to adopi
RBr0612 any special procedure belore cleaning them.
Earlier control boxes. for instance. the RF95. RF96,
RF97 and RB106/l employed the LRT9 regulator, and
it is impossible to clean the regulator contacts. untii
the contact plate is swung ontu'ards.
The fixed contact plate is secured by trvo scre\\s.
These are both slackened. especially the upper screii'
(that is, the one farthest from the base plate). The
contact plate is then srvun-e outrvards.
Different materials are required lor cleaning the
regulator and cutout contacts. The regulator contacts
are made of tungsten. and should be cleaned uith
carborundum stone. or silicon carbide paper.
The cut-or.rt contacts are made of silver. and should
CLEANING OF CONTACTS be cleaned with fine glass paper.
A11 dust should be removed rvith a cloth soaked in
methylated spirits.

ARMATURE
@ FIXING SCREWS
REGULATOR @
FRAME ARMATURE

REGULATOR AtR GAPS (LRTg)

As indicated in this illustration letter "A" is the
armature carrying the moving regulator point which
is mounted on the spring blade and located by two
screws in slotted holes. Thus the armature is move-
able in relation to the regulator frame (B).
The bobbin core face is shown at (C) and the
regulator points at (D).
There are three important dimensions:
(l) The air gap in the vertical plane between the
regulator frame and armature which should be
.020". It is permissible for this gap to taper,
either upwards or downwards, between the limits CONTACT
FrxED O.006 - O.Ot7 "
of .018" and .020". BRACKET WITH ARMATURE
(2) The bobbin core face to the horizontal member PRESSED TO CORE
of the armature: which should be maintained at
.012" to.020", with the gauge placed underneath
o
Note. the latest pattern of the LRT9 regulator.
the brass pip, or shim. - On
adjustment of the contact gap is made by bending
(3) With the armature pressed against the regulator the flxed contact carrier with a suitably slotted
frame, the contact point gap must be between bending tool. It will be found that shims are not now
.006" and .077". used for varying this gap, as on the earlier models.

Page 16
 o. o3o'-o.oro" n9r, ARMATU RE
CUT.OUT AIR GAP AND ELECTRICAL PRESSED AGAINST A\UGES
SETTTNGS (LRTg)
The cut-out switch seldom calls for any attention
ARMATURE FXING
rvhatsoever.
SCRE:WS
It should to 13.3 volts for the 12 volt
be close at 12.7
rnodel and 6.J to 6. / volts on the 6 volt model and
should re-open at betu'een 8.5 and l0 vglts on ,the,l2 o.ol4" @
voliEocl:l or 4.5 to 5 volts on the 6 volt model, with
a reverse current reading of between 3.5 and 5 amperes
in both cases.
SCRE\Y
The correct air gaps are as indicated in this illus- SECURING
tration:
FTXED CONTACT
A should be .014 inches.
B .0ll to .015 inches.
C .002 to .006 inches. @
D .030 to .034 inches. WITH O.O25 GAUGE BETWEEN ARM.ATURE SHIM
& coRE, CoNTACT cAP TO BE O.OO2: 0.006.

REGULATOR CONTACTS RESISTOR

There are three standard types of contacts resistor
used on the previously mentioned regulators to protect
the contacts from damage by arcing.
ll The CARTRIDGE type on the right is nominally
f f rated at 63 ohms and is used on 12 volt regulators.
Illt fn" 6 volt version is nominally rated at 3-8 ohms.
The CARBON PELLET type on the left is generally
built into sealed control boxes such as we use on
tractors and motor cycles.
It is mounted on the back of the regulator frarne
and has a nominal resistance value of 38 ohms for 6
volt sets and 63 ohms for 12 volt sets.
The WIRE WOUND type below is nominally
rated at 60 ohms for 72 volt units and 30 ohms for
6 volt units. This is used on the latest RB106/2.

R8107, R8108 AND RBl05/2 CONTROL BOXES

_ REGULATOR AIR GAP SETTINGS TENSION SPRING ARIVIATURE SECURING
Adjustment of the regulator is obtained by altering scREws
the spring tension on the blade of the contact set by
means of the adjusting screw B and lock nut A on LOCK NUT FIXED CONTACT
earlier units or by means of a spring loaded screw on USTMENT SCREIY
current units.
The air-gaps which are slightly different from the ARMATURE
LRT9 can be re-set as follows:
Unscrew the fixed contact adjustment. CORE FACE
Unlock armature securing screws.
Insert .021" feeler gauge between armature and
core face.
FOR OPEN-CIRCUIT
Press armature down squarely against the VOLTAGE SETTINGS
gauge and re-tighten armature fixing screws. REFER TO PART 3
..CHECKING THE
With gauge still in position, screw the flxed CHARGING SYSTEM''

contact down until it just touches the moving

contact and tighten lock nut.
Reset the voltage in the normal manner.

Page 17
R8107, RB108 AND RB105/2 CONTROL BOXES
AIR GAP AND ELECTRICAL
-CUT.OUT
SETTINGS
It is unlikely that the cut-out switch will require
any attention or adjustment, but for general infor-
mation the electrical settings are similar to those for
the LRT9 Units: SIOP PLATE

Cut-in Drop o.ff Reverse

Voltage Voltage Current

12 volt models 12.7 - 13.3 8.5 - 11.0 3.0 - 5.0

6 volt models 6.3 - 6.7 4.8 - 5.3 3.0 - 5.0 TENSION SPRING

FIXED @NTAST

Note: By means of the bi-metal compensation device,

cut-out settings remain substantially constant CORE
over a wide range of temperatures. Any small FACE
variations in setting due to changes in tem-
perature result merely in proportionately small
increases or decreases in the generator cutting-
in speed. No temperature correction factors
need therefore be applied to the above settings.
The gaps should be:
A : .025" - .040'with the armature pressed down.
B : .015" - .020" with the armature released. The
cut-out fixed contact follow through should be between
.010" - -020".

supplied directly from the control box terminal A1,

FUSES and may include such heavy current units as Windtone
The modern system of assembled wiring looms has Horns.
offered such protection to the main circuit wiring that
safety fuses are not generally installed in these circuits. LIVE SPARE
The most vulnerable points will be the accessory FU SES FUSES
circuits, particularly when additional accessories are
fitted.
It will have been observed that on the RF series of
control boxes two accessory fuses are incorporated:
one fuse generally known as the ,A.4 fuse will protect
those accessories which are directly controlled by the
ignition switch. The other, the A2, will provide for
the remainder of the accessories, not under the
master control of the ignition switch.
The RBl06 box has no fuses. With this box, it is
convenient to employ a separate twin fuse base for the
accessories as shown in this picture. Or, when re-
quired by the car manufacturer multiple fuse boards
can be used.
The fuse base shown is the type FS6 which is
normally equipped with a 35 and a 50 amp. fuse. The
35 amp. fuSe on the right will protect those items
connected through the ignition switch; the 50 amp.
fuse on the left will serve the miscellaneous accessories

Page 18
 PUSH-ON COVER

FUSE UN!T MODEL 5JF

This unit incorporates the Lucar terminal blade
and is for use in conjunction with the standard
RB106/2.
As standard the unit incorporates a 35 amp. fuse.
It provides for connecting six 17'5 amp. connectors.
SPARE FUSE

AUXILIARY
TERM INAL

FUSE UNIT MODEL 4JF

This unit is also used in conjunction with the
"Lucarised" RB106/2, when two-way connexions are
required.
It incorporates either two 35 amp. fuses or, one
35 amp. and one 50 amp. fuse, depending on the
application.
Provision is made for connecting several l7'5 amp.
connectors. A single grub-screw type terminal is also
provided.
SPARE
FUSES

Page l9
PART THREE
Checking the Charging System

SYSTEMATIC CHECKING
It must be understood that the circuit as a whole good tackling the job haphazardly. The fault must
rvill not function correctly unless each of the individr.ral be localised to a particular section, at the same time
units is in order. not forgettin-q of course the wiring verifying the rest ofthe charging circuit on the vehicle.
between them.
In checking for a fault on the charging systenl.
therefore, proceed according to a set plan; it is no

HYDROMETER TEST
First check the specific gravity of the electrolyte in
each cell. Remember, specific gravity is affected by
temperature variation and the figures quoted in the
table below are corrected to 80oF. (26.6"C.). Specific
gravity readings taken at electrolyte temperatures
other than this must be corrected before a true
indication of the state of charge, of battery under test.
can be determined.

I
Hone trade Climates
I
and climqres frequently
Cell lordinarilyl ot'er
belot' | 80't'
800F. I Q6.6'C.)
(26.6"C.)

Fullycharged .. | 1270-1290 | 1210-1230

Abouthalf-charged.. I 1190-1210 | ll30-1150
Completely discharged 1110-1130 1050-1070
| |
The battery should normally be at least half-charged.

THE HEAVY DISCHARGE TEST

The hydrometer test gives a fairly accurate account
of the state of charge of each cell, but a further
test must be made to make sure that the battery
rvill supply heavy currents at the required voltage, the
heavy starting currents for instance. For this purpose,
a "heavy discharge tester" is used which puts an
electrical load on each cell. The load, or resistance.
takes at least 150 amperes from the cell in the case of
batteries whose capacities at the 10 hour rate are below
75 aH. thus reproducing conditions similar to those
existing when the starter motor is operated. If the
hydrometer test showed the cell to be charged and if,
under these test conditions, the voltage remains
constant at approximately 1.5 to 1.6 volts, we can be
sure the cell is serviceable. A rapidly falling voltage
reading indicates a weak cell. The drop tester should
be held in position for about l5 seconds per cell.
The same type of tester is used for motor cycle
batteries, but a smaller load, this timeof 12 amps. is
adequate. A load of 300 amps. must be used for
batteries whose capacities at the 10 hour rate is 75 aH
and above.
Having made certain that the battery is serviceable.
next test the source of the charging current, the
generator.

Page 20
CHECKING THE DRIV!NG BELT AND
GENERATOR BEARINGS k: in.* lin. FRtt PLAY ilETWEIA
The first operation should always be to check the erilrnAT0R 1il0 Eil&lll[ PuLLEYl
driving belt. Atter all the generator can hardly be
expected to give of its best il it is not being driven
correctly. There should be about haif an inch move-
ment in the belt. tested at this point. And remernber
that a belt that is ercessively tight not only strains the
generator bearings. but is aiso liable to damage the
lvater pump gland. Make sure too that the belt is not
frayed or oily. as this will cause slipping when tl.re
generator is under any appreciable load.
One last point. the "V" belt must not be bottomin-u
in the pulley. If it is. either the pulley or the belt is
worn. A check should also be made at this stage for
side plal' or end float in the bearings. Make sure too
that the _senerator leads are tight at the terminals. T[$T Xtnr

TESTING THE ARMATURE AND BRUSH

CIRCUIT
The first electrical test will be to see that the armature
is operative and the brushes properly contacting the
commutator.
The generator leads must be disconnected as you
can see and a voltmeter connected between the D
terminal and earth.
The generator should then be run up to charging
speed approximately 3,000 rev./min. when a reading of
between 2 and 3 volts should register on the voltmeter.
This reading is applicable to both 12 ar,d 6 volt units.
The earth lead can be attached at any convenient
point preferably the one shown.

TESTING THE FIELD CIRCUIT

The nert step is to ascertain that the field coils
and leads are operative and not in any way earthed.
shorted or open-circuited.
Connect an ammeter between the D and F terminals
still Ieaving the voltrneter connected as in the previous
test. Increase the engine speed slowly until the read-
ing on the voltmeter is 6 or 12 volts, i.e., the normal
battery voltage of the vehicle system. At this point
the ammeter should not read more than 2 amps.
The ammeter reading should be the same for either
system. Suppose the ammeter had registered 3 or 4
amps., instead ol 2 amps. This reading could be
caused by either an internal short or an earth on the
field coils, which reduces the resistance of the field
circuit and hence increases the current flowing in it.
A zero ammeter reading would indicate an open field
circuit.

Page 2l
CHECKING THE GENERATOR CABLES
If the generator is in order the next step is to check
lhe generator cables electrically, unless a complete
visual examination is possible. i{l'iix)*oei'ffif s
iwffi$pttt
** $
Repeat tl,e last two tests to prove both the D and F
cables as far as the control box.
First re-connect the cables at the generator and
disconnect them at the control box terminals.
The picture shows the first test, namely the volt- ,,t
r,
yneter between D and earth. If there is any doubt as /-!
to rvhich is the D and F cables, obviously this test will ,,u
-1
prove the point. Only one of the two leads should
give a voltage reading D lead. It will record
- the obtained,
trhe armature voltage previously if the lead
,::-...{:S3]

is intact.
At this point it should be stressed, that if the D and
F leads have been accidentally crossed, the regulator
contacts will show very obvious signs of having passed
excessive current. The points will be badly burnt and
in some cases welded together. So be careful when
:e-connecting the leads.

CHECKING THE CONTROL BOX

6Hmff$n sPfft 3C{]0R,l*.
The next check is at the control box. to see if
regulation is taking place.
ftt$lltAi0& $iTIlx$ r6- i6'8 Y. The regulation point, remember, is the voltage at
rvhich the generator is controlled. The check must
be made with the battery open-circuited.
First insert a piece of dry card between the cut-out
contacts. A voltmeter is then connected between
earth and the regulator frame which you will remember
is actually connected to the generator D terminal.
Run up the generator to about 3,000 rev./min. The
voltage reading will increase with rising speed, until
the setting point of the regulator is reached. When
the generator speed is raised to 4,000 rev./min. there
should not be an increase in voltage of more than 0.5
for 6 volt machines. and I .0 volt for 12 volt machines.

REG ULATOR
- STANDARD OPEN.CIRCU IT
VOLTAGE SETTINGS

Pre-Jarurury, 1956, v,ith .012" bi-metal strip Post-January, 1956, witlt .010" bi-metal strip

Antbient Temperature At 3,0N generator rev.f min. ll 3,000 generqtor rev.f min.

6 volt

l0oc. (50oF.)
*20oc. (68'F.)
t6.3
- 16.9 8.1
- 8.s 16.1
-16.7 I 8.05-8.4s
16.0
- 16.6 8.0
- 8.4 16.0-16.6 I 8.0
-8.4
- 16.5 I
30oc. (860F.) 15.7 16.3 7.9 8.3 5.9 1.95 8.35
40'c. (104'F.) 15.4 - 16.0 7.8 - 8.2
r
rs.8-16.4 I 7.9 -
- - -8.3
*Normal workshop temperature. Correction must be made if prevailing temperatures differ from the standard

Page 22
TO OPEN.CIRCUIT THE CONTROL UNIT-
REMOVE "A'' AND "AI" LEADS
The foregoing method of open circuiting the
regulator will provide an approximate idea of the v# a_ffi &tr ffi fl&{JL&T* ffi &*J U $Tffi r${y$
setting, but in order to get a true reading the following
procedure should be adopted.
The A and A1 lead should first be removed from
the terminals at the control box. This does two
things: it disconnects the battery from the generator
and puts the regulator load winding out of circuit.
In other words, as we are only making a voltage adjust-
ment, all we want in circuit is the voltage regulator
shunt (Voltage-Coil). Tll: series turns would affect
the voltage setting and must be out of circuit if an
accurate reading of the voltage setting is to be obtained.
The A and A1 leads rvill have to be twisted together
after detaching fron-r the control box terminals in order
to provide a feed from the battery to the ignition coil
to enable the en-eine to be run.

RUN GTTIERAT(}T AT
ADJUSTING THE REGULATOR SETTINGS
"q_[sguJ-I=E!g,_"g And now that the regulator is on open-circuit, its
adjustment is very simple.
Run the generator at charging speed. 3,000 rev./min.,
RIASI
. with the voltmeter already connected between regulator

N
frame (Gen. D) and earth. Turn the regulator adjust-
ing screw clockwise to increase the voltage, or anti-
clockwise to lower it, Reconnect A and Al leads.
Remove card from cut-out points.
Do not set the O/C voltage to exceed the maximum
$iInif,$t of the tolerbnce given in the table of settings and
temperatures.
''.
,;, * :
i,

1A
#
Se t
t

POSSIBLE FAULTS- HIGH VOLTAGE

READ!NG
If turning the adjustrnent screw has no effect p*$sf ilr'P&{itYffi
whatsoever on the O/C voltage and the reading is

ffi
'''"qe8ti:lirilldrlli!l;riu$*ili$!$ise'--'
right off the scale, the most likely fault is a bad control
box earth.
There are two other less likely possibilities: an
open-circuit regulator shunt winding or a short
between the D and F terminals. In all three cases '$ *$$r"erfi*ijr{{}}
*!'$$ {t$l*tli& ,i.
ffiffiffi
#
there can be no regulation of the generator voltage. $i'tilffi wte&i** $:'
Regulation. you remember, depends on the shunt .
.' , '.', . '.......|i:,..1. l

winding and one end of this is connected to the

- earth terminal. Also, if the field
control box and
dynan.ro terminals are shorted at atry point, neither
the regulator points nor the resistance can ever be in
circuit to limit the generator output voltage.
ffi
Page 23
 - LO\^/ VOLTAGE
POSSIBLE FAULTS
READING
If on the other hand the regulator setting is found
to be low and cannot be adjusted. take a look at the
regulator contacts. In all probability they u,ill be
burnt and oxidised, thus r-r-raking a good contact
impossible and preventing the _qenerator building-up
its normal voltage.
If the burning is obviously excessive check the
resistance or examine for crossed D and F leads either
at the control box or generator.

WARNING LlGHT AND AMMETER

Finally check the operation of the warning light,
the ammeter and the cut-out. And do not forget the
wiring behind the panel, make sure there are no loose
connexions or frayed leads. These can easily cause
intermittent or complete failure of the charging
system. The warning light for instance is connected
directly to the control box D terminal and an earth
on this cable would short circurt the generator output.

TO CHECK THE CHARGING CURRENT

If an ammeter is not fitted to tlre particular vehicle,
the charging rate can easily be checked by connecting
&ffru &€fffrx&}*R &r
a test ammeter in series with the A lead. The most
convenient point is at the control box.
rM&xfi{ffm $rrx*
To check the battery charging rate see that all
switches are off, the charge should be approximately
r8l{x[0t*M*rrI$ $mfie as shown in the table below.
'&
&il$ &r&"& ff*lrfier.
Specific Gravity Antperes

1210 5,A' or Lower

1250 or Lower 8A to 12 amps.
1200 or Lower 15 to 17 amps.

As a final check, switch on the full normal lighting

load, i.e., Heads, Sides and Tail. With generator
running at full charging speed the reading on the
ammeter should lie between zero and approximately
four amperes on the CHARGE side.

?age 24
THE CHARGING CIRCUIT COMPLETE
-
And just to remind you what we have been checking,
here is a typical charging circuit.
The first check, you will remember, is made at the
battery: the hydrometer and high rate discharge tests.
A check is then made at the generator and the D
and F cables from it to the control box. First with a
voltmeter between D and earth which checked the
armature and brush circuit, and then an ammeter
was added between the D and F terminals to check
the field current. -
Then, at the control box, to check the regulator
open circuit setting. To adjust this setting, the Al
and A leads are disconnected and joined together. We
also made sure that the control box earth was good.
We then checked the operation of the cut-out and
finally the warning light and ammeter. Remember
too, the importance of good wiring and connexions
throughout the circuit. CHAPGING CIRCUIT

CHECXING CHAFGING SYSTEM

'HE

@xvonoveren resr @DRrvrNG BELI @o/c serrrrc

fi*(eavv orscHAFGE 6)aeanrxos 6D) wnpxrHc LtGHr,& THE TEST ROUTINE
rEsr - AMMETEP
And finally, to summarise the whole procedure on
G) snusxes I ^
c oMMUrAroR (D tottStnIa.
the left is a list of the operations rvhich should be
r,on, carried out in the order shown.
@ mvarunt ono.lr
(3)cur-our
@ rreuo onorrr - .PERATIoN

@craues

Page 25
PART FOUR
Current-Voltage Regulators (RB 310, 6GC & R8340)

CU RRENT-VOLTAGE CONTROL
The increasing number of electrical appliances now Current-voltage control of the generator rs more
being fitted to the modern vehicle, many of which positive because not only is the generator output
consume relatively heavy currents, has made necessary controlled at a safe maximum, but this maximum
the introduction of a system of regulation more output is used to full advantage, being available if
positive in its action than the compensated voltage necessary for a longer period at the beginning of the
system. charge.

C HARGI NG CHARACTERISTICS
Assume our battery to be discharged, as shown by
the broken line curve, with the Compensated Voltage TEO
Control System, charging commences at a relatively VOLT GE PEGULAIOR
high rate, but quickly begins to taper off, after which,
the charge steadily falls away as the battery voltage
r
rises and finally becomes reduced to a "trickle
charge". AMPERES CUFPEA T VOLTAGE

With the Current-voltage Control System, however, t* oto' I L ATOF

tl-re battery is charged at a uniform high rate, thanks to

o
the current regulator, until the voltage of the circuit
reaches a pre-determined figure, when the voltage
regulatot commences to operate and the charging
current tapers off until finaliy only a trickle charge is
\
delivered. oL
Having explained the essential differences between o 5.O
TIME- HOURS
the two systems, let us look at our current voltage GPAPH COMPARING CHARGING CHAFACT€RISTICS-
control boxes, the RB3l0, 6GC and RB340. COMMENCING WITH OISCHAPGED gATTERY

THE RB3IO & 5GC CONTROL UNIT

These two units are identical mechanically, the only
difference being that the 6GC consists of a type R8340
flat base assembly with RB310 working components.
For the purpose of this description the diagrams we
will consider will be of the RB3l0 unit.
The complete unit consists of a normal cut-out (on
the left), but has two regulators: the current regulator
in the centre, and the voltage regulator on the right.
It is the series-wound current regulator which controls
the sustained initial charging rate and the shunt-
wound voltage regulator which takes command of the
system when the current flowing in the charging
circuit has diminished in value.

HOW THE CONTROL UNIT FUNCTIONS Let us study each component of the control
This control box comprises three components: individually after which it will be simple to follow out
the overall method of operation and understand how
(a) A cut-out switch to connect and disconnect the the components combine.
generator and battery automatically.
First let us examine the mechanical build-up of the
(b) A current regulator which allows the generator unit.
to give its maximum continuous output for about
one-third of the time necessary to recharge a
flat battery. YOLTAG€ REGUUTOR

(c) A voltage regulator which takes over control of

the output for the last two-thirds of the battery
charge and thus provides a charge tapering to a
finish.
Each of the items which we have mentioned has its
own separate circuit in the control unit:
(1) The regulator and cut-out operating coil circuits.
(2) The rnain generator cut-out circuit.
(3) The field regulator circuit.
%
Page 26
THE CONSTRUCTION OF THE CONTROL
UNITS
The unit is built up from a metal base (1) upon
which is fixed an insulating pad (2), mounting three
iron angled frames each with an iron core (3) on
which will be fixed a coil winding.
The Voltage and Current Regulator Units (on right
and centre) are basically similar.
A pivot angle bracket (4) the armature - on
which is fastened one contact- point is mounted by
means of a spring blade (5) in metallic contact with the
main frame. The horizontal member of the armature
lies immediately over the bobbin core. On its vertical
member a spring blade (6) is fixed downwards and
coincides with an adjusting screw in the back of the
TEMPERATU RE COMPENSATION
COM PENSATION
frame. This armature is the moving member of the The main coils of the cut-out and voltage regulator
contact set. The fixed contact point is screw mounted consist of many turns of fine copper wire and, con-
on another and smaller bracket (7) and is also fixed to, sequently, the ohmic resistance of these coils rises and
but insulated from, the top of the main frame. By
- part in
falls as the temperature rises and falls due part
means of the setting and adjusting screws the pressure to ambient working conditions and in to the
between the pair of contact points may be varied to normal passage of current. In turn, this causes the
provide the requisite voltage and current settings of operating current and therefore the magnetic pull on
the regulators. the armature to vary inversely with changes in tem-
The main D (Armature) terminal of the generator perature. Thus, to maintain the necessarily close
connects to the frame of the voltage regulator (8) and operating limits expected of these units, some form of
thus to the moving contact point (9). The fixed point compensation is required.
(7) is interconnected with the fixed point ofthe current The method adopted with cut-outs and all voltage
regulator (10) and the current regulator frame connects regulators other than 24-volt units is to utilise a bi-
directly to the F (Field) terminal of the generator. metal strip either to supplement or to take the place of
When at rest the two pairs of contacts will be closed the armature tension spring the hinge spring being
thus completing the circuit between the generator -
of steel, copper coated in cut-outs and blue in voltage
armature line and the "field". In this condition the regulators. The effect of the bi-metal is to cause the
generator will charge, but immediately either of the spring force on the armature to reduce with rises in
contact pairs is opened by the magnetic pull from the temperature and to increase with falls in temperature.
coil bobbins, the field circuit will be opened and the This method also compensates for variations in battery
generator will cease to charge. voltage with temperature a higher operating voltage
When in operation this becomes an alternate rapid -
being provided in cold weather.
opening and closing of the contacts at a frequency in With 24-volt units, it is customary to employ a wire
the order of 30 to 50 times per second, enabling a very wound series (or 'swamp') resistor in the voltage
fine regulation of the generator field to be obtained. regulator shunt coil circuit to minimise the effects of
The contact point assembly of the automatic cut-out temperature fluctuation the resistor being of higher
switch left is of general similar construction but ohmic value than the coil-and having a low temperature
a single - and closing operation connects and
- opening coefficient.
disconnects the generator from the battery. In the Current regulators are not compensated, the resis-
normal position the cut-out points are open whereas tance of the operating coil being too low to vary
both pairs of regulator points are closed. significantly with changes in temperature.

OPERATING WINDINGS
THE REGULATOR AND CUT.OUT
The electro-magnetic relays which operate the
cut-out switch contacts (A) and the voltage regulator
contacts (B) are energised or "excited" by coils of
fine enamelled wire mounted on the respective bobbins
and permanently connected across the generator main
circuit, i.e., "in shunt".
When the generator "builds" a sufficiently high
voltage the current flowing in these windings induces
a magnetic field in the cores of sufficient strength to
pull down the armature and close the contact points,
in the case of the cut-out, and separate them in the
case of the voltage regulator.

Page 27
THE GENERATOR AND CUT.OUT CIRCUIT
The current path from the generator D terminal (or
armature) is taken direct to the frame of the voltage
regulator unit. From there a heavy gauge copper
r',ire is taken to the current regulator and a specified
number of turns of the conductor wound around the
current regulator bobbin. The conductor is then taken
to the cut-out bobbin where several turns are made
befbre it connects to the n-roving cut-out point. From
the fired cut-out point the conductor terminates at the
terminal (B) thus completing the current path from
generator to battery.
The turns of this series winding on the cut-out
bobbin are wound in the same direction as the
previously mentioned shunt winding and so increase
the pull, thus holding the contacts together tightly.
The shunt coil closes the cut-out points at between
12.1 and 13.3 volts on the 12 volt system and current
in the series winding holds them down.
When the generator ceases to charge and the voltage
flalls, these points should re-open at between 9.5 and I 1.0
volts. A reverse current rvill commence to flow back
from the battery into the generator windings. This
reverse current de-magnetises the core and immediately
r,hrows the armature off, thus opening the contact
points.

contact point, lrom the flxed contact point through a

number of turns of wire on the upper part of the
voltage regulator and then to the fixed contact point
of the voltage regulator. We continue from the
moving contact on the voltage regulator to its frame
which is the generator main connexion (D). Thus
the field circuit is connected through two pairs of
contact points "in series" and if either is opened
the field circuit will be broken or "opened". When
this occurs a heavy destructive arc takes place at the
contact points and would quickly damage them. To
reduce this, a resistance is connected between D
and F as shown. This provides an alternative path
for the field current, but in passing through this resis-
tance however, it is considerably weakened.
The turns o[ wire shown at the top of the voltage
regulator bobbin what is termed a
- form
right
"Frequency Coil"- and simply serves to increase the
vibration frequency of the armature, resulting in a
steadier charging current.
It can now be seen that the action of the voltage
THE GENERATOR FIELD REGULATION regulator is controlled by the shunt coil and the
CIRCUIT bucking winding together.
To make the generator "build" it is necessary to The current regulator is entirely controlled by the
connect the field coils to the generator nrain circuit, heavy turns of wire which carry the total current from
i.e., connect terminal F to D. the generator.
As sl.rown in this picture the F terminal at the Finally it should be observed that in the normal
generator is connectedto the frame of the current position both pairs of regulator contacts are closed;
regulator. From the franre we pass to the rloving that, is, the field is fully connected.

Page 28
GENERAL METHOD OF OPERATION
Assuming a flat battery in circuit.
Immediately the generator is run it builds up a
voltage. When this rises to between 12.7 and 13.3 in
the case ofthe 12 volt unit the shunt coil ofthe cut-out
is sufficiently energised to close the cut-out points (A)
against the pressure of the adjusting spring.
Current will then flow to the battery and increase
directly with generator speed. By the time the
generator output reaches the permissible uaximurn,
the current regulator coil (B) is sufficiently energised
to pull down the current regulator armature against
its spring setting and so open tl,e contact points.
breaking the field circuit. The generator voltage then
drops, the exciting current in the coil u'eakens and the
regulator points close again allou'in,s the voltage to
rebuild. This opening and closing cycle continues at
between 30 and 50 operations per second. thr"rs limiting increase in amplitude and keep the generator voltage
the total generaror output to a safe marimum. at a sale maximum.
By the time the battery is sornethin-u over one-third In this condition the difference between generator
fully charged its terminal voltage rr'ill l-rave risen, and battery voltage continues to become less and the
resulting in a general rise in the line voitaqe, i.e.. current from the generator is finally reduced to trickle
between generator and battery. When the line charge proportions.
voltage reaches the correct value the voltage regulator
coil (C) is sufficiently energised to pttll down its Frorn the moment that the voltage regulator points
armature against the spring setting. This set of come into operation, the current from the generator is
field contacts will open and ther.r be put into a state of so reduced that the current regulator will no longer
vibration which will reduce and limit the generator operate, and its contact points will remain closed.
voltage. As the battery, and consequently the line In practice. a changeover period often exists when
voltage, continues to rise, the field point vibration rvill both regulators are in operation.

THE FREAUENCY COIL

The frequency coil (sometimes referred to as a
btrcking coil), as you can see in the illustration, is
wound in series with the two sets of contacts in the
fleld circuit. It thus passes field current. The winding
consists of a few turns of thick copper wire, so wound
as to assist the shunt coil of the voltage regulator.
In increasing the ampere-turns of the bobbin, it
therefore influences the operation of the voltage
regulator contacts, quickening the break and increasing
the frequency of vibration. This serves to stabilise the
operation as a whole, smoothing out and steadying
the generator output.

Page 29
CONNECTING POINTS AND The current regulator has no temperature-com-
ADJUSTMENTS pensation.
Let us now examine some of the constructional Adjustment screws for the armature tensioning
details of the RB310 current-voltage regulator.
The first point to note is that there are only three
terminals: B, F and D, reading from left to right in
the picture. The earthing of the box is done through
the fixing screws to the metal base of the assembly.
The fixing holes are provided with rubber cushioning.
The 6GC is slightly different in this respect for it has
an extra terminal "R" provided for earthin_e the base
of the unit to the vehicle chassis. This is similar to the
RB340 covered later in this book, and is fitted because
the base assembly is normally insulated lrom the
vehicle chassis by means of rubber fixing posts.
springs, that is, for adjusting the electrical settings,
The cut-out is temperature-compensated by means are located in the usual position at the back of the
of a bi-metal strip attached to the back of the armature frames.
tensioning spring.
The mechanical settings for the two regulators are
The voltage regulator is also temperature-com- controlled by adjustment screws over the tops of the
pensated by means of a bi-metal strip. bobbins.

THE CONTACTS RESISTANCE

SWAMP RESISTOR The voltage regulator, carbon rod, or wire wound
(WHEN FrrrED) points resistor is located under the base. It must of
cts R6tm
sEcoND coNT
(qFrcN NiDN npE)
FITTEOrc @M AEGUUDh
course be insulated from it, the latter being at earth
FWE OF EARLY UNIE
usEo w[H a7 eN&B
potential. The current regulator resistance is, when
fitted, located at the back ofthe regulator, and is ofthe
carbon button type. The field parallel and swamp resis-
tor, when fltted, are located under the base.
Resistor Yalues (Wire wound)
Contacts Resistor
l2-volt units: 60{5 ohms.
coNrA.rs RESrsroR r,.ro 24-volt units : 240:t 12 ohms.
1",,ill!."1!" 1.,
Field Parallel Resistor
l2-volt units: 40:t4 ohms.
Resistor Values (Carbon) earlier RB3l0 units only 24-volt units: 40=t3 ohms. (This resistor is series con-
nected with a Lucas diode between "F"
Contacts Resistor terminal and base (earth) ).
6-volt units: 50 ;[ 4 ohms. Voltage Regulator Swamp Resistor
l2-volt units: 63*'3 ohms (except earlier units used
with C47 generators which were fitted 24-volt units: 30+1t ohms. (This resistor provides a
with two contacts resistors, Rl 150+15 swamp path to earth for both voltage
ohms, across the VR contacts. and R2 regulator and cut-out shunt windings).
110+10 ohms, across the CR contacts). Resistance qf' Shunt Windings ctt 20oC. (68'f.):
24-volt units: 240124 ohms. 12 and \ Voltage regulator 103-l I 5 ohms.
Field Parallel Resistor 24-volt units: / Cut-out relay 58-65 ohms.
l2-volt units: 3813 ohms. Note. The above shunt winding resistance values
24-volt units: 60=E6 ohms. - units apply only to units in which both
for 24 volt
Voltage Regulator Sv:amp Resistor windings are connected to earth through a common
24-volt units: 120t6 ohms. swamp resistor.

Page 30
 LUCARTSED VERSION (RB3t0) CU RRENT AOJ USTMENT ScRE* VOLIAGE ADJU'IMElI SCRET'

The later pattern RB3 l0 incorporates Lucar terminal

blades, spring-loaded adjustment screws and, in
addition, a different method of cover fixing. The "ear-
CUT-OUT
fixed" cover as it is called allows for shorter through RELAY
fixing screws, without an insulating tube, to be used
for fastening the cover in position. Also, the screws
can be positioned more easily as the threaded hole CUT.IN AOJ USTMENT SCREW

which was originally drilled within the base of the unit

is now positioned externally to line up with the "ears"
on the cover.
B Two 35 amp. blades.
F One 17.5 amp. blade.
D One 35 amp. blade and one 17.5 amp. blacle.
CU RRENT
REGULATOF

CH ECKING THE CURRENT VOLTAGE

CO NTROL REGULATORS
To check or adjust these units it is essential that a
good quality moving coil voltmeter and ammeter
should be available. It is also very necessary to see
that these instruments are maintained in an accurate
state.
Within our experience an extremely simple test set
which may be made up, or purchased, as-illustrated
has been found the most satisfactory arrangement for
use in the service garage.
In this set a 3\" Scale Moving Coil Ammeter
I
f
calibrated 5-0-50 amperes and a similar voltmeter
calibrated 0-40 volts have the correct size of verv
flexible leads and clips permanently connected ready
for use, the assembly being accommodated in a sheei
steel box with detachable cover, thus safeguarding the
instruments against accidental damage in service.-
g
f
d ffi
lSW t'
;-- 'w
Without suitable instruments NO adjustments to
these control boxes should be attempted.
In every case before interfering with the control
unit preliminary checks on the battery, battery
#
connexions,. generator and generator driving beli,
together with an inspection of the generator and
control unit cables should be made. If these are
in order proceed to test, firstly the voltage regulator
and secondly, the current regulator as outlined.

Page 3l
TO CHECK AND ADJUST THE REGULATOR
opEN-crRculT voLTAGE (RB310 & 6GC)
We commence our adjustn.relrts at the voltage
regulator. First disconnect the lead from the control
box terminal "B" (marked "A" on earlier models) and
connect the voltmeter between "D" terminal (generator
armature) and earth. Then raise the generator speed
slowly to approximately 3,000 rev./min. (for C39PV,
C39PVR, C39Q, C40lt, C40L, C45PV, D5LF, GL45,
G524G,5A and GH45), 1,500 rev./min. (for C47. C48
and D5L), 2,000 rev.imin. (for G5 12). The voltage
should rise and steady itself with a slight flick. Accord-
ing to the temperature this reading should be as out-
lined in the table for voltage regulator electrical settings.
If any adjustment is required do not increase the
speed above 3,000 rev./min. Unlock the adjustment
screw on the back plate of the bracket and screw in-
wards to increase the voltage, and outwards to lower
the voltage, when corrected relock the adjustment a.'",--'---a,

screw and reduce the speed to "idling".

VOLTAGE REGULATOR ELECTRICAL SETTINGS

The Standard Open Circuit Voltage Settings with the generator running at approx. 3000 rev/min (1500 rev/min C47
and C48), are as follows:

Ambient Tentperature 12 volt 6 volt 24 volt

volts volts volts

ColdClimate 10oC. (50'F.) 15.1
- 15.7 8.r
-8.5
28.2
- 28.7
Temperate Climate 20oC. (68'F.) 14.9 15.5 8.0 8.4 28.0 28.5
Hot Climate 30oC. (86'F.) 14.7 - 15.3 7.9 - 8.3 27.8 - 28.3
Equatorial Climate 40'C. (104'F.) 14.5 - 15.1 7.8 - 8.2 27.6 - 28.1
- - -
7.0 7.3 volts at 68'F. (20'C.) for 6 volt regulators for "HOLDEN"
14.2- - 68oF. (20'C.) for regulators used with Rootes "EASIDRIVE" units (C45PV/6)
14.8 volts at
Setting or adjusting must be done as quickly as possible in order to preclude heating effects which would introduce
errors into the setting.
wrien the generator speed is above:
'1'd'.! Jlri;t"lroui'#irt3'r:TiT#ifl&:ili:?
8.9 volts at 68oF. (20oC.) for 6 volt regulator
31.0 volts at 68oF. (20'C.) for 24 volt regulator

?age 32
THE CUT-OUT SETTINGS
The cut-out should be adjusted next, for unless the
cut-out points close properly, it is impossible to adjust
the current regulator.
Leaving the voltmeter connected as in previous test,
insert an ammeter between terminal "B" and the "B"
cable. Switch on an electrical load, such as headlamps,
and slowly increase generator speed from zero. Closure
of the contacts, indicated by a slight drop in the volt-
meter reading should occur between the following
figures:

Cut-in Drop-olf
l-?
1.
Voltage Voltage

volts volts
l2 volts t2.7-13.3 i 9.5-11.0
6,. 6.3
- 6.7 i rs.o-23.0
4.8
24 26.s-21.0 - 5.s The drop-offvoltage can be checked by disconnecting
the lead from control box "B" terminal and connecting
the voltmeter between this and earth.
The cut-out is adjusted by means of the screrv at the
_ Run the engine up to 3,000 rev./min., then slowly
back. This is screrved inuards. That is to say clock- decelerate, noting the instant when the voltmeter drops
wise, to increase the voltage. and out$ards (or anti- to zero. This should occur between the limits given in
clockwise) to reduce it. the table.

The current settings, for the standard generators,

are as follows:

Generator Voltage I Serting

volts I amps.
PY_2 t2 I l9+l
39P-2 . 12 I l0+++
C4OA 12 I r0+++
C4o-16iFan).: :: t2 I zz+t
C40-l (4t" Fan) t2 I
C4OAL t2 | 20+l
10+++
C4OL t2 I 2s+t
c40LQ t2|| 2s+1
c42 12 30+r+
c42 (EASTDRTVE) t2 | :s+ri
C45PV-5 t2I zz+r'
C45PV-6 t2 | 2s+l
c45PV-6 (EASTDRTVE) 12 I 30+1+
C45PVS_6 12 I 2s+1
c47 12 I 30+1+
c48 t2 l 3s+3
TO CHECK AND ADJUST THE CURRENT
REGULATOR
Finally the current regulator is adjusted. The volt-
age regulator contacts are short-circuited by means of a
The current setting is then checked against the
crocodile clip placed across the contact plate to the lgures given in the table for the appropriate generator
frame of the voltage regulator as shown. With the fitted to the vehicle.
battery still disconnected from the "B" terminal, the The output is then regulated by means of the screw
test ammeter is again connected between the lead and in the backplate. Once again, the setting is increased
the terminal, and again the complete load is switched by screwing inwards (or clockwise), and reduced by
on. The generator is then run to charging speed turning it outwards (or anti-clockwise).
approximately 4,500 rev./min. (4,000 rev./min. for Note.-Do not switch lights on after starting the
c48). engine otherwise the bulbs may burn out.
Page 33
MECHANICAL SETTINGS FOR RB31O & 6GC IXED CONTACT
ADJUSTMENT
Adjustment of Air Gap Settings SCREIV
Gauge Thicknesses BOBBIN CORE
Air gap settings are accurately adjusted during ARMATURE
SECURI NG
ASSEM BLY
SCREW.C,
assembly and should require no further attention.
If, however, an armature is removed for any reason, TENSION SPRING
care must be taken to obtain the correct setting on
re-assembly. When setting an armature-to-bobbin
core air gap, the correct size of gauge required is
determined by the thickness of the non-magnetic VOLTAGE ADJLi.STMENT SCREW
separation used in the gap and also, in the case of AND LOCKING NUT
voltage regulators, on the thickness of the bi-metal
spring located behind the tensioning spring of the ARMATURE
ASSEM B LY
armature. (nean vrail)
The above variable features are easy to identify SEPARATI ON ON
BOBB IN CORE
and are as follows:
0.015" separation is by means of a disc of copper.*
0.009" separation is by means of a square of copper.
O.Ol2" bi-metal springs are bright and unplated.
@D
Dlsc
@
SQUARE

0.010" bi-metal springs are copper plated. (c) (D)

xAlternatively, two parallel copper wires were used in
some units during 195617.
BI- METAL
BRTGHT uNPLAreo (A)
A flat steel gauge of 0.015", 0.018" or 0.021" is used oR coPPER pr-rreo (B)
as follows: ffi
Voltage Regulators: \ ----- o.ors"\
A+c
rypE oF B1-METAL I a+c --- -.o.ors] [
Use a 0.015" gauge for units fitted with a 0.015" AND-5,EpARAT1qN I A+D ----. o o18' (
disc of copper* and a bi-metal spring of either / B+D-----o02r-,,
0.010" or 0.012" thickness.
Use a 0.018" gauge for units fitted with a 0.009"
square of copper and a bi-metal spring of 0.012" VOLTAGE REGUI-ATOR
thickness.

Use a 0.021" gauge for units fitted with a 0.009"

square of copper and a bi-metal spring of 0.010"
thickness.
Current Regulators:
Use a 0.015" gauge for units fitted with a 0.015"
disc of copper.*
TENS ION Use a 0.018" gauge for units fitted with a 0.009"
SPR ING square of copper.
Voltage and Current Regulator Mechanical Settings
Slacken the two armature assembly securing screws
so that the armature is loosely attached to the regulator
CURRENT MENT SCREY frame.
AND LOCKING NUT
Slacken the fixed contact locking nut and unscrew
ALTERNATIVE COPPER the fixed contact adjustment screw until it is well
SEPARATION ON clear of the armature moving contact.
BOBBIN CORE
Slacken the voltage (or current) adjustment screw
locking nut and unscrew the adjustment screw until

Drsc
@
SQUARE
it is well clear of the armature tension spring.
Using a flat steel gauge of appropriate thickness
(see above) and wide enough to cover the bobbin core,
insert the gauge between the underside of the armature
ARMATURE and the copper discx or square. Take care not to
GAUGE turn up or damage the edge of the disc* or square.
DISC
sllE I
o.ors" I --i _.--+
/ Press the armature down squarely against the gauge
o'or8" /--t-;=== and re-tighten the two armature assembly securing
SQUARE
'tffi frrE screws. With the gauge still in position, screw in the
il fixed contact adjustment screw until it touches the
armature moving contact. Re-tighten the locking nut.
CURRENT REGULATOR Carry out the electrical settings.

Page 34
CUT.OUT RELAY MECHANICAL SETTINGS
Slacken the two armature assembly securing screws
so that the armature is loosely attached to the cut-out
frame. Slacken the adjustment screw locking nut and
unscrew the adjustment screw until it is wel-l clear of ARMATURE
the armature tension spring. ASSEM BLY BACK STOP
SECU R I NG
Press the armature down squarely against the core SCREIYS
face (copper sprayed in earlier units or fitted with a
CONTACT BLADE
square of copper in later units), and re-tighten the two
FRAME
armature assembly securing screws. No gauge is
necessary.
CORE
Press the armature down against the core face and ARMATURE
adjust the armature back stop so that a 0.018" gap is TENSION
obtained between the tip of the back stop and the SPRI NG F IXED
contact blade. CONTACT
POST
Insert a 0.010" thick flat steel gauge between the ADJUST HEIGHT BY
underside of the armature and the copper separation. STRAIGHTENING OR
The gauge should be inserted from the side of the core AD.JUSTMENT SCREW
BOWING LEGS

nearest the fixed contact post. The leading edge of AND LOCKING NUT
the gauge should not be inserted beyond the centre CONTACTS
line of the core face. Press the armature down against JUST TOUCHING
the gauge and check the cut-out contacts. These U

should be just touching. o.ol8

If necessary, adjust the height of the fixed contact
by carefully straightening or bowing the legs of the
fixed contact post.
Carry out the electrical setting.
Note. The second setting air gap can be set at
.015" to-decrease the contact follow through. These
FI RST SECOND
SETTI NG SETT I NG
settings are nominal and may later require modifying
within the limits 0.010" 0.020' to obtain the correct
drop off voltage. -

SETTING THE CURRENT REGULATOR ON

THE BENCH
When setting the current regulator away from the
vehicle, a test generator and an artificial load is needed.
CLIP TO
CIRCUIT V
SHORI
R
The load circuit should comprise a 5l ampere-hour
battery, a 0 40 ammeter and rheostat capable of
- 45 amperes without overheating. The
carrying up to
connexions are shown in the illustration on the left.
The control box, it will be noted, is shown with its
AMM ETER terminals pointing vertically upwards. This is the
iA2 position in which electrical settings are made during
production and is the mounting position recommended
to vehicle manufacturers. However, since settings can
be affected by change of position, bench settings should
be made with the control box mounted as on the
Al indicates
vehicle. Adjust the rheostat until ammeter
a current slightly in excess of the maximum rated
output of the generator normally controlled by the
regulator. Run the test generator at approximately
4,500 rev./min. and adjust the current regulator until
the required setting is indicated by ammeter 42.
The permissible tolerances on current regulator
settings are * I ampere for generators of up to ?5
amperes maximum output and :E 1] amperes for
generators of up to 35 amperes maximum output.

Page 35
THE RB34O CONTROL UNIT _ GENERAL
DESCRIPTION
The model RB340 control box rvill eventually super-
sede the model R83l0. Whilst the electrical functions
of the RB340 are the same as the RB3l0 and 6GC,
the mechanical arrangement of its regulators, and cut-
out unit is different.
Also, the base which was previously a box type
pressing now consists of a simple flat plate to which the
resistors and Lucar connectors are riveted (see illus-
tration). The contacts, which on the RB310 and 6GC
are positioned above the bobbin-cores, are, on the
RB340, situated parallel to the rear limb of their magnet
frames. The cut-out, voltage and current regulator
tensioning springs are riveted to the upper limb of the
armature. Another notable feature of the assembly The main service feature is the simplicity of making
are the toothed adjustment cams carried on the front mechanical and electrical adjustments. Simple
limb of each frame. With the aid of a special tool armature-to-bobbin-core air gap settings are the only
electrical adjustments are made by turning the cams to mechanical adjustments to be made. The three
vary the spring tension acting on the associated armatures are riveted to the rear limb of U-shaped
armature, except for the cut-out drop-offvoltage, which magnet frames thus their back air gap is fixed and non-
is effected by bending the fixed contact bracket. adjustable.

TEMPERATU RE COMPENSATIO N
As in the case of the RB3l0 and 6GC, the voltage
regulator and the cut-out of the RB340 are temperature
TTMPTRATURE compensated, by means of bi-metal strips. But, in
C(}MPENSATlof'J addition, tlie RB340 has a double swamp resistor. con-
nected in series with the two shunt coils.
The resistor has a higher resistance than the two
shunt coils, and it is made of an alloy, which is not
affected by changes in temperature. Thus, for all
practical purposes, the resistance ofthe shunt windings,
and the resistor will remain constant, although there
are considerable changes in temperature.

RESISTORS
SWAMP RESISTOR CONTACTS RESISTOR
As in the RB3l0 and 6GC, the resistors are posi-
tioned beneath the base. Contacts resistors and swamp
resistors are fltted to all units but an additional resistor,
the field parallel resistor, is fitted to units controlling FIELD PARALLEI.
C48 generators. RESISTOR

Resistor Values (Wire wound) (wHEN FrrrED)

Contacts Resistor Identifl-
Resistance cation
in ohms colour
As fitted in units controlling
l2-volt generators having 4j
ohm field windings: 37-43 Yellow 'F' 'Wrl 'D' 'L'
As fitted in units controlling
l2-volt generators having 6
ohm field windings: 55-65 Red Note. Coloured paints used for indicating ohmrc
As fitted in units controlling values of- these resistors are applied to one end of the
generator model C48: 75-85 Violet fibreglass cores.

Page 36
 Identifi-
Resistance cation
in ohms colour
Sw'amp Resistor (12-volt units)
Measured on unit betrveen
centre tag and base: 13.25-14.25
R eplacement resistor measured
between end ta_es before fitting
to unit: 53-57
Field Paraliel Resistor
As fitted in units controlling
model C48 generators: 95-105 Orange
Slunt Winditzgs ot 20oC. (68',F.)
Voltage regulator ( l2-volt !.el!:
UNT|L rN 1962, THE Vn. I *. MAGNET F&MEs WEFE LTNXEO 6y A CONN€CIOn THpMH Warca
units): r0.8-12.0 EARLY
(ril rHE coNi€rs cuoseo eosrror)rre FrELD oRRrNr pAssEo. vr^ rHa c.o, r qn. saRras
Cut-out Relal (12-volt r.rnits): 8.8- r 0.5 ttNotNcst lo TERMTNAL'D:

SYSTEMATIC CHECKING
As the R8340 is electrically similar to the R83l0 We will assume that both the battery and generator
& 6GC the instruntents and preliminary checks given have been tested, and have been found satisflactory.
on page 3l also applr'. ['e now proceed to adjust the control box.

RB34O VOLTAGE REGULATOR

We
-comnrence at the voltage regulator. The
battery lead is disconnected front the "B" terminal.
and a voltn.reter is connected bettveen the "D" terminal
and Earth. (ll nrore than one lead is on "B" terrninal.
join thenr together). Then. the -qenerator speed is
gradually increased. At first, tl.re volta_ue rises rvith
increasing speed. Then. the needle flicks back, rises
again, and finall,r, remains steady, although the speed r$ff},
continues to increase. The voltage regulation must
alwavs take place uhen the generator voltage relnains
steady (or is stabilised). That is u,hy u,e normalll,
€l'"-.?"
specify the generator speed as 3,000 rev./min. (This
applies to most standard _qenerators).
Houever. C48 generators are steady at 1,500 rev./
min. and C42 generators are steady at 4,500 rev./min.
tr{
VOLTAGE REGULATOR SETTINGS
The niethod of setting the voltage regulator is the
Service Serr:ice
same as for the RB3l0 & 6GC. However, the actual
Open-Circuit Open-Cirait settings are different. The RB340 should be set within
Voltuge Voltage
the follorving limits.
Ambient Checking Setting
Temperature I-imits Lirttits The voltage is regulated by nieans of a special tool
which locates with the toothed cams (see fig. above).
10"c. (50'F.) 14.5 15.8 14.9 15.5 When the setting is made, the speed should be reduced
20oc. (68oF.) t4.4 - 15.6 14.1 - t5.3 to "idling", and therr gradually accelerated. The
30"c. (86"F.) 14.3 - 15.3 14.5 - 15.1 voltage should increase, until the voltage setting is
40oc. (104oF.) .. t4.2 - 15.1 14.3 - 14.9 reached, at the appropriate speed.
- - Note. For every l8oF. (10'C.) aboye 20oC.,
subtract- 0.2 volts from the lin-rits, conversely, the
See notes on hot setting of units on page 40. same corrections must be added for every 10"C. below
200c.

Page 37
CUT.OUT SETTINGS AND ADJUSTMENT
Again as in the RB3l0 and 6GC the cut-out should
be adjusted nert. for unless the cut-out points close
properly, it is impossible to adjust the current regulator.
The voltmeter can be left connected between the
"D" terrninal and earth as in the open circuit test, and
the ammeter inserted between the "8" terminal and
tire "B" leads (these should be joined together if more
than one is fitted as shown).
Switch on an electrical load, such as the headlamps
and slowly increase the generator speed from zero.
Observe the voltmeter pointer, it should rise steadily,
as engine speed is increased and then drop slightly at
the instant of the contacts closing. The cutting-in
\--
volta-qe should occur between the following limits. '*
\
Generator Cutting-in Drop-o.fJ
Voltage Voltage Voltage

l2 volts 13.3 volts 9.5-ll.0volts

approximately 3,000 rev./min. and then slowly deceler-
If tl,e cutting-in voltage does not occur within these ate and observe the voltmeter pointer.
limits, the setting is adjusted by turning the adjust- Opening of the contacts will be indicated by the
ment cam with the special tool. voltmeter pointer dropping to zero, and this slrould
When the tool is turned in a clockwise direction, the occur between the limits given in the table.
setting is raised. But, when it is turned anti-clockwise, If this setting is found to be outside the given limits
the setting is lowered. it can be adjusted by carefully bending the fixed
To check the drop-off voltage, disconnect the cable contact bracket, closing the contact gap will raise the
from the control box terminal "B" and connect the drop-off voltage and opening the gap will reduce the
voltmeter between this and earth. Run the engine up to drop-off voltage.

CURRENT REGULATOR: ADJ USTMENTS

While the current regulator is being adjusted. the
generator must develop its maximum rated output,
irrespective of the state of charge of the battery.
Hence, we make the voltage regulator inoperative, by
short-circuiting the contacts by means of the crocod.ile
clip as shown. Once again, the method of adjusting
the current regulator is precisely the same as for the
RB310 and 6GC.
The ammeter is still connected in the "B" lead.
(Joined together if more than one lead), and the lamp
load is switched on. Then, the generator is run at
charging speed. (This varies with the type of generator).
If a C48 is used, the generator speed should be 4,000
rev./min., but all other models should be driven at
4,500 rev./min.).

Page 38
CURRENT REGULATOR SETT!NGS
The current regulators should be set to the following Generalor Voltage Setting
values with the generator running at 4,500 rev./min.
(4,000 rev./min. for C48). volts amps.
C39PY.2 t2 19+ I
Unsteady readings are probably due to dirty c3sP-2 :: 12 l0+++
mechanical settings. C4OA 12 l02L+i
lf, however, the reading is steady, but is higher or C40-l (5" Fan) .. 12 22Ll
lower than the maximum rated output of the genera- C40-l (4j" Fan) 12 20+l
tor, the regulator setting must be altered, by turning C4OAL 12 10++i
the adjustment cam, with the special tool. C4OL 12 )s-L
When, for instance, the tool is turned in a clockwise c40LQ 12 ?{-!
direction, the setting is raised. On the other hand, C40T 12 18+
the setting is lowered, when the tool is turned anti- C4OT t2 )) -)-
clockwise. c42 t2 30* l1
c42 (EASTDRIVE) 12 35+t+
C45PV_5 t2 22+.1
C45PV_6 12 25+l
c4sPv-6 (EASTDRTVE) t2 30+ t+
C45PVS_6 t2 25+l
c47 t2 30+ l+
c48 t2 15-L I

or voltmeter.
MECHAN ICAL SETTI NGS: I NTRODUCTION In general, fluctuating readings are due to three
We have told you how the RB340 control box is factors:-
checked and regulated, while it is still in position on the (i) Oxidation of contacts.
vehicle. However, during the course of the tests, you (ii) Foreign matter in air-gaps.
may have obtained fluctuating readings on the ammeter (iii) Incorrect air-gap settings.

CLEANING THE CONTACTS wiped away by means of a fluffiess cloth, which has
We will first consider oxidised contacts. This is a been moistened with methylated spirits (de-natured
condition, which arises normally in service. Hence, all alcohol).
contacts should be cleaned periodically. Different The cut-out contacts are made of silver, and should
materials are required for cleaning the regulator and be cleaned with a piece of fine glass paper. All dust
cut-out contacts. The contacts for the voltage and should be removed with a cloth soaked in methylated
current regulators are made oftungsten, and so should spirits. On no account should carborundum stone or
be cleaned rn'ith fine carborundum stone or silicon emery paper be used for cleaning the cut-out contacts,
carbide paper. The dust and foreign matter should be or the silver contacts will be damaged.

CURRENT AND VOLTAGE REGULATORS: underneath the armature. Particular care must be
AIR-GAP SETTTNGS (EARLIER UNTTS) taken to avoid damaging the copper shim).
We will now consider how the air-gaps of the While the gauge is kept in position, you should
RB340 Current Voltage Control Box are set. press down the armature, and screw in the adjustable
Once again we must remind you that the air-gaps
contact, until it just touches the armature moving
and the fixed contact setting have been accurately set contact. The locking-nut is then retightened, and the
gauge is withdrawn.
during production. However, if the settings have been
disturbed in any way, they must be carefully reset.
Let us first describe the method for adjusting the
AIR GAP SETTING
regulator air-gaps. o 5'!O.O4g-
As we have already stated, the RB340 has toothed
adjustment cams, instead of the adjusting screws on
other control boxes. A special tool is, therefore,
needed, and the cams are turned as far as possible in
an anti-clockwise direction. (That is, to the point
giving minimum lift to the armature tensioning spring).
The adjustable contact is then screwed back, and a
gauge of .045" is inserted between the armature and
the copper separation on the core face. (The gauge
must be inserted, so that it reaches the two riyets CONTACT ADJUSTMENT

Page 39
REVISED AIR.GAP SETTINGS FOR LATER
UNITS
Later units manufactured since Decernber, 1963 do used to allou, for the space fonlerly occupied by
not have the copper separation in the top gap of the copper, the total gap measurement being unchanged.
voltage and current regulator. Therefore, when setting. To do this, the gauge thickness of 0.045" previously
the air-gaps of these units, a thicker -eauge must be given nTust be increased by .007" to 0.052".

CUT.OUT AIR.GAP SETTINGS

Finally, we will describe how to set tl,e air-gaps of MOVING CONTACT
the RB340 Cut-out.
The armature is pressed down on the copper
(rollow THROUGH
o oto"-o 035')
separation on the core face. Then, the fixed contact
bracket is set so that the "fo11ow-through" (or blade
---=K--
$.9-' JI
deflection) of the moving contact is within the lirnits
.010" .035", and the armature backstop is adjusted,
until -the air-gap betrveen the armature and core is
.035' .045". E
-
- ARMATURE-TO-BOBBIN CORE GAP
(o.oas'o.o45') Ir

HOT SETTING OF UNITS DURING

MANUFACTURE
During manulacture control boxes are heat-soaked
at 70oC. ( I 58'F.) before electrical settings of the
voltage regulators are made. Then, while at this
temperature, the voltage regulators are set to operate
at a comparatively low voltage (14. l+0.3 volts, for
12 volt units). This method, known as "l.rot-setting", (J

ensures tl-rat accurate and stable settings obtain at F

J
normal working temperatLrres. o
On cooling to 20oC. (68"F.) tl-re ten-rperature com- F
)u
pensation device causes units to regulate at higher
voltages and between slightly rvider lirnits (15.0j0.6 -
volts, for l2 volt units). Before units are despatched, SERVICE SETTING
z
"cold" checks are carried out at this lower temperature LIMITS
to see that open circuit voltage performances fall
between these wider linrits. lt follows, therefore, that B SERVICE CHECKING
.HOT.SET
these wider, "cold checkin-e", lirnits are the correct LiMITS FOR
figures to use when checking factory-set units in service. UNITS
Figures for service setting, l.torvever, must be to closer ro 20 30
limits to ensure that ad.iustments carried out at lower AMBIENT TEMPERATURE (..)
temperatures shall result in correct regulation at higher
temperatures. Voltage regulator setting limits shown graphically,
including checking limits of units set at
700c. ( I 580F.)

CONCLUSION an adjr.rstn.rent which is stable and permanent in its

Having obtained a pretty fair idea of the various subseqrrent working. For this reason only a lirrrited
forrns of generator control units and tlieir working it anlcunt ol work can be successfully executed in the
may be desirable to add a note ol caution. general garage. If the control unit, for example, will
The successful servicing of these in.rportant com- not respond to the adjustments outlined an exchange
ponents does not rest entirely upon an adjustment should be made and the original unit suhjected to
here arrd there. The success of any of the servicing bench examination in a properly equipped electrical
operations outlinecl depencls entirely on having nrade u orkshop.

Pa*ee 40