THE DELCO ELECTRICAL SYSTEM--BUICK CARS
The motor generator which is located on the right side of the engine
is the principal part of the Delco System. This consists essentially
of a dynamo with two field windings, and two windings on the armature
with two commutators and corresponding sets of brushes, in order that
the machine may work both as a starting motor, and as a generator for
charging the battery and supplying the lights, horn and ignition. The
ignition apparatus is incorporated in the forward end of the motor
generator. This in no way affects the working of the generator, it
being mounted in this manner simply as a convenient and accessible
mounting. The motor generator has three distinct functions to perform
which are as follows:
1.--Motoring the generator.
2.--Cranking the engine.
3.--Generating electrical energy.
Motoring the generator is accomplished when the ignition button on the
switch is pulled out. This allows current to come from the storage
battery through the ammeter on the combination switch, causing it to
show a discharge. The first reading of the meter will be much more
than the reading after the armature is turning freely. The current
discharging through the ammeter during this operation is the current
required to slowly revolve the armature and what is used for the
ignition. The ignition current flows only when the contacts are closed,
it being an intermittent current. The maximum ignition current is
obtained when the circuit is first closed and the resistance unit
on the front end of the coil is cold. The current at this time is
approximately 6 amperes, but soon decreases to approximately 3¹⁄₂
amperes. Then as the engine is running it further decreases until at
1000 revolutions of the engine it is approximately 1 ampere.
[Illustration:
LEAD TO SWITCH.
TO SHUNT FIELD.
IGNITION COIL.
RESISTANCE UNIT.
TO THIRD BRUSH.
TO POS. BATTERY.
DIS. HEAD LOCATING TONGUE.
TO NO 1 TERMINAL.
TO NO 2 TERMINAL.
BRUSH OPERATING ROD.
OILER A.
TO STARTING PEDAL.
STARTING GEARS.
A
FIELD COIL.
OILER B.
DISTRIBUTOR
SHAFT GEAR.
FLY WHEEL.
PUMP SHAFT.
ARMATURE.
LUBRICATOR C.
GENERATOR
CLUTCH.
ROLLER BEARING.
BALL BEARING.
OIL DRAIN.
ONE WAY CLUTCH BUILT IN
THIS GEAR.
MOTOR COMMUTATOR.
GENERATOR COMMUTATOR.
Fig. 93. Delco Motor Generator--Showing Parts]
This motoring of the generator is necessary in order that the starting
gears may be brought into mesh, and should trouble be experienced
in meshing these gears, do not try to force them, simply allow the
starting pedal to come back giving the gears time to change their
relative positions.
A clicking sound will be heard during the motoring of the generator.
This is caused by the overrunning of the clutch in the forward end of
the generator which is shown in Fig. 93.
The purpose of the generator clutch is to allow the armature to revolve
at a higher speed than the pump shaft during the cranking operation
and permitting the pump shaft to drive the armature when the engine is
running on its own power. A spiral gear is cut on the outer face of
this clutch for driving the distributor. This portion of the clutch
is connected by an Oldham coupling to the pump shaft. Therefore its
relation to the pump shaft is always the same and does not throw the
ignition out of time during the cranking operation.
The cranking operation takes place when the starting pedal is fully
depressed. This causes the top motor brush to come in contact with the
motor commutator. As this brush arm lowers, it comes in contact with
the gear in the generator brush arm raising the generator brush from
its commutator. At the same time the current from the storage battery
flows through the heavy series field winding, motor brushes and motor
winding on the armature. The switching in this circuit is accomplished
by means of the top motor brush which is operated from the starting
pedal. (Shown in Fig. 94).
This cranking operation requires a heavy current from the storage
battery, and if the lights are on during the cranking operation, the
heavy discharge from the battery causes the voltage of the battery
to decrease enough to cause the lights to grow dim. This is noticed
especially when the battery is nearly discharged; it also will be more
apparent with a stiff motor or with a loose or poor connection in the
battery circuit. It is on account of this heavy discharge current that
the cranking should not be continued any longer than is necessary,
although a fully charged battery will crank the engine for several
minutes.
[Illustration:
_BRUSH OPERATING ROD_
_MOTOR BRUSH_
_GENERATOR BRUSH_
_GENERATOR
COMMUTATOR_
_MOTOR COMMUTATOR_
_THIRD BRUSH_
_PLATE SLOTTED TO PERMIT
THIRD BRUSH ADJUSTMENT_
Fig. 94. Delco Motor Generator--Diagram of Operation]
During the cranking operation the ammeter will show a discharge. This
is the current that is used both in the shunt field winding and the
ignition current; the ignition current, being an intermittent current
of comparatively low frequency, will cause the ammeter to vibrate
during the cranking operation. If the lights are on the meter will
show a heavier discharge.
The main cranking current is not conducted through the ammeter, as this
is a very heavy current and it would be impossible to conduct this
heavy current through the ammeter and still have an ammeter that is
sensitive enough to indicate accurately the charging current and the
current for lights and ignition.
As soon as the engine fires the starting pedal should be released
immediately, as the overrunning motor clutch is operating from the time
the engine fires until the starting gears are out of mesh. Since they
operate at a very high speed, if they are held in mesh for any length
of time, there is enough friction in this clutch to cause it to heat
and burn out the lubricant. There is no necessity for holding the gears
in mesh.
The motor clutch operates between the flywheel and the armature pinion
for the purpose of getting a suitable gear reduction between the motor
generator and the flywheel. It also prevents the armature from being
driven at an excessively high speed during the short time the gears are
meshed after the engine is running on its own power.
This clutch is lubricated by the grease cup A, shown in Fig. 93. This
forces grease through the hollow shaft to the inside of the clutch.
This cup should be given a turn or two every week.
When the cranking operation is finished the top brush is raised off
the commutator when the starting pedal is released. This throws the
starting motor out of action (Fig. 94). The top brush comes in contact
with the generator commutator, and the armature is driven by the
extension of the pump shaft.
At speeds above approximately 7 miles per hour the generator voltage
is higher than the voltage of the storage battery which causes
current to flow from the generator winding through the ammeter in the
charge direction to the storage battery. As the speed increases up to
approximately 20 miles per hour this charging current increases, but
at the higher speeds the charging current decreases.
=Lubrication.=--There are five places to lubricate the Delco System:
1. The grease clutch for lubricating the motor clutch.
2. Hole at B (Fig. 93) for supplying cup grease for lubricating the
generator clutch and forward armature bearing.
3. The oiler C in the rear end cover for lubricating the bearing on
the armature shaft. This should receive a few drops of oil once a
week.
4. The oil hole in the distributor at A (Fig. 93) for lubricating the
top bearing of the distributor shaft. This should receive oil once a
week
5. This is the inside of the distributor head. This should be
lubricated with a small amount of vaseline, carefully applied two or
three times during the first 2000 miles running of the car, after
which it will require no attention. This is to secure a burnished
track for the rotor brush on the distributor head. This grease should
be sparingly applied and the head wiped clean from dust and dirt.
The combination switch (Figs. 95 and 96) is for the purpose of
controlling the lights, ignition, and the circuit between the generator
and the storage battery. The button next to the ammeter controls both
the ignition and the circuit between the generator and the storage
battery, the latter circuit being shown in the heavier line as shown
on the circuit diagram (Fig. 98). The button next to this controls the
head lights. The next button controls the auxiliary lamps in the head
lights. The button on the left controls the cowl and tail lights.
The circuit breaker is mounted on the combination switch as shown in
Fig. 96. This is a protective device, which takes the place of a fuse
block and fuses. It prevents the discharging of the battery or damage
to the switch or wiring to the lamps, in the event of any of the wires
leading to these becoming grounded. As long as the lamps are using the
normal amount of current the circuit breaker is not affected. But in
the event of any of the wires becoming grounded an abnormally heavy
current is conducted through the circuit breaker, thus producing a
strong magnetism which attracts the pole piece and opens the contacts.
This cuts off the flow of current which allows the contacts to close
again and the operation is repeated, causing the circuit breaker to
pass an intermittent current and give forth a vibrating sound.
[Illustration: Fig. 95. Delco Ignition Switch Plate]
[Illustration:
Circuit Breaker
Numbers of Lower Terminals
Fig. 96. Delco Ignition Switch Circuit Breaker--Mounted]
It requires 25 amperes to start the circuit breaker vibrating, but
once vibrating a current of three to five amperes will cause it to
continue to operate.
In case the circuit breaker vibrates repeatedly, do not attempt to
increase the tension of the spring, as the vibration is an indication
of a ground in the system. Remove the ground and the vibration will
stop.
The ammeter on the right side of the combination switch is to indicate
the current that is going to or coming from the storage battery with
the exception of the cranking current. When the engine is not running
and current is being used for lights, the ammeter shows the amount of
current being used and the ammeter hand points to the discharge side,
as the current is being discharged from the battery.
When the engine is running above generating speeds and no current is
being used for lights or horn, the ammeter will show charge. This
is the amount of current that is being charged into the battery. If
current is being used for lights, ignition and horn, in excess of the
amount that is being generated, the ammeter will show a discharge as
the excess current must be discharged from the battery, but at all
ordinary speeds the ammeter will read charge.
The ignition coil is mounted on top of the motor generator as shown
in Fig. 94 and is what is generally known as the ignition transformer
coil. In addition to being a plain transformer coil it has incorporated
in it a condenser (which is necessary for all high tension ignition
systems) and has included on the front end an ignition resistance unit.
The coil proper consists of a round core of a number of small iron
wires. Wound around this and insulated from it is the primary winding.
The circuit and arrangement of the different parts are shown in Fig.
97. The primary current is supplied through the combination switch
through the primary winding and resistance through the coil, to the
distributor contacts. This is very plainly shown in Fig. 98. It is the
interrupting of this primary current by the timer contacts together
with the action of the condenser which causes a rapid demagnetization
of the iron core of the coil that induces the high tension current
in the secondary winding. This secondary winding consists of several
thousand turns of very fine copper wire, the different layers of which
are well insulated from each other and from the primary winding. One
end of the secondary winding is grounded and the other end terminates
at the high tension terminal about midway on top of the coil. It is
from this terminal that the high tension current is conducted to the
distributor where it is distributed to the proper cylinders by the
rotor shown in Fig. 98.
[Illustration:
Connects
To Switch
High Tension Wire
To Center Of Distributor
Connects To
Distributor
Primary
Winding
Resistance
Unit
Secondary
Winding
Iron Core
Condenser
Coil Bracket Must Be Grounded
Fig. 97. Delco Ignition Coil]
The distributor and timer, together with the ignition coil, spark
plugs, and wiring, constitute the ignition system.
The proper ignition of an internal combustion engine consists of
igniting the mixture in each cylinder at such a time that it will be
completely burned at the time the piston reaches dead center on the
compression stroke. A definite period of time is required from the time
the spark occurs at the spark plug until the mixture is completely
expanded. It is therefore apparent, that, as the speed of the engine
increases, the time the spark occurs must be advanced with respect to
the crank shaft, and it is for this reason that the Delco ignition
systems are fitted with an automatic spark control.
[Illustration:
CIRCUIT BREAKER
AMMETER
COWL LIGHT
RESISTANCE UNIT
SWITCH
BRUSH SWITCHES
OPERATED BY
STARTING PEDAL
CONDENSER
IGNITION COIL
TONNEAU
LIGHT
HEAD
LIGHTS
SERIES FIELD
ROTOR FOR DISTRIBUTING
HIGH TENSION CURRENT
MOTOR
GENERATOR
TAIL LIGHT
STORAGE
BATTERY
SHUNT
FIELD
TO SPARK PLUGS
DISTRIBUTOR
ADVANCE
TUNGSTEN
TIMING
CONTACTS
AUX
LIGHT
HORN BUTTON
IN WHEEL
Fig. 98. Delco Wiring Diagram--Buick Cars]
The quality of the mixture and the amount of compression are also
factors in the time required for the burning to be complete. Thus a
rich mixture burns quicker than a lean one. For this reason the engine
will stand more advance with a half open throttle than with a wide open
throttle, and in order to secure the proper timing of the ignition due
to these variations and to retard the spark for starting, idling and
carburetor adjusting, the Delco distributor also has a manual control.
[Illustration:
Rotor Button
Rotor
Breaker Cam
Timing Adjustment
Automatic Weights
Advance Lever
Fig. 99. Delco Ignition Distributor]
The automatic feature of this distributor is shown in Figs. 99 and
100. With the spark lever set at the running position on the steering
wheel (which is nearly all the way down on the quadrant), the automatic
feature gives the proper spark for all speeds excepting a wide open
throttle at low speeds, at which time the spark lever should be
slightly retarded. When the ignition is too far advanced it causes loss
of power and a knocking sound within the engine. With too late a spark
there is a loss of power which is usually not noticed except by an
experienced driver or one very familiar with the car and heating of the
engine and excessive consumption of fuel is the result.
The timer contacts shown at D and C (Fig. 100) are two of the most
important points of an automobile. Very little attention will keep
these in perfect condition. These are tungsten metal, which is
extremely hard and requires a very high temperature to melt. Under
normal conditions they wear or burn very slightly and will very seldom
require attention; but in the event of abnormal voltage, such as would
be obtained by running with the battery removed, or with the ignition
resistance unit shorted out, or with a defective condenser, these
contacts burn very rapidly and in a short time will cause serious
ignition trouble. _The car should never be operated with the battery
removed._
[Illustration:
3 AUTOMATIC
WEIGHTS
DISTRIBUTOR
CONTACT BREAKER
CAM
Fig. 100. Delco Ignition Contact Breaker and Timer]
It is a very easy matter to check the resistance unit by observing
its heating when the ignition button is out and the contacts in the
distributor are closed. If it is shorted out it will not heat up, and
will cause missing at low speeds.
A defective condenser such as will cause contact trouble will cause
serious missing of the ignition. Therefore, any of these troubles are
comparatively easy to locate and should be immediately remedied.
These contacts should be so adjusted that when the fiber block B is
on top of one of the lobes of the cam, the contacts are opened the
thickness of the gauge on the distributor wrench. Adjust contacts
by turning contact screw C, and lock nut N. The contacts should be
dressed with fine emery cloth so that they meet squarely across the
entire face.
The rotor distributes the high tension current from the center of the
distributor to the proper cylinder. Care must be taken to see that the
distributor head is properly located, otherwise the rotor brush will
not be in contact with the terminal at the time the spark occurs.
The distributor head and rotor should be lubricated as described under
the heading “Lubrication.” The amount of ignition current required
for different speeds is described under the heading “Motoring the
Generator.”