As electricity has been so successful in the street railway, where it
has superseded all other forms of motive power, it might naturally
be supposed that it would do equally well in the automobile; but
when the difference in the conditions is taken into consideration it
will be found that such a conclusion is not justified. In the street
railway systems the cars run continuously over the same route, and on
that account the electric current required to operate the motors can
be conveyed to them from a central power station by means of wires.
With the automobile the case is very different; the vehicle has no
fixed course, but is required to go everywhere, and the current must
be supplied from a source carried by it. If primary batteries could
be made so as to furnish electric currents at a low cost, then the
electric carriage would be in the same position as those operated by
steam or gasoline, and it could go wherever the proper chemicals to
renew the battery could be obtained. But as there are no such primary
batteries, the only way in which the current can be supplied is by the
use of storage batteries, and these cannot give out any more energy
than is put into them, and in practice cannot give quite as much. Thus
if the capacity of the battery is sufficient to run the vehicle forty
miles when this distance has been traversed the propelling power will
be exhausted, and the batteries will have to be recharged before the
carriage can go any further. If the recharging could be done in a few
minutes, the storage battery would be as good as a primary battery that
would generate electricity economically; but as it requires three or
more hours, the electrical vehicle cannot be used for long runs, unless
the user is willing to make long stops each time the battery has to
be recharged. Even then an electric vehicle could not go everywhere,
for it would be compelled to follow routes along which facilities
for recharging the batteries could be found. From this fact it can
be seen that the electric automobile carriage cannot cover the same
field as the steam or the gasoline (in the present state of electrical
development). Within the limits to which it is applicable, however, it
can perform its work in the most satisfactory manner, and, in fact,
no possible objection can be raised against it. Its operation is
noiseless and vibration of the vehicle is impossible. There is no heat
to inconvenience the passengers, no disagreeable smell, no escaping
steam. Any desired speed can be obtained, although, of course, a heavy
delivery wagon cannot be used also as a racer. The power can be made
sufficient to propel any desired load up any grade, including grades
far steeper than any to be encountered on streets or highways.
The only point in which the electric vehicle suffers in comparison
with the others is in the weight. The capacity of a storage battery is
proportional to its weight, and if it is made light, the power derived
from it will be small or the time during which it is furnished will
be short. To furnish one horse power for one hour requires about one
hundred pounds of battery, so that if the average consumption of energy
is at the rate of two horse power, one thousand pounds of battery will
keep the vehicle in motion for five hours. The weight of batteries used
in automobiles ranges from four or five hundred to about two thousand
pounds, and the distance traversed without recharging varies from
twenty-five to ninety miles, so that the radius of action of electric
vehicles can be said to vary from about twelve to forty-five miles from
the charging station.
[Illustration: FIG. 1. GENERAL ARRANGEMENT OF AN ELECTRIC CARRIAGE.]
The general arrangement of an electric carriage can be understood
from Fig. 1. The rectangle shown in broken lines at _A_ represents
the storage battery. The circle _B_ under the seat represents the
controlling switch. The motor is at _C_ and imparts motion to the axle
or wheels through the gearing contained in the casing _D_. When the
carriage is stopped the controller _B_ is turned into such a position
that all electrical connections between the battery and the motor _C_
are broken. To start the vehicle the controller _B_ is turned so as to
make the necessary electrical connections between the battery _A_ and
the motor _C_, and then the electric current passes from the battery
through the controlling switch to the motor, and thence back to the
controller and the battery. The heavy broken lines indicate the path
of the current and the arrows show the direction. The velocity of the
motor and the speed of the carriage are varied by varying the strength
of the current, and this is effected by the movement of the controlling
switch _B_. There are many ways in which the movement of this switch
can vary the strength of the current, but an explanation of any one
of them would be dry and rather technical; hence it is sufficient to
say that whatever the arrangement of the connections of the controller
with the other parts of the system, their relation is such that by the
movement of the switch handle the speed of the motor is changed from
zero to the maximum velocity.
[Illustration: FIG. 2. DOUBLE REDUCTION.]
[Illustration: FIG. 3. SINGLE REDUCTION.]
In the majority of American vehicles the motion of the motor is
transmitted to the wheels by means of spur gearing. In some cases a
single motor is used, in others two; and in one or two designs that
have come to public notice, four motors are employed, one for each
wheel of the carriage. Fig. 2 illustrates what is commonly called a
double reduction gear for single motor equipment. The outline _A_
represents the motor, _B_ being the shaft. Upon this shaft is mounted
a small pinion which meshes into a larger wheel on the intermediate
shaft _C_. This shaft carries a pinion which meshes into the wheel _D_
mounted upon the axle of the vehicle.
Fig. 3 illustrates a single reduction double motor equipment, the
motors being located at _AA_. In this arrangement the pinion on the
end of the motor shaft meshes directly into a large gear secured to
the carriage wheel, thus dispensing with the intermediate shaft _C_
of the previous figure. The single reduction gear is the more simple
in construction, but the motors run at a lower velocity, and on that
account must be larger for the same capacity. With the double motor
construction each wheel is driven independently and the axle _C_,
in Fig. 3, remains stationary, as in any ordinary vehicle; but in a
single motor equipment, arranged as in Fig. 2, the wheels are fastened
to the axle and the latter rotates. When a carriage runs round a short
curve the outer wheels will revolve faster than the inner ones, if
free to move independently, as in Fig. 3. If they are rigidly attached
to the axle, as in Fig. 2, one or the other will have to slide over
the ground, and this is decidedly objectionable with rubber tires. To
prevent this slipping of the wheels in rounding curves, the axles, in
designs following the construction of Fig. 2, are made in two parts,
and the gear _D_ is arranged so as to drive the two halves, imparting
to each one the proper velocity. Gear wheels of this kind are called
compensating gears; they are made in many designs, but the most common
form is that illustrated in Fig. 4. In this drawing _A_ is the gear _D_
of Fig. 2, and _BB_ are bevel gears which are mounted upon studs _C_,
which are virtually the spokes of wheel _AA_. Large bevel gears _E_ and
_F_ are placed on either side of _A_ _E_, being secured to _G_, which
is one-half of the axle, and _F_ and _H_, which is the other half. If
the carriage is running in a straight line, the two parts of the axle
_G_ and _H_ will revolve at the same velocity and the gears _BB_ will
not revolve around the studs _C_, but in rounding a curve one of the
halves of the axle will revolve faster than the other and then the
gears _B_ will rotate round the studs _C_. The compensating gear is not
a feature peculiar to electric vehicles; it is used on all kinds of
automobiles when the construction is such as to require it.
[Illustration: FIG. 4. COMPENSATING GEARS.]
[Illustration: FIG. 5. SINGLE MOTOR EQUIPMENTS.]
If a compensating gear is placed upon the axle the latter, instead of
supporting its end of the vehicle, will itself have to be supported,
for as it is cut in two at the center, it has no supporting strength.
By placing the compensating gear on another shaft this difficulty can
be overcome. Fig. 5 shows the construction used by the Columbia Company
in its single motor equipment. In this arrangement the motor casing is
made of sufficient length to reach from one side of the vehicle to the
other. The armature and field magnets of the motor, which are the parts
that develop the power, are located at _A_ and the compensating gear
is placed at _B_. The motor armature is mounted upon a hollow shaft,
which is connected with the compensating gear. The shafts _D_ and _C_,
upon which are mounted the pinions _E_ and _F_, are turned by the
side wheels of the compensating gear, and therefore will run at such
velocities as the motion of the carriage wheels may require.
[Illustration: FIG. 6. A COLUMBIA VICTORIA.]
[Illustration: FIG. 7. COLUMBIA VEHICLE WITH DOUBLE MOTOR EQUIPMENT.]
Fig. 6 shows a Columbia Victoria provided with a single motor equipment
arranged in accordance with the diagram, Fig. 5. Fig. 7 shows another
Columbia vehicle in which a double motor equipment is employed. The
position of the motor, with reference to the carriage wheel, in the
single motor design, is shown in Fig. 8. The gear attached to the
carriage wheel is used also as a brake wheel, a friction band being
located so as to bear against the periphery, while the pinion on the
end of the motor shaft meshes into teeth on the inner side of the
rim. This single motor design is also used in the omnibus made by the
Columbia Company, a number of which are now in regular service on Fifth
avenue, New York. These omnibuses, which are illustrated in Fig. 9,
seat eight passengers, and are able to carry as many as are willing
to crowd into them. One feature of the electric motor which fits it
admirably for automobile service is the fact that for a short time it
can put forth an effort far greater than its normal capacity, and it
can do this at all times, without any special preparation. Owing to
this feature it is practically impossible to stall the vehicle. If the
wheels run into a rut or sink into a mud hole, the motor will be able
to turn them around, and if they do not slip the carriage will be moved
ahead.
[Illustration: FIG. 8. POSITION OF MOTOR IN THE SINGLE MOTOR DESIGN.]
The management of the vehicle is exceedingly simple and entirely free
from care, the driver having nothing to tax his mind but the steering
lever and the handle of the controlling switch. As the moving parts
all have a rotatory motion and are perfectly balanced, there is no
possibility of vibration, and there is an entire absence of heat or
disagreeable odors.
[Illustration: FIG. 9. A COLUMBIA OMNIBUS.]
Any one who has observed the action of a two-horse team will have
noticed that, unless the pavement is very smooth, the tongue
continually swings from side to side, and occasionally with a
considerable amount of violence. It will be evident from this fact
that if the front axle of an automobile were the same as that of a
horse vehicle, the driver would have an unpleasant task, to say the
least, in holding the steering lever in position, and should one of
the wheels drop into a rut, the handle would be jerked violently out
of his hand and the vehicle would sheer off to one side, possibly
with serious results. To avoid this difficulty the front wheels of
horseless carriages are arranged so as to swing round on a center close
to the hub, if not actually within it. The most common construction
is illustrated in Fig. 10, the first being a view of the axle and
wheels as seen from the front, and the second a view from above. On
the left-hand side of Fig. 10, _A_ is the axle proper, and _BB_ are
the portions upon which the wheels are placed. The central part _A_ is
held rigidly to the body of the vehicle or to the truck which carries
it, and the ends _BB_ are swung round the studs _PP_ in a manner more
clearly indicated on the right-hand side. Here the levers _CC_ are
shown, and these extend from the side of _BB_. The right-angle lever
_E_ is connected with the steering lever _G_ by means of rod _F_,
hence, when _G_ is moved, rod _D_ moves, and thus levers _CC_ are
rotated round the studs _PP_, and in that way the supporting studs
_BB_ which carry the wheels are turned. As the studs _PP_ are not
exactly in line with the plane passing through the center of the rim of
the wheel, there is a slight tendency to jerk the steering handle round
when a wheel drops into a hole in the pavement, but the leverage of _B_
being very short, this tendency is so small as to be hardly noticeable.
[Illustration: FIG. 10. ARRANGEMENT OF AXLES AND WHEELS.]
[Illustration: FIG. 11. FRONT AXLE.]
[Illustration: FIG. 12. FRONT AXLE WHEELS.]
Fig. 10 illustrates the general principle upon which the front axle is
designed, but the construction of the swivel joints _P_ is far more
elaborate, as can be seen from Fig. 11, which illustrates the actual
design employed in the vehicles just described. Looking at Fig. 9,
it will be noticed that the front axle consists of two bars, one of
which runs in a straight line from side to side, while the other is
curved with the convex side upward. In Fig. 11 _B_ is the end of the
upper curved rod and _C_ is the lower straight one. These two rods
are secured into the casting _A_, which holds the part _D_ upon which
the wheel is carried, _D_ being the part _B_ at the left side of Fig.
10. The end _E_ which is broken off in the drawing extends through
the hub of the wheel and is provided with ball bearings so as to run
without friction. The upper end _F_, of _D_, is arranged so as to be
held by a ball bearing, as shown, against the end of _J_. By means of
an adjusting screw _I_ at the lower end, the parts are brought into
proper position with reference to each other. The shaded portion _H_ is
the lever _C_ at the right side of Fig. 10.
The left-hand end of Fig. 12 shows a design for front axle wheels
which is one of the many modifications of the general arrangement just
described. In this construction the wheel swings round the stud _C_,
which is placed within the hub, and in a line, or nearly so, with
the center of the rim. The rod _A_ is the axle and _F_ is the lever
extending from the inner part of the wheel hub by means of which the
steering is effected. The left-hand side of Fig. 12 is a view as seen
from the front and the right-hand side shows the device as seen from
above. In this last drawing it will be observed that as the lever _F_
is attached to the inner portion of the wheel hub, if it is moved to
one side or the other of axle _A_, by pulling or pushing on rod _G_,
the wheel will be swung round. The advantage of designs of this type
is that there is no strain whatever brought to bear upon the steering
handle, and the objection is that the wheel hub is made much larger and
the whole construction is somewhat more complicated.
[Illustration: FIG. 13. CONSTRUCTIONS SHOWING POWER APPLIED TO FRONT
WHEELS.]
The arrangement of the front axle, so as to swing the wheels round a
center close to the hub or within it, as described in the foregoing
paragraphs, is used on all types of automobiles and is not a
distinguishing feature of the electric carriage. In some of the lighter
vehicles the front wheels are held in forks of a design substantially
the same as that of the front wheel of the ordinary bicycle, the tops
of the forks being connected with each other by means of a rod, as in
the lower part of Fig. 10, so as to obtain simultaneous movement of the
two wheels by the movement of a single steering handle.
In the majority of electric vehicles the power is applied to the rear
axle, but some are made with the motors geared to the front axle. In
a few of these designs the wheels and axle are made the same as in an
ordinary carriage, so as to swing round a pivot or king bolt located
at the center of the axle and reinforced by a fifth wheel. When this
construction is used the steering gear is made so as to hold the axle
in position more firmly than in the other designs; but even with this
assistance the driver has a harder task than with the independently
swinging wheels. The advantage derived from swinging the whole axle
is that the carriage can be turned round in a very small space, and on
that account the construction is well adapted to cabs.
Several arrangements have been devised by means of which the power can
be applied to the front wheels, while these may at the same time swing
round independent centers. One of these constructions is illustrated
in Fig. 13, the first drawing presenting the appearance when seen from
above, the second being a view from the front. In the first diagram
the motor is shown at _A_, and by means of pinion _B_ and gear _C_,
motion is transmitted to the axle, which is shown more clearly in the
right-hand figure. On the ends of the axle are bevel gears _FF_, and
these mesh into other bevel gears which revolve round the vertical
studs _D_. Through this train of gearing the bevel wheels _E_ are
driven, and these are attached to the hubs of the carriage wheels. From
the first diagram of Fig. 13 it can be seen at once that the gears _EE_
can swing round _D_ in either direction without in any way interfering
with the transmission of motion from gears _FF_. The levers _HH_ are
secured to the sleeves _GG_ which swing round the studs _DD_, hence, by
connecting these with the rod _J_ and moving the latter to one side or
the other by means of the steering handle, the wheels are turned in any
direction desired.
[Illustration: FIG. 14. KRIEGER COUPÉ.]
While this construction renders the carriage as easy to steer as those
in which the motors are connected with the rear axle, it sacrifices
the advantage derived from applying the power to the front wheels,
namely, the ability to turn round in a small space.
Another design for driving the front wheels which allows them to swing
round independent pivots, is shown in Fig. 14, which is a coupé made
by Krieger in France. The power is supplied by two motors, one being
mounted on each swivel point. The construction can be understood by
considering that in the lower part of Fig. 13 the motor would be
secured to a suitable support at the end of the frame _L_, being held
in such a position that the shaft would replace pivot _D_ and a pinion
mounted thereon would gear into wheel _E_. What the advantage of this
construction may be, the writer is not able to point out; it certainly
shows, however, that there are many ways in which the object sought may
be accomplished.
[Illustration: FIG. 15. JENATZY DOG-PHAETON.]
American manufacturers of electric vehicles, at least the great
majority of them, resort to spur-gearing to transmit the motion of the
motor to the driving wheels, but with the French designers the chain
and sprocket appears to be in great favor. Fig. 15 shows a Jenatzy
vehicle (French), in which the chain is used. This construction would
not be received with favor by Americans, who as a rule desire to
have the mechanical part of the apparatus hidden from view as much
as possible. In the Jenatzy vehicle two chain gears are used, one on
each side of the body, and from the engineering point of view this
is the most desirable arrangement, as with it the driving wheels are
independently operated and a compensating gear need not be placed
upon the axle. The American designer, however, would in most cases be
controlled more by the artistic appearance and would use a single chain
which would be placed under the body of the carriage, and thus as much
out of sight as possible.
Fig. 16 shows an English design of electric dog cart. The mechanism
consists of a single motor which is connected with the axle by means of
spur gearing, this being so arranged that several different speeds can
be obtained for the vehicle with the same velocity for the motor. To
obtain variable speeds by means of gearing it is necessary to introduce
a considerable amount of complication, and in this country the opinion
of most designers appears to be that the gain effected thereby is
not sufficient to compensate for the increased complication, and
differential speed gearing is not often used.
[Illustration: FIG. 16. THE ELECTRIC MOTIVE POWER COMPANY’S DOG CART.]
A comparison of Figs. 14 and 16 with 6 and 9 will clearly show that in
so far as artistic effect is concerned, our manufacturers of electric
vehicles have little to learn from Europeans, although the industry
here is much younger than abroad. As to the operative merits, all that
can be said is that the American carriages run so well and possess such
endurance that it is probable that they are not second to any in these
respects.