Improvements in or relating to Electric Traction.
Year: 1896

page_text: Date of Application, 15th May, 1906
4007
10th
Ana 1007
Complete Specification Left, 15th Feb., 1807 Accepted. 10th Apr., 1807
PROVISIONAL SPECIFICATION.
Improvements in or relating to Electric Traction.
We, JOHN PERRY, of 31, Brunswick Square, in the City of London, Professor
of Engineering, and THOMAS TOMLINSON, of Mayford Villa, Gartmoor Gardens,
Wimbledon Park, in the County of Surrey, Electrical Engineer, do hereby declare
the nature of this invention to be as follows:-
This invention relates to an improved system of electric traction and in
particular to a system wherein the power is collected from the main by means of
magnetic induction, a mass of iron carried upon the car hereinafter called the
"car iron" being magnetized inductively by a trough of iron laid in the track
hereinafter called the "track iron." Such a system is described in the Specifica-
tion of British Letters Patent Number 12241 of 1894 granted to us.
Our present improvements consist in various details by means of which the
system is rendered more practicable than was formerly the case.
According to our invention we construct an improved track iron of sheets
arranged vertically in the ground said sheets being kept apart at suitable distances
either by means of non-magnetic washers of the required thickness, or by pro-
jections raised upon the surfaces of the plates such as corrugations produced by
pressing the sheets between suitable dies. The sheets are held together in suitable
lengths by end plates and connecting rods or tubes and the interstices are filled in
with a material (such as asphalte, which will form with the edges of the plates a
good road surface. The lengths so formed are joined together to form a continuous
or nearly continuous trough.
To provide for a due supply of energy upon curves of small radius we may
support the car upon bogie trucks or radial axles and form the car iron in sections
which by the action of the bogies or radial axles are compelled to follow the curve
as a series of tangents, at the same time the road surfaces of the track iron are
slightly broadened so that the polar surface covered by the car iron is sufficient to
supply the proper amount of energy to the car.
In another arrangement we construct the car iron in one unbroken length and
arrange to take energy upon curves from that part of the car iron which does
follow the curves; we ensure by increasing the iron or the current or both in the
track iron at the point that the energy from this reduced length shall be sufficient
for the purpose of driving the car.
In order to maintain the polar faces of the car iron at a constant distance from
the track iron we suspend the two portions of the car iron forming the poles
from the car axle the part called the yoke magnetically connecting these two
portions is however preferably supported from the car by springs or pneumatic or
other suitable cushions.
We provide for varying the power delivered to the car at different parts of the
line where necessary by altering the section of the track iron or by varying the
current in the section or by other suitable means.
We may use for the propulsion of our cars synchronous motors or dynainos
suitably excited used as motors, in which case we arrange so that both parts shall
revolve and we gear the two parts separately to one or more axles of the car
preferably at different rates. We provide for connecting these two gears to the

page_text: axle or axles by means of clutch couplings such that the one being driven slower
than the shaft slips round on it without action (as a ratchet would) and we would
arrange means for braking either part at will so that the other alone drives.
Under these conditions if both parts of the motor are permitted to rotate the car
axle is driven by both parts together at a low speed; if either part of the motor
is braked the axle is driven by the other part of the motor which is not braked.
Intermediate speeds are obtained by suitably manipulating the brakes.
Our improved gear is not only suitable for use with synchronous motors but may
be applied to other motors in order to obtain a large torque at starting.
In order to be able to utilise the flywheel effect of a rotating part moving at a
high rate of speed to help in starting the car and at the same time to convey this
to the axle without shock, we use a spring which is deformed when the rotating
part is clutched to the axle before the car starts and so exercises upon the axle a
gradually increasing torque. The usual spring carrying the free end of the motor
may be utilised for this purpose.
For economy it is necessary to divide up the line into sections, and one arrange-
ment we adopt with lines of moderate length as follows;-We place underneath
the track iron a series of lengths of insulated conductor and these we connect each
at one end to the conductor lying in the trough of the track iron, and at the other
end of each section a switch is provided which when closed connects that end also
to the main conductor. When the switch is open the current passes in the upper
conductor only and the section is active, when the switch is closed the current
flows in both conductors in the same direction the section is thereby rendered
inactive and the iron losses are reduced to a minimum.
For long distances we prefer to use another system in which we connect the
main conductor lying in the trough of the various sections to the secondary
terminals of feed transformers. The primaries of these feed transformers are
placed in series and are made inactive by shortcircuiting their terminals by means
of suitable switches being made active by opening these switches.
When very
high voltages are employed we prefer not to make and break the current as
hereinbefore described and we therefore construct the iron portion of the feed
transformer in such a manner that its magnetic circuit may be completed in two
ways. in one way both the outgoing and return wires of the primary coil lie
inside the iron ring and the primary is then a coil of very small induction, in the
other way the outgoing and return wires of the primary coil lie on opposite sides
of the iron circuit and the coil acts as the primary of a transformer of which the
coil supplying the section is the secondary. The switching may be said in fact to
be magnetic instead of electric.
We sometimes use a combination of both systems the sections fed by the feed
transformers on the second system being subdivided as hereinabove described on
the first system.
For automatically operating the necessary switches or for signalling the position
of the cars to a station from which the requisite switches are operated we either
wind a coil upon the track iron or take a derived circuit from two points upon the
main conductor, in either case the fact of the car iron of the car coming above
the track iron is immediately manifested by an increased current being caused to
flow in the coil or derived circuit, which circuit may be utilised either to actually
operate the required switch or to signal that it should be operated.
Dated thin 15th dor of Mar 1906
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicants.

page_text: Improvements in or relating to Electric Traction.
We, JOHN PERRY, of 31, Brunswick Square, in the City of London, Professor
of Engineering, and THOMAS TOMLINSON, of Mayford Villa, Gartmoor Gardens,
Wimbledon Park, in the County of Surrey, Electrical Engineer, do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
This invention relates to an improved system of electric traction and in particular
to a system wherein the power is collected from the main by means of magnetic
induction, a mass of iron carried upon the car hereinafter called the "car iron
being magnetized inductively by a trough of iron laid in the track hereinafter
called the "track iron." Such a system is described in the Specification of British
Letters Patent Number 12241 of 1894 granted to us.
The objects of our present invention are to improve various constructional details
by means of which the system is rendered more practicable than was formerly the
case, to provide means for regulating the supply of energy to a car, and to provide
means whereby a long line can be operated with a number of cars without danger
of collision occurring between the cars. A further object of our invention is to
provide improved means for gearing the motor to the car axle and suspending the
same from the car whereby the speed of the car may be varied very considerably
and a large torque obtained at starting.
In order that our invention may be clearly understood we will now proceed to
describe the same with reference to the accompanying drawings in which
Figure 1 is a plan of a portion of a track shewing our improved construction of
track iron and
Figure 2 is an elevation of a single plate for use in such a track iron.
Figure 3 is an elevation and
Figure 4 is a plan shewing the manner in which we suspend the car iron from the
car when we use bogie trucks.
Figure 5 is a transverse section illustrating an improved construction of car iron.
Figure 6 is a diagram illustrating our improved method of controlling a number
of cars upon a double track.
Figure 7 is a similar diagram hereinafter referred to.
Figure 8 is an elevation and
Figure 9 is a plan shewing our improved gearing for car motors and the method
of suspending such motors from the framework of the car.
Referring now to Figure 1 the track iron is composed of sheets A placed
vertically in the ground and perpendicular to the rails. These sheets are maintained
at the required distance apart either by non-magnetic washers A' or by projections
or corrugations formed upon the surface of the plates.
Figure 2 illustrates one form of a corrugated plate in which the corrugations are
arranged diagonally, so, that when the trough is being laid alternate plates may be
reversed and the corrugations thereby prevented from coinciding with each other.
Other forms of corrugations may be employed.
For convenience the track iron is made in sections each section consisting of a
number of plates strung upon connecting rods or tubes. The lengths of the
separate sections are as long as possible and said sections are joined together by
connecting pieces A' of substantially the same form as the plate, through these
connecting pieces the rods or tubes pass, being bolted thereto as shewn at A³,
Figure 1. Either before or after laying, the interstices between the plates are filled
in with Portland cement grouting, artificial stone composition, asphalte, or other

page_text: material so as to preserve the plates and also with the sheets form a wear resisting
surface at the polar face.
The variation in power required at various points of the line may be met by an
increase or decrease in the amount of iron used (by increasing or decreasing the
number or depth of the sections); by an increase or decrease of the current passing
through the conductor or conductors of the track iron; or by any suitable
combination of the two.
For rounding curves the tubes or rods are bent as required by the carve, washers
or projections of suitable thickness being used upon the outside and inside of the
curve so as to keep the plates radial, or short lengths of straight troughing may be
joined so as to follow the curve.
In addition to this round curves we increase the breadth of the polar faces of the
track iron on the convex side so that the car iron pole faces do not at any point pass
beyond it, or we increase the iron, or the current, or both so that the extra electric
energy which can be taken from the reduced length of track iron coverel by the
car-iron may compensate for the loss incurred where the car iron does not cover the
track iron.
The car iron also requires special arrangements for rounding curves, especially
those of sharp radius or where the breadth of the polar faces of the track iron is
small (a in street railways). For this purpose we preferably use double bogie
trucks i illustrated for example in Figure 4 where a, b, c, d and a, b, c, d, are
frames pended from the axles of the bogies. The car iron is divided into
lengths B C D E carried upon the cross bars efghi and e¹ƒ¹g¹¹¹ of the
frames.
The lengths B and D are rigidly attached to the frame but the lengths A C
and E are capable of certain independent movements in a horizontal direction.
A bar fixed to the back of the length C is pivoted to the frame a bed at F¹ and
slotted longitudinally at F where the pin F passes through.
When the bogies come upon a curve the bar F slides upon the pin F³ and the
parts B CD follow the curve.
The parts A and E are pivoted to the frame at A' E' and are free to slide upon
the cross bars e and e' near their outer end.
The horizontal movement of these parts is provided for by producing the bar F
backwards and forwards to the points F F and carrying the bars G and H
(attached to the parts E and A) heyond the pivots of the truck to the points A²
and E. The pairs of bars are slotted longitudinally where they cross between F
and A, and F and E and in these slots are pins A³ E' carried by a plate sliding
upon bars transversely to the line of rails.
The movement of the ends F and F of the bar F caused by the bar running
upon a curve moves also the bars G and H and turns the sections E and I to the
required direction. The sections of car iron are wound independently and connected
as desired. Instead of bogie trucks we may use radial axle trucks the arrangement
of car iron being similar to that hereinabove described except that the central
length does not alter.
It will be seen that the brushes or polar faces of the car iron then assume at
curves the form of a series of short tangents to circles having the same centre as
the curve of the rails the deviation of these tangents necessitating the increased
breadth of polar faces or if this is not done the provision for the supply of electric
energy per foot of the line above that which would be required if the whole length
of the track iron under the car iron were covered as on the straight portion of the
line. We may also use the ordinary fourwheel carriages and have the car iron in
one length, making the track iron at curves such that it gives sufficient energy to
the part covered by the car irou and cutting out of action the wiring upon that
part of the car iron which does not cover the track iron.
In order to keep the polar faces of the car iron at a constant distance fro:n or
actually brushing these of the track iron, it is necessary that the poles of the car
iron-usually formed of iron wire-should be attached to the car axles without

page_text: springs at the same time where large amounts of power are required to be taken
from the line per foot of length covered by the car iron or where for any reason a
large weight of iron must be carried per foot of car iron, it is desirable and may
be necessary to carry as much of the weight of the car iron as possible upon springs.
With this object we may employ the arrangement shewn in Figure 5 which is a
transverse section. The polar extension or brushes G G of the car iron are rigidly
supported on the frame and the yoke G which connects the same is supported on
cushiens GG. These cushions may be either pneumatic, metallic spring or other
cushions as desired. Contact between the yoke and brushes admitting of the
requisite small vertical motion may be ensured by forming the yoke G' of vertical
sheets, provided with distance pieces and free to slide hetween wires or sheets.
forming the poles G, G.
In an induction system of traction such as this specification refers to, the presence
of a car or train on the track causes a larger difference of potentials to exist
between any two points in the couductor carrying current and lying in the trough
iron than there would be if the car or train was not there. This is owing to the
fact that the car iron when present increases the conductivity of the magnetic circuit
formed by the track iron.
This increase of potential difference may be utilized either to automatically
operate the switches controlling the supply of current in the neighbouring sections
of the track or to give warning to a signalman who will manually operate said
switches. In Figure 6 a diagram is shewn of a double track in which
H, H represent the rails and I the track iron of one track and H, H', the rails
and the track iron of the other track. The main conductor JJ J is laid
in loops in the track iron of both tracks being supplied with current from the
secondaries K, K, K² of transformers the primaries kkk of which are in a feed
circuit j.
On the track iron are wound independent coils L, M, L, M, L M which are
connected to magnetic devices operating the switches on the primaries of the
respective transformers as shewn. Considering now the sections marked 1 and 2,
when a car running on the track in the direction of the arrow passes over the track
iron at the place where coil L is wound the coil develops an increased electro-
motive force and energizes the magnet which operates switch 1, whereby the
primary is opened and main conductor J is energized in the section 1 which the
car is approaching. When the coil passes over coil M' a short distance along
the section 1 a current due to the increased electromotive force is developed in this
coil, and thereby energizes an electromagnet which operates the switch to short
circuit the primary coil K in the section in rear of section 1, so that said section
will not be energized. When as in the case shewn the same transformer serves the
up and down line of a section the switch for example if operated automatically
must be kept from closing by the action of coil M' when a car reaches them, while
there is still a car upon the other line of the same section; this is accomplished by
holding the switch open by a catch held back by a spring, which, however, cannot
draw it clear till it overcomes the pull of an electromagnet whose coil is a shunt
between the low tension terminals of the section transformer; the tensions of the
spring, and strength of the electromagnet being such that this does not occur till
the voltage between said terminals is that necessary to supply a section on which
there is no car. The switches etc. can be placed across the terminals of the
secondaries K Kete. instead of as shewn with equally good results.
Instead of using the electromagnets energized by coils L, M etc., to operato
switches on the primaries of transformers in series we find it advisable when high
voltages are used on the line to employ the electromagnets to alter the magnetic
circuit of the transformer by pushing in or out a portion of the iron core of the
same, we thereby avoid the sparking which would occur at the contacts of a
switch.
If the feed transformers have their primaries joined in parallel to the feeders we
use choking or impedance coils with movable cores in the primary circuit and

page_text: cause the electromagnets governed by the coils L, M etc. to move the coils of such
choking coils in or out.
Figure 7 shews diagrammatically the manner of using the increased E.M.F. to
indicate only; the actual switching being done from a centre and not necessarily
automatically.
The terminals X Y of the low tension side of the section transformer are
connected to the terminals of a coil Z wound up in the electromagnet which
controls the section switch leading from the terminals of another coil wound upon
the same electromagnet are conductors going to the switch station, bridging these
conductors is a volt-indicator V (which may be a static instrument) placed on the
switch station, also bridging them is a secondary battery or other source of
electricity (preferably direct current) with a switch C.
The electromagnet with its double coils acts as a transformer so far as registering
the electromotive force between terminals X and Y is concerned the changes in
which are shewn on the volt-indicator V.
We might of course bring the conductor direct from X and Y, one conductor
passing round the electromagnet; but we prefer not.
To operate this switch L we close momentarily the switch C and energize the
electromagnet controlling L by direct current sent along the volt indicator wires.
The switch L may be of any type capable of being operated from a distance
along a single pair of wires as in the direct current transformer system of electric
lighting or the electromagnet may be used as keeper of a fixed steel magnet when
a change in the direction of the current sent along the conductors will give the
attraction and repulsion necessary to open and close the switch.
As the currents operating the switches are only required momentarily very small
wires will carry very large currents, and so ample power to move the switches will
be available.
We can in the second case as in the first by increasing the number of points
from which indications are conveyed, and by suitably selecting the points, obtain
at the switch station indications of the exact instant at which each switch should
be operated or we can operate the switches automatically.
We may also subdivide the line after another manner as follows, that is to say,
we lay under the track iron lengths of the insulated conductor each joined at one
end to the main conductor lying in the trough of the track iron and capable of
being connected to it at the other end by means of a switch suitably operated.
When the switch is closed current passes above and below the track iron in the
same direction so that the section is dead and a car thereon is not energised, the
iron losses also become very small. When the switch is open the section is alive
and a car thereon will be energized. This method of dividing the line may be
adopted in addition to the method of division by cutting out feed transformers in
the manner hereinabove described.
Referring now to Figures 8 and 9 the method of gearing the motor to the car
axle and suspending the same from the car therein illustrated is designed for use
with single phase alternating current motors without commutators or with suitably
excited dynamos used as motors in which case special provision must be made for
starting the car and for varying the speed of the same when running on account of
the low torque of such motors at starting, and their constant or nearly constant
speed. Similar arrangements can however be used with ordinary motors.
According to our invention we arrange that both parts of the inotor shall revolve
and we gear the two parts separately to a car axle preferably at different rates.
In the drawing the two parts of the motor one of which may be considered the
field niagnet, and the other the armature, are indicated at N and N. The part N
is secured on the spindle n' which is provided with the worm O. The part N is
secured to a sleeve n loosely mounted on the spindle n' which sleeve carries a
gear wheel n³ which engages with a second gear wheel n' mounted on a spindle n
carrying the worm P. "The spindles a' n are journalled in suitable bearings or

page_text: the frame N', the sleeve n' being also arranged to run in bearings concentric with
the spindle n'. The worms O and P engage respectively with the worm wheels O
and P which worm wheels are connected to the car axle Q through friction
clutches P P for going in one direction, and 0 0 lor going in the other direction.
The worm wheels O' and P' are also provided with suitable brake surfaces. The
clutches are so constructed as to pussess the property that even when in gear
they run loose when the shaft to which they are clutched is rotated faster than the
clutch, that is to say, the faster of the two gear wheels O' and P will alone drive
the axle the other wheel being practically inoperative, its clutch behaving as if it
were a ratchet. It is for this reason that we provide two pairs of clutches so that
the shaft can be rotated at will in either direction. The frame N2 above mentioned
is pivoted upon the axle Q by arms Q Q at one end, the other end being
suspended from the frame by springs R which partly absorb the vibrations of the
motor due to the unevenness of the track but which also serve for another purpose,
hereinafter indicated. The clutches are controlled by forks p p p carried by a
bar p sliding on a cross benm p' secured to the frame. Said bar is moved to
and fro upon its support by a rack and pinion as indicated at p or by other suitable
means driven from a shaft p, suitable mechanism for rotating the shaft from the
car platform being provided. At suitable places in the shaft joints are provided in
order that the shaft may bend when the car is going round curves, and in addition
when bogie trucks are used the shaft is arranged to be capable of extension by
means of suitable sliding joints. The brakes for braking the gears O and P' may
be band brakes operated by the chains or wires O and P. Any suitable form of
brake may, however be provided.
The operation of our improved device is as follows:-If S be taken as the
combined speed of the two parts N and N of the motor, and S₁ be the speed of the
shaft m', and S2 be the speed of the shaft n' and the ratio of the number of
teeth in wheel a to the number of teeth in wheel n be T, and the gearing
between the worms O and P and their respective wheels be T, then S+ T S'-S
and so long as this relation is fulfilled we can, firstly, brake the spur wheel P¹ and
thereby drive the axle from the worm O at the speed equal to S/T or, secondly,
brake spur wheel O' and drive the axle through the gears n n and worm P at a
speed of S/T T or, thirdly, allow both spur wheels to revolve, thereby driving the.
axle at the speed of S/T T + 1. Intermediate speeds may be obtained by suitably
manipulating the brakes so as to allow rotation of one of the parts N or N' while
the other part is driving the axle. For example, by allowing the spur wheel O' to
slip past the brake, the part O' will rotate at a certain low speed by which means
the actual speed of the part N will be reduced, and since the axle is driven from
the spur wheel P' it will run at a lower speed than if the spur wheel O' were
braked dead.
As an instance of the range of speeds to be obtained without permitting any
slipping at the clutches let us assume that S = 1500, T = 3, T₁ = 15, then the
speeds of the axle which can be obtained will be 100, 33, or 25, while if T be 1
the speeds are 100 100 and 50 while if T be 2 the speeds will be 100, 50
and 33. The benefit of the gearing is mainly at starting for it will be seen
that if the clutches P or P be put in when the part N is running above and the
part N below the speed at which the two parts will together drive the axle, and if
then the clutches O2 and O³ be now put in then as the speed of N lessens that of N¹
increases the change of momentum involved in producing a very great effort just
when it is required for starting the car.
We will now describe the operation of our improved device for gradually
increasing the torque upon the car axle at starting so as to start the car without
shock. We have hereinabove mentioned that the frame N' in which the shafts n' n
are mounted is pivoted by arms Q Q on the car axle Q at one end the other end
of said arm being supported by springs R. If when the car is at rest the motor
circuit is closed and the clutches which connect the worm wheels P O are put in

page_text: gear, one or both of said worm wheels being unbraked, it will be clear that as the
worms OP rotate while the worm wheels O¹ P¹ owing to the inertia of the car are
prevented from rotating the frame N' will, by the action of the worm or worms
upon the wheels, rotate in one or other direction round the axle Q thereby
deforming the spring or springs R. The stress in the spring or springs R will
gradually increase until the torque exerted thereby on the car axle causes said
axle to rotate, and thus move the car forward or backward. It will be observed
however, that the movement of the car will take place very gradually inasmuch as
the stress in the springs is increased gradually until it becomes so great as to
overcome the opposing force and directly this happens the car begins to move.
Since, however, the difference in the forces is very small the car starts very
slowly and without jerk. When starting it will of course be advisable to operate
the clutches and brakes in such a manner that the greatest reduction in speed
occurs between the moving part of the motor and the car axle.
Although we have hereinabove described and illustrated a particular form of
our improved gear we wish it understood that we do not restrict ourselves to
the details described, for example, we may arrange the motor axle parallel to the
car axle with one part of the motor geared to the axle by the usual single
reduction gear, the other part being geared through a double reduction gear.
The application of our improved gear is not confined to synchronous motors but
may be used with advantage with electric motors of any ordinary description.
Furthermore, our improved arrangements for starting the car gently without
shock are not confined to the cases where our improved reducing gear is employed
since our arrangements may obviously be applied to those cases where one part
only of the motor is permitted to revolve as has hitherto been customary.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In an electric railway of the kind described, the provision of an iron trough
located in the track formed of plates placed perpendicular to the rails said plates
being separated by washers or by corrugations formed on the plates, substantially
as described.
2. A car iron formed in lengths and suspended from the car in such a manner
that when the car is rounding a curve portions of said car iron can move horizontally
so as to approximately coincide with the curve.
3. In an induction system of electric traction such as described, the provision of
means whereby the increased difference of potentials between two points of the
main conductor due to the presence of a car is utilized to automatically operate
the switches controlling the supply of current to neighbouring portions of the main
conductor.
4. A transformer provided with an iron core portions of which are movable
relatively to the other portions thereof, so that the amount of energy supplied to
the line by said transformer can be varied without opening or closing the electrical
circuit, for the purpose specified.
5. In an induction system of electric traction such as described, utilizing the
increased difference of potentials between two points of the main conductor due
to the presence of a car, to give warning to a signalman, for the purpose
specified.
6. For driving an electric car, the improved gearing wherein both parts of the
motor are capable of rotating, said parts being independently connected to the
car axle through clutches so designed that when both are in gear the axle is
driven through the clutch which is rotating at the higher speed.
7. In an electric car, a motor mounted in a frame which frame is pivoted on the
driving axle of the car and is supported by a spring or springs from the car frame,
so that at starting the motor and frame tend to rotate round the driving axle
thereby deforming the springs, for the purpose specified.

page_text: 8. The various improvements constructed and operating as described with
reference to the accompanying drawings.
Dated this 15th day of February 1897.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester, and Birmingham,
Patent Agents for the Applicants.