Year: 1886

page_text: We EDWARD MANROSS BENTLEY and WALTER HARRIS KNIGHT, both Electricians,
residing at Providence, in the County of Providence, and State of Rhode Island,
United States of America, do hereby declare the nature of this invention to be as
follows:-
Our invention relates to electric railways and especially pertains to tramways or
street surface roads where one or both of the supply conductors are enclosed in a
conduit having a slot or opening flush with the surface of the ground through which
extends the contact device, usually termed a plow, for maintaining the electrical con-
nection between the supply conductor and the propelling electric motor of a tramcar
or locomotive; several features of this invention however are applicable to electric
railways of all kinds.
Our invention consists
1st. Of means for branching the conduit tramway so that a car can readily pass
from one track to another. To accomplish this we provide with each branch.track a
ranch slotted conduit, which starts from the main conduit at the branching point of
the track, and continues parallel therewith, the branch slot leading directly into the
main slot at the point of branching.
One or more electric conductors are enclosed in each conduit and the tramcars are
provided with contact plows adapted to enter the slot of either conduit and make con-
nection with the conductor in either.
To guide this plow into the desired conduit we provide a moveable tongue or point
upon the conduit or the conductor or both, which may be turned so as to send the
plow in the same direction as the passing car. These moveable tongues or guides are
preferably connected with the switching rail of the track so that by no accident can
the car take one track and the plow the other.
In places where it would be impracticable to employ the tongues we make the plows
moveable laterally with respect to the car and place the track switch in advance of the
branching point of the slot or provide a handle for the plow to be thrown by the
driver, so that the plow may always be guided into the right slot.
Where the track switch is set to guide the car always in the same direction, the
conduit tongue may normally rest over the branching point of the slot and form a

page_text: cover for it at that place, where the opening is necessarily larger than usual, and be
thrust aside by the guard of the plow striking its bevelled end.
2nd. The plow itself has also received several modifications since our English
patent No. 12,703 of 1884 the main shank being of metal, through which passes a
small insulated wire terminating in a contact shoe carried by an insulating block
hinged to the shank.
We have also provided means whereby in case of accident, such as derailment or
closing of the slot, the connection between the car and the supply conductor both
mechanical and electrical may be interrupted without breakage.
Our preferred method for accomplishing this is to make the contact part of the
plow within the conduit collapsible, so that it will assume such dimensions that it can
be readily withdrawn through the slot; the plow is then hung from the car by a joint
having a transverse axis and held in its normal vertical position by a spring catch
adapted to give way when an obstruction is met by the plow, such as a filling up of
the conduit, the closing of the slot or the binding of the plow in the slot when the
car is derailed. When such an accident occurs the plow turns on the transverse axis
and the lower end is thrown up out of the slot without injury and may be readily
replaced.
At the same time. a switch on the car for breaking the motor circuit is operated by
the release of the spring catch so that no arc follows the contact shoe as it leaves
the conductor.
Instead of making the separation between the plow and the conductor, it may he
made between the car and the plow, the plow being detachable at a point either within
or without the conduit. In this case the plow may have contacts embracing the con-
ductors or be otherwise inseparable therefrom and the shank or other device connected
with the car be withdrawn from the plow.
The plow may, if necessary, be suspended from a small truck or trolly, running on
the top of the conduit and propelled by the locomotive or car.
3rd. In the operation of electric motors at variable speeds on a circuit having a
constant difference of potential between its main leads, it is necessary when the motor
is running at a speed below the normal to introduce a certain aniount of artificial
resistance in order to maintain the counter potential of the motor and prevent a
dangerous or abnormal current through the machine.
As this resistance must be under the control of the operator who may at the same
time have control of the commutator brushes, it is very liable that the resistance will
be cut out when there is little or no counter electro-motive force being generated by
the motor.
We therefore provide means for automatically preventing any excess of current in
the motor circuit; we preferably place an electro magnet in the circuit which is
adapted to respond to a definite current and which either acts to cut in a resistance or
prevent the cutting out of resistance or even to break the motor circuit entirely.
If entirely automatic, the device will restore the normal condition of affairs when
the abnormal current is reduced. Each car will carry a current indicator showing to
the operator the volume of current on the motor circuit.
In order to keep the conduit free from snow and dust a cleaning device is provided
which is carried by the locomotive and extends into the conduit. We have found a
splint broom of hickory wood to serve this purpose in a satisfactory manner.

page_text: COMPLETE SPECIFICATION.
Improvements in or Connected with Electric Railways.
We EDWARD MANROSS BENTLEY and WALTER HARRIS KNIGHT, both Electricians
residing at Providence, in the County of Providence, and State of Rhode Island,
United States of America, 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:-
Our invention relates to electric railways and especially pertains to tramways or
street surface roads where one or both of the supply conductors are enclosed in a
conduit having a slot or opening flush with the surface of the ground through which
extends the contact device, usually termed a plow, for maintaining the electrical
connection between the supply conductor and the propelling electric motor of a
tramcar or locomotive; Several features of this invention however are applicable to
electric railways of all kinds.
Our invention consists First, Of means for branching the conduit tramway so that
a car can readily pass from one track to another.
To accomplish this, we provide with each branch track a branch slotted conduit,
which starts from the main conduit at the branching point of the track, and continues
parallel therewith, the branch slot leading directly in to the main slot at the point of
branching. One or more electric conductors are enclosed in each conduit and the
tram cars are provided with contact plows adapted to enter the slot of either conduit
and make connection with the conductor in either.
To guide this plow into the desired conduit we provide a moveable tongue or point
upon the conduit or the conductor or both, which may be turned so as to send the
plow in the same direction as the passing car. These moveable tongues or guides are
preferably connection with the switching rail of the track so that by no accident can
the car take one track and the plow the other.
In places where it would be impracticable to employ the tongues we make the plows
moveable laterally with respect to the car and place the track switch in advance of the
branching point of the slot or provide a handle for the plow to be thrown by the
driver, so that the plow may always be guided into the right sloi.
Where the track switch is set to guide the car always in the same direction, the
conduit tongue may normally rest over the branching point of the slot and form a
cover for it at that place, where the opening is necessarily larger than usual, and. be
thrust aside by the guard of the plow striking its bevelled end.
Second. The plow itself has also received several modifications since our English
Patent No. 12,703 of 1884 the main shank being of metal, through which passes a
small insulated wire terminating in a contact shoe carried by an insulating block
hinged to the shank.
We have also provided means whereby in case of accident, such as derailment or
closing of the slot, the connection between the car and the supply conductor both
mechanical and electrical may be interrupted without breakage. Our preferred,
method for accomplishing this is to make the contact. part of the plow within the

page_text: conduit collapsible, so that it will assume such dimensions that it can be readily
withdrawn through the slot; the plow is then hung from the car by a joint having a
transverse axis and held in its normal vertical position by a spring catch adapted to
give way when an obstruction is met by the plow, such as a filling up of the conduit,
the closing of the slot or the binding of the plow in the slot when the car is
derailed.
When such an accident occurs the plow turus on the transverse axis and the lower
end is thrown up out of the slot without injury and may be readily replaced. At the
same time a switch on the car for breaking the motor circuit is operated by the release
of the spring catch so that no are follows the contact shoe as it leaves the conductor.
Instead of making the separation between the plow and the conductor it may be
made between the car and the plow, the plow being detachable at a point either within
or without the conduit. In this case the plow may have contacts embracing the
conductors or be otherwise inseparable therefrom and the shank or other device
connected with the car be withdrawn from the plow.
The plow may, if necessary, be suspended from a small truck or trolly, running on
the top of the conduit and propelled by the locomotive or car.
Third. In the operation of electric motors at variable speeds on a circuit having a
constant difference of potential between its main leads, it is necessary when the motor
is running at a speed below the normal to introduce a certain amount of artificial
resistance in order to maintain the counter potential of the motor and prevent a
dangerous or abnormal current through the machine.
As this resistance must be under the control of the operator who may at the same
time have control of the commutator brushes, it is very liable that the resistance will
be cut out when there is little or no counter electro motive force being generated by
the motor.
We therefore provide means for automatically preventing any excess of current in
the motor circuit; we preferably place an electro magnet in the circuit which is
adapted to respond to a definite current and which either acts to cut in a resistance or
prevent the cutting out of resistance or even to break the motor circuit entirely.
If entirely automatic, the device will restore the normal condition of affairs when
the abnormal current is reduced.
Each car will carry a current indicator showing to the operator the volume of
current on the motor circuit.
In order to keep the conduct free from snow and dust a cleaning device is provided
which is carried by the locomotive and extends into the conduit."
We have found a splint broom of hickory wood to serve this purpose in a
satisfactory manner.
In the accompanying drawing Figure 1 is a plan view of a branching Electric
Railway and a branching slotted conduit with switching points for the conduit slot
and for the track. Figure 2 is a side elevation of the switching points for the slot
and the conductor. Figure 8 is a plan view of the conduit with the top removed
showing the insulated conductors and the conductor switching point.
Figure 3 is a modified form of conductor point.
In Figure 1, a and b, are the track rails of the railway and a, b, and a², 12, are the
rails of two branch tracks respectively, arranged in the usual manner; e is a pivoted
switch point for directing a vehicle onto either branch track.
The slot of the conduit is shown midway between the two rails and is branched
correspondingly with the track. The slotted conduit is of any well known construction
and therefore does not need any further description herein.
In Figure 3, A, A1, represents the positive conductor of the electric railway
supported from the side walls of the conduit by insulating pins K.
A represents a corresponding positive conductor which extends along the branch
track and is connected to A, A¹, by the wire E.
B, B. is the negative conductor corresponding to the positive conductor, and B¹, is
a branch thereof corresponding to the positive branch A².
At the point of branching is pivoted an independent conductor point C which is

page_text: normally in connection electrically with neither positive nor negative conductor, but
is adapted to be turned from one side to the other to form a connection between
either positive or negative branch conductors and the corresponding main conductor.
In Figure 3 this point C, is shown in a position to form a continuation of the branch
conductor B, leading to the main conductor B.
This conductor point is connected by means of the insulating block F, to the slot
point C which is pivoted by a bolt 1, to the standard D, the swinging support G,
being placed under its outer end, by this means both the conductor point and the slot
point move simultaneously.
The slot point C', as is shown in Figure 1, is adapted to be turned so as to make
the main slot continuous with either branch slot and any depending conductor
extending from the travelling vehicle into the conduit through the slot will be guided
by the proper position of the said point C', from main slot into either branch slot at
will.
The slot point C', is shown flush with the surfaces of the conduit. The means which
we employ for maintaining a continuous connection between the two main conductors
and the travelling locomotive on the road are shown in detail hereinafter they being
similar to that which is shown in Patent No. 12,703 granted Septr. 23, 1884; they
are indicated in Figure 3 by the two shoes m, ml, L representing the motor.
It will be seen that in operation the two contacts sliding along the positive and
negative conductors A and B will be guided into either branch according to the
position of the conductor point C.
In Figure 3, the motor passing from left to right the two contact shoes mod will be
guided so as to pass into the upper branch, the conductor point C, having its
extremity resting against the negative conductor B and being therefore in electrical
connection with it, while if the conductor point were turned into the position shown
by the dotted lines the contact shoes would be guided into the lower branch and the
conductor point resting against the main positive conductor would be in electrical
connection therewith, and in either case the contact shoes would pass into the desired
branch and the electrical connection with the proper conductors would be constantly
maintained throughout.
The slot point C¹, being connected to the conductor point the position of the latter
will be indicated upon the surface by the position of the former, the former also
serving to guide the part of the contact device which passes through the slot, in the
same manner as the conductor point guides the shoes which rest against the conductors
themselves. Instead of having the conductor point constructed of a single independent
piece of metal it may be made as shown in Figure 3, and representing two
insulated strips placed upon opposite sides of the insulating block F, and connected
respectively to the positively and negative branch conductors B, and A..
The insulating block F, is continued out to the point so that neither d nor d, rest
against the main conductors when the point is turned into its two operative positions
and any short circuiting is thereby prevented. Although we prefer in practice, the
form of point shown in Figure 3, yet the principle of the two points is the same,
there being in each case a moveable conductor point forming a continuation of the
branch conductor and leading to its corresponding main conductor.
The conductor point only may be moveable as will be seen from the following.. In
the drawing Figure 4 represents a plan of a road at the point of branching and
Figure 5 represents a section of the roadway taken on the line 2, 2, of Figure 4.
In Figure 4A. B, are the two main conductors and are shown in dotted lines, as
they are supposed to be enclosed in the conduit in the usual manner, the slot of the
conduit being represented by S.
AT, B', are the corresponding main conductors in one branch, and A², B², are the
corresponding main conductors in the other branch.
At the meeting point of the conductors B₁ and A² is pivoted a conductor
switching point C.
This conductor point is electrically independent of any of the main conductors but
it is adapted to be turned in one direction or the other so as to form a continuation of

page_text: either of the branch conductors 13 and A, and leading from said branch conductor to
its corresponding main conductor. In Figure this point is shown turned to
the position where it forms a continuation of A, and leading from said branch
conductor, to, A.
In Figure 4, the two contact shoes are represented by mm² and the two conductors
extending through the slot and protected by a plow as described in our said patent are
shown in section. As this contact device moves in the direction of the arrow K, it,
will be seen that the two contact shoes will be guided by the conductor switch point C,
along the branch conductors A2, B2, and the plow will be pressed over so as to follow
the contact shoes and will enter the slot of the corresponding branch. By means of
this arrangement we are enabled to do away with any switching point upon the slot,
relyingentirely for guidance of the contact device upon the conductor switchingpoint C.
In order that this conductor point may be readily turned from one side to the other
we make a connection between it and the track switching point so that they may be
moved simultaneously and the plow never be turned into one branch while the vehicle
is turned onto the other branch as might occur if the two points were not connected
together.
The arrangement for moving the points is shown in Figure 5 A, and B. are the
main conductors supported from the side walls of the conduit in the manner described
in our said patent. C is the switching point, F, being the supporting insulating block
and and being the two conducting parts of the point.
M, is a bar connecting the two points, it is bent down so as not to interefere with
the contact shoes in their passage from the main into either branch conduit.
N, is a connecting rod pivoted to M, at one end and at the other end pivoted to
lever J. This lever L is pivoted at the point P, and is adapted to be turned from one
side to the other, and thereby throw the two points into the desired position.
The points and the lever are shown in Figure 5 in their middle position. In
Figure 4 they are shown thrown to one side so as to direct the vehicle and the plow
into the lower branch. When in its extreme position the lever L, lies horizontally
and flush with the surface of the roadway.
The conduit only may be provided with the moveable tongue as will be seen from
the following.
In the drawing Figure 6 represents a plan view of the branching slot and Figure 7,
is a view of the conduit with the top removed and Figure S shows a plow similar to
that in the above mentioned patent.
In Figure 6 represents the slot of the main conduct and 7 and c represent the
slots in the two branching conduits respectively, C represents the guide piece pivoted
at the branching point 1.
This guide piece is normally held in the position indicated by the full lines by
means of a spring S, which acts upon the tail piece A, forming a continuation of the
guide piece beyond the point P, and when in this position it closes the slot band
leaves a substantially clear passage from the slot a into the slot c.
The lower edge of the guide piece is bevelled and the plow. H is pointed at either
end as shown in Figure 6; when therefore the plow moving in the direction of
arrow K, passes from the slot a into the slot c. it strikes the lower edge of C and
thrusts it to one side, should the passage be not quite clear; or the spring may
normally hold the point centrally over the slot and be always thrust in a definite
direction by the plow striking the bevel.
In passing from slot b. to slot a the plow will encounter the guide piece C as is
shown in Figure 6 and will thrust it aside against the pressure of the springs, into
the position indicated by the dotted lines so that the guide piece being held in a fixed
position by means of the spring the passing plow will be deflected in a definite
direction this is of special value in turnouts where the switches of the track are
always set so as to guide a vehicle in a definite direction, for example to the right.
In Figure 7, A, B, are the two main conductors supported upon insulating pins in
the manner described in our said patent.
AB, are the conductors in one branch and A B are the conductors in the other

page_text: branch. The positive conductors are connected by bridge wire E throughout, and
the negative conductors are connected by bridge wire F; the plow being guided by
the slot piece, the contact shoe or brush carried by said plow will also be guided
thereby in the proper direction.
We have shown in Figure 7 a contact brush which may take the place of the shoe
or spring, and it is of sufficient length to bridge the space between the positive
conductor A, A, and the branch conductor A2 so that the connection will be maintained
while the plow is passing from the main to the branch conduit. A corresponding
contact brush will be employed for the negative conductor.
It is also possible to dispense with any moveable points either upon the slot or upon
the conductors and yet be enabled to guide the contact plow at will.
We therefore have both the conductors and the edges of the slot stationary at the
branching point and provide means for directing the plow into the proper-slot.
Various means for directing the plow and the contacts may be employed..
In Figure 9 we have shown the track switching point, e somewhat in advance of the
branching point of the slot, so that the vehicle from which the plow is suspended will
be turned into one branch or the other before the plow reaches the branching point of
the slot so that the plow will have a tendency to follow in the same direction with
the vehicle; and in the same manner the branching point of the conductors is placed
behind the branching point of the slot.
The resiliency of the brush gives sufficient flexibility to the plow to allow it to
follow the slot and conductor at the same time, though we do not limit ourselves to
this means of gaining the desired flexibility.
Instead of this arrangement however, the arrangement illustrated in Figure 12 may
be used.
The plows P, P', are pivoted at the points p, p, about two lateral axes in the
manner described hereafter.
These axes are carried by a frame D which has a swinging movement about the
longitudinal axis d, d'.
A handle E may be added to the frame so that it may be turned about the said
axis and thereby force the two plows to one side or the other of the slot.
When now the vehicle approaches the branching point of the slot, the driver by
means of the said handle E can throw the plows to one side or the other so as to
direct them into the proper slots.
As the conductors are also fixed, it will be necessary that the contact device should
be of a length sufficient to bridge any breaks that may be occasioned by the branching.
In Figures 10 and 11. A and B represent the two main conductors, A¹ and 13¹
represent the corresponding conductors in one branch while A2, B2 represent the
corresponding conductors in the other branch.
In Figure 10 a long contact brush is shown which is of a length sufficient to bridge
the break between the main conductor B and its branch conductor B'.
Instead of having one long brush a double plow such as is shown in Figures 11
and 12 may be employed.
By means of this double plow. contact will always be maintained, one plow being
in contact with the conductors, while the other is passing over the break.
In order that the slot point C, when used. may always be turned correspondingly
with the track switching point we connect the two together so that they can only be
moved simultaneously. This is done by the mechanism illustrated in Figures 10ª
and 11ª.
D, represents an upright post journalled in the top and bottom plates of the conduit
and carrying at its upper end the slot switching-point C. A connecting rod E, is
fastened to D and extends back from it horizontally.
To the end of E, is pivoted a rod F. having its opposite end pivoted to lever G.
Lever Ghas also a connection H, with the track switching-point e and an operating
lever K, is pivoted with a connecting rod between it and H, so that when K is
turned to one side or the other both the slot switching point and the track switching-
point will be thrown into the corresponding position.

page_text: .
The slot switching-point Crests upon the top plate of the conduit so that its extreme
end is constantly upheld by the edge of the slot while if upheld from beneath the
support would interfere with the insulated conductors enclosed in the conduit. In
the arrangement shown in 9a, 1fta, 11a, and 12a the plow is guided by the slot point
alone.
We will now describe the plow in the accompanying drawing; Figure 18 is a side
view of the device. Figure 14 is a section of a single plow. Figure 15 is a side
view of the device when thrown out of position. Figures 16, 17, 18 are details.
In Figure 3ay represents the line of the conduit top, and A, A', are the depending
carriers or plows. E, is a supporting frame hung from fixed parts o o of the locomotive
by the pivot e el about which as a longitudinal axis it is free to swing; to this frame E
the plows are attached by means of rigid connections F, F, which are pivoted to the
frame so as to swing freely about a transverse axis, the two plows being connected
together by pivoted connecting bar G, so as to have a parallel movement about the
said axis; such movement is normally prevented by a stop which in this case is a
spring lever K pivoted at and g and held by its own resiliency in a notch P, in E.
(Figure 16). The edges of the notch P, and of the lever K are bevelled so that when
the plows meet an obstruction the lever is, thrown out of the notch and the plows
come up through the slot into the position shown in Figure 15.
Each plow consists of the solid metallic shank extending through the slot and
taking the wear against the sides; to the lower end of this shank is hinged a foot B.
of insulating material by means of spring hinge D, and a metallic contact shoe C. is
fastened on the foot so as to be pressed constantly against the main conductor by the
said spring hinge.
Through the shank and the foot B. is drilled a small hole as shown in Figure 14
(which is a section on line 2, 2, Figure 18) and a small insulated conductor Lis
passed through it and connected at its lower end to contact shoe C, and at its upper
end to binding post A, whence a flexible conductor leads to the motor on the locomotive
in the usual manner.
By this arrangement the motor is kept in constant connection with the mains as it
advances, the two plows connecting with the iwo mains respectively.
When the plow is thrown out as shown in Figure 5, it is desirable that the motor
circuit should be broken at the same time and this is accomplished by placing a switch
in the circuit which is automatically operated by the movement of lever K, in either
direction from its vertical position.
In the drawing S is an insulating base holding two contact plates,, connected to
the two terminals of the motor circuit; this base is fastened to frame E. so as to move
with it and the lever K, when in its normal position, closes the circuit between the
plates
but breaks the circuit when thrown over as in Figure 15.
It will be seen by reference to Figure 14 that the insulating foot B, is larger than
the contact shoe C, and in Figure 17 it is shown that the shoe is not of a suflicient
length to bridge the space between the conductor and the edge of the slot, but that
the foot is; so that the foot and shoe may be withdrawn from or inserted in the
conduit and no electrical connection be made between conductor and conduit, for the
insulating foot will guide the shoe on to the face of the conductor and the conducting
shoe will not bridge across from slot to conductor.
The foot B, is preferably made of vulcanized fibre.
The separation may take place within the conduit in the following manner.
In Figure 19 K. represents a slotted conduit enclosing the two main conductors A,.
and which are supported upon insulating pins from the side walls of the
conduit.
C, C¹, are two bow-shaped pieces of insulating material such as stout hickory wood
connected together at their ends as shown in Figure 20.. Upon the underside of each
of these two bows are two contact shoes F, and I adapted to fit on to the conductors A
and A' and to slide along in contact therewith.
B represents a flat strip of insulating material extending into the conduit through
At their lower ends
the słoi and having embedded therein, two metallic strips, a².

page_text: these metallic strips are bent out as shown in Figure 19 and form two elliptic springs
which rest against the two shoes F, and I respectively.
The lower ends of and a are left free so that they can be readily compressed.
E, E. Figure 20 represent two metallic protecting pieces. placed in line with the
insulating strip B, to protect the same from wear against the edges of the slot
extending down to engage with the two ends of the insulating frame formed by the
two pieces C, C, so as to propel the contact device formed by the frame c, c, and the
shoes F. F.
The strip B, with its protecting pieces E, E, and its conductors & a form a plow
analogous to that shown above and are supported in any well known way from the
electric locomotive or vehicles travelling upon a track over the conduit.
It is apparent, that should the plow for any reason be pulled upward the whole
plow will be pulled out of the contact device, the springs a slipping up out of
contact with the shoes E, F, and being compressed against the sides of B, so as to be
readily withdrawn through the slot.
In Figures 21 and 22 the contact shoes F, F, are replaced by eight rollers to above
and two below each of the conductors A. A',
The rollers are journalled to the bow shaped pieces C, C, which in this case are of
metal and are insulated from each other at the ends where they are joined. The
whole forms a trolly which is adapted to travel along the iwo conductors and collect
the current therefrom..
The plow is of the same construction as that in Figures 19 and 20.
The following describes the plow supported from a separate truck and detachable
at a point outside of the conduit.
In Figures 23 and 24 A is the plow frame and G is the panel of insulating material
in which are embedded the two flat conductors which at their upper ends have flexible
conductors attached leading to the motor on the car in the usual way, and at their
lower ends terminate in curved plate springs R, to which are fastened contact shoes V,
adapted to press against the under horizontal surface of the conductors D, D.
The conductors D, D, are supported from the walls of the conduit by insulating
pins in a well known manner.
Without the conduit two sets of rollers B, are journalled in frame A, and are
adapted to roll on the top plates of conduit C; a flexible chain F, connects the small
truck thus formed to a brace E, projecting from a fixed part of the car.
H, is the tie, I the stringer and K the rail of the roadway.
In Figures 25 and 26 are shown a detachable plow and also some rigid guide bars
for connecting the truck with the car.
In this case the frame A, terminates at each end in a square loop or eye O, whicli
embraces a rigid guide bar N.
N, is in the shape of a horizontal I beam and is fast to the car while the embracing"
loops O, have both a vertical and lateral play upon it.
The plow in this case has a separate frame A', upon which is a square shank W.
adapted to extend up through a recess in A, where it is secured by the spring clips L
and M, encircling a neck on the end of the shank. P, P, are two fixed stops extending
downward from the car and adapted to engage with the projecting arms of L. and
release the plow when it slides too far in a lateral direction upon guides N, as for
instance when the car runs off the track.
The conductors in the plow terminate in two contact pins adapted to engage with
fixed contact springs a and b so that the electrical as well as the mechanical connection'
can be readily broken.
We will now describe our devices for protecting motors on a constant potential
circuit from an abnormal current.
In the drawing Figure 27 M, and M³ represent two electric motors in multiple are
from the two main conductors A, B; C, being the main generator.
These two motors are represented as geared to the driving wheels of an electric.
locomotive and in this situation they will be required to run at variable speeds occa
sioned by the variable load or by the circumstances of the railway,

page_text: In the circuit of each motor is included an electro magnet D, and these electro-
magnets each operate a variable resistance R, in the circuit of their corresponding
motors, thus the circuit of the motor M, may be traced from the main conductor A,
through the motor to resistance R, to lever d, to wire a magnet D, to main
conductor B.
In their normal condition the current in the motor circuit will allow the magnet D,
.to hold the lever d, at a point where little or no resistance will be included in the
motor circuit.
.
But suppose that from any cause a motor as M, should be running quite slowly so.
that its counter electro motive force is small, then the current passing through the
motor, will tend to become abnormally great thereupon the magnet D, will become
stronger and will throw the lever d, to a point where a great resistance is included in
the motor circuit.
By this means an abnormal current can never pass through any motor, and no
motor can rob others upon the line of their due share of the current.
With each magnet D we provide an indicator which will be placed in view of the
operator on the locomotive so that he can always know the amount of current passing
through his machine.
We also provide with each magnet a short circulating key K, by means of which
when it is desired to increase abnormally the power of the motor for a moment, as for
example at the instant of starting, the operator may press this key and thereby shut
the current from the magnet which instantly cuts out the resistance and allows a
sudden impulse of current to be sent through the motor.
This short circuiting key is of course for the purposes of an emergency and to be
used but for a moment so that the motor can never be burned out by an excess of
current.
Levers L are shown connected to the brush carrier of the motor and adapted to
shift the brushes in either direction so as to reverse the direction of rotation of the
motor or control its speed at will.
We may provide a variable resistance in the circuit of cach motor and also provide
a catch or stop which will automatically prevent the removal of too great an amount
of resistance from the motor circuit.
In the drawing Figure 28 M and
represent two electric motors connected
respectively to the driving wheels of two electric locomotives.
Each motor is provided with a lever L for shifting the position of the commutator
brushes and also with a lever L', which controls an artificial resistance R, in the motor
circuit.
Both the commutator brushes and the resistance may be controlled by a single lever
if desired.
Upon each lever L'. is a toothed sector A concentric with the axis of the lever and
in each motor circuit is an electro-magnet S. whose armature has a pawl C adapted to
engage with the teeth of sector A. when the magnet is energized.
The magnet S, is adapted to respond only to an excess of current beyond a deter-
mined point.
The operation of this arrangement is as follows:-Suppose that the operator of the
motor has brought it to a standstill by the insertion of the resistance R, or by the
movement of the brushes or both; should he now desire to start the motor under a
heavy load or in a situation where the motor may be blocked in any accidental manner
he would in the usual manner throw his lever cutting out the resistance R, and there
would result a sudden flow of current through the motor which would destroy it
before it could overcome the inertia of its load or its block were it not for the action of
magnet S.
C
The magnet S becoming energized when it reaches a predetermined maximum point
draws up its armature and interposes the pawl in the path of any further movement
of the resistance lever, so that a driver will be warned that his motor is in danger of
being burned out, so that he cannot by any degree of carelessness or haste permit the
motor to be injured,

page_text: The safety magnet may also act to break the circuit of the motor entirely i.e. insert
an infinite resistance. This is illustrated in Figure 29, 13 being the magnet which in
case of an abnormal current draws up lever D, and breaks its connection with contact
plate K, as shown in the case of motor M.
When the resistance lever L, is drawn back to its vertical position so as to include
the maximum resistance it restores, by means of rod R, and cams d, d, the lever D to
its normal position and thereby closes the circuit again; a very high resistance K,
may be left in if necessary.
In order to keep the conduit free from snow and dust we provide a cleaning device
which is carried by locomotive and extends into the conduit.
We have found a splint broom of hickory wood to serve this purpose in a satisfactory
manner.
A broom of this kind is shown in Figures 30 and 31 fixed in a clamp a which is
pivoted to the locomotive like one of the plows heretofore described.
In Figure 31 al is a depending brace, is a joint having a transverse axis and. K²
ara draw chains.
The operation of the broom in cases of emergency are exactly like those of the
plows, it being readily thrown out of the slot by the breakage of the chains or derail-
ment of the locomotive.
The broom being of insulating material it exercises no injurious effect upon the
conductors.
It extends to the floor of the conduit beneath the conductors and sweeps all accumu-
lations into pits provided for the purpose at intervals along the conduit."
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed, we declare that what we claim is:-
1. We claim the means described, whereby in an electric railway having one or
both of its supply conductors enclosed in a conduit the contact device may pass with
the car or locomotive from one track to another.
2. We claim the branching conduit with one or more electric supply conductors in
each branch and a contact plow connected with a passing car or locomotive, and
adapted to make travelling connection with the conductor in either branch conduit
together with means for directing the plow into the desired branch with proper
preservation of the electrical connection substantially described.
3. We claim with a branching conduit a moveable tongue or guide substantially as
described upon the conduit or conductor or both.
4. We claim with a stationary branching conduit a moveable conductor section for
carrying the travelling contact into the desired branch conductor.
5. We claim the movable conductor tongue and slot tongue connected so as to move
together.
6. We claim the moveable conductor tongue or slot tongue or both of them
connected to the track switching rail so as to move therewith.
7. We claim in any electric railway a main conductor and a branch conductor
having a moveable section substantially as described.
8. We claim in any electric railway with the positive and negative conductors at
the branching point the independent moveable section, substantially as described.
9. We claim the bevelled slot tongue with a protected plow for pushing it aside.
10. We claim a detachable contact plow substantially as described.
11. We claim a contact plow substantially as described having a detachable
connection with the supply conductor either within or without the conduit.
12. We claim a collapsible contact plow adapted to be released in case of an
obstruction or other accident whereby no breakage of any important part will occur.
13. We claim a contact plow and a switch in the motor circuit controlled by the
normal or abnormal position of the contact plow.
.
14. We claim all the details shown and described of the construction of contact
plows.

page_text: 15. We claim with an electric motor adapted to work at variable speed upon a
constant potential, gircuit an automatic safety device adapted to limit the current
through the motor.
16. We claim with an electric motor adapted to work at variable speed upon a
constant potential circuit an electrically operated resistance or circuit breaker in the
motor circuit adapted to limit the current through the motor.
17. We claim with an electric motor propelling a car and means for controlling its
speed at will of a current indicator carried by the car and placed in view of the
operator.
18. We claim the combination with a slotted conduit containing the supply
conductor of an electric railway of a vehicle without the conduit cleaning device and
carried thereby adapted to extend into the conduit below the conductor and sweep any
accumulations into pits, placed at intervals.
19. We claim a cleaning device for a conduit containing an electric conductor, so
insulated as not to interfere electrically with said conductors.
20. We claim a cleaning device for a slotted conduit containing an electric supply
conductor for an electric railway, having a contracted shank adapted to travel along
the slot and adapted to be drawn out through the slot.
21. We claim an electrically propelled vehicle with its supply conductors enclosed in
a slotted conduit and a connection plow with contact devices adapted to extend into
the slotted conduit to the supply conductor and to be withdrawn therefrom through
the slot.
E. M. BENTLEY.
W. H. KNIGHT.
By Harris & Mills.
23, Southampton Buildings,
Agents.