APPARATUS FOR THE REGULATION to be as OF CURRENTS EMPLOYED IN TELPHER AND OTHER ELECTRIC MOTORS follows:-
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I FLEEMING JENKIN of 3 Great Stuart Street Edinburgh Civil Engineer do
hereby declare the nature of my invention for "APPARATUS FOR THE REGULATION
to be as
OF CURRENTS EMPLOYED IN TELPHER AND OTHER ELECTRIC MOTORS
follows:-
"
This Invention has more especially for its object the regulation of currents
employed in what is now termed the cross over system of driving telpher trains.
This system was part described in the Patent N° 4548-1882 granted to me and is
shown in Figure 5 of that Patent.
My invention has three objects-It does away with a dead point or dead length
which has hitherto been inseparable from this system of driving-it substitutes a
continuous current in one direction for a current which has hitherto been reversed
at each section and it regulates the speed of the motor and train, morcover it
secures these objects without allowing any spark or voltaic are to occur at any
point in any circuit where it can be injurious. In a less complete form the
apparatus avoids the dead length and regulates the speed but lets the current be
reversed at each section. In a still less complete form the apparatus simply
regulates the speed of the train and finally by imitating one peculiarity in the cross
over system of driving this regulation of the speed becomes applicable to the
system of driving a train by letting two contact pieces or brushes run along a
positive and negative conductor respectively and by an obvious extension can be
applied to any motor whether driving a train or not-its use is in these cases
confined to effecting the regulation without the introduction of an injurious spark
an object of much utility.
In describing the invention I will begin with the most complete form which
I will term a non-reversing step-over.
In place of two contact wheels or brushes putting the motor in connection with
the positive and negative sections I employ at least three contact wheels or brushes.
To avoid repetition I will call all wheels brushes or rubbers used for the above
purpose brushes-I will call the three brushes the leading middle and trailing
brushes and denote them by the letters L M and T. I will call one terminal of the
motor the positive terminal and the other the negative terminal-each brush can
be connected with either terminal of the motor, also each brush can be rendered
inoperative by a break in its connection either to the positive or negative terminal
of the motor. This inoperative position may be the middle position of a tongue.
used to connect the brush either with the positive or negative terminal. The
brushes are so spaced that the distance between the leading and trailing brush
exceeds the length of the longest section of the line. The distance between the

page_text: section of the line.
The apparatus is so arranged that whenever a brush is on a positive section it is
held in connection with the positive terminal of the motor. When a brush is on a
negative section it is held in connection with the negative terminal of the motor
and when it is on an insulated gap piece between two sections it is rendered
inoperative that is to say it is disconnected from both terminals. The sequence of
events as the locomotive runs may be described as follows beginning with that
position in which the leading and middle brushes are on a positive section and the
trailing brush on a negative section.
L positive M positive T negative.
L disconnected M positive T negative.
L negative A positive, T negative.
L negative M positive T disconnected.
L negative M positive T positive.
L negative M disconnected T positive.
L negative M negative T positive.
This series of changes is then repeated substituting positive for negative in the
above description.
It is obvious that the same series of changes may be effected by using six
brushes three of which are exclusively used for positive and three exclusively for
...negative currents. Then in the above description the words positive and negative
denote which brush is operative.
.
::
In the arrangements for carrying out these changes the brushes are set in their
proper position by secondary fine wire circuits and what I will call polarized
relays; the brushes may be held in the proper connection by the main current
which flows through them to the motor. I mean by polarized relay any electro
magnètic arrangement such that when a current flows through it in one direction
one contact or set of contacts is completed and when the current is reversed
another contact or set of contacts is completed. A third combination of contacts
or a break in the contacts may follow when no current flows through the polarized
relay. It is obvious that these secondary circuits derived from the main brushes
afford an easy mode of regulating the connections in the manner described. I some-
times make the polarization depend on a contact current dorived from the two
constant terminals of the motor.
The required series of changes for the three brush system can be made with tho
following arrangement of a triple polarised relay.
A fine wire circuit from L to M works the tongue connecting L to the positive
or negative terminal when no current flows through this circuit the tongue is at a
middle position and leaves the brush disconnected. Similarly a fine wire circuit
from M to T works brush M and a fine wire circuit from L to T' works brush T
cach fine wire coil is supplemented by a thick wire coil conveying the main current
which coil holds the tongue of the electro magnet wherever it may be so long.as
the current passes. With the six brushes all that is wanted is six fine wire by
paths which set the brush in or out of connection as it is on or off the section for
which it is intended.
These arrangements enable me to govern the speed of the train or motor by
means of a centrifugal governor used to make or break one or more of the
secondary or fine wire circuits employed as described above to set the main
contacts. The curront through these secondary circuits is small so that these
circuits can be broken with impunity. And I arrange the centrifugal governor so
that the weight shall be in unstable equilibrium at two critical speeds so that
when the higher speed is exceeded tho weight flies out breaking the circuit
suddenly and for a considerable distance and the contact is not again made until
the lower critical speed is reached when the weight suddenly flies back to its first
position this prevents chattering and sparking even in the secondary circuits.

page_text: The effect of breaking the fine wire circuit will not be immediate but the device
acts by stopping the change which is required to make a given brush operative-
an operative brush drives the motor until it reaches a gap between two sections of
the line here the current ceases causing a spark between the brush and the line
where it is harmless-tho brush then becomes inoperative and when the gap is
passed owing to the interruption caused by the governor in the fine wire circuit no.
circuit is completed through the motor. So soon however as the fine wire circuit
is completed by the governor the brushes will be all properly set and the train will
be once more driven.
It will be seen that no interruption in the driving circuit can occur until some
brush crosses a gap but that the current can be restored at any point-the effect
will be that the driving current will be supplied during part of each section which
will be a large part when the the train is running up hill a smaller part on the levol
or down hill and on steep downward inclines the current may be cut off altogether.
Instead of being wholly interrupted the current might be diminished by being
passed through a resistance.
Secondly. The step over may be simplified when the reversal of the main
current is not objectionable. The simplest arrangement of the reversing form of
step over is to have four brushes two in front of the train and two behind. I will
call the first and second leading brushes L, and L, the first and second trailing
brushes T, and T. The distance between T, and L. is greater than the largest
section-the distance between L, and T, is less than the smallest section-the motor
may either be connected between L, and T, or between L, and T. Whenever
either of these circuits is broken by the arrival of a brush at a gap the other
circuit is made-this can be done by the secondary fine wire circuits as follows-
circuit No 1 goes from L, to T, circuit No 2 goes from L, to T, when a current flows
through No I an electro magnet in this circuit connects the two ends of the motor
to L, and T, when a current flows through N° 2 an electro-magnet in this circuit
connects the two terminals of this motor to L, and T, when a current flows
through both circuits it leaves the connections as they may happen to be, when no
current flows through either circuit the terminals of the motor aro disconnected.
The governing can be effected by cutting a secondary wire as in my first form of
step over.
Thirdly if the dead length is not found objectionable the same invention of
governing is applied as follows-there are only two brushes a loading brush and a
trailing brush, these are habitually joined by a main circuit through the motor and.
also by a secondary fine wire circuit which can be interrupted by the governor-
the main circuit goes round an electro magnet which keeps the circuit closed so,
long as a current Bows; the secondary fine wire circuit closes the main circuit by
means of the same electro magnet. If the secondary. circuit is broken by the
governor the main circuit is broken immediately after reaching] a gap-the spark
occurs at the brush or gap as in the more complex cases-when the secondary
circuit is closed by the governor the main circuit is thereby closed and the train is
again driven.
The same method of governing is applied to ordinary parallel are driving by.
inserting short insulated pieces in the main conductors to imitate the action of the
gaps in the cross over system. A spark will occur when each of these is passed,
but this spark will be harmless, the action of the governor will then result in
breaking the operative circuit before the gap is passed-when the secondary circuit
is closed by the governor the main circuit becomes operative again and the train
is driven.

page_text: I, FLEEMING JENKIN of 3 Great Stuart Street Edinburgh Civil Engineer do
hereby declare the nature of my invention for "APPARATUS FOR THE REGULATION
OF CURRENTS EMPLOYED IN TELPHER AND OTHER ELECTRIC MOTORS" and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
This invention has more especially for its object the regulation of currents
employed in what is now termed the cross over system of driving telpher trains.
This system was part described in the Patent No 4548–1882 granted to me and
is shown in Figure 5 of that Patent.
My invention has three objects:-It does away with a dead point or dead length
which has hitherto beon inseparable from this system of driving-it substitutes a
continuous current in one direction for a current which has hitherto been reversed
at each section and it regulates the speed of the motor and train, moreover it
secures these objects without allowing any spark or voltaic are to occur at any
point in any circuit where it can be injurious. In a less complete form the
apparatus avoids the dead length and regulates the speed but lets the current be
reversed at each section. In a still less complete form the apparatus simply
regulates the speed of the train and finally by imitating one peculiarity in the
cross over system of driving this regulation of the speed becomes applicable to the
system of driving a train by letting two contact pieces or brushes run along a
positive and negative conductor respectively and by an obvious extension can be
applied to any motor whether driving a train or not-its use is in these cases
confined to effecting the regulation without the introduction of an injurious spark
an object of much utility.
In describing the invention I will begin with the most complete form which
I will term a non-reversing step-over.
In place of two contact wheels or brushes putting the motor in connection with
the positive and negative sections I employ at least three contact wheels or brushes.
To avoid repetition I will call all wheels brushes or rubbers used for the above
purpose brushes. I will call the three brushes the leading middle and trailing
brushes and denote them by the letters L M and T. I will call one terminal of
the motor the positive terminal and the other the negative terminal each brush
can be connected with either terminal of the motor; also each brush can be
rendered inoperative by a break in its connection either to the positive or negative
terminal of the motor. This inoperative position may be the middle position of
a tongue used to connect the brush either with the positive or negative terminal.
The brushes are so spaced that the distance between the leading and trailing brush
exceeds the length of the longest section of the line. The distance between the
middle brush and either of the others must be less than the length of the shortest
section of the line.
The apparatus is so arranged that whenever a brush is on a positive section it is
held in connection with the positive terminal of the motor. When a brush is on

page_text: L positive M positive T negative.
L disconnected M positive T negative.
L negative M positive T negative.
L negative M positive T disconnected.
L negative M positive T positive.
L negative M disconnected T positive.
L negative M negative T positive.
This series of changes is then repeated substituting positive for negative in the
above description.
It is obvious that the same series of changes may be effected by using six
brushes three of which are exclusively used for positive and three exclusively for
negativo currents. Then in the above description the words positive and negative
denote which brush is operative.
In the arrangements for carrying out these changes the brushes are set in their
proper position by secondary fine wire circuits and what I will call polarized
relays; the brushes may be held in the proper connection by the main current
which flows through them to the motor. I mean by polarized relay any electro
magnetic arrangement such that when a current flows through it in one direction
one contact or set of contacts is completed and when the current is reversed
another contact or set of contacts is completed. A third combination of contacts
or a break in the contacts may follow when no current flows through the polarized
relay. It is obvious that these secondary circuits derived from the main brushes
afford an easy mode of regulating the connections in the manner described.
I sometimes make the polarization depend on a contact current derived from the
two constant terminals of the motor.
The required series of changes for the three brush system can be made with the
following arrangement of a triple polarized relay.
A fine wire circuit from L to M works the tongue connecting L to the positive
or negative terminal when no current flows through this circuit the tongue is at
a middle position and leaves the brush disconnected. Similarly a fine wire circuit
from M to T works brush M and a fine wire circuit from L to T works brush T-
each fine wire coil is supplemented by a thick wire coil conveying the main current
which coil holds the tongue of the electro magnet wherever it may be so long as
the current passes. With the six brushes all that is wanted is six fine wire by
paths which set the brush in or out of connection as it is on or off the section for
which it is intended.
These arrangements enable me to govern the speed of the train or motor by
means of a centrifugal governor used to make or break one or more of the
secondary or fine wire circuits employed as described above to set the main
contacts. The current through these secondary circuits is small so that these
circuits can be broken with impunity. And I arrange the centrifugal governor
so that the weight shall be in unstable equilibrium at two critical speeds so that
when the higher speed is exceeded the weight flies out breaking the circuit
suddenly for a considerable distance and the contact is not again made until the
lower critical speed is reached when the weight suddenly flies back to its first
position this prevents chattering and sparking even in the secondary circuits.
The effect of breaking the fine wire circuit will not be immediate but the device
acts by stopping the change which is required to make a given brush operative-
an operative brush drives the motor until it reaches a gap between two sections
of the line-here the current ceases causing a spark between the brush and the

page_text: line where it is harmless the brush then becomes inoperative and when the gap is
passed owing to the interruption caused by the governor in the fine wire circuit
no circuit is completed through the motor. So soon however as the fine wire
circuit is completed by the governor the brushes will be all properly set and the
train will be once more driven.
It will be seen that no interruption in the driving circuit can occur until some
brush crosses a gap but that the current can be restored at any point-the effect
will be that the driving current will be supplied during part of each section which
will be a large part when the train is running up hill a smaller part on the level
or down hill and on steep downward inclines the current may be cut off altogether.
Instead of being wholly interrupted the current might be diminished by being
passed through a resistance.
Secondly. The step over may be simplified when the reversal of the main current
is not objectionable. The simplest arrangement of the reversing form of step over
is to have four brushes two in front of the train and two behind. I will call
the first and second leading brushes L, and L, the first and second trailing
brushing T, and T. The distance between T, and L is greater than the largest
section-the distance between L, and T, is less than the smallest section-the
motor may either be connected between L, and T, or between L, and T. Whenever
either of these circuits is broken by the arrival of a brush at a gap the other circuit
is made this can be done by the secondary fine wire circuits as follows-circuit
N° 1 goes from L₁ to T₁-circuit N° 2 goes from L₂ to T, when a current flows
through N° 1 an electro magnet in this circuit connects the two ends of the motor
to L₁ and T₁ when a current flows through N° 2 an electro-magnet in this circuit
connects the two terminals of this motor to L, and T, when a current flows through
both circuits it leaves the connections as they may happen to be, when no current
flows through either circuit the terminals of the motor are disconnected. The
governing can be effected by cutting a secondary wire as in my first form of
step over.
Thirdly. If the dead length is not found objectionable the same invention of
governing is applied as follows-there are only two brushes a leading brush and a
trailing brush these are habitually joined by a main circuit through the motor
and also by a secondary fine wire circuit which can be interrupted by the
governor the main circuit goes round an electro magnet which keeps the circuit
closed so long as a current Hows; the secondary fine wire circuit closes the main
circuit by means of the same electro magnet. If the socondary circuit is broken by
the governor the main circuit is broken immediately after reaching a gap—the
spark occurs at the brush or gap as in the more complex cases-when the secondary
circuit is closed by the governor the main circuit is thereby closed and the train is
again driven.
The same method of governing is applied to ordinary parallel are driving by
inserting short insulated pieces in the main conductors to imitate the action of the
gaps in the cross over system. A spark will occur when each of these is passed,
but this spark will be harmless, the action of the governor will then result in
breaking the operative circuit before the gap is passed-when the secondary circuit
is closed by the governor the main circuit becomes operative again and tho train is
driven.
Figure 1 shows diagrammatically an arrangement of brushes circuits contacts and
electro magnets for a complete governed non reversing or continuous stop over-
Thick lines show circuits of thick wire or small resistance in this and all other
diagrams; thin lines show circuits of comparatively high resistance L M and T
are the leading middle and trailing wheels or brushes. The terminals of the motor
which are to be maintained positive and negative are indicated by the signs +
and. The tongues Im and t are connected with LM and T by thick wires
which pass round the electro magnets at F, F, F, forming what I will call hold fast
coils The tongues shown in Figures 1 to 7 are steel magnets having_constant
poles not liable to be reversed by any reversal of the current in F, F, or F, (This

page_text: constant polarity may also be secured even in soft iron tongues by the use of a
magnetizing derived current led from the positive to the negative terminals of the
motor The current through the motor is never reversed hence the derived
current will always run in a constant direction, but the polar character of this
arrangement will depend on the due setting of the tongues at starting whereas
with the permanent steel magnets shown the step over is absolutely automatic.)
In Figures 1 to 7 each tongue l, m, t when up throws its brush by a thick wire
into connection with the negative terminal of the motor-Each tongue when down
throws its brush by a thick wire into connection with the positive terminal of the
motor.
There are three fine wire circuits led round the three electromagnets at fif and
fs as well as the three thick wire coils F₁, F., and F.. The magnetised tongue and
the coils whether thick or thin are so arranged that when a current flows up from
a positive section of the line as from B₂ round the electro magnet the corresponding
tongue is pulled down so as to connect the positive section with the positive motor
terminal When on the contrary the current flows down through the brush to a
negative section the action of the coils whether thick or thin is to lift the tongue
and so connect the negative section with the negative motor terminal and keep it
so connected-The circuit for fi leads from L to M-the circuit for f, leads from
M to T-the circuit for f, leads from L to T; when the speed of the train is to be
governed these three circuits are led to a centrifugal governor by which when the
desired speed is exceeded they are simultaneously broken as at G, G, Gs; when no
current passes through either f and F the tongue of that electro magnet remains in
an intermediate position leaving the corresponding brush disconnected from both
motor terminals,
The action of this step over can be best understood by following the successive
changes which occur as the train moves along-the successive positions assumed
by the tongues are shown in Figures 1 to 7 and it will be seen that these are
necessarily produced and maintained by the action of the coils.
-
In Figure 1, L and M are on a positive section and T on a negative section of a
telpher line arranged for cross over driving that is to say with alternate sections
+and-of nearly equal length separated by gap pieces W, and W, roughly insulated
from both sections. If the train be simply set down on the sections as in Figure 1
but with all the tongues l, m, t, in the intermediate or insulated position a current
will flow up through f₂ and down through f, with the effect of bringing two of the
tongues into the position shown in the figure so that M is brought into contact
with the terminal and T into contact with the terminal. The hold fast coils
F, and F, will increase the pressure at the contacts and would hold the tongues in
the position shown even if the thin wire circuits were interrupted as by the
governor at G₁ G₂ and G, or when no current flows through them as in f₁ Figure 1
provided the contact has been previously made. The motor being supplied with
current will drive the train which in the figures is supposed to move from right to
left. The first change in the position of the tongues occurs when L reaches the
gap piece W, as shown in Figure 2. The currents through both F, and f, are cut
off by the insulated gap piece and the tongue & consequently goes to the inter-
mediate position as shown but the motor continues to be driven by the current
flowing up from M and down to T. Strictly speaking the current through f₁ is not
wholly cut off but only halved as there still remains an indirect route for the
current from M through fand fs but the effect is by proper adjustments of the
springs of the relay equivalent to cutting off and for clearness I shall continue to
use this term.
The next change occurs when L comes on to a negative section as shown in
Figure 3. By the action of coil the tongue is then put to the negative terminal
as shown and retained there by the action of F₁ The next change occurs when T
arrives at the gap piece W, as shown in Figure 4. The tongue is then freed by
the cessation or great diminution of current in f, and F, and the tongue goes to
the intermediate position. Now M and L are the only operative brushes. Next T

page_text: arrives on the + section Figure 5 when t is brought to the + terminal by the
action of fs and held there by F; now L M and T are all operativo brushes.
This
Next M reaches W, Figure 6 the tongue m goes into the intermediate position
leaving L and T operative lastly M reaches the negativo section B Figure 7 when m
is put to the negative terminal by the action off, and held there by F.
completes the cycle of changes. It should be observed that the position of all
the tongues is quite independent of what may be termed the previous history of
the train. Wherever the train may be put down a sufficient number of tongues go
at once to their right places. If as the train is running the speed becomes excessive
a governor is used to interrupt the three fine wire circuits simultaneously. When
this is done no change will at first occur. Any brushes which may be operative
will remain operative in consequence of the action of the hold fast coils F, F, F,
but the first brush which becomes inoperative by arriving at a gap piece will allow
its tongue to fall to the disconnected position so that the brush will remain
inoperative after passing off it to the next section the fine wire coil being cut out-
even this change will not cut off the current from the motor if the inoperative
brush has formed one of a pair both on one section or sections at one potential―
but each brush as it arrives in succession at a gap piece will successively become
and remain inoperative so that at the latest the current will be cut off when a
second brush reaches any gap piece. The moment a governor restores the fine wire
connections the brushes will come into operation. The spark which must occur
when the main current is cut off from the motor will pass between the brush and
the line where iu harmless and can never occur between the tongue and its
contact piece which it would speedily destroy.
JO
The delay in the action of the governor prevents chattering or continuous
sparking at the contacts G, G, G, allowing the currents to be put on and off for
considerable intervals of time instead of for mere fractions of a second.
: No details of mechanism are shown because any electrical instrument maker
would supply relays or electro magnetic arrangements to fulfil the conditions
stated. Moreover it is obvious that the details could be varied considerably
without departing from the general scheme above describod. The fine wire
circuits may be differently connected. The electro magnets tongues and brushes
differently arranged and the polar character of the arrangement may be given by
other means than the permanent steel magnets which are employed in the example
given to select the right connection.
For instance six brushes may be used as shown in Figure 8 with six tongues.
In this arrangement the three forward brushes of each pair are used exclusively
for the positive terminal of the motor the three following brushes are used
exclusively for the negativo motor terminal. There are six fine wire coils ƒ¡ to fe
and six thick hold fast coils F₁ to F, round six electro magnets with polar tongues
l₁ by, my ma t₁ tų.
-
-
Coils f f f end in the + terminal of the motor fiffe end in the terminal
A current up through f₁ F₁ ƒ Ff F, from the line attracts the armature; a
current down repels it. A current down through f, F, ƒFƒo Fo to the line
attracts the armature; a current up repels it. It is clear that assuming the
terminals of the motor to be already+ and the currents flowing in Figure 8
hold the armatures as shown. When L, reaches B₁ the downward current will
continue to repel the armature and keep the contact broken with . But when L.
reaches B₁ the downward current will make the contact with : Similarly each
contact will be broken as each brush reaches each gap and correctly made on
reaching each new section.
Figure 9 shows a similar arrangement of six fine wire circuits and six polar
tongues but with only three brushes,
Figure 9a shows a similar arrangement with six fine wire circuits and six
electromagnets but three polarized tongues which like those of Figuro 1 go to an
intermediate position when no current circulates through the coils as when L is
on W, as shown. This arrangement might be made to work with only three of

page_text: the pairs of coils attraction making one contact repulsion another and the absence
of all current making neither contact. These arrangements require that when the
train is first put on the line the tongues or at least two of them shall be rightly
placed. The hold fast coils are essential as the fino wire coils will be short
circuited when the connection is made.
I have shown these various modifications of the non-reversing or continuous
step over as examples of various ways in which my invention may be carried out
but I do not restrict myself to any special arrangement of fine wire circuits or
thick wire circuits. A double set of circuits are moreover essential if governing
is to be effected according to my invention. In all the arrangements the governing
is similarly effected by cutting the fine wire circuits. The step over by itself may
bo simply described as follows:-The operative brushes are rendered inoperative
when they are on a gap piece and before any brush is rendered inoperative another
brush on a soction of the same sign is rendered operative. Thus a connection
between either end of the motor and the line is nevor broken until another
equivalent connection has been made.
All the arrangements described are consistent with very considerable variation
in the length of the line sections relatively to the distance between the brushes.
This peculiarity is of much importance not only in making the accurate spacing of
parts less important but also in allowing different lengths of line sections inside
and outside curves or when crossing streams or other obstacles.
.
Figure 10 shows a simpler arrangement of stepover which can be used when the
reversal of the current is not considered objectionable. It prevents the motor
from ever being left without a current even when the insulated gap pieces are of
considerable length.
The tongues and t alternately connect the terminals of the motor to L₁ and T₁
and to L, and T.; the position of the two tongues depends on whether and f
receive a current or f f receive a current. When a current flows through both
pairs of coils as is often the case the armature remains where it has been previously
set both because the armatures are nearest the operative electro magnets and because
of the action of the hold fast coils; the tongues and t always move together and
therefore may be mechanically connected and worked by two coils as f, and f, in
Figure 10 where l and t are connected by an insulated spring. The action of the
hold fast coils is not essential to the step over when governing is not required but
even in this case I prefer to add the hold fast coils as shown in Figure 11 in order
to avoid nice adjustments of the coils f₁ and f, and because these may be then
allowed to work with less current.
Figures 12 to 17 show the successive positions of the tongues as the train
progresses. Reversal of the current occurs between the position shown in Figure 12
and that shown in Figure 13, this reversal occurs after the spark has passed
between the line and brush at T, when T, comes to the gap piece. No change of
connections occurs except when the current has already been cut off by one of the
insulated gap pieces W where alone the sparks occur.
Figure 18 shows a modification of the reversing step over in which only three
brushes are used this arrangement is reached from that shown in Figure 10 by
running the two middle wheels as it were into one but it is necessary further to
introduce a pair of springs S, S, by which when no current flows through any fine
wire coil the tongues are put in connection with L and T. The action performed
by these springs may be effected by a pair of fine wire coils operated by a circuit.
(as in the first non reversing step over) between L and T as dotted.
Figures 19 to 24 show the series of changes which occur in the connections-no
change of current occurs except when the main circuit has been interrupted by the
arrival of one of the brushes on to a gap piece.
This is an important feature in all forms of the reversing step over.
Governing can be effected as in the case of the non reversing step over by cutting
the fine wire circuits.

page_text: All the forms are consistent with considerable variation in the relative length of
the line sections and the distance separating the brushes.
Figure 25 shows the arrangement for governing without the use of a step over.
F is a thick wire coil in the main circuit joining L and T the leading and trailing
brushes and passing through the motor. This circuit can be made or broken by
the tongue t worked like the tongues, previously described by thick and thin wire
coils F and f; the thin wire coil f is included in a circuit also joining L.and T
through the motor but which can only be cut by the action of the governor as
at G. If the speed is below that required the governor maintains the contact at G
and assuming that L and T are on sections differently electrified the coils f and F
both attract the tongue t maintaining the main circuit. If the speed rises above
the fixed limit the governor cuts the connection at G but this does not release the
tongue t unless one of the brushes is on an insulated gap piece. On arriving at the
next gap piece however the main current is cut off by the gap piece causing a
spark between the brush and the line where it is harmless and the tongue ₺ then
flies back under the action of spring S. The current is not restored until the
speed falls below the fixed limit but when this has happened the contact at G is
remade, the coil then remakes the main circuit and the motor is at once driven.
The interruption of the main current is by this device delayed until this can be
done harmlessly but the restoration of the current is effected the moment it is
required.
2
Figure 26 shows the same method of governing applied to the ordinary parallel
rail system of driving; W, and W, are two of a series of insulated gap pieces
inserted at intervals along ono rail, which is joined round these by a separate
conductor not touched by the wheels or brush-A spark occurs at the rail when a
brush reaches one of these gap pieces; the tongue t is then released being pulled
back by a spring. If before reaching the gap piece the governor has cut the fine
wire circuit the coil f will not act to reestablish the main circuit after the gap
picce has been passed until contact at G is reestablished by the governor. If the
short dead arcs at the gap pieces are found objectionable step overs with fino wire
circuits analogous to those already described can be employed.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. In a system in which a motor is supplied with current by brushes from a
line arranged in alternate sections maintained at different potential and with gaps
between the sections; the employment of three brushes (at the least) so arranged
that two are at all times on sections of different potential and in connection with
such brushes the employment of automatic electric circuit changers operating to
change their connections as each brush passes a gap in such manner as to maintain
a current through the motor in every position either continuously in the same
direction or alternating in direction substantially as described.
2. The means herein described for governing electro motors by a centrifugal
governor and a switch without producing injurious sparks at the switch contact;
such means consisting in so arranging the apparatus-(a) that the motor current
is intermitted from time to time (6) that the said current whilst flowing holds
the switch closed leaving it free to open in the intervals-(c) that the centrifugal
governor closes or retains the switch when the speed is not excessive but liberates
it when the speed becomes too high.
3. Non-reversing step overs by which a continuous current is maintained
through a motor although the direction of the driving current is continually
reversed relatively to the train as in the cross over system of driving substantially
as described.
4. Non-reversing step overs so constructed as to allow considerable variation in
the distance separating the brushes or considerable variation in the lengths of
sections of live at different potentiele euhatantially os described.

page_text: 5. Non-reversing step overs actuated by auxiliary fine wire circuits interrupted
by a governor allowing the speed to be governed with no injurious spark in the
main circuit substantially as described.
G. Reversing step overs by which a driving current is ensured from a line
consisting of alternate sections at different potentials notwithstanding the presenco
of insulated gap pieces or dead arcs substantially as described.
7. Reversing step overs by which a driving current is ensured from a lino
consisting of alternate sections at different potentials notwithstanding considerabie
variations in the length of these sections relatively to the spacing of the brushes
substantially as described.
8. Reversing step overs actuated by auxiliary fine wire circuits combined with
gap pieces allowing the speed of trains to be governed without a spark at the
working tongues substantially as described.
9. The combination of gap pieces with the thick and thin wire coil tongue and
governor by which the speed of a train driven from two parallel conductors can be
governed with no injurious sparks substantially as described.
10. Apparatus substantially as herein described for the regulation of currents
employed in telpher and other electric motors.