IMPROVEMENTS IN ELECTRIC RAILWAY SIGNALS AND IN ELECTRIC SAFETY APPLIANCES FOR RAILWAYS AND RAILWAY TRAINS
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by Theodore Al Burtis Putnam at the
Office of the Commissioners of Patents on the 17th September 1879.
THEODORE AL BURTIS PUTNAM, of New York City, in the County and State
of New York, one of the United States of America, Electrician. "IMPROVEMENTS
IN ELECTRIC RAILWAY SIGNALS AND IN ELECTRIC SAFETY APPLIANCES FOR
RAILWAYS AND RAILWAY TRAINS,"
My Invention consists generally in a system and appliances whereby a moving
locomotive or train of cars at different times forms automatically a part of several
electric circuits, by closing the same to operate an alarm placed on such locomotive
or train, or operate any desired signal on the line of the railway, or lock a closed
switch or draw as follows:-
First. To denote when a switch or draw-bridge is misplaced by sounding or
operating a signal on the locomotive or train.
Second. To lock by the action of the locomotive or train a closed switch or
draw-bridge, and unlock it mechanically while passing the same.
Third. To signal one locomotive or train by another locomotive or train on the
same line or on different approaching lines.
Fourth. To signal by the action of the locomotive or train its approach to a
station or crossing.
Fifth. To signal an approaching locomotive or train from a station or depôt.
Sixth. To denote by an alarm on the locomotive or train any defect in the
circuit for all signals.
The above system may also be adapted without alteration to operating other
classes or kinds of signals.
All of the signals can be transmitted any given or required distance by means
of conducting wires, or if found feasible the track-rails may be utilized as con-
ductors. In ordinary practice I employ one battery placed on the locomotive, but
more than one battery may be used placed in any part of the circuit, or mechanical
or other kinds of electricity may be used.
The word locomotive or engine where employed herein must be understood as
including the tender and attached train as well.
The signals may be visible or audible, steam whistles, gong bells, or any form of
semaphore, but I prefer to employ on the locomotive a vibrating bell.
The mechanical devices employed and the signals may be operated either by
magnets attracting armatures by reversing polarities to repel armatures, or by
Prine 4d7

page_text: demagnetizing helices attached to permanent magnets to allow armatures to be
drawn from the same, and open or closed circuits or divided circuits may be
employed as found most desirable arranged in any manner.
The general construction and operation are as follows:-
An electrical conductor is arranged in a cavity on the road-bed, preferably mid-
way between the tracks, and adapted to be elevated or protruded by the pressure
of an extra wheel on the locomotive axle acting through levers on the said con-
ductor as the train is passing. This conductor when protruded is swept by
metallic brushes or brush-like conductors on the locomotive, by which means a
circuit or circuits are closed.
Wires lead from the protruded conductor to any point on the line, and are caused
through suitable mechanism to make or break a circuit there also when required.
The brush conductors on the locomotive are connected by wires with the battery
and with an alarm on the locomotive, and should the whole circuit above described
be complete the proper signal is given.
Where circuits are to be made merely for the purpose of operating mechanically
as in locking a switch or drawbridge no alarm is permitted, and such will be
provided for by separate or insulated conductors, both on the road-bed and on the
locomotive, in one circuit an alarm being placed, while in another no such alarm
will be needed. Thus we would have two circuits from the same battery, one
including the alarm on the locomotive, and the other operating outside and
independently of such alarm.
I prefer to employ as an alarm mechanism on the locomotive a permanant
magnet with iron helices attached holding an armature against the force of a
resisting spring when the current flows to demagnetize these helices; at a neutral
point the spring forces the armature from the magnet against a projection, whereby
a short circuit is formed to operate a vibrating bell which will sound until the
armature is returned to and held by the helices again. This may be done
mechanically or by reversing the polarity of the circuit through the helices.
The locomotive serves in the capacity of ground wire to form part of and
complete the circuit.
I have described above the circuits for danger alarms and for mechanically
operating signals, switches, or other required signals or mechanism.
The general principles upon which is based the defect signal, or that which
indicates to the engineer that a conducting wire or wires are broken, or that the
signal alarms are otherwise damaged may be described as follows:-
In addition to the circuits already described, another circuit is led from the poles
of the same battery on the locomotive of such higher resistance than those before
mentioned, that this circuit of high resistance cannot operate an alarm placed in
it unless it receives the full battery current, and this it can receive only when the
other circuit or circuits are broken or defective. Thus I have two signals, one to
indicate danger and one to indicate defects in the circuits or inechanism, the latter
being unable to sound while the former is perfect. These two alarms can differ in
character or sound so as to be readily distinguished, or one bell may serve for
both, but in such a case the specific cause of alarm could not be ascertained.
The conducting wires may be laid along the rails in tubes or otherwise, so that
the destruction of any part of the road-bed would break the wires, in which case
the defect alarm would sound and give warning of danger as well as of defect.
Thus it will be seen that I employ three circuits from one battery.
First. The alarin circuit to operate the bell or other alarm on the locomotive
through one conductor on the road-bed and one on the locomotive.
Second. An operating circuit for signals along the line through another con-
ductor on the road-bed and on the locomotive.
Third. A circuit of greater resistance confined to the locomotive, except that it
is closed by means external to the same, which circuit operates freely only when
either of the others is defective.
Only one circuit is usually in oneration at any given time.
4

page_text: The mechanism I employ for carrying out the above system of signals may be
briefly described as follows:-
On an axle of the engine or its tender is a sleeve upon which are mounted two
extra wheels of less diameter than the track wheels reaching barely to a level with
the rails. The sleeve is shorter than the axle between the track wheels and is
adapted to be slipped along the same from side to side by some mechanism con-
nected with the reversing mechanism of the engine. It may be a beveled slide
arranged to play between fixed collars on the sleeve, and by it the shifting of the
reversing lever throws the extra wheels from side to side. This is necessary, as in
the case of single track roads (and also in double track roads if desired) I employ
a double set of conductors and other mechanism for signalling on the road-bed, so
that the locomotive may always signal ahead and not behind, except as specially
provided for, and it therefore becomes necessary to shift the extra wheels to the
opposite side in backing so as to operate the signals in the direction the locomotive
is travelling.
As these duplicate sets of conductors and mechanism on the road-bed are how-
ever intended generally for locomotive travelling in opposite directions head-on,
and the conductors are arranged for this purpose, employ a commutator or
electric switch on the locomotive, which is also arranged to be operated by the
reversing lever, and this shifts the conductors on the locomotive in such a manner
as to bring the proper ones into contact with those on the road-bed.
The conductors on the locomotive are in the nature of wire brushes arranged to
sweep the conductor on the track as the locomotive passes. These are enclosed
for their better protection in boxes, the lids or covers of which are raised through
suitable mechanism by the conductor on the road-bed, so that they may be brought
into electric contact with the latter. At the same time the raising of their covers
closes by proper metallic contact the circuit of high resistance on the engine. The
lids or covers of the boxes may be arranged to close by gravity alone after the
circuit is made, or be closed by a spring.
The brushes within the boxes are connected with wires or other conductors
leading to the battery direct or through the danger alarm, as the case may be, and
they may be arranged to be thrust out by the raising of the box-covers or not as
desired or necessary. As two circuits are to be closed by a conductor on the road-
bed I employ two brushes, but I do not confine myself to any particular construc-
tion with reference to the same, nor to any particular number.
The conductor on the road-bed and its operative mechanism may be constructed
as follows:-
A hinged lever is arranged just inside of the track-rail so as to clear the flange
of the track-wheel. The forward end of this lever rests upon and may be hinged
to a vertical post or link which rests upon or is pivoted to a cross-lever which
extends under the ground to the middle of the track. This cross-lever is ful-
crumed at the proper point in its length, and is connected at its other end with
a conductor which plays vertically in insulated guides. As the train passes the
first named lever is depressed by the extra wheel on the locomotive, and the con-
ductor is protruded vertically to engage the brushes on the engine. The vertically
arranged part which I denominate the conductor may be of wood, provided with
metallic conducting plates on its sides or faces to which the wires for transmitting
the current are attached, and these plates must be properly insulated in their
guides and from each other. To protect these conductors from ice and snow I
secure flat roofs or covers to their tops, which fit closely down to the boxing around
the conductors when they are at rest and protect them from injury.
After the locomotive has passed the conductor the latter is retracted or drawn
down by strong springs, and these springs should be so strong as to prevent any
less weight than that of the locomotive from compressing them, which prevents
them from being tampered with by mischievous persons.
In latitudes where snow and ice do not form, the conductor on the road might
be much simplified.

page_text: As before stated, conducting wires lead from the insulated plates on the con-
ductor to points along the line, one being to a switch. The operation of this I
will now describe.
The motion of the switch lever in throwing open the switch closes a circuit at
the switch with a wire leading from the road-bed conductor, and this conductor
when brought into contact by a passing brush on the locomotive closes a circuit
which leads through the signal alarm on the locomotive, thus notifying the engineer
that the switch is open and there is danger ahead. The motion of the lever in
closing the switch forms another circuit thereat with another wire leading to the
other conductor on the road bed; this conductor when swept by the other brush
on the locomotive closes a circuit direct from the battery and locks the switch
first, so that it cannot be opened until the locomotive has passed the switch and
unlocked it again.
The mechanism at the switch for making these circuits will vary somewhat
When
with the kind of switch employed, but the principle is the same in all cases.
the switch is open a circuit is always formed which leads directly through the
alarm on the locomotive. When the switch is closed a circuit is formed which leads
directly to the battery on the locomotive and locks the switch but sounds no
alarm. The former is easily comprehended and consists simply in bringing two
metallic conductors into contact; the latter consists of an electro magnet suitably
placed so as to attract a catch when the circuit is closed. The movement of this
catch allows a weighted lever to drop and shoot a locking bolt. As the locomotive
passes, its wheel operates on a lever to raise the weight again, retract the locking
bolt, and set all the parts for the next train.
For block signals I contemplate placing road-bed conductors at, say, one mile
apart; and to enable the engineer on one locomotive to know if another train is
within the same block ahead of him, I provide at the proper point a depressor
lever to be acted upon by the wheel as the locomotive enters the block so as to
close a circuit that connects with the road bed conductor just passed in such a way
as to sound the alarm in the locomotive of the train following. This mechanism
may consist simply of pivoted levers, elastic conductors, a drop, and an electro-
magnet arranged to operate thereon. The wires from the conductors lead to the
earth and to the road-bed conductor, and from the magnet in the same manner.
When a locomotive enters the block it actuates the depressor lever mechanically
and closes the circuit; as it passes out of the block it acts through the road-bed
conductor at that end to break the circuit and drop the lever. In this case the
locomotive following gets no alarm, but if it enters the block before its leader
passes out it will get the danger signal; thus trains may be kept any given
distance apart when it is desirable.
To signal the approach of a train at crossings I employ in substance the following
mechanism: A post is set on the road side, and within it or alongside of it is
placed a light rod, hinged to the post at its foot and held upright by a catch at the
top. This catch is within attracting distance of a magnet, and wires from this
As the
magnet are carried to a road-bed conductor at any distance away.
approaching train passes the conductor a circuit is formed, the magnet attracts the
catcb, and the light rod is allowed to fall until it assumes a horizontal position
across the transverse road. This rod may be provided with flags or streamers to
attract the eye, and should be placed high enough to leave the road free from
obstruction. As the locomotive passes it sets the signal rod again mechanically
through the action of the wheel on a depressor lever.
I also contemplate arranging a gong or bell to be sounded before the rod falls,
and thus give a timely warning; the spring or weight which supplies motive
power to the alarm may be wound up by the falling of the rod.
By carrying a wire from the road-bed conductor to a station or depot an
approaching train may signal itself, and conversely by a wire leading from a station
to a road-bed conductor an operator at a station may signal the approaching
locomotive.

page_text: In lieu of the road-bed conductor above described and the arrangement of brush
conductors on the locomotive, I may employ an arrangement which I will now
describe, and which is in some respects preferable to the first.
The locomotive is supplied with a long wooden base piece on which are mounted
so as to be insulated from each other and the base, metal conducting strips arranged
parallel with the road-way, and adapted to be swept by brushes protruded from
the road-bed by the weight of the locomotive as in the first named device. These
strips are connected by wires with the poles of the battery on the locomotive
precisely as in the former case.
The brushes which form the road-bed conductors are mounted in a head and
insulated from it and from each other. This head plays in guides and is operated
through links which connect it with cross arms secured to the same, simultaneously
provided with quadrant-shaped covers arranged to close over the brushes when
they are retracted. When the engine or its tender depresses the lever in passing,
the enclosing covers are thrown open and the brushes protruded simultaneously.
When the pressure is taken off the depressor lever a strong spring retracts the
brushes and closes the covers. The circuit of high resistance on the locomotive is
formed by connecting its wires with two of the adjacent strips on the base-piece
under the locomotive, whereby they become negative and positive poles of the
same. These are swept simultaneously by one brush on the road-bed conductor
which is insulated from everything else.
Instead of arranging the brushes to protrude from the center of the road-bed,
they might in some cases be arranged at the sides of the tracks, and instead of
being projected vertically they may project horizontally. Indeed various arrange-
ments and modifications of the parts are possible without departing from my
Invention in a matter of substance.
In this case also I employ extra pressure wheels fixed on the locomotive axle
and on opposite sides of the track. And to prevent these from operating the
duplicate sets of road-bed conductors to the confusion of the signals, I employ two
sets of conductors on the locomotive as well, and provide a commutator arranged
to throw one set of the latter entirely out of communication with the battery when
the other is being operated, which may be operated by the reversing mechanism.
The rod-like conductors on the locomotive may be kept clean by being moved
under rubbers or scrapers, the motion being derived from the locomotive axle
through suitable gearing.
To notify the engineer or guard should the couplings between the cars give way
or the train part from any cause, I lead a wire from the battery on the engine
through a bell or other alarm, and carry similar wires through each car. On
the ends of these wires I fix couplings having two metal faced jaws insulated
from each other, and arranged normally to spring together so as to be in electric
contact. One jaw connects with the wire leading through the car, and the other
jaw with a wire leading to the truck so as to serve as a ground wire. When the
jaw of one of these couplings is slipped between the two jaws of the coupling on
the next car, and a non-conducting plug is inserted between the jaws of the
coupling at the rear of the last car, a continuous electric connection is established
between the engine and every car in the train, and when the coupling jaws become
disengaged by the parting of the train, the jaws of the coupling spring together, a
circuit is closed and an alarm sounded on the engine. This mechanism may be
employed in compartment cars to signal the guard or engineer for any reason if
desired.