Johnson Railroad Signal Company.

Catalogue of interlocking and railroad signaling appliances online

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The Johnson
Railroad Signal Company

Rahway, N.J.




CHARLES R. JOHNSON - President and General Manager
WALTON O. KERNOCHAN - - - - - Treasurer

HENRY JOHNSON Manager of Works

GEORGE E. READ Secretary



Interlocking and Railroad Signaling Appliances



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M WttT 14TN rrMCT, N. V.

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The Johnson Railroad Signal Co.
Rahway, N. J.


THE credit of the introduction of Interlocking Signals in the United States is
due to Messrs. Toucey & Buchanan, of the New York Central & Hudson
River Railroad, the former, General Superintendent, and the latter Superintendent
of Motive Power. These two gentlemen very early saw the advantages of concen-
trating switches as much as possible so that they could be worked from a cen-
tral point and protected by a much smaller number of Signals than would be
necessary if a Signal was placed for every switch. They devised an Interlock-
ing machine, and the first one was fixed at Spuyten Duyvil Junction, in New
York city, in 1874, and remained in service until 1888. This machine compares
very favorably with the earlier machines used in England which was the
birthplace of Interlotking Signals.

The Pennsylvania Railroad was also early in the field but they sent to the
well known firm of Saxby & Farmer of London, England, for a complete ma-
chine, etc., with Signals and connections, which were sent over and fixed at East
Newark Junction on the New York Division, being put into service on February
II, 1875 where they are now working.

In 1876 Messrs. Saxby & Farmer sent a very complete model of their system
of interlocking and block signals, to the Centennial Exhibition in Philadelphia.
This exhibit did more perhaps than any other one thing to acquaint railroad
managers in this country with the systems of 'interlocking and block signals,
which were then extensively used on European Railroads.

Very shortly after this, the Elevated Railroads of New York were built and
equipped at the most important points with the Saxby & Farmer machine
manufactured by the Jackson Manufacturing Company of Harrisburg, Pa., who
had purchased the patent rights for this country.

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The slow progress of the introduction of Interlocking up to the year 1887,
was due partly to a want of knowledge of its advantages and partly to the seri-
ous depression of trade which was felt so long. The Railroad Gazette and other
Railroad papers, did their utmost to urge Railroad Officers to take up and inves-
tigate the subject and did much to point out its uses and advantages, but even
at the present time there are still comparatively few railroad engineers who
have a thorough knowledge of the latest improvements in interlocking and
block signaling.

In this preface the writer can do no more than point out the chief merits of
the Interlocking system.

The advantages of Interlocking may be classed under two heads :

I, Increased safety.
II, Increased facility in the handling of traffic at busy points.

Increased safety is assured by working each system of switches and signals
from a central point, the mechanism for operating such system being so ar-
ranged that so long as the apparatus is kept in good condition, movements tak-
ing place under the sanction of the operator, as expressed by the lowering of a
signal or signals — ^and no other movements can take place without such sanction
— are secure against collision from conflicting directions, and disturbance of the
switches traversed by such authorized movements.

Much of the increased facility that may be obtained depends upon a good
lay out of tracks as well as of the Signals, When switches are arranged so as to
obtain the greatest number of movements with the least possible running,
much more rapid handling of trains can be obtained with safety by one man
who handles all switches and Signals from an elevated point, where he can see
each movement and anticipate each requirement, than by a number of men who
have to run from switch to switch to throw them.

One can best realize this by watching the movements of trains at Grand
Central Station, New York ; Broad Street Statiofi, Philadelphia, or the Boston
Yard of the Boston & Albany R. R., and comparing them with those at other
busy places which have no Interlocking.

The introduction of Interlocking Signals and switches has not always been a
complete success, for pbvious reasons, viz. : faulty arrangement of tracks and in-
complete signaling. The existence of either or both these conditions will, of
course, mar the complete efficiency of any system, and if from desire to economize
or other reasons, systems having such faults are introduced or allowed to re-
main, satisfactory results can scarcely be expected.

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It is very satisfactory to all concerned in good Signaling to know that an
increasing number of roads are alive to the importance of having a properly
equipped Signal Department. Several important roads have appointed Signal
Engineers whose duty it is to superintend the construction of new work and
maintain it in good condition afterwards.

In making these appointments it is well to secure the services of men of
some years' experience, because, although Signaling may appear to be very simple
and is so in small plants, there are so many intricacies in large ones (and every
road will have some such), that nothing but long and varied experience can fit a
man to fill the position satisfactorily.

There is something about signals very fascinating to the inventive faculty,
and the application for patents, and the patents granted for Signaling devices
must approximate very nearly to the infinite nuipber of car couplers and rail sec-
tions. While it is very laudable to desire to improve Signaling devices, it must
be remembered that there is great economy in uniformity, and changes should
not be made unless some decided advantage is gained.

The experience of twenty-five years has pretty conclusively shown among
other things that the Semaphore Signal is the most satisfactory type of signal ;
that switches and locks should be worked by pipe ; that facing switches should
be fitted with facing point locks; that facing point locks should be duplex, /. ^.,
so arranged that in the event of the breakage of connections, the plunger of the
lock cannot be thrown into the wrong position of the switch ; that two lines of
wire should be used to each signal ; that signal blades should be so constructed
as to go to the danger position in case of breakage of connections anywhere
between the operating lever and blade ; that wires to distant signals should be
automatically compensated ; that iron plates should be fixed under switch points
to keep the track accurately to gauge; that plungers of facing point locks
should not be pointed ; that cranks and pipe compensators should be fixed on
foundations firmly embedded in concrete ; that all side tracks connected to main
tracks should be ''trapped," /. ^., have a derailing switch to prevent cars coming
on to the main track until the switch is set for the side track ; that a signal
shoud be given for every train movement; that high signals should only be
used for main running tracks ; that separate signal posts should be used for each
track running parallel or converging ; that one post with one or more blades
(various systems are in use for indicating the route open) should be used for
diverging tracks; that it is a most dangerous and reprehensible practice to
displace or disconnect any part of safety appliances such as detector bar,
switches, switch locks, machine interlocking, except in cases of absolute neces-
sity, and then only temporarily and under proper protective conditions, such

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as pad Jocking the switches affected, issuance of caution notice and employment
of flagmen at the positions of danger; that all ground connections should be
well drained and all the appliances kept clean.

The points on a railroad where the most train movements are found are
usually chosen to introduce Interlocking Signals, but an exception to this rule is
found at grade-crossings and drawbridges, of which there are so many in this
country. Most of the States some years since passed laws compelling Railroad
Companies to bring their trains to a full stop before crossing a drawbridge or a
grade-crossing. These laws have been found very irksome, not only on account
of the cost of an unnecessary stop, but, from the delay caused by stopping pas-
senger and heavy freight trains. This has been very clearly pointed out in some
of the reports of Railroad Commissioners.

For a simple grade-crossiivg protected by 4 derailing switches, 4 home and
4 distant signals, the most simple form of Interlocking answers every purpose,
and great efforts have been made to reduce the cost to as low a figure as possible.
It must be remembered, however, that no matter how simple the interlocking, it
should be arranged to be perfectly safe under all circumstances, and easy to
maintain in good condition so that one man will be able to properly maintain
several crossing towers. In the struggle to introduce cheap appliances, too
little attention has sometimes been given to a proper factor of safety. There
are crossings now being used with the derailing switches worked without a facing
point lock or detector bar. This should absolutely be prohibited, as innumerable
wrecks have occurred through the throwing of a switch under a train, and one
of the most disastrous accidents that ever occurred was caused in this manner
before, however, the facing point lock was in general use. It must not be for-
gotten that a derailing switch is a facing switch, which ought to be avoided as
much as possible, consistent with proper handling of traffic. One of the first con-
ditions, then, in connection with derailing switches should be to make it impossible
to give a clear Signal with the switch open or partially open. With ordinary In-
terlocking this is improbable but not impossible. The only absolutely certain
method is by working the Signal by means of the last movement of the plunger
of facing point lock as shown on page 68. A switch detector, however, worked by
the home signal connection may well be accepted as suflSciently certain, but with-
out this a crossing should not be considered absolutely safe. In this connection
we may consider the working of switches and locks by two lines of wire which is
far less costly than pipe, but which is open to objections that should be clearly
stated and understood. It has been demonstrated that switches and locks can
be worked by means of continuous wire and they are certainly easier for the
operator. But it is equally certain that perfect means have not yet been found to

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automatically counteract the effects of the stretching of the wires caused by
varying strains. Adjusting screws are furnished and answer perfectly well when
handled by competent men, but just at those places where wire working switches
are likely to be used, competent repair and maintenance men are least likely to
be found. While, therefore, we are prepared to connect switches by wire, and
have the most perfect appliances in the field for so doing, we recommend the
pipe connections solely because they are more easily kept in order. The wire
working can be made perfectly safe, except that, when from any cause they be-
come too slack to throw the switch, the operator is usually not sufficiently skilled
to know how to tighten them to do their proper work. A passenger train may
be standing waiting for the signal which the operator is unable to lower, owing to
the imperfect action of the switch. He becomes excited, and instead of going to
the switch to ascertain the trouble, he will wave his lantern" for the engineman to
come ahead, which the latter will frequently do, and so derail his train. This has
happened several times.

A great many efforts have been made to work and lock a switch by means
of one lever, and various devices are in existence for accomplishing that purpose.
We believe we have the only movement that does the work perfectly and in a
thoroughly satisfactory manner. We have accomplished this by giving a long
initial stroke to the pipe connection which thereby reduces the power of the opera-
tor for rupturing them by giving him less leverage. At the same time, by using
our anti-friction pipe carriers, the force required to move the connection is much
lessened, and finally the switch and lock movement itself is so designed as to
give the minimum of resistance in its proper work, and the maximum for
rupture. With this device we claim that switches can be worked with greater
facility than those having a separate lock lever, and as safely. When a con-
nection becomes broken the operator knows it through his switch detector,
which prevents the signal from being lowered unless the switch is properly

Our devices for working signals and switches from the centre of a draw-
bridge are now so complete, that not only do we obtain as perfect working as
from ordinary towers, but no trouble is experienced from the changing position
of the draw due to expansion and contraction, and the movement caused by
passing trains. It very frequently happens that switches are located near the
end of a drawbridge, and the use of a machine fixed in the centre of the draw
and worked by the draw tender saves the expense of switchmen at one or both
ends of the draw. It is very essential, however, that the connections be so ar-
ranged as to require little adjustment and be easily kept in good order. Due al-
lowance should also be made for the jarring to bridge couplers, caused by trains

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passing on and off the bridge. All these requirements are met by the appliances
shown in our illustrations.

A fruitful source of danger to trains is the misplaced switch which is contin-
ually causing disaster and which can almost invariably be avoided by the use of
distant switch signals. It is absolutely certain that with facing switches unpro-
tected by a signal these accidents will continue to happen in the future, as they
have done in the past. It is not an expensive matter to have these signals and
they can be arranged to be fixed in connection with any kind of switch stand.
We have been unable in this issue of our catalogue to illustrate distant switch
signals, but will be pleased to furnish plans and prices upon application.

For roads not having sufficient traffic to warrant the use of distant switch
signals we can furnish padlocks for the ordinary switch levers so arranged that
the switchman cannot take out the key of the padlock until the switch is set and
locked for the main track. For switches also that are too far from a tower to
be conveniently worked, we have a key locking arrangement, by means of which,
a key must be taken from the tower to open the outlying switch, and until the
key is brought back to the tower no signal can be given for a train to proceed
in the direction of the switch, and of course the key cannot be brought back
until the swftch is set and locked for the main track. This method is a slow
but very safe arrangement.

It very frequently happens that a signal tower is located at or near a street
crossing, in which case it is decided economy to work the gates from the tower,
and they ma/ be interlocked with the signals or not, as may be found most de-
sirable. This is very often found much more convenient, as well as safer, than
having a separate man on the ground, who is liable to raise or lower his gates at
the wrong moment, and besides, cannot see approaching trains so well as the man
in an elevated tower. The ordinary lifting gates may be used, or swinging gates
which close against the street in one position, and against the railroad in the
other, so preventing cattle, etc., from getting on to the railroad when being
driven over the crossing.

Various devices are in use for notifying enginemen of the position of signals
during foggy weather. The most usual method of doing this is to place men at
the signals with torpedoes, which they fasten to the rails according to the posi-
tion of the signal. Unless this is done, or some automatic system used, trains
will necessarily be delayed. So far as we know, nothing has yet been put into
service that gives complete satisfaction, although numerous inventions have been

It is the custom in France to attach a torpedo to each home signal, so ar-
ranged that when the signal is at " danger '* the torpedo is on the track, and when

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the signal is at ** clear/* the torpedo is withdrawn clear of the track, so that only
when an engine or train runs past the signal at danger is the torpedo exploded,
k is often important to know if an engineman has overrun his signal and this
will give some indication^but not certain evidence, as there is nothing to prevent
an operator throwing his signal to '' danger " during the passage of a train, and
so putting the torpedo on the track in front of the wheels.

The Palmer torpedo signal is in use to some extent and has given, so far
as we know, general satisfaction. It works with the home signal as described
above, but the instrument is arranged to hold five torpedos, and when one is ex-
ploded another takes its place until the five are exhausted, when the box has to
be filled again.

Some efforts have recently been made to introduce an illuminated blade for
signals, so as to show a night signal as near as possible like the day signal, but so
far these efforts have not been very successful. The idea of illuminating the
blade is quite an old one, and has been extensively tried, but never with enough
success to displace the usual lamp showing red for '' danger *' and white for '' all
clear." Notwithstanding that some objections can be raised to this method of
night signaling the fact remains that if accidents do occur through its use they
rarely or never come to light and tens of thousands of these signals are in ser-
vice and have been for years. It is quite probable that could equally good re-
sults have been obtained by colors for day signals, color instead of position
would in all probability have been chosen. With a sky background the position
signal by day shows perfectly, but unfortunately we cannot always obtain a sky
background, so that it is impossible to give an equally good signal for all places.
Ordinary observation will convince any one that a day signal may much more
easily be passed unobserved than a night signal. The improvement needed
then, is not in night but in day signals.

In considering the question of position signals for night, we need to be care-
ful not to be allured into its adoption for the sake of comforming to the princi-
ple adopted for day signals. It is quite reasonable to have one principle for
day and another for night ; and unless it can be shown that there are important
grounds for change other than mere uniformity, it would seem to be undesirable
to make a new departure from an old established system which has worked so
well in the past.

What are the advantages to be gained by introducing illuminated blades
instead of the different colored lights, that would warrant railroad companies to
depart from present usage ? They perhaps are more distinctive, but certainly
are not so arrestive as a strong light through a good red lense. Are they less
expensive in first cost or to maintain ? On the contrary, in both they will ex-

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ceed the present methods. Will they retain the same uniform state of illumina-
tion ? No ; they are more liable to derangement, and more difficult to keep
from becoming dim and obscure. Are they more desirable because of color
blindness? No; colorblindness can readily be detected and precaution should
be taken to remove men from a position they are unfitted for. Trains carry
colored lights in their rear and the misunderstanding of such would lead to ac-

It may be said that their chief advantage lies in the fact that they differ
from other lights about cities, more than the old systems.

Let us examine this. What is there in it ? On the surface it is striking.
Are not enginemen conversant with the road they run over ? do they not know
the location of all their signals, and can a light be added to or taken from the
systems through which they pass without being detected by them? If so, we are
in a sorry plight, because neither system gives us security. Lights may be ex-
tinguished and the rule which says, ^^The absence of a signal where there should be
one must be taken as a danger signal " presupposes knowledge of the positions of
all signals which govern the movements of the enginemen, and if one fails to ob-

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Online LibraryJohnson Railroad Signal CompanyCatalogue of interlocking and railroad signaling appliances → online text (page 1 of 7)