IMPROVEMENTS IN SIGNALLING APPARATUS
Year: 1881

page_text: LETTERS PATENT to John Carter Park and Henry James Pryce, both of Bow,
in the County of Middlesex, Engineers, for an Invention of "IMPROVEMENTS
IN SIGNALLING APPARATUS."
PROVISIONAL SPECIFICATION left by the said John Carter Park and
Henry James Pryce at the Office of the Commissioners of Patents on the
29th March 1881.
JOHN CARTER PARK and HENRY JAMES PRYCE, both of Bow, in the County of
Middlesex, Engineers. "IMPROVEMENTS IN SIGNALLING APPARATUS."
This Invention relates to certain improvements in the construction and arrange-
ment of signalling apparatus on railways, for the purpose of controlling one signal
by another, the object in view being to render it impossible for the signalman to
admit a train to a section of the line until the signal for clearing that section has
been first lowered and then raised again.
This arrangement is particularly adapted for use in regulating the admission of
trains to stations.
This Invention also relates to a novel construction and arrangement of apparatus
for preventing a train or locomotive while waiting at a stop signal from being run
into from the rear, owing to the lowering of the signal or signals behind such train
or locomotive through carelessness or forgetfulness on the part of the signalman.
In carrying out the first part of our Invention we provide a small auxiliary or
"permissive" main signal in connection with the main "stop" signal, and we
control the movement of the "permissive" signal by its connection with the
"starter" or advance main signal.
Thus if the line is to be signalled as "clear" the advance main and the main
stop signals will be lowered, and in so doing the "permissive” signal will also be
lowered.
If however a train has to be admitted to the platform between the advance and
main stop signals the operation will be conducted as follows:-The signalman
(assuming he has not received the message "line clear" from the station ahead)

page_text: will merely lower the "permissive" signal, and the train will draw up to the
platform. The "permissive" signal lever on being released will return that signal to
danger, and will be automatically locked so that it cannot be again lowered until
the "starter or advance main signal has been both lowered, to allow of the train
passing out of the station, and subsequently raised to its normal position of
danger.
"
Thus the "permissive" signal lever if once pulled over even to a small degree and
pushed back again, cannot again be pulled without repeating the double movement
of the "starter" or advance main signal lever. By this means the defects and
risk attending the use of hand signals, flags, or lamps, are avoided, and it will be
impossible for the signalman who has charge of the levers above mentioned to
admit more than one train at a time between the main signal and the "starter."
This arrangement may be applied to any number of levers or signals, the
essential feature being that the signals of one set having been lowered and raised
once cannot be actuated a second time until the signals of another set in advance
of them have been both lowered and raised.
In order to give a clearer indication of the nature of our Invention, we will
describe it as applied to the well known system of signalling, in which "lifters" or
"combs" and horizontal locking bars are employed.
Two horizontal parallel bars are fitted on their inner faces with studs having
inclined surfaces. These studs are so arranged that when they are slidden past
each other their broad ends will interlock by reason of the parallel bars being
drawn together by a spring or weight. Thus on lowering the advance main signal
these studs will interlock, and on releasing the advance main lever the inner bar
will be caused to travel a sufficient distance to withdraw a locking catch from the
"lifter" or "comb" of the "permissive" signal which may then be actuated.
On pulling over the lever of the "permissive" signal an inclined projection on
the surface of its "lifter or "comb will separate the parallel bars, thus
disengaging the locking faces of the studs thereon.
The inner parallel bar by reason of a weighted arm or spring attached to it will
then be moved longitudinally a short distance, causing the inclined surfaces of the
studs to overlap slightly; at the same time a solid part of the "lifter" or "comb "
will be brought into such a position as to prevent the further longitudinal move-
ment of the said inner bar until the "permissive "lever has been put back to its
normal position, when its "lifter or "comb" being lowered the locking catch on
the inner bar will be free to enter its proper space in the "lifter" or "comb" and
re-lock the " permissive" signal, which can then only be released by the double
movement of the advance main signal, as already described.
"
It should be remarked that the "permissive" main and the starter will lock and
counterlock in the usual manner. Thus when the lever of one is pulled the other
will be locked in its normal position, no retaining catch (except for keeping it in
its normal position) being used for the "permissive" signal lever, which is weighted
to return it to its normal position.
It will be obvious that the various systems of signals in use will require to be
specially treated in adapting to them the principle above set forth.
The second part of our Invention consists in an arrangement for preventing a
train while waiting at a stop signal from being run into by another train from the
rear, owing to the lowering of the signal or signals in the rear of the standing
train.
This arrangement of mechanism consists of a bar or framing mounted on lever
arms at the side of or between the metals, such bar or framing being of sufficient
length to ensure that when a train or locomotive is walting in its place for the stop
signal to be lowered, some one or more of the wheels thereof shall overlie the said
bar or framing and prevent it from being moved. One of the short lever arms
upon which this bar or framing is mounted is fast upon a transverse shaft, upon
which another longer lever is also fixed. To this long lever is connected the rod
or a continnation of the rod which works the stop signal, and also the rod or wire

page_text: which works the signal or signals in the rear. The rod from the stop signal is
slotted so that the signal may be lowered without pulling over the movable bar or
framing, but when the stop signal is put to danger, the said bar or framing will be
pushed over to its normal position in which it is intended to receive the approaching
train or engine. The rod or wire connecting the long lever with the distant signals
is so arranged that a stop or its equivalent on such rod or wire will engage with
the said lever when in its normal position (that is, when the bar or platform is
ready to receive a train) and permit of the said lever being moved when the bar or
platform has nothing upon it.
So soon as a train has been admitted to that section of the line and any one of
its wheels bears upon the bar or platform when in its normal position, it will be
impossible to lower the distant signal. Thus so long as a train remains in that
section, the line behind it will be blocked by the signals in the rear.
The stop signal by reason of the slot in its rod above referred to, is however
free to move.
The signalman can therefore lower the stop signal and allow the
train to pass it, but not until its last wheel is clear of the movable bar or platform
will he be able to lower his distant signal to admit another train to that section of
the line.
If however a train should be passing the platform or bar (the signal in the rear
being lowered) and the signal man desired to put that signal to danger, he would
be enabled to do so by reason of the slot or its equivalent in the wire or rod from
that signal working freely through the lever arm attached to the bar of the
platform:
It will be necessary under certain circumstances to provide a stiff spiral spring
or its equivalent between the stop signal and the movable bar or platform to allow
of the main stop signal being set to danger and the branch signal lowered, even
though a train may be standing upon or passing over the said bar in the position
it will assume when the main stop signal is lowered. The bar or platform may be
returned if desired to its normal position by means of a weighted lever, and in
this case a slot or its equivalent will take the place of the spiral spring and for the
same purpose.
It is obvious that other means may be devised to carry out this principle of
action, which consists essentially in automatically fixing at danger the signals in
rear of a train or engine, so long as that train or engine is waiting at a stop signal
while at danger, and until the last wheel of that train has passed the position of
the stop signal, or nearly so.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Carter Park and Henry James Pryce at the Great Seal
Patent Office on the 29th September 1881.
JOHN CARTER PARK and HENRY JAMES PRYCE, both of Bow, in the County of
Middlesex, Engineers. "IMPROVEMENTS IN SIGNALLING APPARATUS."
This Invention relates, firstly, to certain improvements in the construction and
arrangement of signalling apparatus on railways for the purpose of controlling
one signalling apparatus by another, the object in view being to render it
impossible for the signalman to admit a train to a section of the line until the
signal for clearing that section has been first lowered and then raised again.
This arrangement is particularly adapted for use in regulating the admission of
trains to stations.
Our Invention also relates to a novel construction and arrangement of apparatus
for preventing a train or locomotive while waiting at a stop signal from being run
into from the rear, owing to the lowering of the signal or signals behind such
train or locomotive through carelessness or forgetfulness on the part of the
signalman.
In Sheet. I. of the accompanying Drawings Fig. 1 is a diagram illustrating an
intermediate station with a starting signal at A and the main stop signal at B.
The post which carries the main stop signal B is also fitted with a permissive
main signal C, the lowering of which, without the signal B being altered, indicates
that a train may enter the station, and it is to prevent this signal being given
before the semaphore at A, which gives the starting signal, has been lowered and
again raised that the improvement constituting the first head of the Invention is
mainly designed.
Fig. 2 is a plan view partly in section of the apparatus by which this result is
obtained, the apparatus being combined with a well known locking signalling
apparatus.
Fig. 3 is a cross section taken in the line 1, 2, of Fig. 2, Fig. 4 is a partial side
elevation of the same, and Fig. 5 is a cross section drawn to a smaller scale in
order to shew the connection of the apparatus with the signalman's cabin.
In this apparatus as in the ordinary locking signalling apparatus, hand levers
are used, as at C*, Fig. 5, for lowering and raising the semaphores through the
ordinary rods or wires, and connected to these levers are the "lifters" or "combs,"
by which the levers are automatically locked to prevent their being used out of
their proper order.
In carrying out our improvements we employ a lifter or comb C¹, with which
the hand lever C* employed for actuating the semaphore C is connected.
This lifter C¹ is provided with any suitable number of notches for receiving the
stops of sliding bars connected with other semaphores of the local signalling
apparatus or with adjacent "points."
-
D, Figures 2 and 3, is a sliding bar mounted in a longitudinal frame D', and
free to slide in guides therein. This bar is fitted with a locking catch d for
entering a notch of the comb C¹ and locking it, and thereby preventing its
lever C✶ from dropping the semaphore C and signalling a train to advance.
The sliding bar D is also provided with a wedge-shaped catch d¹ for the purpose
to be presently explained, and a tendency is given to this bar by means of a
weighted bell crank lever d³ to move in the direction of the arrow, Fig. 2, and
thrust its catch d into one of the notches of the comb C¹.
Sliding in guides in the same frame D¹ is a bar D2, to the back of which near

page_text: its inner end is hinged a bar D³, which is free to slide in a guide provided for it
on the framing D', while it at the same time turns on its hinge coupling.
The bar Ds is fitted on its inner face with a wedge shaped catch d² corre-
sponding in form with the catch d¹ on the bar D by means of a coiled spring d
that couples the bars D and D³ together; the inclined faces of the catches d' and
d' are held in contact.
An endway motion of the bar D2 in the direction of the arrow, Fig. 2, will
cause the catch d² to slide over the catch d¹ and take hold of the latter catch, as
shewn by dots in Fig. 2. The reverse motion of the bar D² will bring with it the
bar D, and cause the catch d of that bar to move out of the notch of the comb C¹
and thereby allow the hand lever C* to be operated for lowering the semaphore
signal C.
It is however requisite that when the signal is thus made for a train to enter
the station the signal of danger shall be raised on the entrance of the train and
locked in that position. To provide for this the sliding bar D must be released,
and allowed to return by the action of the weighted rock lever d³ to the locking
position.
This is effected by means of an incline c attached to the comb C', which incline
bears against a wedge shaped projection d³ on the inner face of the hinged bar D³,
and when raised by the lifting of the comb it will thrust back the hinged bar D
and cause its catch to release the catch d² of the bar D, thus leaving the bar free
to lock the comb C¹ and prevent the working of the lever C*.
To make the unlocking of the semaphore C dependent on the motions of the
starting semaphore signal A, the sliding bar D³ is connected with that semaphore
in the following manner :-Coupled to this bar D2 is a bell crank lever A², one end
of which enters a notch in the lifter or "comb" A¹, to which the hand lever for
operating the semaphore signal A is connected. When therefore this hand lever
is pulled over to lower the starting semaphore it will raise the comb A¹, rock the
bell crank lever connected therewith, and by this means advance the bars D² and
Ds until the catches d', d³, interlock.
•
This movement is only in preparation for that which is to follow. On the hand
lever of the semaphore A being again operated or returned to its normal position
to raise the semaphore A to danger, the comb A¹ will be depressed, the bell
crank lever A2 will be rocked, and a traverse motion will be given to the
bars D2, D³.
Owing however to the interlocking of the catches d', d³, the bar D will be
drawn back in the same direction, and the lifter or comb C¹ will be thereby
unlocked. The signalman will then be able, by pulling over the lever C*, to give
the permissive signal for a train to enter the station.
In order to operate both the semaphores B and C simultaneously by means of
the hand lever which works the main semaphore B (such operation being required
to signal that the line is clear), the contrivance shewn in plan view at Fig. 6 and
in side view at Fig. 7 is adopted. Mounted on a pivot pin carried by the signal
post are three horizontal weighted levers E, E¹, E³; the middle lever E¹ is fitted
with a cross piece, which overlies the side levers, and it is connected by a rod c²
with the semaphore C. The levers E and E2 extend beyond the pivot pin, and
are connected at these extended ends, the one by a wire or rod with the hand
lever C that operates the semaphore C, and the other by a rod or wire with the
hand lever which operates the semaphore B.
This lever E² is also connected at its weighted end by means of a rod b with
the semaphore B. It will now be understood that if the lever E is rocked by the
pulling over of the hand lever C* it will, by reason of the overlying cross piece of
the lever E¹, operate the semaphore C. If however the lever E' is rocked, it will
raise the lever E', and thereby simultaneously act upon both semaphores B and C,
signalling that the line is clear.
From the above description it will be understood that the permissive signal

page_text: lever if once pulled over, even to a small degree, and pushed back again, cannot
again be pulled without first repeating the double movement of the starter or
advance main signal lever.
This arrangement may be applied to any number of levers or signals, the essential
feature being that the signals of one set having been lowered and raised once
cannot be actuated a second time until the signals of another set in advance of them
have been both lowered and raised.
It should be remarked that the "permissive" signal will lock and counterlock
with the main signal and the "starter" signal apparatus in the usual manner,
no retaining catch (except for keeping it in its normal position) being used
for the "permissive" signal lever, which is weighted to return it to its normal
position.
By the use of this permissive signal the defects and risk attending the use of
hand signals, flags, or lamps are avoided, and it will moreover be impossible for the
signalman who has charge of the levers above mentioned to admit more than one
train at a time between the main signal and the "starter."
It will be obvious that the various systems of signalling apparatus in use will
require the apparatus above described to be slightly modified to adapt it to the
special circumstances of the case. These modifications may however be readily
carried out by any competent mechanic.
We will now describe the second part of our Invention which relates, as before
mentioned, to means for preventing a train while waiting at a stop signal or in a
station from being run into by another train from the rear, owing to the lowering
of the signal or signals in the rear of the standing train.
This is illustrated in Sheet II. of the Drawings and consists in utilizing the
train while at the station as a stop for preventing the rising of a bar or frame
connected with the signal apparatus in rear of the train, and thereby preventing
that signal from being lowered until the train has passed out of the station.
Fig. 8 is a side elevation of the apparatus complete, the same being placed near
the end of a bay of a terminus or in front of a stop signal at a station or junction;
Fig. 9 is a plan view of the same, and Fig. 10 is a cross section on an enlarged
scale taken at the line 1, 2, of Fig. 9.
In these Figures A is a horizontal bar of T shape in cross section, set parallel to
and within the rails of the line and close to one side thereof, in the plane of traverse
of the flanges of the running wheels of one side of the train.
This bar is carried by a set of parallel arms a which are jointed thereto, and are
pivotted to bracket pieces pendent from the rail B.
A similar arm a¹ is keyed to a transverse shaft C and jointed to the bar A for
the purpose of preventing the rocking of this shaft until the bar A is free to rise
under the impulse imparted to it by that shaft through the arm a¹.
The shaft C has its supports in brackets D and E, shewn respectively in side
elevation at Figures 11 and 12. The bracket D is made fast to a foundation
plate or to the side wall of the platform, and the bracket E is bolted to the adjacent
rail B.
Mounted loosely on the shaft C, outside the track, is a lever arm F, the free end
of which connects through a rod F' to the pendent limb of a bell crank lever F2
pivotted to the side of the signal post G.
Leading up from the horizontal limb of this bell crank lever is a rod F3 which
connects with the weighted levers employed to actuate the semaphore, as above
explained. The pendent limb of this rock lever is also connected with a rod F
leading to the signalman's cabin, and it is through this rod that the motion for
setting the apparatus in action is obtained.
Close adjacent to the lever F is a one toothed sector H which is keyed fast to
the shaft C. A pawle f carried by the lever F takes onto the tooth of this sector
for the purpose of rocking its shaft when it is desired to lower the signal.

page_text: A segment shaped projection d on the bracket D overlies the path-of the pawle f,
and as the lever F is pulled over in the act of lowering the signal the pawle will
be tripped by its tail coming in contact with the projoction d, as shewn by dots in
Fig. 11, thus leaving the toothed sector free to return to its normal position, as
shewn in the drawn position in the same Figure.
The rocking of the toothed sector H to the dotted position consequent on the
lowering of the signal in the rear of the train causes the bar A to rise to the dotted
position of Fig. 10, but to permit of this taking place the track must be clear, for
otherwise the bar would strike against the overlying flanged wheels, one or more,
and be arrested in its upward movement.
It will now be understood how the presence of a train at the station prevents
the signalman from dropping the semaphore signal in rear of a train at the
platform.
This arrangement does not however prevent the signalman from raising his
signal to danger while the train is in the station and overlying the bar A.
It is however necessary that this rising and falling bar A should, when a train
overlies it, have a slight play to provide for the inequalities in the depth of the
flanges of the wheels.
To permit of this the rod F³ is slotted at the end which connects with the
bell crank lever F2, and thus the bell crank lever is free to move and act upon
the rock shaft C and its connections to a limited extent without affecting the
semaphore.
To ensure the action of the pawle f upon the toothed sector H the bracket D is
cast with a lug or projection, as shewn at d¹, Fig. 13, which serves as a stop
for the tail of the pawle to strike against when the lever F falls back to its
normal position. This striking of the stop d' ensures the pawle being thrown
down into contact with the tooth of the sector, even though by reason of rust
or dirt it should stick and so fail to drop by its own weight into the acting
position.
Figures 14 shew a slight modification of the means for transmitting motion from
the signalman's lever to the rock shaft C.
In this case the lever F is converted into a bell crank lever, the horizontal arm
of which is weighted. This admits of a chain or wire being used in place of the
rigid rod F¹.
To prevent the flanges of the train wheels getting between the bar A and the
adjacent rail B by the bar A yielding to the attempt to raise it (when a train is in
position) and slipping aside past the flanges of the wheels, a lateral support is
provided for the bar in the form of pressing rollers. This arrangement is shewn in
side elevation and cross section at Figures 15.
a² are the pressing rollers mounted vertically in brackets a³ secured, to the
sleepers and extending upwards sufficiently far to form a lateral support for the
bar A, whether in its highest or lowest position. This will prevent all lateral
straining of the joints of the parallel arms a and ensure the overlying wheels of
the train arresting the upward motion of the bar A. when a train is standing at the
platform.
Having now set forth the nature of our Invention of "Improvements in Signalling
Apparatus," and explained the manner of carrying the same into effect, we
wish it to be understood that under the above in part recited Letters Patent we
claim,―
First. The means described with reference to Sheet I. of the Drawings for
preventing the signalling of a train to advance to a section of the line until
the signal for clearing that section has been lowered and again raised.
Secondly. Providing through stations and sections of a line with a permissive
semaphore or other signal capable of being operated upon independently of or
in combination with the main semaphore, as and for the purpose described.
Thirdly. The arrangement of mechanism described with reference to Sheet II. of

page_text: the Drawings for automatically locking at danger the signals in rear of a train or
engine detained by a stop signal or waiting in a station.
In witness whereof, we, the said John Carter Park and Henry James Pryce,
have hereunto set our hands and seals, the Twenty eighth day of
September, in the year of our Lord One thousand eight hundred and
eighty one,
J. C. PARK.
(L.S.)
HENRY J. PRYCE.
(L.S.)