AN IMPROVEMENT IN RAILWAY SIGNALS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, WILLIAM BUCK of No 31 Brondesbury Villas, Kilburn, in the county of
Middlesex, Engineer do hereby declare the nature of my said invention for
AN IMPROVEMENT IN RAILWAY SIGNALS" to be as follows:-
"
It sometimes happens that, in the neighbourhood of a station or signal box,
a railway train or part thereof remains stationary for a time in a position where it
is not seen by the signalman, for example, within a tunnel, and that in consequence
of this obstruction of the line not being seen, a signal may be given admitting
another train. Even in cases where the stationary train can be seen, the signalman
may forget its presence, and may give a signal admitting another train. My
invention relates to means of preventing accidents from this cause, by subjecting
the telegraphic or semaphore signal which might be used to admit a second train
to the obstructed part, to the control of a locking bar, such as is usually employed
for locking points, that is to say, a bar which cannot be moved until the obstructing
train has passed quite beyond tho bar, leaving the line clear. For this purpose,
I apply to the signal lever or telegraph handle a pawl-catch which allows it to be
moved once to give the signal for passage and back again to block the line, but
which prevents it from giving the signal a second time until another lover has been
moved. This other lever is connected to the locking bar above mentioned, and so
long as this bar is prevented from being moved by the presence of a train ovor it,
this second lever cannot be moved, and consequently the signal lever or handle
cannot be moved so as to give a clear signal a second time.
In many cases it is of advantage to provide, as an additional precaution, a second
starting or advance signal near the bar, and so to interlock the bar therewith that
after the bar has been once moved, it cannot be moved again until this signal has
been lowered and raised. When the signals and bar are thus arranged, the
operations of the signalman take the following order. He first moves the lever
which works the locking bar, being able to do so only when the line at the bar is
clear;
he can then give the signal permitting a train to pass on to the bar, and, the
train having passed on, he again moves the signal to block the line. He can then
lower the advance signal near the bar, permitting the train to go forward, leaving
the bar clear, and, the train having passed on, he puts this signal back to "danger."
He can now move back the bar, so restoring the system to the condition in which
it was at the commencement of the operation.
-

page_text: When it is intended to pass a train on without allowing it to remain over the
bar, the signalman first moves the bar, thereby making sure that this part of the
line is clear. He then lowers the advance signal near the bar, thus locking the bar,
and he can now move the signal permitting a train to advance, and again move it
to block the line. Having done so, he puts the advance signal to "danger" and
moves back the bar to its original position, thus restoring the system to the condition
in which it was before the commencement of the operations.
In cases where a considerable length of line has to be under protection of the
kind described, I make the bar in a number of separate lengths, taking care that
the successive lengths and the intervals between them shall be such that no engine
or carriage can stand on this part of the line without having at least one of its
wheels over the bar.
I prefer to counterbalance the bar or its sections, so as to reduce as much as
possible the effort necessary to move them. In cases where the bar is at such
distance beyond the signal which allows a train to approach, that the signalman
could operate as above described during the time occupied by the train in reaching
the bar, I apply to the bar, or to its first length, a catch connected to a treadle, this
catch preventing the bar from being moved until a train shall have passed over the
treadle, releasing the bar.

page_text: COMPLETE SPECIFICATION.
I, WILLIAM BUCK of No 31 Brondesbury Villas Kilburn in the County of
Middlesex, Engineer do hereby declare the nature of my invention for " AN
IMPROVEMENT IN RAILWAY SIGNALS" and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
It sometimes happens that in the neighbourhood of a station or signal box
a railway train or part thereof remains stationary for a time in a position where it
is not seen by the signalman, for example, within a tunnel, and that in consequence
of this obstruction of the line not being seen a signal may be given admitting
another train. Even in cases where the stationary train can be seen, the signalman
may forget its presence and may give a signal admitting another train. My
invention relates to means of preventing accidents from this cause by subjecting
the telegraphic or semaphore signal which might be used to admit a second train
to the obstructed part, to the control of a locking bar, such as is usually employed
for locking points, that is to say, a bar which cannot be moved until the obstructing
train has passed quite beyond the bar, leaving the line clear. For this purpose,
I apply to the signal lever or telegraphic handle a pawl-catch which allows it to be
moved once to give the signal, for passage and back again to block the line, but
which prevents it from giving the signal a second time until another lever has been
moved. This other lever is connected to the locking bar above mentioned, and so
long as this bar is prevented from being moved by the presence of a train over it,
this second lever cannot be moved, and consequently the signal lever or handle
cannot be moved so as to give a clear signal a second time.
In many cases it is of advantage to provide as an additional precaution a second
starting or advance signal near the bar, and so to interlock the bar therewith that
after the bar has been once moved, it cannot be moved again until this signal bas
been lowered and raised. When the signals and bar are thus arranged, the
operations of the signalman take the following order. He first moves the lever
which works the locking bar, being able to do so only when the line at the bar is
clear. As this lever is interlocked in the usual way with the signal lever, he can,
after moving the bar lever, give the signal permitting a train to pass on to the bar,
and, the train having passed on, he again moves the signal to block the line. He
can then lower the advance signal near the bar, permitting the train to go forward,
leaving the bar clear, and, the train baving passed on, he puts the signal back to
danger." He can now move back the bar, Bo restoring the system to the condition
in which it was at the commencement of the operation.
"
When it is intended to pass a train on without allowing it to remain over the
bar, the signalman first moves the bar thereby making sure that this part of the
line is clear. He then lowers the advance signal near the har, thus locking the bar,
and he can now move the signal permitting a train to advance, and again move it
to block the line. Having done so, he puts the advance signal to "danger" and
moves back the bar to its original position, thus restoring the system to the condition
in which it was before the commencement of the operations,

page_text: In cases where a considerable length of line has to be under protection of the
kind described, I make the bar in a number of separate lengths, taking care that
the successive lengths and the intervals between them shall be such that no engine
or carriage can stand on this part of the line without having at least one of its
wheels over the bar.
I prefer to counterbalance the bar or its sections so as to reduce as much as
possible the effort necessary to move them. In cases where the bar is at such
distance beyond the signal which allows a train to approach, that the signalman
could operate as above described during the time occupied by the train in reaching
the bar, I apply to the bar or to its first length, a catch connected to a treadle this
catch proventing the bar from being moved until a train shall have passed over the
treadlo releasing the bar.
Fig. 1 of the accompanying drawings represents part of a line protected by
a safety bar as above described, this bar being made in several lengths A linked
together and counterbalanced at several points B. H is the signal for admitting
a train on the protected part of the line, and J is the signal permitting it to depart.
Figs. 2 and 3 are respectively a part side elevation and transverse section shewing
the bar A which is, as usual, mounted on radii C, and one of the counterbalances B.
The rod by which the bar is worked from the signal cabin is shown at D. Fig. 4
is a side elevation partly in section, and Fig. 5 is a transverso section of the treadle
and catch which prevent the bar being moved until a train has passed the treadle.
E is the treadle which is fitted to slide between guides with a frictional resistance
determined by the pressure of an adjustable spring F, this friction being so adjusted'
that the treadlo will not descend unless it is pressed down by the flange of
a wheel W passing over it. D₁ is a rod connected to the rod D which works the
bar A so as to move simultaneously with D. This bar D' has near its end
a protuberance & sloping both ways. When the treadle E has been pressed down,
by the passage of a wheel over it, it presents a slot through which the end of the
rod D¹ passes when this rod is advanced in the act of moving the bar A. In this
movement the protuberance & raises the treadle E, and when the rod D¹ is retracted a
the treadle remains up as shewn in Fig. 5, but the end of the rod D¹ drops so as to
be obstructed by the raised treadle; consequently as D' cannot again be advanced,
the bar A cannot be moved until the treadle E is again depressed by a passing
whoel.
.
In cases where it is desirable to leave the bar A free to be moved, so as to
ascertain whether a train is standing on the part of the line protected by the bar
or not, the treadle E may be interlocked directly with a signal, without being
interlocked with the bar and through it indirectly with the signal as above
described. For this purpose the rod D', instead of being a continuation of tho
rod D which works the bar, may be an extension from the rod that connects
a signal lever with a signal, so that, in lowering the signal, the rod D' has to
advance through the slot of E when E is depressed. When E is not depressed, it
obstructs the forward movement of D' and consequently locks at danger the signal
to which D' is connected.
Fig. 6 is a plan of three levers in the signal box, namely G the lever which moves
the safety bar A, H the lever which works the signal H Fig. 1 admitting a train to
that part of the line which is protected by the bar, and J the lever which works
the signal J Fig. 1 permitting a train to pass from that part of the line. Fig. 7 is
a'transverse section on Z Z Fig. 6. Figs. 8 and 9 are longitudinal sections showing
the interlocking of the levers G and H in their two conditions, and Figs. 10 and 11 ¿
are similar sections shewing the interlocking of the levers G and J in their two
conditions. On the lever G there is fixed a projecting stop g, and to the lever H is
jointed a bar h with ratchet teeth h' and h on its under side. On the framing is
mounted a lever K carrying a tumbling weight, and to this lever is linked a swing
stop lever by a connecting plate M in which there is a curved slot m engaging
a stud on a vertical bolt n. The action of these parts is as follows:-The lever G
having been pulled over moving the safety bar Ar and at the same time, through the
1

page_text: ordinary interlocking, releasing the signal lever H, this lever is pulled over from
the attitude shewn in Fig. 8 lowering the signal, and is then put back as indicated
in Fig. 9, having again raised the signal. In thus putting back the lever H, the
tumbling lever K is thrown over by one of the teeth h¹, and it pushes forward the
stop and raises the bolt n as indicated in Fig. 9. Now the lever H cannot be
pulled over again because one of the teeth his obstructed by the bolt n. But when
the lever G is put back, its stop g acting on 6, moves back the parts to the condition
shewn in Fig. 8, when the operation can be repeated. The interlocking of the
levers G and J is arranged as follows. To G and J are jointed respectively the
bars gl and j and under the paths of these bars a sleeve P is mounted free to turn
and having on it two pinions p' p³ each of three teeth, the teeth of the one corre-
sponding with the spaces between the teeth of the other. The levers J and G are
so correlated by ordinary interlocking that when J is in the position shown, the
lever G is freo. When Ğ is pulled over to the attitude shewn in Fig. 11, having
moved the safety bar A, it cannot be put back because a tooth g³ on the bar g' is
obstructed by the edge of the fixed framing. On now pulling over J a tooth on
the bar j in passing the pinion p³ turns it partly round so that a tooth of p¹ passing
under the bar g' raises it so that its tooth g³ is clear of the obstruction. If now J is
put back, thereby, through the ordinary interlocking, releasing G, then G can be
moved back, restoring the parts to their original condition.
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 combination with the safety bar A. and its rods D D¹, the lever G, the
treadlo E, the signal levers H and J and their respective gears interlocking them
with G, arranged and operating substantially as described.
2. In combination with the safety bar A and its rods D D' the lover G, the
treadle E, the signal lever H and the gear interlocking G and H substantially as
described.
3. The combination of the treadle E and the rod D' connecting to a safety bar
or signal, arranged and operating substantially as described.
Dated this 6th don of Tmin 1008