Improvements in or connected with Railway Signal Apparatus.
Year: 1896

page_text: Date of Application, 14th Jan., 1896
LE 12th Dot 1806 Accented 12th Dec. 1896
PROVISIONAL SPECIFICATION.
Improvements in or connected with Railway Signal Apparatus.
We ALFRED GEORGE WALKER of 6 Victor Road, Holloway in the County of
London, Fitter, and PETER BLACK of Canterbury Road, Kilburn in the County of
London, Engineer do hereby declare the nature of this invention to be as follows:-
If often happens that there are places on a railway where the presence of a train
standing would interfere with safe working of the traffic, and therefore it is desirable
that if a train happens to be there, such of the signals should be locked as might,
if free, be lowered to admit other trains to that part of the line or to adjacent lines
obstructed by the standing train. In order to effect this it is usual to provide at such
a part of the line a clearance bar like the safety bar used at points, so mounted that
it cannot be moved while a train is over it, and so to connect the motor of this bar
to the signal motor that the signal cannot be lowered to the "safety" attitude until
the signalman bas first, by moving the clearance bar, ascertained that no train
is over it.
It may happen, however, that the rods or pulls for moving the clearance bar have
given way so that the signalman, finding no impediment to the movement of his
clearance bar lever, may consider that there is no train over the bar, and may so
work his lever as to release his signal..
Our invention relates to means of detecting and providing against any such
accident to the clearance bar motors as renders them ineffective in moving the bar
and consequently might permit a signal to be given in cases in which it should not
be given.
For this purpose, we connect to the clearance bar a slide which can move parallel
to a slide connected to the signal lever by a pull, which, when the signal is at
"danger," is normally slack so that the movement of the signal lever merely takes
up the slack of the pull and does not act on the signal. In order that the lever may
be rendered operative, the signalman must first move the clearance bar to and fro.
If a train is over it he cannot do so, and therefore he cannot render bis signal lever
operative, but if no train is over the bar then by its movement in the one direction
the slide connected to it becomes engaged by a spring detent with the slide connected
to the signal lever, and by its back movement this latter slide is also moved back
with it tightening the signal pull and thus rendering the signal lever effective on the
signal which can then be moved to "safety." By means of a treadle, at a suitable
place, moved by a passing train, the detent which holds the slides in engagement is
released, and thereupon the signal slide returns to the normal position, the signal
going to "danger." By interlocking the two slides above mentioned in the known
manner, by providing a cross slide, or tappet to engage in notches at their edges,
the same result is attained without requiring the action of a treadle, that is to say,
the signal slide is locked so that the signal cannot be lowered to "safety" until the
clearance bar has been pulled to and fro, its slide accompanying it and unlocking the
signal slide which can then be moved, setting the signal to "safety." On raising
the signal to "danger" its slide becomes again locked by the slide of the clearance
bar, so that it cannot be moved till the clearance bar has again been moved to and fro.
The locking slides above described may be placed in any convenient position between
the clearance bar and the signal cabin.
Or interlocking slides may be arranged in the signal cabin, connected respectively
to the levers that work the clearance bar and the signal, and a set of return connections
from the clearance bar may operate on these slides, so that the signal lever remains

page_text: locked until the return connections from the clearance bar are moved so as to
release it.
Dated this 14th day of January 1906
ABEL & IMRAY,
Agents for the Applicants.
Improvements in or connected with Railway Signal Apparatus.
We, ALFRED GEORGE WALKER of 6 Victor Road, Holloway in the County of
London, Fitter, and PETER BLACK of Canterbury Road, Kilburn, in the County of
London, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
It often happens that there are places on a railway where the presence of a train
standing would interfere with safe working of the traffic; and therefore it is desirable
that if a train happens to be there, such of the signals should be locked, as might,
if free, be lowered to admit other trains to that part of the line or to adjacent lines
obstructed by the standing train. In order to effect this it is usual to provide at
such a part of the line a clearance bar like the safety bar used at points so mounted
that it cannot be moved while a train is over it, and so to connect the motor of this
bar to the signal motor that the signal cannot be lowered to the "safety" attitude
until the signalman has first, by moving the clearance bar, ascertained that no
train is over it.
It may happen, however, that the rods or pulls for moving the clearance bar have
given way so that the signalman, finding no impediment to the movement of his
clearance bar lever, may consider that there is no train over the bar, and may so
work his lever as to release his signal.
Our invention relates to means of detecting and providing against any such
accident to the clearance bar motors as renders them ineffective in moving the bar
and consequently might permit a signal to be given in cases in which it should not
be given.
For this purpose we connect to the clearance bar a slide which can move parallel
to a slide connected to the signal lever by a pull which when the signal is at
"danger," is normally slack so that the movement of the signal lever merely takes
up the slack of the pull and does not act on the signal. In order that the lever may
be rendered operative, the signalman must first move the clearance bar to and fro.
If a train is over it he cannot do so, and therefore he cannot render his signal lever
operative, but if no train is over the bar then by its movement in the one direction
the slide connected to it becomes engaged by a spring detent with the slide connected
to the signal lever, and by its back movement this latter slide is also moved back
with it.tightening the signal pull and thus rendering the signal lever effective on the
signal which can then be moved to "safety." By means of a treadle, at a suitable
place moved by a passing train, the detent which holds the slides in engagement is
released, and thereupon the signal slide returns to the normal position the signal
going to "danger."
This arrangement is shewn on Sheet I of the accompanying drawings.
Fig. 1 is a plan, Fig. 2 is a side view of the treadle.
Figs. 3, 4 and 5 are sections on the lines 3, 3, 4, 4 and 5-5 respectively of
Fig. 2.
Fig. 6 is a section on the line 6-6 of Fig. 1.
Fig. 7 is a section on the line 7-7 of Fig. 1.
Fig. 8 is a part of the treadle and detent drawn to an enlarged scale.
Sis the signal loves the 11

page_text: inoperative to lower the signal s1. B is the lever which works the clearance bar b..
The bar is connected to a slide 1 which is connected by a projecting arm to a
sliding treadle T. Another slide parallel to 1 is connected to the signal pull s..
To the slide is fitted a cross slide 3 under the front of which is a wedge shaped
detent, which when the slide is moved to the right is forced by an incline 6³
projecting from the treadle to engage in a notch 6 thus locking together the two
slides b' and ' so that when b' is pulled back to the left, the signal pulls is tightened
rendering the lever S effective for lowering the signal. When the wheel flange of
a passing train depresses the treadle T to the position shewn in Figures 2, 3, 4, 5
and 6 and thus the projecting incline 63 being lowered below the end of the cross.
slide allows that slide to be pushed forward by the spring withdrawing its detent
from the notch and thus releasing the slide s from b. When the slide 6¹ is moved
to the right the arm 62 moves the treadle T to the right and as an incline on its.
underside passes over a roller & the left end of the treadle is raised its projecting
incline 63 passes on to the end of the cross slide 3. By interlocking the two slides
above mentioned in the known manner by providing a cross slide or tappet to.
engage in notches at their edges the same result is attained without requiring the-
action of a treadle, that is to say, the signal slide is locked so that the signal cannot
be lowered to "safety" until the clearance bar has been pulled to and fro its slide-
accompanying it and unlocking the signal slide which can then be moved, setting the
signal to safety. On raising the signal to "danger" its slide becomes again locked
by the slide of the clearance bar, so that it cannot be moved till the clearance bar
has again been moved to and fro. The locking slides above described may be
placed in any convenient position between the clearance bar and the signal cabin.
This arrangement is shewn on Sheet II of the drawings.
Fig. 9 is a plan, Figures 10 and 11 are longitudinal sections of the slide box.
Figs. 12 and 13 are side views of the tappets t¹ t².
Fig. 14 is an end view of the slide box and
Fig. 15 is a side view shewing the connection of the slide s to the signal lever S.
The apparatus is shewn in the condition in which the signal s' is free to be.
lowered. On moving the bar s² to lower the signal the inclined end s³ of its long
notch acts on the inclined end of the tappet 2 pushing that tappet into a notch b²-
of the bar b. On pulling back to raise the signal an inclines on its under-
side rides over an incline t on the flange of the tappet t2, and dropping behind
locks the bar s2 so that it cannot again he moved to lower the signal. Now on
moving the lever B thereby pushing forwards an incline 63 under the left side-
of its notch brides over an incline on the edge of 2 raising the bar b¹ on the
dropping of which a second notch presents itself to the end of 2. On now
moving the lever B so as to draw back, the incline of its notch acting on
the incline on the end of t2 pushes 2 into the notch of 2 thereby leaving the-
signal again free to be lowered. In order to ensure that the bar must he
pushed quite back before the signal is unlocked, the tappet which by the-
forward movement of becomes engaged in a notch of 2 cannot release s until
it finds the corresponding notch of into which it can be pushed by the move-
ment of s for lowering the signal.
The interlocking slides and 2 instead of being arranged in the signal cabin
as shewn in Sheet II may be connected respectively to the clearance bar and to.
the signal pull in any convenient position, the slide being operated only by a
set of return connections from the clearance bar, se that the signal remains locked
at danger until it is released by the bar which can only happen when the.
return connections from the clearance bar and therefore the bar itself are moved.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In combination with a signal lever and a lever for working a clearance bar
or pair of bars, the one connected to the clearance bar the other to the signal

page_text: pull with an interlocking slide and treadle arranged and operating substantially
as described with reference to Sheet I of the accompanying drawings for the purpose
set forth.
2. The modified arrangement substantially as described with reference to Sheet II
of.the drawings.
Dead : 104L Jon of Octable 1904
ABEL & IMRAY,
Agents for the Applicants.