IMPROVEMENTS IN RAILWAY SIGNALLING APPARATUS
Year: 1882

page_text: LETTERS PATENT to Douglas Knight, of Cambridge, in the county of
Cambridge, Engineer, for an Invention of "IMPROVEMENTS IN RAILWAY
SIGNALLING APPARATUS"
PROVISIONAL SPECIFICATION left by the said Douglas Knight at the
Office of the Commissioners of Patents on the 5th July 1882.
DOUGLAS KNIGHT, of Cambridge, in the county of Cambridge, Engineer,
"IMPROVEMENTS IN RAILWAY SIGNALLING APPARATUS
13
This invention is designed to provide simple and efficient signalling apparatus
for use on railways, being especially useful in dark, stormy or foggy weather, and
consists in an arrangement of mechanism for automatically manipulating a hammer
or trigger for exploding detonating signals, or striking a bell or gong, in such
manner that the trigger is put in gear ready for exploding or striking (or out of
gear) from the signal cabin as the semaphore arm is raised or lowered, at the same
time that a rod or standard carrying the signal lights is revolved by the detonating
apparatus.
At or near the signal post I fix a suitable frame or standard carrying a revolving
chamber or disc analogous to a revolving fire-arm, and placed in a horizontal,
vertical or other convenient position. The disc or chamber may carry recesses for
detonators either on its periphery or face as desired. I will, however, describe the
apparatus with the chamber on a horizontal axis and the recesses on its face.
Facing the standard I provide an elbow lever pivoted on a fulcrum and with a
joint in its upper extension which is furnished with a slot and with an incline on
its lower arm. From the standard carrying the revolving chamber, or otherwise,
I bring out, an arm having a fulcrum, on which is pivoted a bell crank lever
carrying a pin on its inner end forming a stop to the play of the elbow lever. The
horizontal artn of the bell crank is pivoted to the fulcrum of another bell crank
lever having a pin on the inner side of its vertical arm. traversing the slot of the
elbow lever and its horizontal arm carrying a counterweight or spring. The outer
side of the upper arm of this bell crank lever carries another pin. A weighted

page_text: vertical bar slides on pins or guides on the side of the main frame and projecting
therefrom is a double inclined plane having a slot or notch in its centre and
carrying at its upper end a.pawl taking into a ratchet wheel fixed to or forming
part of the revolving drum. Another pawl prevents reverse motion of, this drum,
and a counterweighted band or chain is attached to the periphery of the drum,
acting as a feed. Facing the drum I provide a weighted shaft carrying a spring
hammer mounted on a fly catch or pawl and capable of being forced back or
released by the movement of a wiper fixed on the aforesaid weighted vertical bar.
Attached to the firstnamed bell crank lever is a rod connected to a bell crank
preferably by a screw coupling for compensating its length, and which bell crank
carries a treadle by the side of the rail capable of being depressed by the train
wheel. The semaphore arm is connected to the levers of the locking gear, as usual,
and a rod or chain is connected from said gear to the second-named bell crank
lever of the detonating or sounding apparatus. The rod or standard on or by the
said apparatus carrying the revolving lamp, having, say, a green and red light, is
also connected to said chain or other moving part.
The mode of working is as follows:—
The signal-man setting his lever at "line clear," the semaphore arm is down at
the same time, and the chain or rod holds the aforesaid second bell crank lever
of the detonating or sounding apparatus, thus bringing the upper arm of the elbow
lever out of gear.
The pin on the second bell crank lever can thus run down the slot freely, as the
treadle is depressed, the pin on the first bell crank merely running along the incline
on the elbow lever, and the counterweight rising.
But if the signalman release his gear and let the signal arm rise to danger, the
chain running back allows by such action the counterweight on the first bell
crank to fall, and the outer pin on the second bell crank to run up the incline and·
drop into the notch on the weighted sliding bar.
Now, if a train depresses the treadle, this bar rises, its wiper striking the fly-
catch of the spring hammer and exploding a signal or sounding a bell or gong. At
the same time the whole system of levers is locked by the pin on the first bell
crank over-running the incline on the elbow lever, so as to prevent fresh signals
exploding, until the semaphore arm is pulled off, releasing the weighted vertical
bar which feeds the drum (by its pawl) one signal forward ready for a fresh train.
The revolving lamp is of course put to "danger" when the signal is ready for
exploding, and shewn "line clear" as the locking lever is pulled back.
I may more or less vary the mechanical details of my invention without departing
from the nature therof.

page_text: crank lever I is a rod A' connected to a bell crank B¹ (preferably by a screw coupling
for compensating its length shewn in Figures 1 and 2) and which bell crank carries
a treadle C' by the side of the rail capable of being depressed by the train wheels.
The semaphore arm is connected to the levers of the locking gear, as usual, and a
rod or chain is connected from said gear to the bell crank lever E of the detonating 5
or sounding apparatus. The rod or standard D¹ on or by the said apparatus
carrying the revolving lamp or having as shewn a pair of spectacles shewing say
green and red light, is also connected to said chain or other moving part. Figures 2
and 3 shew this rod worked off the shaft F forming the fulcrum of the levers E
The mode of working is as follows:-
The signal man setting his lever at "line clear," the semaphore arm is down at
the same time, and the chain or rod holds the bell crank lever of the detonating
or sounding apparatus, thus bringing the upper arm of the elbow lever E out of
gear.
The bell crank lever L can oscillate on its fulcrum K as the treadle is depressed,
the pin J on the bell crank 1 merely running along the incline G on the elbow
lever E and the counterweight N rising.
But if the signalman release his gear and let the signal arm rise to danger, the
chain running back allows by such action the counter weight on the bell crank to
fall, and the outer pin O on the bell crank L to run down the incline of the
gabs R. R. on the weighted sliding bar P.
Now if a train depresses the treadle, this bar rises, its wiper Z striking the fly
catch Y of the spring hammer X and exploding a signal or sounding a bell or gong.
At the same time the whole system of levers is locked by the pin J on the bell
crank I over running the incline G on the elbow lever E so as to prevent fresh
signals exploding, as shewn in Figure 7 until the semaphore arm is pulled off,
releasing the weighted vertical bar P which feeds the drum B (by its pawl) one
signal forward ready for a fresh train.
The revolving or spectacle lamp is of course put to "danger" when the signal is
ready for exploding, and shews "line clear" as the locking lever is pulled back.
The two sets of locking apparatus as shewn by the Drawings are connected to
and operated by the lever E, but the shots are fired separately by the two
treadles C'.
I may more or less vary the mechanical details of my invention without
departing from the nature thereof.
Having now described the nature of my said Invention and the best manner
known to me of performing the same I would have it understood that I claim as
my Invention.—
Firstly. The combination with the treadle operating by the train and with
apparatus for putting in and the throwing out of gear from the signal box of the
revolving chamber B containing cartridges or detonators and operated substantially
as described.
Secondly The combination of levers E, I, and L and their appurtenances for
working the bars P for operating the revolving chamber B and the triggers of the
same or striking a bell or gong substantially as described.
Thirdly. The general arrangement and combination of apparatus substantially as
and for the purposes described.
In witness whereof I the said Douglas Knight have hereunto set my hand
and seel this third day of January in the year of our Lord One thousand