An Improvement in Apparatus for Ensuring Safety of Traffic on Single Lines of Railways.
Year: 1898

page_text: Date of Application, 19th Feb., 1898-Accepted, 19th Mar., 1898
An Improvement in Apparatus for Ensuring Safety of Traffic on
Single Lines of Railways.
I, EDWARD TYER, of Ashwin Street, Dalston, 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:
For the purpose of ensuring safety on single lines of railway, every train on
entering a section has to obtain a staff or tablet which, after this section is traversed,
has to be given up, and the issue of a second staff or tablet from either end of the
section is electrically prevented, so that no second train can enter the section until
it is clear of the first train. It has happened, however, that, through neglect of the
signalman at a station, a signal has been lowered to adinit a train on a section which
a train is already traversing. The object of my present invention is to prevent this
from happening. For this purpose, I provide apparatus such as I shall describe
referring to the accompanying drawings.
Figure 1 is an elevation of apparatus according to my invention, the front of its
casing being removed to shew the parts within in their normal condition.
Figure 2 is a similar view partly in section shewing the parts moved to the
position for giving a starting signal.
Within a casing A placed at the side of a starting lever B I fix a ratchet wheel C
on an axis c on which is fixed a wheel D having rounded teeth corresponding in
number to those of the ratchet wheel; and on a spring lever E I mount a roller e
which by engaging between teeth of the wheel D ensures its turning fully froin each
tooth to the next. On the axis c I fix a corresponding wheel 'outside the casing
facing the signal lever B, and on the spring catch rod of this lever I fix a tooth b
which projects into one of the intervals between the teeth of the outer wheel. The
teeth of the ratchet wheel C are engaged by a tooth f on one arm of a spring pawl
lever F the other arm of which extends to be in the path of a pin g which projects.
down from a lever G. This lever has three arms, one G from which the pin g
projects, and which is concavely curved on its upper side, a weighted second
locking arm g', and a third vertical arm K having a pin k engaged behind a hook lon
the arin of a lever attached to the armature L of an electromagnet M. Over a slot
in the upper part of the casing is hinged a lid H having a downwardly projecting
locking arm h. There is also provided on the top of the casing a spring plunger N
which, when depressed, pushes down the arm g₁ of the lever G. The apparatus is
worked as follows:-
The parts being in the position shewn in Figure 1 the official who is to
accompany a departing train having obtained from the regular tablet instrument a
tablet T has to use it for unlocking the starting lever B, which is locked by its
spring catch rod being engaged in the notch of the quadrant Q in the usual way.
The raising of the rod out of the notch is prevented by its tooth 6 being engaged with
teeth of the wheel outside the casing which cannot be turned because the ratchet
wheel C is held by the pawl f. The official raises the lid H and inserts the tablet
which rests on the lever G and then closes the lid. The lever G can be only slightly

page_text: depressed because the pink on its vertical arm K is stopped by the hook on the
armature lever L. When the tablet has been inserted, the signalman makes a
contact sending a current by which the magnet M is energised attracting its
armature L and so releasing the pink whereupon the parts take the position shewn
in Figure 2, the tablet T having descended depressing G and so disengaged the
ratchet wheel C leaving the wheel free to turn. The signalman can now raise the
catch rod of the lever B and give the starting signal, but the official cannot yet get
the tablet T because the lid is locked in its closed position by the arm g¹ stopping
the arm h. In order to release the lid H, the official depresses the plunger N
pushing down one arm of the lever G and thus releasing the pawl lever F so that the
tooth f on its one arm ré-engages with the ratchet wheel C. The plunger also
raises G and the tablet, withdrawing the locking arm g¹ and putting all the parts
in the position shewn in Figure 1. The official taking out the tablet T proceeds
with the train for which the starting signal has been given, and the signalman
moving back the lever B re-engages its catch rod in the notch of the quadrant Q
thus turning back the wheel, this being permitted by the pawl f slipping over the
rear incline of the ratchet tooth. All the parts being thus restored to their normal
condition, the operation for liberating the starting signal can be repeated when the
magnet M is again energised as described. In order to provide against accident
should the signalman neglect to restore the starting signal to "danger," I provide
that the lowering of the starting signal opens the signalling circuit of the section
so that the signalman cannot communicate with the distant station until he has
restored the starting signal to " danger."
'
⚫ Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
Apparatus for ensuring safety of traffic on a single line of railway, so arranged
that a tablet which has been issued by apparatus electrically controlled from a
distant station is employed to release the starting signal lever, substantially as
described.
Dated this 19th day of February 1808