Improvements in Interlocking Levers in Railway Point and Signal Apparatus.
Year: 1893

page_text: Date of Application, 21st Jan., 1893-Accepted, 25th Feb., 1893
COMPLETE SPECIFICATION.
Improvements in Interlocking Levers in Railway Point and Signal
Apparatus.
I, WILLIAM GEORGE SCOTT, Engineer in Chief of the Cheshire Lines Rail-
way, of Central Station, Ranelagh Street, Liverpool, in the County of Lancaster,
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 :-
My invention has reference to improvements in interlocking levers in railway
point and signal apparatus, and has for its object the minimizing of the chances of
collisions through vehicles being forgotten while standing on passenger roads and
the stop signals being lowered to admit trains from the rear section.
66
In a former Specification of Letters Patent, No. 19575 of 1891, granted to me,
I described a system of interlocking levers by which when the stop signal for a
section is lowered, a train is passed into the section and the stop signal replaced to
Danger," that the lever operating the said stop signal cannot be operated a
second time until some predetermined movement takes place with the object of
moving the train clear of the line to which the said stop signal applies. I effect
that result by interlocking the cross-over road lever and the disc signal lever, or
starting signal lever, but in that invention I did not provide for a train being
divided into two or for any vehicles becoming detached and remaining on the
passenger road, the first portion of the train performing its movement clear of the
said road thereby freeing, according to the interlocking, the stop signal for a second
operation.
In the said Specification of Letters Patent No. 19575 of 1891, although the
drawing clearly illustrates that the starting signal has to be operated and replaced
to its normal position before the stop signal can be operated a second time, as one
way in which the stop signal may be released, yet I did not so claim it. In the
present invention, however, I arrange that under certain conditions the movement
of the starting signal lever and the replacing of the said lever to its normal position,
is necessary for the stop signal to which the starting signal applies to be operated
a second time.
The way in which I carry out my invention is as follows:-
I arrange that the normal position of the disc operating lever is in the centre of
the segment, such disc operating lever applying to the cross-over road or to any
movement in connection with points adjacent to the main line.
I arrange that the movement of the cross-over road or other point lever effects
the said locking on the stop signal lever, but the operation of the corresponding
disc signal lever from its middle position forward and its replacement to its normal
position, which is midway, still leaves the stop signal locked. The natural tendency
of a signalman, more especially when he is careless, is to move a lever in the forward
direction for the purpose of actuating a signal, and such movement, supposing a
portion of the train is left upon the main line, would still leave the stop signal
applying to that line in the locked position at "Danger." If the signalman now
wishes to clear his stop signal he has to perform an unusual movement of operating
his switch by means of its lever and operating his corresponding disc signal lever
from the middle position backward and then replacing it to its middle position
again before the corresponding stop signal is free to be operated a second time.
It is obvious that my invention is applicable to disc signal operating levers in
connection with the switch operating levers themselves, to the extent that any
main line stop signal is held locked and continues to be held locked notwithstanding

page_text: any movement of the switches and forward movement of the corresponding disc
signal levers.
With my invention, as an alternative method of disposing of the train, assuming
that it does not require to be shunted, the section ahead at the time not being
clear, the operation of the starting signal lever forward and its replacing to its
normal position, would release the stop signal and allow it to be operated again a
second time.
Generally, where a single cross-over road and no other switches are provided at
a block section, there would hardly be need in the ordinary circumstances of traffic
working, to divide a train and shunt a portion of it through the cross-over road,
the application of my invention would be to where there are sidings, and although
I describe it with reference to sidings, yet it is obvious I do not debar myself from
using it in connection with a cross-over road, should such unusual movement require
to be performed.
Under certain conditions, on a train arriving, the stop signal 2 (Fig. 1.) is
deflected to allow it to enter the section, signal 2 is again replaced, and it is required
that the train be shunted into the down siding, for this purpose the crossing 7 is
operated, the disc signal lever 11 is operated to the backward position, this operation
releasing the stop signal lever and allowing it to be operated a second time, provided
the levers 7 and 11 are returned to their normal positions; now if a movement
takes place from the siding with signal 4 over, and 7 had not been replaced, when
the train is on the down main line and then 7 replaced, 2 would be free to be
operated, the release upon lever 2 being, as before described, effected by the back-
ward motion of the shunting signal 11. It is therefore necessary that under the
conditions stated, the operation of lever 4 would again lock the down stop signal 2,
and the train arriving on the down line, the crossing being replaced, the stop signal 2
would be interlocked in precisely the same manner as it was on its first arriving in
the section, to release it therefore the signalman would have to go through a move-
ment similar to the movements hereinbefore described under which the releases
of 2 would take place.
In order that my invention may be better understood and more readily carried
into effect I will proceed to describe the drawings hereunto annexed, in which
similar letters and numbers refer to similar parts in the several figures :-
:-
Figure 1 illustrates a diagrammatic view of a double line of railway with a siding
out of either line.
The numbers 2 and 3 are the stop and starting signals referring to the down
line, Nos. 14 and 15 are the starting and stop signals respectively referring to the
up line. The siding points on the down line are operated by lever 7, the cross-over
road by lever 8, and the siding points on the up line by lever. 10, lever 4 operates
the signal out of the siding on the down line, lever 11 is the shunting signal from
the down line to the down siding, lever 6 is the shunt back signal from the up line
to the up siding, and lever 13 is the shunt out signal from the up siding to the up
line. Levers 5 and 12 are the respective disc signal levers operating the discs
from the up to the down and the down to the up lines respectively.
Figure 2 illustrates a plan of the mechanism necessary to effect these results,
showing the locking trough, the tappets which are connected to the several
operating levers (for the purpose of illustrating the locking in connection with the
down line), and the connecting slide of the locks.
Figure 3 is a cross section of the locking trough.
Figure 4 is a longitudinal section of the locking trough, showing the relative
tappet apertures and the positions of the locks and tappets.
Figure 5 is a front elevation of the special locks operating in connection with the
tappets 2 and 3ª..
Figure 6 is a plan view of figure 5.
In Figures 2 and 4, 2, 3, 4, 7 and 11 are tappets attached to the
levers 2, 3, 4, 7 and 11, which operate respectively the down stop, the down starter,
the signal out of the down siding, the down siding points, and the shunt back signal

page_text: into the down siding from the down main. These are the levers necessary to
illustrate the interlocking in 'connection with the down line; the interlocking of the
up line would be analogous in all respects.
2b, 4, 7, are pawls, respectively, upon the tappets 2ª, 4ª, 7ª, the bevelled part
being as shown in the side view sketch at lever 4.
"
2, 4, 7, are notches, respectively in tappets 28, 4ª, 7. The tappet 3 is bevelled
or tapered from the portion attached to the lever to its end. The tappet 11 is, in
accordance with the normal position of its point lever, midway, and it is practically
straight from the lever to the lock 11d and widened from that to the end of the
tappet.
2 is a lock of a shape as shown in elevation and plan, Figures 5 and 6, the tappet
normally resting about the bevels 2° and upon the ledge 2.
4d and 7"
34 is a lock of a design shown in elevation and plan, Figures 5 and 6.
are ordinary locks, but are of such a height as to be below the under side of the
tappet when the tappet is in its pulled over position raised by the pawls 4 and 7.
11 is an ordinary
The same applies to the lock 2d when the lever 2 is pulled over.
square lock. 25 and 35 are blocks inserted in the apertures for the tappets 2ª and 3ª.
In the normal position of the tappet 2* such block does not obstruct the forward
movement of the tappet 2", but in the normal position of the tappet 3* the block 3*
does obstruct the passage.
The action of this mechanism is as follows:-
When 2 is operated the bevel 2 thrusts out of the notch the lock 2d; by that
movement the bevel upon the lock 3d is moved under the tappet 3* raising the said
tappet 3ª clear of the block 38, the lock 4ª is drawn out of the notch 4, 7 is drawn
out of the notch 7, and 11d is drawn into contact with the tappet 11ª, the pawl 2b
on the tappet 2 in the pulled over position of the said tappet, acts that should the
starting tappet 3* be operated while the said home signal tappet 2 is pulled over,
the lock 2 would be moved and would pass under the tappet 2°. Upon now
replacing the tappet 2ª, the tappet would drop until the notch 2 came opposite the
bevelled portion of the lock 2 preventing that from being operated a second time
until 3 had been replaced, that giving the freedom for the lock 2d to be thrust out
by tappet 2 as before described.
The tappet 7 in connection with the stop signal 2 operates in exactly the
same manner and has exactly the same result as regards the interlocking mechanism,
as tappet 2 itself, except that under these conditions it can be released by the
backward movement of the tappet 11.
Referring to the tappets 4* and 7ª, it will be observed that the forward motion of
these levers which lock the tappet 2*, that the forward movement of 11 can have no
effect upon releasing the said tappet 2", but it is obvious that, assuming 11 to be
normal, in consequence of the tapered end of the tappet being wider, that as
the tappet is moved backward it would operate 11d and so draw the locks into
their normal position releasing 2ª.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
1. In interlocking apparatus for railway point and signal levers, arranging the
shunt operating lever normally in the middle position, the forward movement of
which, and its replacement to the normal position in conjunction with the operation
of the point lever, still leaves the relative stop signal lever locked, the whole
operating substantially as herein described and as illustrated in the accompanying
drawings.
2. In interlocking apparatus for railway point and signal levers, arranging the
shunt operating lever in a normal middle position, the backward movement of
which, and its replacement to the normal position in conjunction with the
movement of the point lever, releases the corresponding stop signal lever, allowing
it to be operated a second time, all substantially as herein described.

page_text: 3. In interlocking apparatus for railway point and signal levers, arrangements
whereby in lieu of the release upon the stop signal referred to in Claim 2, the
operation of the corresponding starting signal and its replacement to its normal
position, releases the stop signal a second time, all substantially as herein described.
4. In interlocking apparatus for railway point and signal levers, the arrangement
of special locks operating in conjunction with corresponding notches and pawls in
and underneath or upon the said corresponding tappets, substantially for the
purposes herein described and as illustrated in the accompanying drawings.
Dated this 21st day of January 1893.
JOHN P. O'DONNELL,
70 & 71, Palace Chambers, Bridge Street, Westminster, S.W.,
Agent for the said Applicant.