Signalling during Fog and otherwise on Railways.
Year: 1890

page_text: Date of Application, 2nd Aug., 1890
Complete Specification Left, 10th Mar., 1891-Accepted, 18th Apr., 1891
PROVISIONAL SPECIFICATION.
Signalling during Fog and otherwise on Railways.
We, ARCHIBALD DRUMMOND MACDONALD, Doctor of Medicine, 26, Spellow
Lane, Liverpool, England, and JAMES DODD, Millwright, 22, Weldon Street,
Walton, Liverpool, aforesaid, do hereby declare the nature of this invention to be as
follows:-
An electrical and mechanical apparatus to be used instead of the present
system of detonators, especially during fog, brought into action automatically by
the train passing over a "contact" placed between the rails, which contact causes
the ringing of a signal-bell within hearing of the engine driver, the whole being
under the control of the signalman.
Dated in 21 1
fl 1000
ARCHD. D. MACDONALD.
JAMES DODD.
COMPLETE SPECIFICATION.
Signalling during Fog and otherwise on Railways.
We, ARCHIBALD DRUMMOND MACDONALD, of Number Twenty-six, Spellow
Lane, Liverpool, in the County of Lancaster, Doctor of Medicine, and JAMES
DODD, of Number Twenty-two, Weldon Street, Walton, Liverpool aforesaid, Mill-
wright, 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:-
Our invention consists of an electrical and mechanical apparatus capable of being
employed in signalling by the sound of bells, gongs or other audible signals within
the distance from railway stations over which detonators are at present used during
fog, falling snow, repairing of the line from distant signals to stations, and other
conditions. The apparatus is self-testing as to its working condition electrically,
and a mechanical test is also applied or it may be tested electrically only, or
mechanically only, by anyone in charge of the signal-levers.
The electrical mechanism is arranged as follows:-
Firstly, From one pole of an electric battery, accumulator or accumulators,
dynamo, or other source of electricity, (hereinafter for brevity's sake termed an
electromotor), [Sheet I, Diagram 1], a wire (d) is led to a 'signal on'
division (b) of a contact hereinafter more particularly described, and called the
lever-contact,' (L. c.), in relation to the distant-sigual lever, which is usually
placed in or near the signal-cabin. (A reserve battery (1) may be placed close
to the former (1), so as to be easily put in circuit when required.) From the
other pole of the electromotor, a wire (k) is led to a small bell or sound signal
within the signalman's hearing, called the test sound-signal' (T. S. S), and thence
to a larger and sufficiently loud sounding bell, gong, or other sound-signal (D. S. S),
called the danger sound-signal, erected beside the railway in such a position
beyond the distant-signal (d. s) as to be heard by, and give warning to, the
enginemen of a train approaching such distant-signal, of the signals being at
danger or against the train. All sound-signals before and after-mentioned to
be of any required pitch, tone, or variety in repetition. From the danger sound-
signal (D. S. S.) the wire (hk) is led to one division of a contact (R. c., 1) to be
hereinafter more particularly described, placed between the rails, called the rail-
contact. Then from the other division (R. c., 2) of the said rail-contact, the circuit
is completed, with signal "on," and rail-contact "made," through wire or earth (7)
"

page_text: to the opposite division (a) of the lever-contact (L. c.), and through division b, and
wire d already mentioned, to the electromotor in which is generated the current
passing round the circuit described above.
Secondly, From the division of what is hereinafter termed the signal-off"
portion of the lever-contact (L.), a wire is led to a second electromotor (2)
[there may also be a reserve battery (2) as above referred to with regard to
the other electromotor]; thence the wire is led to a second test sound-
signal (t. s. s.) in the signal cabin, and thence (h¹¹) to another sound-signal erected
near the danger sound-signal, but of different tone, pitch, or variety of sound, called
the line-clear intimation sound-signal (C. S. S.). The wire is then connected
with the wire hk, between the sound signals and the rail-contact, and the return
circuit is completed by the same means as is used for the circuit above-described.
Thus the line clear' intimation sound-signal (C. S. S) is the only signal heard by
the enginemen when the signals are "off," and the line is clear.
"
Thirdly, The foregoing arrangement of sound signals may be tested mechani-
cally by the rail-contact (R. c) being made by a separate switch, lever, or
similar contrivance (Diagrams 1 and 2 MTs) in the signalman's cabin, having a
chain, rod, or wire attachment connected with the sliding-slip after-mentioned of
the rail-contact, over a pulley or pulleys (p). This is employed to pull down the
lid of the rail contact box (Sheet II Figs. 3 & 4, Reb., L), and thus, by moving
the tumbler (Figs. 3 & 4 T), perform the circuit-test for the danger sound-signal
when the signals are "on," and for the "line-clear" intimation sound-signal when
the same signals are "off" Diagram 2 shows the mechanical test (MTs, MT)
alone applied.
The electrical automatic test is applied through a wire (Diagram I,
Sheet 1) being led from division y of the lever-contact (I. c.) to division 1 of the
Fail-contact (R. .,-1). The division a of the lever-contact is thus brought into
action simultaneously with the divisions by and respectively, according to the
direction of movement of the signal-lever, as follows: When the distant signal-
lever is being moved, (firstly), past a point at or about midway between the signal-
on division (with a), and the test division (y with a), of the lever-contact, in the
act of altering the signal from "on" or danger, to "off" or clear, a momentary
sounding of the test danger sound-signal (T. S. S.) in the cabin, and of the danger
sound signal (D. S. S) is caused by the passage of the current from pole to pole of
the electromotor (1). Similarly, (secondly) when the said distant signal lever is
at or about midway between the said test division (y with a) and the signal off
division (e with a) of the lever-contact-the lever still moving in the same direction
the test line-clear' sound signal (t. s. s.) and the line clear intimation sound
signal (C. S. S) give a momentary sound-the current passing from pole to pole
of the electromotor. When the signal lever is moved from "off" to "on in
the opposite direction from that above-describel, the test sounds are in like manner
produced. In all instances, the fact is demonstrated of the sound signals being in
order.
Fourthly, The lever-contact (Sheet II Figs. 1 & 2, L. c.) consists of a metal
clamp (X) carrying one contact piece (W) in front, and another (V) behind-
said contact pieces being so placed as to be capable of touching lever-contact
divisions a and b (Diag. 1) and a and y, or a and y and a and c, at the same moment
in passing. The contact-piece in front makes the contact only between divisions a
and when the signal is "on," and the contact-piece behind makes the contact
only between divisions a and c when the signal is off." The clamp (X) referred
to is attached to the distant signal lever (d. s. 1.), and retained in position by a
binding-screw (U) which permits the clamp with the contact-pieces (W and V) to
be raised out of, or lowered into contact, when out of use, or in use respectively.
The said contact-pieces are easily removeable for changing or repair, and the
clamp and contact pieces are insulated within the clamp from the lever.
Attached to the surface of the lever bracket (L. B.), and on each side of the
slot through which the distant signal lever passes, are three pieces of metal (above

page_text: 22
referred to as a, b and c in Diagrams 1 and 2, Sheet I. and figured in Sheet II..
Figs. 1 & 2) and also a fourth piece, if required, (referred to as y in Diagram 1,
Sheet I., and Sheet II. Figs. 1 & 2),-which are insulated from the said bracket,
and from each other, and are placed in such situations as permit the contact
pieces within the above-described clamp to assume the positions specified during
the movements, or during the "off" and " on positions of the signal-lever..
Divisions a and b are connected with the danger sound signal circuit; a and y are
employed in the working of the electrical test circuits, together with a and b or
a and (the "a" is here repeated to shew the couples), as the case may be; and.
a and c are connected with the line clear intimation circuit, as before referred to.
Fifthly, The rail-contact (Sheet II. Figs. 3 & 4, R. c. b.) is placed between the
rails, and by the side of one of them. It consists of a strong box-shaped enclosure,
so shaped partly because of the need for excluding, as far as possible, sand, rain,
ice and snow, firmly fixed to the ground, and clamped to the rail. The lid (L)
is moveable on a strong hinge (H), beyond which there may be a counterpoise, and
at its free end there is a sliding slip catch (S. S. C) which prevents the box from
being opened either through having its extremity padlocked or fixed to the arrange-.
ment of the mechanical test before described. The lid is pressed downwards by
the flanges of the wheels passing over it. This movement actuates a tumbler (T)
set inside the box, by pressing its one extremity (E), part of which (R. P.) is
easily removeable to enable the rail-contact lid to sink below the level of the flanges
of the passing train wheels, when the apparatus is not in use. The tumbler is.
weighted (W) so as to rather more than counterbalance the weight of the lid
bearing upon it, thus elevating it after depression. The other extremity of the
tumbler has one cross-piece insulated from the body of the tumbler, which, when in
action, meets the two contact divisions (Sheet II. Fig. 3 C D, and Fig. 4 C D, 1,
& CD, 2) which are insulated (1) from the box, and complete the danger sound
signal and line clear' circuits, when the signals are ::
on ог "off" respectively.
These contact divisions are made curved so as to ensure contact with the cross-piece
of the tumbler, and the wires to them are fastened inside the box by the binding-
screws (B S and b. s.).
27
Sixthly, On the home, or starting-signal post, or both, is fixed a bell or gong
(Sheet I. Diags. 1 & 2, s-B) moved by a ratchet arrangement which is actuated
by the rod and lever-weight moving the signal for the purpose of giving a 'line-
clear sound signal to the engine driver whose engine has been brought to a
standstill, inside the distant sigual distance, by the danger signals. When the
signal is being placed at "off," the bell or gong gives intimation of that fact.
2
ALTERNATIVES.
1. The tumbler-spindle (Sheet II. Figs. 3 & 4, T. S) of the rail-contact may
be prolonged externally, and so made to actuate a sound signal, to be used instead
of the intimation line-clear' signal above-described.
II. The electrical test portion L. c.—y and wire 1 1 (Sheet I. Diag. 1) may
be dispensed with, and the mechanical test alone used (Diag. 2).
III. The mechanical test (M Ts and M T Diagram 1) may be dispensed with,
and the electrical test above referred to alone employed.
IV. The apparatus may be connected with the home-signal lever, instead of the
distant-signal lever, but the danger sound-signal, and line clear intimation
sound-signal to remain in their former position with reference to the distant-signal
itself.
V. The line clear' intimation sound-signal, and its test, may, when desired,
be dispensed with, and the danger sound-signal circuit be only used.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
First. The application of electrical and mechanical apparatus, (including, as

page_text: part thereof, the electrical and mechanical arrangements for testing whether or not
the apparatus is in working condition), in the giving of danger' and 'line-clear'
intimation sound signals on railways, the whole being constructed and arranged
substantially as hereinbefore described.
Second. The arrangement in connection with the mechanism of the rail-contact
consisting of the tumbler (T), with easily removeable part (R. P.) and contact
divisions (C D, 1, and C D, 2) insulated from, and enclosed within, a box (R. c. b.),
whose lid is moveable and actuated by the flanges of the wheels passing over it, as
before-described.
Third. The arrangement in connection with the mechanism of the lever-contact,
consisting of the portion (X with W & V) clamped to the signal-lever, whose
contact divisions are insulated and removeable, as before described, and of the
contact-divisions (a, c,y and b) attached to the lever-bracket, as described above.
Dated this Ninth day of March 1891:
ARCHIBALD DRUMMOND MACDONALD.
JAMES DODD.