Year: 1897

page_text: We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
Westminster, S. W., Electrical Engineers, and GEORGE FORREST of 44 Woodland
Terrace, Old Charlton, Kent, Electrical Instrument Maker, 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 :-
This invention relates to an electrical signalling instrument so arranged that
when, on sending a current, a signal is displayed, it becomes locked, so that shocks,
vibrations or other disturbances do not change the indication which remains
displayed until another current causes the lock to be released, and the indication to
be changed and to be locked in its altered position.
We shall describe a signalling instrument according to this invention referring to
the accompanying drawings.
Fig. 1 is a front elevation, with part of screen broken off,
Fig. 2 is a side elevation, Fig. 3 is a plan, Fig. 4 is a vertical section.
E E are the two limbs of an electro magnet the coils of which are in circuit with
the key or other transmitter at the signalling station. The lower ends of their
cores are provided with pole pieces P P which can be adjusted by screwing.
The upper ends of the cores have on them parts Y Y of a yoke which does not
extend across, the two parts being separated by a piece of brass or other non-
magnetic metal N. In front of the parts Y Y is a keeper K carried on the one
arm k of a bell crank lever, the other arm of which is strained by an adjustable
spring S so as to hold the keeper K away from the yoke parts Y Y and against an
adjustable stop A. A lever carrying a screen B is pivotted at b and in a slot of it
is engaged a pin projecting from an iron tongue T which is pivotted at t on a
permanent magnet M, by which the tongue T is polarised.
A pin C projects from the arm k.
Words, symbols or other indications being marked on the face of the screen B Bo
as to be seen through an aperture in the front of a case in which the instrument is
enclosed, one indication being given when the screen is deflected to the right and
another when it is deflected to the left, the instrument operates as follows. When
a current arrives which reverses the polarity of the electro magnet, the first effect
of the excitation is that the keeper K is attracted and connects the two parts Y Y
of the yoke, at the same time drawing the pin C out of the way of the lever which
carries the screen. The electro-magnet, being rendered more powerful by the
completion of its yoke, attracts the tongue T to the opposite side thus causing the
screen B to be deflected to the opposite hand, and then on the circuit being opened
the keeper K is retracted by the spring S and the pin C again projects at the side
of the screen lever locking it in position until the circuit is again closed, effecting
reversal.

page_text: 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 :-
:-
A self locking electrical signalling instrument constructed and operating
substantially as described with reference to the drawings.
1
1007
ABEL & IMRAY,
Agents for the Applicants.