Improvements in Electric "Call" Signal Apparatus.
Year: 1888

page_text: Date of Application, 21st Jan., 1888
Complete Specification Left, 22nd Oct., 1888
Complete Specification Accepted, 23rd Nov., 1888
Improvements in Electric "Call" Signal Apparatus.
I, CHARLES SPRATT, of 9 Erlanger Road, New Cross Gate, in the County of
Kent, Electrician, do hereby declare the nature of this invention to be as
follows:-
The object of this invention is to provide electric "call" signal mechanism suitable
for being used with systems of speaking tubes and in other cases where it may be
desired to enable persons at any one or other of a number of points say different parts
of a ship or building to call the attention or "ring up" any of the others.
To effect this I provide at each of the several points a combined step by step
transmitter and receiver.
The transmitter as in other step by step transmitters has a spring contact arm
carried by an axis and a concentric circle of insulated contact blocks over which the
spring arm rubs and makes contact when the axis is turned and is made to transmit
electric currents to the receivers.
In each receiver the transmitted currents by exciting an electro magnet give as is
common in these instruments a step by step revolving motion to the axis of a pointer
working n front of a circular dial plate and cause it to turn in unison with the axis of
the transmitter.
To effect this the coils of the electro magnets of the receivers are all made to form
part of one continuous conductor from one pole of a battery and the opposite end of
this conductor is by a return wire coupled to the contact pieces of all the transmitters.
The axes of the contact spring arms of all the transmitters are coupled to a wire from
the other pole of the battery.
In all the spaces (except one) between the several contact pieces in each trans-
mitter is a contact piece with which normally the spring contact arm does not come
into contact but when brought opposite to it can be brought into contact by
imparting an endway movement to the axis.
These are the bell contact pieces-there are as many of them as there are receiving
instruments in the system and numbers, or it might be names, letters or other signs
are placed against each on the dial face."

page_text: The space between the two step by step contact picces in which there is no bell
contact piece is marked zero-and normally the index hands of all the receivers are
kept pointing to the zero mark.
The hell contact piece next to it is marked number one in all the transmitters
and these are all coupled to a wire No. 1. Similarly all the bell contact
pieces No. 2 are coupled to a wire No. 2 and so on. The wire No. 1 is coupled to one
end of the coil of the electric bell at No. 1 station. The wire No. 2 to one end of the
coil of the bell at No. 2 and so on.
The other ends of all the bell coils are coupled to a wire leading to one pole of a
battery used for ringing the bells whilst the opposite pole of the battery is connected to
the wire to which the axes of the spring contact arms of all the transmitters are all
coupled.
In this way if when the contact spring arm of any transmitter is opposite say to a
number two contact the axis of the spring arm is pressed end wise and the spring arm
thereby brought into contact with the contact piece No. 2 the bell at No. 2 station
will be rung No. 2 could then acknowledge the call by turning the handle of his
transmitter and so moving the index hands of the receivers and the person calling up
No. 2 can afterwards by turning the handle of his transmitter turn the hands of the
receivers to his own number so that No. 2 will know by whom he has been called.
Dated this 21st day of January 1888.

page_text: COMPLETE SPECIFICATION.
Improvements in Electric "Call" Signal Apparatus.
I, CHARLES SPRATT, of 9 Erlanger Road New Cross Gate, in the County of Kent,
Electrician, 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 :-
The object of this invention is to provide electric "call" signal mechanism
suitable for being used with systems of speaking tubes and in other cases where it
may be desired to enable persons at any one or other of a number of points say
different parts of a ship or building to call the attention or "ring up" any of the
others.
To effect this I provide at each of the several points a combined step by step
transmitter and receiver.
The transmitter as in other step by step transmitters has a spring contact arm
carried by an axis and a concentric circle of insulated contact blocks over which the
spring arm rubs and makes contact when the axis is turned and is made to transmit
electric currents to the receivers.
In each receiver the transmitted currents by exciting an electro magnet give as is
common in these instruments a step by step revolving motion to the axis of a pointer
working in front of a circular dial plate and cause it to turn in unison with the axis
of the transmitter.
To effect this the coils of the electro magnets of the receivers are all coupled at one
end to a continuous conductor passing from one pole of a battery and at their oppo-
site end to a conductor or return wire which is coupled to the contact pieces of all
the transmitters.-The axes of the contact spring arms of all the transmitters are
coupled to a wire from the other pole of the battery.
In all the spaces (except one) between the several contact pieces in each transmitter
is a contact piece with which normally the spring contact arm does not come into
contact but when brought opposite to it can be brought into contact by imparting
an endway movement to the axis.
These are the bell contact pieces-there are as many of them as there are receiving
instruments in the system and numbers, or it might be names, letters or other signs
are placed against each on the dial face.
The space between the two step by step contact pieces in which there is no bell
contact piece is marked zero-and normally the index hands of all the receivers are
kept pointing to the zero mark.
The bell contact piece next to it is marked number one in all the transmitters and
these are all coupled to a wire No. 1. Similarly all the bell contact pieces No. 2. are.

page_text: coupled to a wire No. 2 and so on. The wire No. 1 is coupled to one end of the coil
of the electric bell at No. 1 station. The wire No. 2 to one end of the coil of the
bell at No. 2 and so on.
The other ends of all the bell coils are coupled to a wire leading to one pole of a
battery used for ringing the bells whilst the opposite pole of the battery is connected
to the wire to which the axes of the spring contact arms of all the transmitters are
all coupled.
In this way if when the contact spring arm of any transmitter is opposite say to
a number two contact the axis of the spring arm is pressed endwise and the spring
arm thereby brought into contact with the contact piece No. 2 the bell at No. 2
station will be rung. No. 2 could then acknowledge the call by turning the handle
of his transmitter and so moving the index hands of the receivers and the person
calling up No. 2 can afterwards by turning the handle of his transmitter turn the
hands of the receivers to his own number so that No. 2 will know by whom he has
been called.
The drawings annexed show electric call signal apparatus constructed as above
described.
Figure 1 is a diagram view of apparatus for calling to or from any one or other of
a number of different places or stations.
Figure 2 is a front view of the transmitting and receiving apparatus at each station.
Figure 3 a front view of the same with the front of the casing removed and
Figure 4 a side elevation with part of the casing in section. Figure 5 is a face view
and Figure 6 a transverse section of the contact blocks and trailing arm which is to
be moved over them.
In Figures 2, 3, 4, 5 and 6, A is a circle of metal contact blocks secured to a
plate B of insulating material which is itself fixed to the metal back plate C of the
casing of the apparatus.
It will be seen from figures 5 and 6 that the several blocks stand out from a metal
ring so that they are all in electrical connection with one another.
B is a spindle concentric with the circle of contacts-it has upon it a toothed
wheel D¹ by which it can be rotated and a spring contact arm D2 the block at the end
of which comes successively into contact with the several contact blocks A as the
spindle D is turned.
The spindle is supported at its back end in a bearing in the metal back plate C and
at its front end in a plate (secured to this back plate so that the spindle and spring
contact arm are in electrical connection with the back plate and the back plate is con-
nected to a metallic return circuit in any suitable way. E is a coiled spring
by which the spindle is pressed end wise until a collar Dx upon it comes against the
plate C¹.
F is a disc with figures on its face for the several call stations-any one or
other of which can be brought behind an opening in the front dial face Ġ of the
apparatus.
H is a spindle having upon it a pinion H¹ which gears into the toothed wheel D¹-
seven turns of the pinion are required to make the toothed wheel complete one
revolution.
H2 is a crank handle on the spindle H by which it can be turned. H³ is a ratchet
wheel on the spindle with which spring pawls I engage to ensure that the spindle
shall only be turned in one direction. H is a disc on the spindle having a notch
formed in it at one point of its circumference into which one end of a spring bolt J
enters.
The notch is in such a position on the disc that when it comes opposite to the bolt
and the bolt springs into it the spindle D will have been turned into such a position
that the outer end of the spring contact arm D2 is between two contact blocks A but
is not in contact with either of them.
When the spring boit J enters the notch in the disc H its rear end is drawn away
from the collar Dx on the spindle D and this spindle is free to be pressed a distance
end wise by pressure applied to a thumb piece D³ in its front end but when the

page_text: spindle H is turned the bolt is forced back out of the notch and its rear end then
comes behind the collar Dx and prevents the spindle D from being then moved
end wise. This ensures that the spindle shall only be pressed inwards when in proper
position for the bell to be rung.
KK are contact pins carried by the back plate of the casing and insulated from
it-they are situated between the contact blocks A. When the spindle D is moved
endwise by pressure applied to the thumb button on its end the spring contact
arm D2 is brought into contact with one or other of these contact pins.
From the several pins insulated wires are led to the several conducting wires for the
bells as above explained.
The receiving portion of the mechanism is composed of the electro magnet L whose
armature is carried by one arm of a rocking lever M the other arm of which carries
escapement pallets which engage with the teeth of an escapement wheel on a spindle N
and give to it a step by step rotating movement when the lever is rocked. O is a
spring acting to draw the armature away from the magnet. P, Q, are insulated
terminals by which one end of the insulated wire coils of the magnets are coupled to
a wire from one pole of a battery U and the other ends of the magnet coils to the
return wire T which as shown is also coupled to the circle of contacts A-R is a
terminal by which the metal casing of the instrument and consequently the spindle D
and spring contact arm D2 are put in electrical connection with the other pole of the
battery.
The arrangement of the wire connections between the instruments at the several
stations is shown by the diagram Figure 1.
In this way if the spring contact arms of any one or other of the instruments is
brought into contact with any one of the contacts A the return conductor T is
coupled to the opposite pole of the battery to that from which the wire S is led and
the several magnet coils being in parallel between their wires a current passes
through all the coils and all the magnets attract their armatures and the spindles N
of all the instruments are simultaneously revolved one step.
The number of currents caused to be sent by one turn of the handle H2 is sufficient
to cause each spindle N to make one seventh of a complete turn.
The bell contacts K numbered 1, 2, 3, 4, 5 and 6 have each an insulated wire led
from them. The wires from the number I contacts of all the instruments are coupled
to a wire No. 1 which leads through the coils of an electric bell 1x at No. 1 station
to one pole of the bell battery W-the other pole of which is connected to the spring
contact arms of all the instruments. The wires from the No. 2 contacts of all
the instruments are similarly coupled to a wire No. 2 which leads through the coils
of an electric bell 2× at No. 2 station and from thence to the bell battery and so on
for the bells at each of the stations.
In this way when the indicator disc of any transmitter has been turned into position
say for No. 3 to be exhibited through the opening in the dial face G and the spindle
of this disc is pressed inwards the bell battery circuit will be completed through the
bell 3* at No. 3 station and consequently No. 3 can be rung up from any one or other
of the stations and No. 3 can indicate in the manner herein before explained that he
has heard the call.
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. The combination of step by step rotating instruments one at each of a number
of stations each having a circle of bell contacts, as many bell contacts as there are
stations and a wire passing from the No. 1 contact in each to a bell at No. 1 station
a wire from the No. 2 contact in each to a bell at No. 2 station and so on and means
for completing a battery circuit through No. 1 wire and bell at No. 1 station from
any station where the transmitter indicator of that station indicates No. 1 station
and so on for all the other stations.

page_text: 2. The arrangement of circuit wires illustrated in the diagram figure 1 whereby not
only may a step by step rotating instrument at each of a number of stations be
rotated from any of the stations, but also in such manner that when the transmitter
indicator of any station indicates say No. 1 station, a battery circuit can be completed
from that station through a bell at No. 1 station and so on for all the stations
substantially as hereinbefore described.
3. The construction of electric call instruments substantially as hereinbefore
described and illustrated in the drawing annexed.
Dated this 001
1000
CARPMAEL & Co.,
Agents.