Improvements in Speed Indicators.
Year: 1889

page_text: Date of Application, 22nd Oct., 1889
Complete Specification Left, 22nd July, 1890-Accepted, 23rd Aug.. 1890
PROVISIONAL SPECIFICATION.
Improvements in Speed Indicators.
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:-
This invention is applicable to speed indicators such as are described in the
specification of a former patent granted to me No. 1711 in the year 1888.
These speed indicators are so arranged that they can be made to show at any time
when required the speed of rotation of a steam engine or other machine in connection
with which the indicator may be applied. The indicator is in two parts, one, which I
call the transmitter, may be in the immediate vicinity of the engine or machine,
the other, which I call the receiver, is in any place where it may be convenient
that the indication should be given. The two parts are connected by electric
circuits. When desired two or more receivers can be used in connection with
one transmitter. In the transmitter there is a mechanism which, when the apparatus
is in operation, closes for a definite (usually a quarter of a minute) gap in an
electric circuit which circuit is also opened and closed by a contact wheel or
equivalent instrument driven by the steam engine or machine, the speed of which
is to be measured. In the receiver there are counting wheels which are actuated
by the succession of electric circuits which are thus transmitted; and there is also
mechanism by which these counting wheels can be set back to the zero position
before a speed measurement is taken.
My present invention relates more especially to the transmitter and to the clock
train forming a part thereof-this I so arrange that no winding is required and
so it is impossible for the apparatus to become deranged by running down. I also
provide in the transmitter apparatus for originating an electric current in the
circuit which serves for placing the counting wheels of the receiver to the zero
position, an operation which was formerly performed by the movement of the
clockwork. In the transmitter as I now construct it there is an electro magnet
through the coils of which a call signal passes. The call signal is transmitted by
means of a button which is pressed in by the observer whenever he desires to
make use of the instrument. The above mentioned magnet in the transmitter then
attracts its armature, which is carried upon a rocking lever.
The magnet in
drawing down the armature overcomes a spring which tends to remove the armature
from the magnet poles. The movement of the lever opens the call circuit by
lifting two contact studs at one end of the lever away from two little spring pistons
upon which they previously rested. These parts are so adjusted as to insure that the
call current shall be of sufficient duration. At the other end of the lever there are two
similar contact studs which, when the armature is attracted, are brought down upon
another pair of spring pistons or adjustable contacts, and so another circuit is closed.
The closing of this circuit brings into operation the electro nagnets in the receiver
which replace the counting wheels in the zero position.
When the call current ceases to flow in consequence of the press button being
released the armature which it caused to be attracted is not permitted immediately to
return for the lever on which it is mounted carries a pawl which engages with the
teeth of a ratchet wheel. This ratchet wheel is geared by a clock train with an
escapement. Thus the armature and lever are only able to return slowly to the starting
point and in so doing the lever and pawl drive the clock train for a period of about
wenty seconds, which is the time needed for taking the speed measurement.
On one of the axes of the clock train (preferably an axis which rotites once in a
ninute) there is a cam wheel, and this, two or three seconds after the clock-work is ut
a movement, lilts a small lever and in so doing closes a gap in the counting circuit

page_text: so that this circuit may be alternately opened and closed by the running of the engine.
The gap in the counting circuit is kept closed by the clock cam for a definite time,
preferably fifteen seconds precisely, and during this time the currents which flow in
the circuituctuate the counting wheels of the receiver and these wheels record the
number of currents passing, and hence the speed of the engine or machine.
Immediately after the expiration of the measuring period the clock itself comes to
rest. The call circuit is completed immediately before the clock train comes to rest
by the return of the armature lever.
In order that the receiver may indicate whether the engine is running ahead or
castern I make the following arrangements :-As described in my former specification
there are two electro magnets in the receiver to control the indicator and according
as the instrument is running ahead or astern the counting circuit is closed through
one or other of these magnets. On the engine shaft is a metal wheel insulated from
the shaft and there are two metal brushes pressing upon the periphery of the wheel.
At equal distances around the wheel four or other number of pieces of insulating
material are inserted into the periphery and as each insulting piece passes beneath one
of the brushes the counting circuit is opened.
These brushes are set nearly but not quite radially to the wheel and springs press
the brushes forward into contact.
I now mount these brushes upon an axis about which they are able to turn through
a small angle the motion being limited by stops. When the direction of rotation is
changed the brushes move about the axis and I utilise this motion to direct the current
in the course required. One of the brushes has two spring arms one on either side of
the axis and these are arranged to come against two stationary contacts connected with
the indicator magnets each to each.
The action then is as follows:-
So long as the engine runs forward the counting current passes through the "ahead"
indicator magnet but when the engine is reversed the brush is carried round for a
short distance with the wheel on which it rests and then one of the spring arms on
the brush opens its contact whilst the other closes the counting circuit through the
"astern" indicator magnet. Thus in a very simple manner the ahead and astern
indicator is made to operate.
Dated this 22nd day of October 1889.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Speed Indicators.
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 :-
This invention is applicable to speed indicators such as are described in the specifica-
tion of a former patent granted to me No. 1711 in the year 1888.
These speed indicators are so arranged that they can be made to shew at any time
.when required the speed of rotation of a steam engine or other machine in connection
with which the indicator may be applied. The indicator is in two parts, one, which I
call the transmitter, may be in the immediate vicinity of the engine or machine, the
other, which I call the receiver, is in any place where it may be convenient that the
indication should be given. The two parts are connected by electric circuits. When
desired two or more receivers can be used in connection with one transmitter. In the
transmitter there is a mechanism which, when the apparatus is in operation, closes for
a definite time (usually a quarter of a minute) a gap in an electric circuit which circuit
is also opened and closed by a contact wheel or equivalent instrument driven by
the steam engine or machine, the speed of which is to be measured. In the receiver

page_text: there are counting wheels which are actuated by the succession of electric circuits
which are thus transmitted; and there is also mechanism by which these counting
wheels can be set back to the zero position before a speed measurement is taken.
My present invention relates more especially to the transmitter and to the clock
train forming a part thereof-this I so arrange that no winding is required and so
it is impossible for the apparatus to become deranged by running down.
In the annexed drawing-Figure 1 is an elevation with the front plate removed of
an improved transmitter. Figure 2 is a plan of the same. Figures 3, 4 and 5 shew
separately some of the parts. a is an electro-magnet mounted upon an adjustable
support. Through the coils of this magnet (which are omitted in Figure 1) a call
signal is transmitted by means of a button which is pressed in by the observer whenever
h: desires to make use of the instrument. The above mentioned magnet in the
transmitter then attracts it armature, which is carried upon a rocking lever b. The
magnet in drawing down the armature overcomes a spring c which tends to remove
the armature from the magnet poles. The movement of the lever opens the call circuit
by lifting two contact studs d' d² at one end of the lever away from two little spring
pistons upon which they previously rested. These parts are so adjusted as to ensure
that the call current shall be of sufficient duration. At the other end of the lever
there are two similar contact studs e e² which, when the armature is attracted, are
brought down upon another pair of spring pistons or adjustable contacts, and so
another circuit is closed. The closing of this circuit brings into operation the electro
magnets in the receiver which replace the counting wheels in the zero position.
When the call current ceases to flow in consequence of the press button being
released the armature which it caused to be attracted is not permitted immediately to
return for the lever on which it is mounted carries a pawlf which engages with the
teeth of a ratchet wheel g. This ratchet wheel is geared by a clock train with an
escapement. The escapement is not shown in position in Figure 2 but is represented
separately in Figure 4. The escapement wheel is driven from the extremity of the
axis of the clock train. The nature of the escapement is sufficiently indicated by
the drawing. Thus the armature and lever b are only able to return slowly to the
starting point and in so doing the lever and pawl drive the clock train for a period of
about twenty seconds, which is the time needed for taking the speed measurement.
l
On one of the axes of the clock train (preferably an axis which rotates once in a
minute) there is a cam wheel i, and this, two or three seconds after the clock-work is
put in movement, lifts a small lever k and in so doing closes a gap in the counting
circuit so that this circuit may be alternately opened and closed by the running of the
engine. The lever with the parts connected with it is mounted on a slab of vulcanite
and the cam is of the same material. The wire k¹ connects the lever in circuit and
another circuit wire leads away from the lower stop. The cam is not shown precisely
in the position at which it comes to rest. The rotation stops when the glass or jewel
pin upon the lever against which the cam acts is about midway in one or other of the
notches or recesses in the cam. The gap in the counting circuit is kept closed by
the clock cam for a definite time, preferably fifteen seconds precisely, and during this
time the currents which flow in the circuit actuate the counting wheels of the
receiver and these wheels record the number of currents passing, and hence the speed
of the engine or machine. Immediately after the expiration of the measuring period
the clock itself comes to rest. The call circuit is completed immediately before the
clock train comes to rest by the return of the armature lever.
In order that the receiver may indicate whether the engine is running ahead or
stern I make the arrangements which are illustrated by the Figures 6 and 7.
Figure 6 is a front view and Figure 7 is a side view; in both a portion of the case is
emoved.
As described in my former specification there are two electro magnets in the
eceiver to control the indicator and according as the engine is running ahead or
stern the counting circuit is closed through one or other of these magnets. On the
ngine shaft is a metal wheel and there are two metal brushes n' n³ pressing upon
he periphery of the wheel. At equal distances around the wheel four or other

page_text: number of pieces of insulating material mare inserted into the periphery and as
each insulating piece passes beneath the brushes the counting circuit is opened.
These brushes are set nearly but not quite radially to the wheel and springs n* press
the brushes forward into contact.
I now mount these brushes upon axes o' o² about which they are able to turn
through a small angle the motion being limited by stops p p.
When the direction of
rotation is changed the brushes move about the axes and I utilise this motion to
direct the current in the course required. One of the brushes n' has two spring
arms 97 one on either side of the axis and these are arranged to come against two
stat onary contacts connected with the indicator magnets each to each.
The action then is as follows:
1
So long as the engine runs forward the counting current passes through the
"ahead indicator magnet bnt when the engine is reversed the brush n' is carried
round for a short distance with the wheel on which it rests and then one of the spring
arms 99 on the brush opens its contact whilst the other closes the counting circuit
through the "astern" indicator magnet. The other brush n² moves similarly about
its axis o' but its movement does not affect the course of the current in the circuit.
In Figure 6 the brushes are radial to the wheel m, but this is a position they
occupy only momentarily in passing from the ahead to the astern position or vice
versa.
Thus in a very simple manner the ahead and astern indicator is made to operate.
Another form of the improved transmitter, and that which I prefer is shown by the
figures 8, 9 and 10. Figure 8 is a front elevation, Figure 9 à longitudinal section
and Figure 10 a rear elevation.
A is the electro magnet which receives the call current, when a finger key at the
receiver is pressed; it is supported on an adjustable stand A¹ and it attracts an
armature carried by the lever B; thereby it extends the spring C. Upon the lever
there is a driving pawl D which engages with the teeth of a wheel E. F is a retaining
pawl which takes into the teeth of the same wheel. The ratchet wheel E is the first
of a train driving an escapement wheel G, in connection with which there is a balance
wheel a hair spring and an escapement of ordinary type. The train also drives an
ebonite cam H which rotates in twenty seconds. Upon the same axis with the cam
there is a steel tooth E'; when the instrument is at rest, the tooth bears against the
spring I. When the armature on the lever B is attracted the spring which is
attached to the lever is elongated and as soon as the attraction ceases it commences to
drive the train, the tooth H' then passes beneath the spring I and it travels on until it
has completed a revolution and then it is again stopped by the spring, the operation
being then complete. Upon the cam H there is a pin H which as soon as the cam
commences to turn acts upon the lever K and causes it to press upon the contact
screw L thus closing a gap in a battery circuit which includes an electro magnet in
the receiver. The magnet in the receiver then attracts its armature and the counting
wheels are brought to the zero position. The lever K is mounted on a block of
vulcanite which insulates it from the frame; it is connected in circuit by the wire M.
The circuit wire N is attached to the piece which carries the contact screw L and also
the stop screw beneath the lever; this screw is tipped with insulating material. When
the pin H2 has passed away from the lever K the periphery of the cam comes to act
against a glass a jewel pin upon the end of the lever O and by the movement of the
lever a gap at P in the counting circuit is closed and it remains closed for fifteen
seconds by which time the notch in the cam again comes round. Qand R are the
circuit wires. The lever O and parts connected with it are carried upon an insulating
block as the drawing indicates. S and T are the connections of the call circuit in
which the coils of the magnet A are contained. The call circuit may be traced from S
to the frame of the instrument; thence by the tooth H' and spring I to an insulated
arm upon the lever B; thence to the magnet A and to the binding screw T. Thus
the call circuit is closed in the transmitter when the instrument is at rest but open
when it is in movement so that a second call cannot interfere with the first.
To ensure the starting of the escapement when the armature upon the lever B is

page_text: aracted this lever is provided with an
adjustment. The end of this screw strikes upon a lever U furnished with a spring
arm in which is a screw B' capable of
finger U. The lever is thus moved suddenly and the finger rubs against the
periphery of the balance wheel and causes it to rotate.
lever U to return. The case of the instrument is provided with a plunger which can
A spring U causes the
he pushed in by hand. This plunger then acts upon the lever U and starts the
clockwork, if in any case it should stop when the tooth H and spring I are not in
contact.
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 :-
and
1. In a transmitter of a speed indicator, the combination substantially as described
of a clock train controlled by an escapement and driving a cam which serves to bring
together electric contact surfaces; an electro magnet; armature; spring;
driving pawl; the whole so arranged that after a call current has been passed through
the coils of the electro magnet the driving pawl engages with and drives the clock
train for the short time requisite for the completion of a speed measurement.
2. A speed indicator transmitter substantially as herein described.
3. In a speed indicator the apparatus substantially as described by which currents
re directed into different circuit wires according as the engine is running ahead or
stern.
Dated this 21st dow of L.1
1000