IMPROVEMENTS IN INDICATORS OF SPEED AND DIRECTION OF ROTATING SHAFTS
Year: 1883

page_text: LETTERS PATENT to Edwin John Payne Gallwey, of Thirkleby Park, Thirsk,
in the County of York for an Invention of IMPROVEMENTS IN INDICATORS
OF SPEED AND DIRECTION OF ROTATING SHAFTS.
PROVISIONAL SPECIFICATION left by the said Edwin John Payne Gallwey
at the Office of the Commissioners of Patents on the 17th October 1883.
EDWIN JOHN PAYNE GALLWEY, of Thirkleby Park, Thirsk, in the County of
York, "IMPROVEMENTS IN INDICATORS OF SPEED AND DIRECTION OF ROTATING
SHAFTS"
This invention has for object improvements in indicators of speed and direction
of rotating shafts, and is more particularly applicable to marine engines to show to
the captain, officer of the watch, chief engineer and others the approximate speed
of the engines, and whether they are moving ahead or astern.
According to my invention a small mechanical electric generator giving continuous
currents, such as a dynamo-electric or magneto-electric machine, is driven by the
shaft whose motions are to be indicated, and its current is led by means of
conductors to one or more indicators placed on the bridge, and in other suitable
parts of the vessel. These indicators may be variously constructed according to
the degree of accuracy with which it is desired to measure the speed of the shaft,
but they all have the common characteristic that the movement of the index is
greater or less as the current increases or decreases. In a simple form they resemble
the ordinary detector used in telegraph testing, or the single needle instrument; in
a more perfect instrument greater accuracy and range are obtained by gearing the
index finger to the moving part, and greater power and steadiness may be obtained
by substituting magnets and armatures, or cores and solenoids or sucking coils for
the usual needle and galvanometer coils. Instruments of the kind now known as
Pi e27

page_text: Ampère meters make also good indicators, as the deflections of the index are
exactly proportioned to the strength of the current within the range of the dial.
The action of the apparatus is as follows:-
When the engine commences to move in one direction (say ahead) the generator
immediately produces a current which traverses all the indicators. At first the
current is of moderate intensity, and turns the indices slightly in the direction
corresponding to forward motion. As the engine speed increases the movement of
the index follows it, the dial being marked either in revolutions or like the present
ships' telegraph "slow," half," and "full "-If the engine is reversed a current is
generated flowing in the opposite direction to the previously mentioned current
and all the indices move to the opposite side of the zero point. These indicators
may be let into the top of an ordinary engine room telegraph, so that when the
handle is moved, the needle shows the instant the engines begin to obey the order.
"7"

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edwin John Payne Gallwey in the Patent Office on the 9th April
1884.
EDWIN JOHN PAYNE GALLWEY of Thirkleby Park Thirsk in the County of
York. IMPROVEMENTS IN INDICATORS OF SPEED AND DIRECTION OF ROTATING
SHAFTS
This invention has for object improvements in indicators of speed and direction
of rotating shafts and is more particularly applicable to marine engines to show to
the captain, officer of the watch, chief engineer and others with more or less
exactitude the speed of the engines and whether they are moving ahead or astern.
According to my invention a small mechanical electric generator giving continuous
currents such as a dynamo-electric or magneto-electric machine is driven by the
shaft whose motions are to be indicated and its current is led by means of
conductors to one or more indicators placed on the bridge and in other suitable
parts of the vessel. These indicators may be variously constructed according to the
degree of accuracy with which it is desired to measure the speed of the shaft, but
they all have the common characteristic that the movement of the index is greater
or less as the current increases or decreases,-unless it is desired to indicate direction
only in which case the index goes to its extreme directly the shaft commences to
move. In a simple form they resemble the ordinary detector used in telegraph
testing or the single needle instrument.
When this simple form is used the exact number of revolutions can be counted
by the following devices.
(1) The rotating shaft carries a cam which breaks the electric circuit of the
generator once in every revolution so that the indicator needles return to zero
partly once in every revolution, and the exact number of revolutions, made in a
given time can thus be counted (Fig 1).
Instead of a cam the circuit can be broken by a rubbing contact the continuity
of which is interrupted in one position.
(2) Or, the current may be passed through a relay put in any part of the circuit,
so that when the circuit is broken an electric bell or any other electrical signal, in
connection with a local circuit is actuated once in every revolution. This gong is
placed in circuit by pressing an electric pusb, the strokes can then be counted
between any desired interval (Fig 2)
In a more perfect instrument greater accuracy and range are obtained by
substituting magnets and armatures or cores and solenoids or sucking coils for
the usual needle in the Galvanometer and gearing the index finger to the moving
parts.
Instruments of the kind now known as ampère meters make also good indicators
as the deflections of the index are exactly proportioned to the strength of the
current within the range of the dial.
The indicators can be regulated by means of compensating magnets, switches, or
adjustable resistances for variations of resistance in the conductors or of directive
power in the magnets.
The action of the apparatus is as follows:-
When the engine commences to move in one direction (say ahead) the generator
immediately produces a current which traverses all the indicators. At first the
current is of moderate intensity and turns the indices slightly in the direction
corresponding to forward motion.
As the engine speed increases as the deflection of the index is proportional to the
speed of the generator the movement of the index follows it, the dial being marked

page_text: "
either in revolutions or like the present ships' telegraph "slow'
half" and "full."
If the engine is reversed a current is generated flowing in the opposite direction to
the previously mentioned current and all the indices move to the opposite side of
the zero point.
These indicators may be let into the top of an ordinary engine room telegraph
so that when the handle is moved the needle shows the instant the engines begin
to obey the order.
Referring to the accompanying drawing in Fig 1 A represents the shaft whose
direction of rotation or speed or both it is desired to indicate. It drives a
mechanical electric generator B either by a belt as shewn or by gearing. This
generator is connected by conductors to indicators C. C. C. placed in convenient
positions and it sends a current through them in one direction or the other
according to the sense in which it is driven. The strength of this current will vary
within certain limits almost as the speed of the generator and consequently its
strength will be a measure of the speed of the shaft A. Whether the variations
of the current will be visible on the dials of the indicators or not will depend upon
the construction of the latter and their adjustment. If they are detectors of the
usual construction they will go right over with a very feeble current and will shew
the direction of rotation only. Detectors, however, may be modified by inserting
resistances, or weighting or otherwise controlling the movements of the needles so
that they may be more or less sensible to any variation in the current, or directing
permanent magnets may be used for the same purpose. The index may take the
form of a polarized pointer or a shutter moved over a divided dial and it may be
operated by means of the attraction or repulsion between permanent magnets and
coils or permanent magnets and electro-magnets, or both or other known electrical
expedients.
The indicators need not all be of the same construction but some may be more
exact in their indications than others according to the position in which they are
to be placed, a more and a less exact one may be placed side by side the latter
serving to indicate the direction of motion the instant the engines start and the
other to shew approximately all variations in speed from nearly stopped to full
speed.
Having thus described the nature of the said invention and the manner in which
it is to be performed I would have it understood that what I consider to be novel
and original and therefore claim as the invention secured to me by the Letters
Patent hereinbefore in part recited is :-
1. The use for indicating the speed and direction of rotation of a shaft of an
electric generator driven by such shaft in combination with one or more indicators
operated by the current from the said generator, the index or indices of such
indicator or indicators being arranged to move in correspondence with the shaft
substantially as described.
2. Apparatus for indicating the direction in which a shaft is rotating comprising
an electric generator driven by such shaft, and one or more indicators operated by
the current from such generator substantially as described.
In witness whereof the said Edwin John Payne Gallwey have hereunto set
my hand and seal this fifth day of April in the year of Our Lord one thousand
eight hundred and eighty-four.
E. J. P. GALLWEY. (L.S.)

page_text: If a circuit breaker be used that part of the circuit between a-b is to be
omitted and the circuit shown in dotted lines substituted.