Improvements in and connected with Indicating Apparatus for Engines and other purposes.
Year: 1892

page_text: · Date of Application, 7th Jan., 1892
Complete Specification Left, 7th Oct., 1892-Accepted, 7th Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in and connected with Indicating Apparatus for
Engines and other purposes.
We WILLIAM CARLTON FARNUM of Arlington in the State of Vermont, United
States of America, and HAROLD EGBERT BODLEY of 7 Kehern Terrace, Mortlake
in the County of Surrey, Mechanical Engineers, do hereby declare the nature of
this invention to be as follows:-
:
This invention relates to certain improvements in and connected with indicating
apparatus for ascertaining the variations of pressure in engine cylinders and other
pressure vessels, and has for its objects to provide apparatus capable of accurately
indicating engines running at high speeds; also to obtain more perfect diagrams of
the work performed in the cylinder or otherwise, and to minimise the errors in
indicator diagrams inherent with the use of indicators as heretofore constructed
owing to the vibrations of springs and parts, and the rapid changes of directions of
motion under high velocities of the paper drum and pencil: and also to render
manipulation in use more simple than heretofore.
To these ends we reduce the movement, number, and weight of working parts as
far as possible in order to diminish the inertia and momentum thereof, and we
arrange and construct our apparatus substantially as hereinafter set forth.
Although our indicating apparatus may be used for indicating pressures in
vessels other than engine cylinders, we will describe it for the sake of convenience
as for engines.
Our apparatus may be constructed in various forms but it consists essentially of a
cylindrical or other form of casing or frame of suitable material and having a
chamber adapted to be put in communication with the engine cylinder or pressure
vessel in which chamber is placed a diaphragm, steam tight piston, puppet valve,
or equivalent device capable of vibrating, pulsating, or reciprocating movements
(and hereinafter alluded to for the sake of brevity as "the diaphragm;") which is
fixed by unions or suitable contrivances for ready accessibility, removal or change
when required.
The motion of this device is limited by suitable stops which, in the case of a
flexible diaphragm, serve also as the holder thereof and so enable its effective area
to be readily varied.
One side of the said diaphragm is placed in communication by an ordinary pipe
and cock with the interior of the engine cylinder or pressure vessel, and the other
side with atmosphere. To the latter side by a suitably arranged lever or levers
delicately mounted, is connected the indicator pencil, the holding member of which
has sufficient resilience to allow it to follow any irregularity of thickness of the
paper or "card."
The same side of said diaphragm is connected to a spiral or other spring attached
to a sleeve or spindle capable of reciprocal motion in the casing or frame: the said
spindle is operated by a screw held in suitable bearings and provided with an
actuating handle arranged conveniently outside the casing, and upon or to said
spindle in some cases is fixed in suitable manner an arm or bracket working through
a slot in the said casing, which may carry the vibratory paper drum so as to impart
to it a longitudinal travel simultaneously with the spindle actuating the spring
when required; or, in other cases for the same purpose the bracket arm carrying
the
paper drum
may be fixed to the casing, and the pencil may be arranged to slide
upon the lever connected with the diaphragm which is suitably extended for the

page_text: purpose, and a longitudinal motion upon the said extended portion will be imparted
to the pencil from the spindle which is actuated as stated by the motion of the
screw and handle.
In order to make our apparatus available for indicating great ranges or variations
of pressure without changing springs or other parts, and thus simplify manipulation
in use we modify the above described apparatus as follows:-
The moving part whether it be the pencil or the drum is attached to a separate
slide projecting through the casing or frame which slide is connected to the spindle
operating the spring (which may be in the same or a separate casing) in such
manner as to permit of a differential movement between the two. This may be
obtained by connecting the separate screws together by change wheel gearing for
varying the velocity ratios; or the two may be connected by suitably arranged
levers mounted upon fulcrums one or more of which is adjustable so as to give any
desired relative movement between the spindle operating the spring and the spindle
operating the paper drum or pencil as the case may be.
The diameters of the above mentioned change wheels, or the positions of the
fulcrums of the levers (whichsoever be employed) will be so varied that without
regard to the pressure acting on the diaphragm and balanced by the spring, the
paper drum or pencil will be moved through its maximum travel with the minimum
movement of the spindle operating the springs, and thus diagrams of uniform size
will be produced.
An index finger may be provided in couvenient position for denoting the
atmospheric line.
According to our invention we move the pencil from or against the card directly
in accordance with the reciprocations of the diaphragm or equivalent vibratory
device caused by the varying pressures of the vapours acting on one side and the
varying tension or compression of the said spring acting on and controlling the
other side thereof.
The contact of the pencil with the card continues during the period or that
portion of the stroke in which the vapour pressure exceeds the tension or com-
pression of the spring; the ends of the lines of varying lengths thus produced
indicate the outline of the diagram, and the distance between them is equal to the
distance through which the drum or pencil is moved by the screw during an
oscillation of the drum.
The construction of the card drum is a novel and important feature of our
invention; our object is to construct it as light and strong as possible, so that when
at work its inertia and momentum will be reduced to a minimum, and thus the
diagrams will not be distorted and hence at high speeds more reliable results will be
obtained.
The barrel is made preferably of thin sheet steel bent to circular form and the
ends of the sheet are turned in so as to leave a small longitudinal opening; it is
then teinpered' to retain the true shape. This barrel is secured in grooves turned
in the end fittings which are also preferably of steel, and may be securely fastened
together in a longitudinal direction by a central tube or hub which may form a
bearing upon which the complete drum can oscillate.
To secure the paper well and tightly upon the drum a resilient rod is pivotted to
one end fitting and capable of swinging against the card or paper and pressing, it
into the longitudinal opening, the said rod being fastened by springing it into a
catch or slot in the other end fitting.
..
The whole is mounted upon a central spindle carried by the before mentioned
bracket arm or the casing, the bearing end of which is or may be turned eccentric
to advance or retire the drum and card to or from the pencil as and when
required.
The said eccentric may be also used for holding the drum stationary when
changing the card or paper, in which case the eccentric is turned to throw the
drum away from the pencil and against a projection from the bracket arm or
casing.
5

page_text: The carrying boss of the bracket arm is split and provided with a clamping
device to adjust and fix said spindle as required.
Also by slackening the clamping device the drum and spindle may be bodily
removed and re-placed at once and without trouble.
A feature of our invention is the use with the drum described of diagram paper
or cards made in cylindrical form which can by means of the before mentioned
resilient rod be made to fit the drum tightly.
Upon one end fitting the usual groove or grooves are provided for obtaining the
reduced motion of the engine piston.
The operation of our indicating apparatus in taking a diagram is as follows:-
The indicator diaphragm, piston, puppet valve, or equivalent, being placed in
communication with atmosphere on both sides and the spring in equilibrio, the
drum with its card is vibrated in the usual manner; sufficient tension is given to
the spring to bring the pencil against the paper or card to draw the atmospheric
line, then, air being excluded, the steam or vapour pressure is admitted to the
enclosed side of said diaphragm which is accordingly depressed. Then by turning
the handle the spring attached to the diaphragm is compressed or extended and the
drum or pencil (as the case may be) is simultaneously travelled at right angles to
the direction of its vibratory motion, and as the tension or compression of the
spring is changed lines are produced of varying lengths as before described, tho
ends of which may afterwards be connected and form an outline of the diagram.
When the diagram is completed vapour is shut off from the indicator and the
card removed by releasing the fastening device.
For portability and convenience the before mentioned spiral or other spring-may
be arranged around the screw, and the parts combined together and so disposed as
to occupy the smallest effective space.
Deted this 7th day of January 1892.
J. C. CHAPMAN, C.P.A.,
Agent.
COMPLETE SPECIFICATION.
Improvements in and connected with Indicating Apparatus for
Engines and other purposes.
We, WILLIAM CARLTON FARNUM, of Arlington, in the State of Vermont,
United States of America, and HAROLD EGBERT BODLEY, of East Lynn,
Caversham Road, Kingston-on-Thames, in the County of Surrey, Mechanical
Engineers, 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 certain improvements in and connected with indicating
cards," the variations of
apparatus for ascertaining by diagrams registered on
pressure, under the usual conditions of confinement and expansion, in engine
cylinders and other pressure vessels, and has for its objects to provide apparatus
capable of accurately indicating engines running at high speeds, also to obtain more
perfect diagrams of the work performed in the cylinder or otherwise, and to
minimise the errors in indicator diagrams inherent with the use of indicators as
heretofore constructed owing to the vibration of springs and parts, and the rapid
changes of direction of motion under high velocities of the paper drum and pencil,
and also to render manipulation in use more simple than heretofore.
To these ends we reduce the movement, number and weight of working parts as
far as possible in order to diminish the inertia and momentum thereof, and we
arrange and construct our apparatus substantially as hereinafter set forth.
Although our indicating apparatus may be used for indicating pressures in vessels
other than engine cylinders, we will describe it for the sake of convenience as for a
steam engine.

page_text: =
Our apparatus may be constructed in various forms, but it consists essentially of
a cylindrical or other form of casing or frame of suitable material, and having a
chamber or cylinder adapted to be put in communication with the engine cylinder
or pressure vessel. In the chamber or cylinder is placed a diaphragm, piston,
puppet valve or equivalent device, capable of a suitable degree of pulsating,
vibrating or reciprocating movements. One side of the said reciprocating device
is adapted to be placed in communication with the interior of the engine cylinder
or pressure vessel, and the other side with atmosphere. To the latter side, by a
suitably arranged lever or levers delicately mounted, is connected the indicator
pencil, which is arranged to have sufficient resilience to allow it to follow any
irregularity of thickness of the paper or "card."
:-
The same side of the said device is connected by a spiral spring to a sleeve or
spindle (hereinafter called the "slider") capable of reciprocal motion in the casing
or frame, and operated by a suitable screw and a conveniently arranged external
actuating handle. This slider has a dual function, viz. to apply compression or
tension to the connecting spring as and when required, and to effect a longitudinal
travel by which a registration of lines upon the card in a direction or directions at
right angles to the direction of its oscillation is obtained. This may be effected
either by keeping the pencil stationary and connecting the oscillating drum to the
slider in such a manner as to partake of its motion and so travel endwise before
the pencil; or by fixing the oscillating drum (in regard to endwise travel) and
connecting the slider to a sliding pencil travelling before the drum, the result being
in either case equivalent.
In order to make our apparatus available for indicating great ranges or
variations of pressure, without changing springs and thus simplify manipulation in
use, we arrange the apparatus as hereinafter appears.
We will now fully describe our invention in reference to the accompanying
drawings, in which similar letters of reference indicate similar parts.
Fig. 1 is a longitudinal section of a complete apparatus with a reciprocating
piston.
Fig. 2 is a cross section on line 1-1 of Fig. 1.
Fig. 3 is a longitudinal section of part of an alternative arrangement with a
flexible pulsating diaphragm.
Fig. 4 is a plan of Fig. 1 with drum removed.
Fig. 5 is an elevation of drum.
Figs. 6 and 7 are end views of the drum.
'Fig. 8 is a detail and Fig. 9 is a representation of a diagram obtained with
the instrument.
We will in the following description refer to the vibrating device as the piston P;
flexible diagrams such as P, Fig. 3, and analogous devices being mechanically
equivalent thereto. The piston P has a rod p passing through the cover of the
cylinder B, situated at one end of the casing A, and it is capable of a suitable
degree of reciprocal motion being limited by suitable stops; for example, we have
illustrated a tubular thimble G, screwed into the cylinder on the atmospheric side
of the piston and surrounding rod p; or any suitable stops may be inserted in the
cylinder B on one or both sides of the piston P against which it would strike at
each stroke. The steam side of piston P is placed in communication with the
interior of the engine cylinder by a pipe and union, such as U, in the usual manner,
and the other with the atmosphere by a hole or holes p', which also serve for the
escape of any steam which may leak past the piston. The atmospheric side of
said piston P. by its rod p, is connected through a lever L to a spiral spring S
attached to the slider T, to which reciprocal sliding motion in the casing A is
imparted by the screw T₁, which works in a suitable bearing boss in the casing
cover a as illustrated in Fig. 1, and is operated by the external handle t.
lever L may advantageously be made of the rectangular form shown in cross section
in Fig. 2, for preventing any lateral vibration, and it is fulcrummed on a pin E,
passing across casing A as shown. Motion of the free end of lever L is limited in
The

page_text: both directions either by an I-shaped stop H passing through a slot in it as
illustrated in Figs. 1, 2 and 4, or by allowing the lever to strike against the casing
which is narrowed for the purpose as illustrated in Fig. 3. This limitation of
motion also secures steadiness of action of the lever L and guards against over-
strokes of the pencil. To the free end of lever L is attached an arm D carrying
the indicator pencil d and sufficient resiliency is given to the holding member D as
in Fig. 3, or to the mounting of the pencil itself as in Fig. 1 (by means of a small
spring d',) to allow the latter to follow any irregularity of thickness of the card on
the drum V.
By the above described arrangement it will be seen that inward or outward
movement of slider T by handle t will respectively compress or extend spring S
proportionately, and so correspondingly force to and fro the lever L. These
movements of lever L on its fulcrum E will correspondingly advance and retire the
pencil d to and from the card and mark lines thereon in the direction of its rotation
when the pencil makes contact. In order to distribute such lines over the total
height of the diagram it is necessary that either the card should move upon the
pencil or the pencil on the card at right angles to the direction of oscillation of the
card. We may effect this in either of the following ways. W is an arm or
bracket which, as shown in the drawings, is fixed to the slider T and works
through a slot a¹ in casing A; this bracket carries the oscillating drum V and so
imparts to it an endwise longitudinal travel with the slider T. Instead, however,
of this arrangement, we may for the same purpose fix the bracket W carrying the
paper drum to the casing A, and cause the pencil carrier to slide in or upon the
pencil arm D, which is connected with the piston P as shown, and which would
then be suitably extended for the purpose. A longitudinal motion upon the said
extended portion would thus be imparted to the pencil by the slider T with the
same effect as the above described method, and which will be readily understood
without illustration.
F is an index finger fixed to the slider T or bracket W (when connected
thereto) to indicate the atmospheric or zero lines which may also be marked on the
casing.
In most existing indicators, variations of range of pressure necessitate changes of
springs, for which purpose a series of springs of different strengths is a necessary
accompaniment to every instrument. To avoid this inconvenience, we may use
change wheels, or a lever or levers suitably mounted upon adjustable fulcrums, for
effecting the purpose, but we find the following to be the most simple means of
accomplishing this part of our invention.
We make the fulcrum pin E, of the above mentioned lever L, movable, and we
bore a number of holes 1, 1, 1, through the lever L and the sides of the casing A,
corresponding with each other and with the pin E which is extended to the outside
of the casing as shown, and has a knurled or conveniently made head e for mani-
pulation. The effective power of the spring S on the piston P, Fig. 1 (or
diaphragm P, Fig. 3) is either increased or diminished according as the distance
between the pin E and piston rod p (or centre of diaphragm P¹) is diminished or
increased. Therefore by simply adjusting the position of fulcrum pin E, the
indicator can be adapted at once for taking diagrams from engines working at
widely different pressures.
Thus it will be seen that according to our invention we cause the pencil to move
from or against the card directly in accordance with the reciprocations of the
piston P, caused by the varying pressures of the steam acting on one side and the
varying tension or compression of the spring S, connecting slider and moving drum
or pencil, acting on and controlling the other side of the piston P..
The contact of the pencil with the card continues during the period or that
portion of the engine stroke in which the steam pressure exceeds the tension of the
spring S; the ends of the lines of varying lengths thus produced indicate the
outline of the diagram as illustrated in Fig. 9, and the distance between them is

page_text: equal to the distance through which the drum V, or pencil d, as the case may be, is
moved by the screw T¹ during an oscillation of the drum V.
It might be desirable under certain circumstances to turu the pencil arm in the
direction shown in dotted lines in Fig. 3 in which case pressure on the diaphragm P
would reverse the action of the pencil d on the card and produce a registration on
which the space within the contour of the indicated diagram would be left blank
while the exterior boundary would be lined, the internal termini of the lines
registered marking the true line of the diagram.
The construction of the card drum V is a novel feature of our invention, our
object is to construct it as light and strong as possible, so that when at work, its
inertia and momentum will be reduced to a minimum, and thus the diagrams will
not be distorted, and hence at high speeds more reliable results will be obtained.
The barrel is made preferably of thin sheet steel or aluminium, bent to circular
form and the ends of the sheet are turned in so as to leave a small longitudinal
opening, Figs. 5 and 6, and if of steel, it is then tempered to retain the true shape.
This barrel is fixed to the end fittings V1, V2, in any convenient manner, and they
are securely fastened together in a longitudinal direction by a central tube or
hub K, which forms or may form a bearing upon which the complete drum can
oscillate.
To secure the paper well and tightly upon the drum a resilient rod is pivotted
to one end fitting V, and made capable of swinging against the card or paper and
pressing it into the longitudinal opening, the said rod being fastened by springing
it into a catch or slot, Fig. 6 in the other end fitting V
The whole is mounted upon a central spindle R, carried by the before mentioned
bracket arm W, or the casing A, the bearing end of which is or may be turned
eccentric to advance or retire (as illustrated) the drum and card to or from the
pencil as and when required. This eccentric part is made of considerable length
for the purpose of allowing the paper drum to be longitudinally adjusted with
reference to the pencil to accommodate varying conditions of pressure and vacuum.
The carrying boss to of the bracket arm is split, see Figs. 1, 4, and 8, and
provided with a clamping device Y to adjust and fix the end of the spindle R as
required; also by slackening the clamp Y, the drum V and spindle R may be bodily
removed and replaced at once and without trouble.
A feature of our invention is the use with the drum described of diagram paper
or cards made in cylindrical form which can, by means of the before mentioned
resilient rod v¹ be made to fit the drum tightly.
Upon one end of the drum the usual cord groove k is provided for obtaining the
reduced motion of the engine piston.
The operation of our indicating apparatus in taking a diagram is as follows.
The indicator piston P being placed in communication with atmosphere on both
sides and the spring S in equilibrium, which is indicated by the index F, the
drum V with its card is oscillated in the usual manner, in unison with and in pro-
portion to the engine stroke, contact between the pencil d and card is then made
by turning the eccentric part of spindle R or moving the pencil as the case may
be, and the atmospheric line drawn. Then the pencil contact is broken and air
being excluded, steam pressure is admitted to the enclosed side of the piston P
which is accordingly depressed. This depression moves the lever L on its
fulcrum E in such a manner as to cause the pencil to again make contact with
the card and simultaneously it effects a minute extension of the spring S; the
point of the pencil d will continue in contact with the card during that portion
of the engine stroke in which the steam pressure on piston P exceeds the tension
of the spring S. Then by turning the traversing screw T', so that the slider T is
moved outwards, the drum V with its card is travelled endwise (or at right-angles to
the direction of its oscillating motion) and the spring S is simultaneously extended.
The continued endwise movement of the drum brings unused portions of the card
under the pencil point and each successive increase of tension of spring S tends to

page_text: break contact between the pencil and card at an earlier part of the engine stroke
as at 1, 2, 3, 4, Fig. 9. Thus in an expansive engine, at each stroke lines are
produced and registered of varying lengths as before described, and eventually the
tension of the spring S is increased until it is sufficient to overcome the highest
steam pressure acting against the piston P, when the lever L will be pulled against
the stop H (or the casing A) and held motionless against the steam pressure on P,
and in so doing it will break contact between the pencil and card, holding the
former entirely off the latter; but the moment these conditions are reversed, so
that the tension of the spring S is sufficiently lowered to be overcome by the steam
pressure on the piston P, the pencil will again make contact with and mark
the card.
This is clearly shown in the diagram, Fig. 9, taken from a non-condensing
engine. The lines 1, 2, 3, &c., denote by their lengths the duration of the excess
of steam pressure on the pistou P over the tension of the spring S, and the heights
of any of the lines in the diagram, made at each stroke of the engine piston,
measured at right-angles to the atmospheric line, indicate the varying degrees of
spring pressure. The duplication of lines in the right-hand corner is due as above
described to the pressure on P causing the pencil to remake contact before the end
of its return stroke owing to the compression in the engine cylinder. When the
diagram is completed, steam is shut off from the indicator and the card removed by
releasing the fastening device v'.
The ends of the several lines may then be connected as shown dotted, Fig. 9, to
form an outline of the diagram.
In using our apparatus to register vacuum or pressure below the atmosphere, the
spring S is put in compression so as to hold the pencil d against the card, except
at such times as the pressure of the atmosphere exerted on the open side of the
piston P overcomes the said compression of the spring S and breaks contact
between the pencil and card.
For portability and convenience the before mentioned spiral spring S may be
arranged round the screw T and the parts combined together and so disposed as to
occupy the smallest effective space, for example, we may arrange the drum V
concentrically around the exterior of the casing A, and adapt it or the pencil to
travel endwise upon same, substantially in the manner above described, and without
departing from the nature of our invention.
:
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:-
:-
1. An indicating apparatus for engines and other purposes arranged to register
at each stroke of the engine piston upon a card oscillated in unison with and in
proportion to the same, certain lines together forming or producing a diagram
representing the pressures exerted against the engine piston during its outward
and return strokes, by means of a pencil connected to a pulsating, vibrating, or
reciprocating device subject to the engine cylinder pressure and connected by a
spring to a screw operated "slider" arranged to impart longitudinal motion to the
oscillating drum (or if preferred, to the pencil) in such manner that the pencil will
make contact with and mark the card when the engine cylinder pressure exceeds
the force of the spring, and will break contact and cease to mark the card when
the said spring force exceeds the cylinder pressure, substantially as set forth.
2. An indicating apparatus for engines and other purposes having a device
capable of a limited degree of vibrating or reciprocating motion and subject to the
pressure or pressures to be indicated and connected to the indicator pencil, and by
spring to a movable "slider" adapted to impart longitudinal motion to an
oscillating card drum or to the pencil, and also to simultaneously compress or
extend the spring, the whole being arranged substantially in the manner herein-
bove described, whereby the pencil will make or break contact with the oscillating
card by the reciprocations of the said vibrating or reciprocating device and the

page_text: operation of the slider and spring, and describe a diagram upon the card as
set forth.
3. In an indicating apparatus such as is above described the combination with
the reciprocating or vibrating device of the means for limiting the degree of
movement thereof, substantially as set forth in reference to Figs. 1 and 3.
4. In an indicating apparatus such as is above set forth and claimed, the means
described for adapting the instrument to or for widely varying ranges of pressure,
consisting in the provision of an adjustable fulcrum pin E for the vibratory lever L
connecting the vibratory or reciprocating device with the spring S and the operating
connections thereof, substantially as described and illustrated.
5. In an indicating apparatus of the class described the combination with the
vibrating or reciprocating device, the spring S, the adjustable slider T, and
oscillating card drum V, of the pencil d attached to a lever L interposed between
and connecting the said vibrating or reciprocating device with the spring S, and
fulcrummed on an adjustable pin, such as E, substantially as and for the purpose
specified.
6. The indicating apparatus for engines and other purposes constructed,
arranged, and adapted to operate as a whole instrument, substantially in the
manner hereinabove set forth.
7. In indicating apparatus for engines and other purposes the construction of the
card drum and the means of fixing the card thereupon by pivotted resilient rod v',
and catch, all substantially as set forth.
8. The means of adjusting the drum in any required positions consisting in
mounting said drum upon a spindle with eccentric extension, and the holding boss
therefore with clamping device, substantially as set forth.
9. The use of cylindrically made cards adapted to be fixed upon the drum, as
and for the purpose set forth.