IMPROVEMENTS IN INDICATORS FOR STEAM ENGINES
Year: 1876

page_text: LETTERS PATENT to William Clark, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN INDICATORS
FOR STEAM ENGINES." A communication from abroad by Joseph Warren
Thompson, of Salem, in the County of Columbiana, State of Ohio, United
States of America.
PROVISIONAL SPECIFICATION left by the said William Clark at the Office
of the Commissioners of Patents on the 1st August 1876.
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. "IMPROVEMENTS IN INDICATORS FOR STEAM ENGINES."
The indicator of this Invention is designed to register the relative amounts of
steam pressure exerted on the piston at each portion of its stroke, and it is in part
an improvement upon the Richards' automatic recording indicator.
The object of the Invention is chiefly to reduce the number and weight of the
parts composing Richards' recording mechanism proper, and thus correspondingly
reduce their momentum when in action to the end of securing a more perfect record
of the several steam pressures existing in the engine cylinder during a given stroke
or strokes of the piston. This reduction in momentum is particularly important in
relation to quick stroke engines, for the indication given or delineation made on the
paper barrel by the marking point will be more or less imperfect as the momentum
of the moving parts is greater or less.
In carrying out the Invention I dispense with a separate holder for the pencil
by which the record is made on a drum or paper barrel and attach the pencil
directly to the main lever, to which a vertical vibratory movement is imparted by
the reciprocation of the spring piston under the varying pressure of steam in the
cylinder.
To preserve the desired parallel movement I pivot the working or marking lever
to a movable or oscillating fulcrum, connect its free end to a fixed standard by
means of a link or bar, and pivot it intermediately of said fulcrum and link
directly to the piston rod, which latter is necessarily vibrated at each movement of
the niston.

page_text: The Invention further includes a compensating connection or joint between the
piston rod and piston, and the means for adjusting the tension of the spring of the
drum upon which the record is made, all as herein-after more fully described.
According to this Invention the piston works in a tube, which is in immediate
communication with the engine cylinder. The piston rod is pivoted to the working
lever, which has a socket in its free end to receive a pencil and is pivoted at the
other end to a link hinged to the tube. The said link therefore constitutes a
movable fulcrum, oscillating freely in the lengthwise direction of the marking lever
whenever the piston changes its position by reason of variation in steam pressure.
To preserve the desired parallel movement and cause the pencil to move in a
straight line over the paper barrel, I connect the lever to a fixed vertical standard
by a link pivoted to the lever at a point near the piston rod and between it and
the pencil.
+
It is evident that since the lever has a lengthwise reciprocation (as well as
vertical vibration) at every movement of the piston up or down, the upper end of
the piston rod must vibrate correspondingly in the arc of a circle whose radius is
determined by the extent of such movement of the piston. It is hence necessary
to have a flexible connection between the rod and piston. To this end I arrange
the piston rod to work in a tube or trunk (as in trunk engines) which slides
through the head of the piston tube. Said trunk screws on the end of piston stem,
and has a concavity or socket thereat suitable to receive the head of the piston rod.
The latter is rounded or spherical on its upper side corresponding to the socket of
trunk, and has a concavity in its under side corresponding to the conical head of a
small stud, which is screwed into the end of the main piston stem. The parts are
thus firmly connected by a compensating joint, which has the freedom of movement
required for the piston rod. The trunk and stem of the piston are encircled by a
spiral spring, whose tension must be overcome by the steam pressure to produce an
upward movement of the piston. The vertical pivoted paper barrel is provided
with the usual form of paper holding device, and is caused to make partial
rotations back and forth coincident with the movement of the piston of the engine
by means of a cord or other suitablo means of connecting it with some reciprocating
part of the engine, substantially as in Richards' indicator. The drum is supported
by a stem or standard which rises vertically from a lateral arm of the piston tube,
and a coiled spring is arranged in the drum case which is fixed on a tubular stem
of the barrel. The top of the case is formed by a disk having a hub which turns
loosely on the standard, the tension of the spring can be adjusted at will by turning
and clamping the disk by means of a nut on the upper end of the standard, the hub
of said disk and the inner side of the case having each a lug with which the ends
of the spring are in contact. The spring case accurately fits the drum and thus
forms one of the bearings or supporters therefor.
In part recapitulating it will be seen that when the steam pressure in the engine
cylinder increases the piston will rise, and when it decreases the piston will fall,
in either caso causing a vibration of the lever, so that the pencil is caused to move
over the paper barrel in a straight line and faithfully record the limits of varintion
of such steam pressure. Simultaneously with this movement of the pencil the
barrel makes corresponding reciprocating movements, so that the variation during
each stroke of the piston is clearly recorded.
The construction and arrangement of the marking device is such that the inertia
and corresponding momentum are greatly reduced, and greater accuracy and
reliability therefore secured. The spring tension device is easily accessible, and
may be quickly adjusted to vary the quickness of the return movement of tho
paper barrel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said William Clark in the Great Seal Patent Office on the 31st January 1877.
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. "IMPROVEMENTS IN INDICATORS FOR STEAM ENGINES." A communication
from abroad by Joseph Warren Thompson, of Salem, in the County of Columbiana,
State of Ohio, United States of America.
The indicator of this Invention is designed to register the relative amounts of
steam pressure exerted on the piston at each portion of its stroke, aud it is in part
an improvement upon the Richards' automatic recording indicator.
The object of the Invention is chiefly to reduce the number and weight of the
parts composing Richards' recording mechanism proper, and thus correspondingly
reduce their momentum when in action to the end of securing a-more perfect record
of the several steam pressures existing in the engine cylinder during a given stroko
or strokes of the piston. This reduction in momentum is particularly important
in relation to quick stroke engines, for the indication given or delineation made on
the paper barrel by the marking point will be more or less imperfect as the
momentum of the moving parts is greater or less.
In carrying out the Invention I dispenso with a separate holder for the pencil
by which the record is made on a drum or paper barrel, and attach the pencil
directly to the main lever to which vertical vibratory movement is imparted by
the reciprocation of the spring piston under the varying pressure of steam in the
cylinder.
To preserve the desired parallel movement I pivot the working or marking lever
to a movable or oscillating fulcrum, connect its free end to a fixed standard by
means of a link or bar and pivot it intermediately of said fulcrum and link directly
to the piston rod, which latter is necessarily vibrated at each movement of the
piston.
The Invention further includes a compensating connection or joint between the
piston rod and piston, and the means for adjusting the tension of the spring of the
drum upon which the record is made, all as herein-after more fully described.
Figure 1 of the accompanying Drawings is a sectional elevation of the improved
indicator; and Figure 2 a similar view of the drum or paper carrying barrel and
its contained spring and tension adjusting device therefor.
The piston A works in a tube B, which is in immediate communication with the
engine cylinder. The piston rod C is pivoted to the working lever D, which has
a socket in its free end to receive a pencil a, and is pivoted at the other end to a
link E hinged to tube B. The said link therefore constitutes a movable fulcrum
oscillating freely in the lengthwise direction of the marking lever D whenever the
piston A changes its position by reason of variation in steam pressure.
To preserve the desired parallel movement and cause the pencil to move in a
straight line over the papel barrel, I connect the lever D to a fixed vertical
standard E by a link b pivoted to the lever at a point near the piston rod and
between it and the pencil a.
It is evident that since the lever D has a lengthwise reciprocation (as well as
vertical vibration) at every movement of the piston up or down, the upper end of
the piston rod must vibrate correspondingly in the arc of a circle whose radius is
determined by the extent of such movement of the piston. It is hence necessary
to have a flexible connection between the rod and piston. To this end I arrange
the piston rod to work in a tube or trunk G (as in trunk engines), which slides
through the head H of tube B. Said trunk screws on the end of piston stem I,
and has a concavity or socket thereat suitable to receive the head of the piston rod.
The latter is rounded or spherical on its upper side corresponding to the socket of
the trunk G, and has a concavity in its under side corresponding to the conical
head of a small stud i which is screwed into the end of the main piston stem I, as
shown. The parts are thus firmly connected by a compensating joint which has

page_text: the freedom of movement required for the piston rod. The trunk G and stem I
of the piston A. are encircled by a spiral spring K, whose tension must be overcome
by the steam pressure to produce an upward movement of the piston. The vertical
pivoted paper barrel L is provided with the usual form of paper-holding device M,
and is caused to make partial rotations back and forth coincident with the move-i
ment of the piston of the engine by means of a cord or other suitable means of
connecting it with some reciprocating part of the engine, substantially as in
Richards indicator. The drum is supported by stem or standard N which rises
vertically from a lateral arm of the tube B. The coiled spring O is arranged in
the case P, which is fixed on the tubular stem Q of the barrel L. The top of the
case N is formed by a disc R, having a hub c, which turns loosely on the
standard N. The tension of the spring can be adjusted at will by turning and
clamping the disc R by means of nut S on the upper end of standard N, the hub c
of said disc and the inner side of the caso having each a lug o with which the ends
of the spring are in contact. The spring case accurately fits the drum, and thus
forms one of the bearings or supporters therefor.
In part recapitulating it will be seen when the steam pressure in the engine
cylinder increases the piston A will rise, and when it decreases the piston will fall,
in either case causing a vibration of the lever D, so that the pencil is caused to
move over the paper barrel L in a straight line and faithfully record the limits of
variation of such steam pressure. Simultaneously with this movement of the pencil
the barrel L makes corresponding reciprocating movements, so that the variation
during each stroke of the piston is clearly recorded.
The construction and arrangement of the marking device is such that the inertia
and corresponding momentum are greatly reduced, and greater accuracy and
reliability therefore secured. The spring tension device is easily accessible, and
may be quickly adjusted to vary the quickness of the return movement of the
paper barrel.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is,--
First. In a steam-pressure recorder, the combination of the working lever carrying
the marker of a movable fulcrum, a fixed standard F and link b, connecting the
lover directly to the standard, substantially as shown and described for the purpose
specified.
Second. In a steam-pressure recorder the combination with the reciprocating
drum of the spring O, spring case P, the disc having hub c and clamping screw
nut S, all as shown and described to permit the spring tension to be adjusted as
desired.
Third. The combination of rod C and stud i, having corresponding concavity and
convexity and the screw socket for connecting said parts C, i, to the piston or
movable part to form a universal compensating joint, as shown and described.
In witness whereof, I, the said William Clark, have hereunto set my hand and
seal, this Thirty-first day of January, in the year of our Lord One thousand