IMPROVEMENTS IN INDICATORS OR APPARATUS FOR ASCERTAINING THE POWER OF STEAM ENGINES AND LIKE MACHINES."
Year: 1880

page_text: LETTERS PATENT to Willoughby Statham Smith, of Westbury Barking, in
the County of Essex, and William Oliver Smith, of Mavis Bank, Woodside, in
the County of Surrey, for an Invention of "IMPROVEMENTS IN INDICATORS
OR APPARATUS FOR ASCERTAINING THE POWER OF STEAM ENGINES AND
LIKE MACHINES."
PROVISIONAL SPECIFICATION left by the said Willoughby Statham Smith
and William Oliver Smith at the Office of the Commissioners of Patents on
the 26th June 1880.
WILLOUGHBY STATHAM SMITH, of Westbury Barking, in the County of Essex,
and WILLIAM OLIVER SMITH, of Mavis Bank, Woodside, in the County of Surrey.
"IMPROVEMENTS IN INDICATORS OR APPARATUS FOR ASCERTAINING THE POWER
OF STEAM ENGINES AND LIKE MACHINES."
This Invention has for its object improvements in indicators or apparatus for
ascertaining the power of steam engines and like machines.
Indicators for this purpose as now constructed consist of a small cylinder, which
is placed in communication at one end with the cylinder of the engine to be tested.
The indicator cylinder contains a piston, which is supported by a spring against
the pressure of the steam entering the cylinder. The motion of the piston of the
indicator resulting from the varying pressure of the steam is multiplied by leverage,
and is imparted to a pencil, which marks upon paper carried upon the surface.
of a drum. The drum at the same time receives a movement in unison with the
piston of the steam engine.
It is to indicators of this class that our Invention applies.
In our indicator the paper drum surrounds the cylinder of the indicator, and
the pencil moves along a guide, which is parallel to the axis of the cylinder and
paper drum.
The pencil holder receives its movement from a link connecting it
with a slide in the upper end of the guide. The slide is linked to one end of a
lever having its fulcrum at the other end, and at a point intermediate of its length.
The lever is connected by a link with the head of the rod of the indicator piston.
The length of the portion of the lever between the two links is several times
greater than the length of that part which is between the fulcrum of the lever and

page_text: A
the link passing to the head of the piston rod, so the movement of the pencil is
proportionally greater than that of the indicator piston. The pencil can be taken
off from the barrel by means of a hinge in the slotted guide. The paper drum
receives its motion by means of a spring and cord in the usual manner.
retaining pawl is applied to act upon the cord, allowing it to pass freely in the
direction in which it is pulled by its attachment with a moving part of the engine,
but preventing its return under the influence of the spring of the paper drum. By
this means the paper drum is kept at rest until the moment when it is desired to
take a diagram, and then, by the movement of a button, the pawl is caused to be
released when the cord is next drawn tight. The paper is fixed in place upon the
periphery of the drum by paper clips in the usual way.
In some cases we modify the construction of the apparatus by fixing the paper
drum so that it remains stationary whilst the indicator is at work. Then in place
of moving the drum we give motion from the engine to the pencil guide and its
support, and to the standard, on which is the fulcrum of the lever from which the
pencil receives its movement. These parts are made to rotate to and fro by means
of a spring and cord. The cord is lapped around a barrel, which in this modifi-
cation carries the moving parts above mentioned, and which is free to revolve
about the cylinder of the indicator.
When this modification is used a continuous supply of paper may be obtained
from a reel placed opposite to the drum, and fixed to a stationary part of the
indicator.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Willoughby Statham Smith and William Oliver Smith in the Great
Seal Patent Office ou the 23rd December 1880.
t
WILLOUGHBY STATHAM SMITH, of Westbury Barking, in the County of Essex,
and WILLIAM OLIVER SMITH, of Mavis Bank, Woodside, in the County of Surrey.
IMPROVEMENTS IN INDICATORS OR APPARATUS FOR ASCERTAINING THE POWER
OF STEAM ENGINES AND LIKE MACHINES."
"
This Invention has for its object improvements in indicators or apparatus for
ascertaining the power of steam engines and like machines.
Indicators for this purpose as now constructed consist of a small cylinder, which
is placed in communication at one end with the cylinder of the engine to be tested:
The indicator cylinder contains a piston, which is supported by a spring against
the pressure of the steam entering the cylinder. The motion of the piston of the
indicator resulting from the varying pressure of the steam is multiplied by leverage,
and is imparted to a pencil which marks upon paper carried upon the surface of a
drum. The drum at the same time receives a movement in unison with the piston
of the steam engine.
It is to indicators of this class that our Invention applies.
In our indicator the paper drum surrounds the cylinder of the indicator, and the
pencil moves along a guide, which is parallel to the axis of the cylinder and paper
drum. The pencil holder is linked to one end of a lever having its fulcrum at the
other end, and at a point intermediate of its length. The lever is connected by a
link with the head of the rod of the indicator piston. The length of the portion
of the lever between the two links is several times greater than the length of that
part which is between the fulcrum of the lever and the link passing to the head of
the piston rod, so the movement of the pencil is proportionally greater than that
of the indicator piston. The pencil can be taken off from the barrel by means of a
hinge in the slotted guide. The paper drum receives its motion by means of a
spring and cord in the usual manner. The paper is fixed in place upon the
periphery of the drum by paper clips in the usual way.
In order that our said Invention may be most fully understood and readily
carried into effect, we will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a sectional elevation of an indicator constructed according to our
Invention; Figure 2 is a plan of the same.
A, screw for connecting the stem of indicator to the cylinder of the engine and
stop cock by means of double nuts; B, entrance for steam; C, piston of indicator;
D, stem of indicator; E, tube or cylinder fitted into D, and within which the
piston C works; F, cap screwed into E, and through which the piston rod works;
G, spring screwed to the cap F and to the top of the piston C in the usual way;
H, spring box, which contains the spring J, and is made to revolve round D by the
action of a cord which passes between the guide wheels K, K. The cord is con-
nected to the piston or some corresponding part of the engine. J, spring in the
box E, attached at one end to the interior of the box, and at the other to the
stem D; K, K, guide wheels carried upon L; L, support for guide wheels and also
for spring box. This is able to turn round to put the wheels in any direction;
Al, nut to retain the parts H and L on the stem D. It is locked in its place by
means of two.screws; N, stops to prevent spring box from unwinding, and also for
limiting the movement of the paper barrel; O, flange or piece onto E, and forming
the top bearing of the paper barrel R; P, moveable cap held by means of a pin

page_text: entering a hole in O and the cap F. This part P supports the standard of the
parallel motion and slotted pencil guide B¹; Q, standard for the parallel motion;
R, paper drum, upon the surface of which the paper on which the diagram is to be
drawn is held in the usual way by paper clips; S, projection from E for barrel to
rest against when the spring of catch piece X bears against its opposite side;
T, handle to slotted guide B', by means of which the pencil U may be moved to
and from the paper; U, metallic pencil; its head is pressed upon by a spring.
The pencil passes freely through a hole in a pencil holder U, which is moved up
and down in the slot of the guide B₁. V, double link connecting the head of the
piston rod with the lever A¹; it forms part of the parallel motion; W, part of a
detent contrivance consisting of a cam like projection from the cylinder E. It can
be moved vertically in guides Z, and actuated by the rod d and handle b. The
part W is rounded on its surface, and has a notch where it projects furthest from
the cylinder, as is represented at Figure 3. X, a catch piece jointed to the paper
drum. X is kept in position by a spring. Y, a cam like projection similar to W,
but placed horizontally and fixed on the spring box H. In the position in which
the parts are shewn in the Drawing the catch piece is engaged with the notch in
the projection Y, thus locking the spring box and the paper drum together.
Z, guides of W; d, a rod connecting the part W with the handle b; b, handle for
moving W. When W is raised in its guides Z it stands in the path of the upper
end of the catch X as it moves with the paper drum. The catch mounts the
incline of the cam like projection, causing the paper drum to be released from the
spring box. The catch then falls into the notch in W, thereby locking the paper
drum fast with the cylinder. c, paper clip; A¹, lever forming part of parallel
motion; B', slotted guide, within which the pencil slide works. It is hinged at its
junction with P, and therefore the pencil can be taken to and from the paper
drum R; C, link connecting A¹ with the pencil holder. This link is four times
the length of the double link V, and the part of the lever A¹ between V and C¹¹ is
four times the length of the part of the lever A' between V and the fulcrum.
Having thus described the nature of our said Invention, and the manner of
performing the same, we would have it understood that we claim,-
First. Our improvements in indicators consisting in enclosing the cylinders
within the paper drum, and arranging the pencil holder so that it may be
traversed along a guide in a direction parallel to the axis of the cylinder and
paper drum by means of a lever and links coupling it with the piston rod, sub-
stantially as described.
Second. Our improved indicator, substantially as described and illustrated in the
annexed Drawings.
In witness whereof, we, the said Willoughby Statham Smith and William
Oliver Smith, have hereunto set our hands and seals, this Twenty second
day of December, in the year of our Lord One thousand eight hundred
WILLOUGHBY STATHAM SMITH. (L.S.)
WILLIAM OLIVER SMITH.
(L.S.)