IMPROVEMENTS IN PISTONS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1857

page_text: LETTERS PATENT to William Robertson, of Glasgow, in the County of
Lanark, North Britain, Engineer, for the Invention of "IMPROVEMENTS
IN PISTONS, AND IN APPARATUS CONNECTED THEREWITH."
Sealed the 24th November 1857, and dated the 25th May 1857.
PROVISIONAL SPECIFICATION left by the said William Robertson at
the Office of the Commissioners of Patents, with his Petition, on the
25th May 1857.
I, WILLIAM ROBERTSON, of Glasgow, in the County of Lanark, North
Britain, Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN PISTONS, AND IN APPARATUS CONNECTED THEREWITH," to be as
follows, that is to say:-
This Invention relates to pistons of various kinds, and used for various
purposes, but particularly to the pistons of horizontal steam engines. In
horizontal steam engines, arranged in the ordinary manner, the weight of the
piston always causes serious wear between its lower side and the corresponding
part of the cylinder's bore, the tendency of the wear being to bring the original
cylindrical bore to an elliptic or irregular form. But according to the present
improvements, the working steam of the engine is made to counterbalance this
tendency to irregularity of wear by acting between the lower side of the piston
and the cylinder, in such way as to relieve the parts from all undue frictional

page_text: pressure. In carrying out this plan in practice, a portion of the piston's
periphery is cut away on the lower side to allow of steam entering in between the
piston and the cylinder at that part. The steam is supplied to the recess in the
piston through the body of the latter by means of a horizontal tube, the inner end
of which opens into the body of the piston, whence by a proper duct the steam
passes forward to the recess. The other or outer end of this tube works out
through a stuffing box in the cylinder cover, and the projecting portion, which
is quite open at the end, works into a stuffing box in the end of a stationary
steam pipe or chamber, which is supplied with steam direct from the boiler.
In this way a free steam communication is always kept up during the piston's
action between the steam boiler and the counterbalancing recess in the piston,
and the area of this recess being proportioned to the weight of the piston and
the working steam pressure, it follows that the piston is fully relieved from
all objectionable lateral or downward pressure upon the cylinder.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Robertson in the Great Seal Patent Office on the
25th November 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERTSON, of Glasgow, in the County of Lanark, North Britain, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of May, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Robertson, Her special license that I, the said William
Robertson, my executors, administrators, and assigns, or such others as I, the
said William Robertson, my executors, administrators, or assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN PISTONS AND IN APPARATUS CONNECTED THEREWITH," upon the condition
(amongst others) that I, the said William Robertson, by an instrument in
writing under my hand and seal, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office

page_text: within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said William Robertson, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say:―
My said Invention relates to pistons of various kinds, and used for various
purposes, but particularly to the pistons of horizontal steam engines. In
borizontal steam engines, arranged in the ordinary manner, the weight of the
piston always causes serious wear between its lower side and the corresponding
part of the cylinder's bore, the tendency of the wear being to bring the original
cylindrical bore to an elliptic or irregular form. But according to the present
improvements, the working steam of the engine is made to counterbalance this
tendency to irregularity of wear by acting between the lower side of the piston
and the cylinder, in such way as to relieve the parts from all undue frictional
pressure. In carrying out this plan in practice, a portion of the piston's
periphery is cut away on the lower side to allow of steam entering in
between the piston and the cylinder at that part. The steam is supplied to
the recess in the piston through the body of the latter by means of a horizontal
tube, the inner end of which opens into the body of the piston, whence by a
proper duct the steam passes forward to the recess. The other or outer end
of this tube works out through a stuffing box in the cylinder cover, and the pro-
jecting portion, which is quite open at the end, works into a stuffing box in
the end of a stationary steam pipe or chamber, which is supplied with steam
direct from the boiler. In this way a free steam communication is always
kept up during the piston's action between the steam boiler and the counter-
balancing recess in the piston, and the area of this recess being proportioned
to the weight of the piston and the working steam pressure, it follows that
the piston is fully relieved from all objectionable lateral or downward pressure
upon the cylinder.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the several illustrative figures on the explanatory
Sheet of Drawings, which I have hereunto appended for the purpose of
showing certain modifications, under which my Invention may be judiciously
carried out in practice :-
Figure 1, on my Sheet of Drawings, is a vertical section of the cylinder,
piston, and slide valve, of a horizontal engine, as arranged with one modi-
fication of my improvements applied thereto; Figure 2 is a transverse section,

page_text: taken at right angles to Figure 1, through the centre of the piston, one half
of the slide valve casing and steam pipes being shown in elevation; Figure 3
is a plan of the upper part of the piston; Figure 4 is a plan of the under side,
showing the steam ports through which the steam exerts its pressure upon the
lower part of the cylinder, and the pipe by which the steam is conveyed to the
interior of the piston; Figure 5 is an end view of the piston showing the
junction of the steam pipe with the piston; and Figure 6 is a view of the
opposite end of the piston.
The cylinder A is similar in its arrangement to those in ordinary use,
excepting that in its front end cover B, there is fitted a stuffing box C, through
which a steam pipe, herein-after described, works. The supplementary, or
additional stuffing box C, is fitted below the ordinary central stuffing box D,
so as to be in a line with the lower part of the piston. Opposite to, or. in a
line with the orifice of the stuffing box C, a hole E is made through the front
plate F of the piston, and this aperture communicates with the space between
this plate and the junk ring G of the piston and its periphery.. The aperture E
in the plate F of the piston is countersunk to admit the flanged end of the
steam pipe H, which is attached to the piston by screws, as shown in the front
view of th piston, Figure 5. The steam pipe H works through the stuffing
box C in the cylinder cover B, parallel to the piston rod I, and the pipe
traverses to and fro in accordance with the movement. of the piston. The
outer end of the stuffing box C is fitted into one end of a stationary steam
pipe J, with which it forms a steam-tight junction. The other end of the
pipe J is connected by means of a stuffing box with another steam pipe K,
which pipe is put in direct communication with the boiler itself, from which
the steam for driving the engine is primarily derived; the horizontal steam
pipe J therefore acts as a casing, in which the moveable steam pipe H traverses
to and fro, in the same manner as the piston rod travels to and fro in the
cylinder. The steam, conveyed by the pipe H to the interior of the piston, is
caused to exert its pressure against the piston and the cylinder, so as to take
off the weight of the piston from the lower portion of the cylinder, and by thus
equalizing the pressure of the piston both upwards and downwards, thereby
prevent the cylinder from being worn to an elliptical shape. The steam from
the pipe His adınitted to the lower part of the piston between the rings which
form its metallic packing. This packing consists of two external spring rings L,
which form the periphery of the piston, these rings being fitted to break joint
with each other in the usual manner, and they have each a slot or opening cut
therein, as shown at M, in Figure 4 of my Drawings. It is by means of these
openings that the steam exerts a downward pressure upon the cylinder, whilst

page_text: its upward pressure is against the piston itself; the area of these openings is
therefore regulated by the weight of the piston which is to be sustained, and
the pressure of the steam admitted thereto. The internal metallic rings N
are arranged eccentrically in relation to the piston, that is to say, the upper
portion of the rings N touch the external packing rings L, whilst the lower
portions are in contact with the annular ring O, forming the body of the piston;
as is shown in Figures 1 and 2 of my Drawings. The rings N are retained
in their places at the lower side of the piston by pins, which project laterally
from the rings, and are held in corresponding holes made in the front and end
plates of the piston F and G. The pin of the front ring N is readily inserted
in the plate F of the piston before screwing on the junk ring G, and when this
ring is adjusted, the pin of the back ring N is inserted in its place, and the
ring fastened to the boss of the piston by the screws P. The packing rings L
and N are made thicker at the lower part than at the upper part, by which
their elasticity is increased. The inner rings L bear solidly against the outer
rings for about half of their circumference; this is done making the metal
of the inner ring sufficiently thick to fill up the space between the rings to the
extent required. The pressure of the spring packing rings against the packing
rings may be increased at pleasure, if necessary, by inserting and fitting either
spiral or flat springs in the space Q between the annular ring O of the piston
and the packing rings. Upon admitting steam to the interior of the piston,
its expansive force acting upon the lower side of the cylinder, and upwards
against the piston, tends to relieve the cylinder from the weight of the piston,
and thus prevent its being worn to an elliptical shape. With this arrange-.
ment for preserving the circular figure of horizontal cylinders, this class of
engines may be constructed to any required size, with as much confidence as
regards the wear of the cylinder as those of the upright or vertical cylinder
kind.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to,
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what I
consider to be novel and original, and therefore claim as the Invention secured
to me by the herein-before in part recited Letters Patent, is,-
First, the general arrangement and construction of the cylinders and pistons
of horizontal engines, with a view of preserving the circular figure or form of
the cylinder, as herein-before described.

page_text: Second, the system or mode of relieving the cylinder of horizontal engines
from the weight of the piston, by admitting steam thereto, as herein-before
described.
Third, the system or mode of arranging the piston, and parts connected
therewith, of horizontal engines, so that the steam admitted thereto shall exert
an upward pressure upon the piston corresponding to its weight, as herein-
before described.
Fourth, the system or mode of arranging and constructing the metallie
packing or spring rings, to be used in conjunction with the improved pistons,
as herein-before described.
In witness whereof, I, the said William Robertson, have hereunto set my
hand and seal, this Twenty-third day of November, One thousand eight
hundred and fifty-seven.
WILLIAM ROBERTSON. (L.S.)