IMPROVE- MENTS IN STEAM ENGINES
Year: 1862

page_text: LETTERS PATENT to John Unsworth, of Rochdale Road, Manchester,
in the County of Lancaster, Engineer, for the Invention of "IMPROVE-
MENTS IN STEAM ENGINES."
Sealed the 13th April 1863, and dated the 29th October 1862.
PROVISIONAL SPECIFICATION left by the said John Unsworth at the
Office of the Commissioners of Patents, with his Petition, on the 29th
October 1862.
I, JOHN UNSWORTH, of Rochdale Road, Manchester, in the County of
Lancaster, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
This Invention relates to certain modifications and combinations of the
valves, cylinders, and ports of steam engines, with a view to avoiding com-
pression or back pressure in the cylinder. For this purpose the pipes used to
convey the steam are placed close to each end of the large cylinder, and additional
ports, which are to prevent resistance or compression, are placed within about 2+
inches of each end of the large cylinder, so that when the piston reaches the end
of the cylinder it covers the port which has been opened to prevent resistance,
but as soon as steam is admitted into the large cylinder it moves the piston
in the small one and covers the port upon which the piston is standing, with
the valve opening a port at the opposite end at the same time; this is performed
whilst the crank is travelling over the centre. The steam admitted into the
small cylinder goes back as soon as the exhaust port is opened for the large

page_text: cylinder; this arrangement prevents any escape of steam. In this arrange-
ment the eylinders: are nearly opposite to each other. The apparatus is fitted
on to a metal plate, the length of which must be in accordance with the
engine cylinder upon which it is bolted, the communication from the large
cylinder to the small one being through the plate. The valve boxes, crank,
and small cylinders are made complete on this plate.
In another arrangement a small cylinder is used with valve boxes attached
to each end of the large one, suitable pipes conveying the steam from the large
cylinder to each end alternately of the small one. Two valve boxes in
connection with the small cylinder are opened in turn as soon as the steam is
admitted into the opposite end of the cylinder, to allow of the escape of the
steam under compression.
In a third arrangement the valves are worked by a lever attached to
any convenient part of the engine, and jointed at one end of a rod, to be carried
to any convenient part, the other end of this lever opening the port in one or
other of two valve boxes to allow the compression to escape.
In a fourth arrangement a small cylinder is used having a small valve box
placed on each end of the large cylinder cover, these valves being made to
answer for the exhaust steam, and also for the escape of the compression.
Suitable pipes convey the steam from the.large cylinder to the small one, which
works through bell or ordinary cranks the valves before referred to.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Unsworth in the Great Seal Patent Office on the 28th
April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
UNSWORTH, of Rochdale Road, Manchester, in the County of Lancaster,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of October, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-sixth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
John Unsworth, Her special license that I, the said John Unsworth, my
executors, administrators, and assigns, or such others as I, the said John
Unsworth, 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

page_text: vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN STEAM ENGINES,"
upon the condition (amongst others) that I, the said John Unsworth,
my executors or administrators, by an instrument in writing. under my hand
and seal, or under the hand and seal of one of them, 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 within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Unsworth, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, 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 certain modifications and combinations of the
valves, cylinders, and ports of steam engines, with a view to avoiding com-
pression or back pressure in the main cylinder. For this purpose, according
to one arrangement, the pipes or passages employed to convey the steam to
two small cylinders alternately are placed close to each end of the main
cylinder, and additional ports, which are to prevent back pressure or com-
pression, are placed within about two and a half inches of each end of this.
cylinder,.so that when the piston reaches the end of the cylinder it covers the
port which has been opened to prevent back pressure, but so soon as steam. is
admitted into the large cylinder it moves the piston valve in the small
cylinders, and closes the port upon which the main piston is standing, opening
at the same time a port at the opposite end of the main cylinder; this is
performed whilst the crank is travelling over the centre. The steam admitted
into the small cylinder returns as soon as the exhaust port is opened to the
large cylinder; this arrangement prevents any escape of steam. If preferred,
the steam may be admitted into the small cylinder or cylinders. direct from the
boiler.
In this arrangement the small cylinders are situate opposite or nearly opposite
to each other. The entire apparatus is fitted on to a metal plate, the length of
which must be in accordance with the engine cylinder upon which it is bolted,
the communication from the large cylinder to the small ones being through
this.plate.
In another arrangement a single small cylinder is used in combination with
valve boxes attached to each end of the main cylinder, suitable pipes or
passages conveying the steam from the large cylinder to each end alternately

page_text: of the small one. The two valve boxes in connection with the small cylinder
are opened in turn as soon as the steam is admitted into the opposite end of
the small cylinder, to allow of the escape of the steam under compression in
the main cylinder.
In a third arrangement the valves are worked by a lever attached to any
-convenient part of the engine, and jointed at one end of a rod, to be carried to
⚫any convenient parts, the other end of this lever opening the port in one or
-other of two valve boxes to allow the compression to escape.
In a fourth arrangement a small cylinder is used having a small valve box
placed on each end or cover of the large cylinder, these valves being made to
.answer for the exhaust steam, and also for the escape of the compression.
Suitable pipes or passages convey the steam from the large cylinder to the small
one, which works the valves before referred to through bell or ordinary cranks.
And in order that my said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose I shall
refer to the several Figures on the Sheets of Drawings hereunto annexed, the
same letters of reference indicating corresponding parts throughout all the
corresponding Figures.
Figure 1 on Sheet 1 of my Drawings represents a longitudinal section of
the upper portion of a locomotive or other steam engine cylinder with my
improvements attached; Figure 2 is a corresponding plan of the same;
Figure 3 is a transverse vertical section taken through one of the small
cylinders, bed plate, and portion of the main cylinder; and Figure 4 is a
similar view, shewing the cranks for working the small piston valves.
a is the main steam cylinder, and 6 its piston, which latter is represented as
covering one of the two additional ports c, c', which are made near each end
of the main cylinder for the free escape of the back pressure steam, herein-
.after designated as the "compression." A small steam port'd, d', is also made
in each end of the main cylinder, leading, like the larger ports c, c', into the
.small supplementary cylinders or valve boxes f, f¹, within which work steam-
tight the piston valves or plugs e, e'. A wide groove or annular recess 9,9', is
.formed in each piston valve, and into these annular recesses or grooves run a
number of longitudinal grooves or slots h, h', (shown clearly in Figures 3
and 4), these longitudinal grooves or channels serving as outlets for the free
escape of the "compression," as herein-after described; the two piston valves
or plugs e, e¹, are connected together, so as to work in concert with each other,
by means of the connecting rods k, k³, which are jointed at i, i, by means of
the joint pins j, ¹, to the outer ends of the plugs e, e¹; the contiguous ends of
.the two connecting rods are respectively coupled with the cranks 1, l, set at right

page_text: angles on a short shaft, which works in bushes m, m, in the brackets n, n,
bulted down upon the bed plate o. To this same bed plate are also bolted the
small cylinders ff, so that the whole of the apparatus is contained on thie
bed plate o, and may therefore be readily fixed to the cylinder of a locomotive
or other steam engine. The piston 6 is supposed to have just completed one
stroke, and the port E of the cylender (in connection with the exhaust) is full
of steam which is confined therein, and exerts a back pressure upon the piston
on its return stroke after the exhaust port of the slide valve has been closed.
So soon, however, as the steam enters the cylinder a on the steam side S of
the piston by the usual port and side valve, a portion of the steam passes by
the small port d into the small cylinder f, and by the time the main piston b
is in motion the plug or valve e in this cylinder has been forced by the steam
pressure beyond the port c, so as to close all outlet for the acting steam, which
would otherwise escape through the part c so soon as it was uncovered by the
main piston b. This forward movement of the plug e is transmitted through
the connecting rod k, cranks 1, 1, and connecting rod k³ to the second plug e¹
in the small cylinder f¹, at the opposite or exhaust end of the main cylinder.
The effect of this movement of the plug e¹ is to bring the recessed portion g¹
over the port c¹, whereupon the "compression".or back pressure steam escapes
freely along the grooves or channels h, h', in the plug during the full stroke of
the piston, and after the ordinary exhaust port has been closed, hence the resis-
tance or back pressure hitherto exerted against the piston whilst it is completing
its stroke is entirely obviated. These valves or plugs e, e¹, are operated in like
manner at each stroke of the main piston 6, the incoming steam at one end
of the main cylinder opening the valve or plug for the escape of the compres-
sion at the opposite end.
Figures 5, 6, 7, and 8 (Sheet 1) are similar views to those herein-before
last described, but representing a modified arrangement of the apparatus.
In these views a is the main cylinder; b, the piston; and c, c¹, the ports for
the escape of the "compression;" these ports communicate respectively with
the valve boxes d, d. In the top of each valve box an escape opening e, e¹,. is
made, and over these openings work the respective side valves f, f¹, which
allows the "compression" to escape into the atmosphere at the required part of
the stroke. Each slide valve f, f¹, is worked by a.valve spindle g, g...passing
through the stuffing boxes h, h¹, and glands i, . A joint j, j, is formed at
one end of each valve spindle coupied by a pin k, k¹, to the links 1, . The
opposite ends of these links are coupled to the short levers m, m³, respectively
keyed on to the ends of the two. crank shafts n, n¹. To these cranks.are coupled
the connecting rods o, o¹, by means of the straps p, p, whilst the opposite ends of

page_text: the rods are connected by the pins q, q', to the cross heads r, r¹, which are
affixed to the opposite ends of the small piston rod s passing through a
gland t and stiffening box u on each end of a small cylinder w. Within
this cylinder works steam-tight a small piston r fitted or formed.in the centre
of the piston rod s. x, a¹, are two steam inlet pipes opening one into each
end of the cylinder w, such pipes being connected with the respective steam
ports of the main cylinder a. The steam on entering the end S of the
main cylinder simultaneously enters the corresponding end. of the small
cylinder e and forces the small piston in the direction of the arrow,
which motion being transmitted to the slide valves f, f¹, through their
respective cranks and connecting rods causes the valve f¹ at the exhaust
end of the main cylinder to open the escape aperture e¹ in the valve box, and
allow of the free escape of the "compression" from the cylinder through the
port c¹, valve box d', and aperture e', the corresponding aperture e in the
opposite valve box being simultaneously closed by the sliding of the valve f
over it, such closing being accomplished before the main piston 6 has had
time to uncover the escape port c. The operations are repeated at every stroke
of the main piston, so that a free exit is left for the "
the piston is making its stroke.
66
compression" whilst
Figure 1 on Sheet 2 of my Drawings represents a longitudinal vertical
section of another arrangement, wherein the valves for the escape of the
"
compresson are actuated by some convenient moving part of the engine
in lieu of by the direct pressure of the incoming steam; Figure 2 is a
corresponding plan of the same; Figure 3 is an end view of one of the
valve boxes, and Figure 4 is a similar view showing a portion of the lever
movement for actuating the valves.
a is the main cylinder; b, the piston covering one of the escape openings
c, c', which communicate with the valve boxes d, d', respectively, each box
being provided with an escape aperture e, e', which apertures are alternately
opened and closed by the slide valves f. f¹. These valves are worked by a
valve spindle 9 passing through the stuffing boxes h, h³, and i, i², and
containing the two valves together. A cross head jis formed on or. fitted
to the valve spindle and provided with a pin k, which engages with one end
of a link l, the opposite end of which link is jointed to the end of a lever m.
This lever works on a stud centre n, and is connected at its opposite. end with
a connecting rod o, actuated from any convenient.part of the motion of the
engine, but so timed that it will move the valves f and f¹ so as to open the
escape aperture e or on the exhaust end of the main cylinder just as the
piston is completing its stroke..

page_text: Figures 5, 6, and 7 on Sheet 2 of my Drawings are similar views to those
last described of a fourth modification.
A portion of the main cylinder a is shown in section with its piston 6 and
escape ports or openings c, c, which latter (in place of being made in the side
of the main cylinder, so as to be occasionally covered by the piston 6, as in
the herein-before described arrangements,) are made in the two end covers
d, d', of the cylinder. To these covers are bolted the two small cylinders f, ƒ³
and into the lower ends of these cylinders the escape ports c, c', respectively
open. e, e, are piston valves working steam-tight within the small cylinders,
and provided with an annular groove or recess 9, 9', and longitudinal
grooves or channels h, h¹, opening into the grooves 9 and 9', precisely as
herein-before described in reference to the modification illustrated by
Figures 1, 2, 3, and 4 on Sheet 1 of my Drawings, and operating in a
similar manner to permit of the free escape of the "compression," when
required. The pistons or plugs e, e¹, are each jointed at their upper ends to
links i,, which are again coupled to the short levers j, j³, fixed to one end of
each of the crank shafts carrying the cranks k, k¹. To these cranks are
coupled the connecting rods 1, l, their opposite ends being jointed to the cross
heads m, m', by the pins n, n¹, The cross heads are fixed to each end of
the piston rod o, which passes through a stuffing box p, p¹, and gland q, q³,
in the two ends of the small cylinders, within which works the small steam-
tight piston r formed on the rod o. t, t¹, are two small steam pipes in connection
with the opposite ends of the main cylinder, and opening into the corresponding
ends of the small cylinder s.
In Figure 5, the piston b. is just completing its stroke and the "compression"
is escaping from the exhaust end E of the cylinder a through the passage c
into the small end cylindrical f, thence by the angular groove g, and channels
h, h, of the plug e into the atmosphere. On the steam end S of the main
cylinder the plug e has been elevated above the escape port c so as to
prevent any escape of steam through the small end cylinder f¹, the proper
working of these two plugs being obtained by the pressure of the incoming steam
on one side or other of the small piston r in the supplementary cylinders, as
will be clearly understood on referring to the Drawings. In lieu of having
the cylinders f, f¹, and plugs e, e', a cork or other valve may be fitted on to
each cylinder cover and opened and closed at the right moment by the links i, i¹,
or their equivalents. It is obvious that these several arrangements for the
escape of the compression are equally adapted for the escape of the whole of
the exhaust steam by making the apertures of the proper area, in which case
the ordinary exhaust port in the slide valve may be dispensed with. By this

page_text: system of construction the engine may be worked with any degre of lap in
the valve and the steam expanded to any extent without increasing com
pression" or back pressure, as the exhaust port may remain open throughout
the entire length of the stroke. The advantages derivable from the use of this
Invention are economy of fuel whilst the shocks and strain produced by the
resistance or back pressure upon the piston, and through it to the crank axles,
are entirely obviated.
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 would observe, in conclusion, that what I consider to be noval
and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent, is,--
1st, the general constructions and arrangements of steam engines as herein-
before described.
2nd, the application and use to and in the cylinders of steam engines of
extra ports or passages, in the manner and for the purpose substantially as
herein-before described.
3rd, the combination with the main cylinder of a steam engine of special
valvular contrivances for the escape of the "compression" or back pressure.
steam actuated either by the direct pressure of the incoming steam or by
suitable mechanism worked by any convenient part of the engine, substantially
as herein-before described and illustrated by my Drawings.
In witness whereof, I, the said John Unsworth, have hereunto set
my hand and seal, this 27th day of April, in the year of our Lord
One thousand eight hundred and sixty-three.
JOHN UNSWORTH. (L.S.)