IMPROVEMENTS IN STEAM CYLINDERS AND THE PECULIAR ARRANGEMENT OF THE MECHANISM CONNECTED THEREWITH
Year: 1867

page_text: LETTERS PATENT to Noah Paxman, jun, of Clifton Hampden, in the
County of Oxford, Farmer, for the Invention of "IMPROVEMENTS IN
STEAM CYLINDERS AND THE PECULIAR ARRANGEMENT OF THE MECHANISM
CONNECTED THEREWITH."
Sealed the 2nd June 1868, and dated the 12th December 1867.
"PROVISIONAL SPECIFICATION left by the said Noah Paxman at the
Office of the Commissioners of Patents, with his Petition, on the 12th
December 1867.
I, NOAH PAXMAN, jun', of Clifton Hampden, in the County of Oxford,
Farmer, do bereby declare the nature of the said Invention for "IMPROVE-
MENTS IN STEAM CYLINDERS AND THE PECULIAR ARRANGEMENT OF THE MECHANISM
CONNECTED THEREWITH," to be as follows:-
This Invention has for its object the more effectual application of steam to
the cylinders, and pistons of steam engines, whether horizontal or vertical,
fixed or moveable, marine, or otherwise. In carrying this Invention into
effect I place two pistons in the same cylinder, which pistons are driven by
steam in opposite directions, the steam being caused to act upon the surface
of each of the pistons; instead of acting upon the cylinder covers as hereto-
fore, the result of which will be that the entire propelling force of the steam
will be utilized and a considerable amount of power obtained. To the back
piston I attach a double, and to the front piston a single connecting rod, which

page_text: are then fixed to and drive a crank shaft which gives motion to the other
parts of the engine, the steam being admitted to the cylinder and acting upon
the two pistons at each stroke when leaving each other.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Noah Paxman in the Great Seal Patent Office on the
11th June 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, NOAH
PAXMAN, junior, of Clifton Hampden, in the County of Oxford, Farmer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of December, in the year of our
Lord One thousand eight hundred and sixty-seven, in the thirty-first year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Noah Paxman, junior, Her spécial license that I, the said Noah
Paxman, junior, my executors, administrators, and assigns, or such others as I,
the said Noah Paxman, junior, 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 STEAM CYLINDERS AND THE PECULIAR ARRANGEMENT OF THE MECHANISM
CONNECTED THEREWITH," upon the condition (amongst others) that I, the said
Noah Paxman, junior, my executors or administrators, 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 bo 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 Noah Paxman, junior, 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 has for its object the more effectual application of steam
to the cylinders and pistons of steam engines, whether horizontal or vertical,
fixed or portable, marine, or otherwise.

page_text: In carrying this Invention into effect I place two. pistons in the same
cylinder, which pistons are driven by steam in opposite directions, the steam
being caused to act upon the surface of each of the pistons, instead of acting-
upon the cylinder covers as heretofore, the result of which will be that the
entire propelling force of the steam will be utilized and a considerable amount
of power obtained. To the rod of the back piston I attach a double, and to.
that of the front piston a single connecting rod, which are then fixed to and
drive a crank shaft giving motion to the other parts of the engine, the steam
being admitted to the cylinder between the two pistons and acting upon them.
simultaneously at each stroke when leaving the centre of the cylinder..
..
And in order that my said Invention may bo fully understood I shall now
proceed more particularly to. describe the same, and for that purpose shall
refer to the Figures on the annexed Sheet of Drawings, the same letters of
reference indicating corresponding parts in both Figures.
Figure 1 of my Drawings represents an elevation of a portable engine.
with the steam chest in section to show my improvements more clearly, and
Figure 2 is a corresponding plan of the same with the cylinder and steam
chest in horizontal section. As the general arrangement of the engine forms.
no part of my present Invention, it is unnecessary to make any further.
reference to it here, and I shall therefore confine my description to the special.
improvements which I have introduced.
A is the steam cylinder, which is of extra length in order to obtain a
suitable throw of crank. This cylinder is bolted or otherwise secured to the.
boiler, or to any other convenient bed plate or support, according to the class.
of engine required, and has working within it the two. pistons B, B', which,
alteruately approach towards and recede from each other. The respective.
cranks C and C, C, of the two pistons are formed on diametrically opposite.
sides of the driving shaft D, and if desired the stroke of one piston may be
greater than that of the other. E is a cross head secured on to the end of
the back piston rod, and F, F, are two connecting rods jointed to the opposite
ends of the said cross head, and coupled to the pair of cranks C¹, C'. G is a
cross head secured to. the front piston rod and coupled to the crank C; both
cross heads carry slide blocks. working in the slide bars Hand H. Tho
working cylinder is provided with one port only, which is situate at or near
the longitudinal centre thereof, or at any other point which coincides with the
part where the two pistons approach nearest to each other, as shown at I.
This port I serves alternately as the induction and eduction port; it communi-
cates directly with the steam chest K, into which steam is admitted from the
boiler by the passage L and steam regulating valve M, which may either be

page_text: made as shown in the Drawing, or otherwise. The eduction port or opening N
for the escape of the exhaust from the steam chest is here shown as being
made in the bottom face O of the steam chest, whilst the cylinder port I opens
into the side of the steam chest. The slide valve P; which is made hollow, is
consequently provided with two rubbing faces at right angles to each other,
and has a port or opening Q made on one side which communicates at certain
positions of the valve with the cylinder port I for the free escape of the
exbaust. R is an opening in the bottom of the steam chest for the admission
of steam therein; the lower side or bottom of the valve is left open, so that
the interior of the valve may be in constant communication with the exhaust
opening N made in the bottom of the steam chest, and communicating directly
with the exhaust pipe T. In my Drawings I have represented the cylinder
port I open, the two pistons being at the termination of their inner stroke:
On admitting steam from the boiler into the steam chest by opening the
steam valve M it passes through the port I direct into the cylinder between
the two pistons and forces them outwards, the port being closed at any portion
of the stroke as heretofore according to the amount of expansion required:
By the time the pistons have arrived at the cylinder covers the slide valve P
will have brought the port I into communication with the interior of the valve
through the port Q, when the exhaust will immediately take place through
the open bottom of the valve and exhaust port or opening N to the exhaust
pipe T. In the meantime the pistons are returned to the middle of the
cylinder by the momentum of the fly wheel, and the next stroke is effected as
before. The slide valve may be worked by an eccentric U in the ordinary
manner. As no steam is required to operate between the pistons and the
cylinder covers it is obvious that tight fitting stuffing boxes may be dispensed
with or the cylinder left open at each end if desired.
The advantages. which I obtain by my improvements are, a considerable
reduction of friction, more particularly in the bearings of the crank shaft, the
strain upon which is more equalised; the vibrations of the engines are greatly
diminished; reduction of condensation from the fact of the steam not coming
in contact with the cylinder covers; a saving of steam, and consequently of
fuel by reason of the shortness of the steam port in the cylinder. It is obvious
that two or more of such cylinders with their pistons and slide valves may be
combined together in one engine.
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 novel'
and original, and therefore claim as the Invention secured to me by the

page_text: herein-before in part recited Letters Patent is, the construction and use of
steam engines wherein two pistons work in a single cylinder in conjunction
with a single port and slide valve arranged and operating substantially in the
manner herein-before described and illustrated by my Drawings.
In witness whereof, I, the said Noah Paxman, junior, have to this
my Specification set my hand and seal, the Thirtieth day of May,
One thousand eight hundred and sixty-eight.
NOAH PAXMAN, JUN. (L.S.)