IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES
Year: 1874

page_text: LETTERS PATENT to Norman Owthwaite, of Croydon, in the County
of Surrey, Engineer, for the Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF STEAM ENGINES."
Scaled the 1st June 1875, and dated the 17th December 1874.
PROVISIONAL SPECIFICATION left by the said Norman Owthwaite at
the Office of the Commissioners of Patents, with his Petition, on
the 17th December 1874.
I, NORMAN OWTHWAITE, of Croydon, in the County of Surrey,
Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES," to be as follows:-
―
This Invention relates to certain improvements whereby great sim-
plicity in the construction of steam engines combined with efficacy of
action is attained. The steam is admitted from the boiler by a pipe
provided for that purpose into the steam chest, from whence it passes
through valve ports into the steam ports, and thence into the cylinder,
in which are two pistons, and, having actuated the latter, returns through
the exhaust ports and the valve exhaust port into the condenser or into

page_text: the external atmosphere, as may be desired. The slide valve instead of
being fixed on a shaft works loosely on a square or angular shaft, so
that as the speed increases the valve owing to the operation of centri-
fugal force moves from the centre and cuts off the steam. The valve is
of a circular form, and has a large back area, the result being that it is
necessarily kept tight, whilst by its being heavier at one portion and
working loosely on the shaft it acts both as an expansion valve and as a
governor, thus obviating the necessity of employing those pieces of
mechanism
+
De Cartinai atmosphere, as may be desired. The shut valve instead UI
being fixed on a shaft works loosely on a square or angular shaft, so
that as the speed increases the valve owing to the operation of centri-
fugal force moves from the centre and cuts off the steam. The valve is
of a circular form, and has a large back area, the result being that it is
necessarily kept tight, whilst by its being heavier at one portion and
working loosely on the shaft it acts both as an expansion valve and as a
governor, thus obviating the necessity of employing those pieces of
mechanism.
The engine is constructed with two pistons, the crank being placed 1
between the same, and the ordinary connecting rod and packing glands
being thus dispensed with.
The nature of this Invention will be more clearly understood upon
reference to the annexed Drawings.
Figure 1 is a sectional elevation, and Figure 2 a transverse section; 1
Figure 3 is a sectional plan, and Figure 4 is a view of the valve.
The same letters of reference indicate similar parts in the several
Figures.
The cylinder is shewn at A, and the piston at B, C being the piston
rod and guide; D is the crank. The steam ports are shewn at E, and the 2
exhaust ports at F. The valve steam ports are indicated at G, and
the valve exhaust ports at H. I is the steam pipe, and J the exhaust pipo.
K is the slide valve. L is the fly wheel, and N the expansion spring.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Norman Owthwaite in the Great Seal Patent Office
on the 17th June 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, NORMAN
OWTHWAITE, of Croydon, in the County of Surrey, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 1
Letters Patent, bearing date the Seventeenth day of December, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-seventh year of Her reign, did, for Herself, Her heirs and

page_text: successors, give and grant unto me, the said Norman Owthwaite, Her
special license that I, the said Norman Owthwaite, my executors,
administrators, and assigns, or such others as I, the said Norman
Owthwaite, my executors, administrators, and 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, excrcise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES," upon the con-
dition (amongst others) that I, the said Norman Owthwaite, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands & scals, 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Norman Owthwaite, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :—
My said Invention relates to certain improvements whereby great sim-.
plicity in the construction of steam engines or other motors combined
with efficiency of action is obtained. The improvements consist in the
greatly reduced number of parts required, in the small space occupied,
in the great saving of first cost, and after attention compared with the
usual form of steam engine as now made. These objects are attained in
the following manner:-The cylinder or cylinders & valve chest are.
all cast in one piece with the holding down footing to form one compact
framing. The crank and fly wheel are supported on bearings. in an
intermediate position between the two cylinders. The steam is admitted
from the boiler by a pipe provided for that purpose into the steam chest,
from whence it passes through ports cast on the side of the cylinder into
the outside steam ends of the cylinder, in which are the piston or
double-headed piston. Having actuated the latter the steam returns
through the same ports, through the exhaust pocket of the valve, into.
the condenser or into the external atmosphere, as may be designed.
The admission and egress of the steam is operated by an exceedingly.
simple valve movement in two alternative ways, first, by a rotating.

page_text: circular valve with suitable steam admission ports on one half and an
exhaust pocket on the other. This slide valve instead of being fixed on
a shaft works loosely in a slot on a square or angular shaft so that as
the speed increases the valve owing to the action of centrifugal force
compresses a spring, & moving from the centre cuts off the steam, &
thus acts as an expansion valve governor, obviating the necessity for
those pieces of mechanism.
The admission & egress of the steam may secondly be operated by a
reciprocating slide valve with or without an expansion slide valve, the
motion of both valves being obtained in a very simple manner by 1
eccentric cams keyed to the crank shaft, which passes through the
exhaust cavity & works inside the said valves.
The engine is constructed with two pistons, or rather a long double-
headed piston, with a slot perpendicular to its length at the centre. The
two piston heads may be bolted together at the slot metal to metal, or
may preferably be secured by fitted steady bolts, with suitable spring or
elastic body underneath the nuts to enable the bearing faces of the slot
to always follow up the wear in the brasses of the crank pin, which
slides up and down in the slot in the transference of the reciprocating
motion of the pistons to the rotary motion of the crank.
2
The manner also in which the feed pump or pumps may be actuated,
as usually forming part of an engine, is very simple, the plunger or
plungers being attached to either or both extremities of the slot in the
piston or to other convenient portion thereof. The reciprocating motion
of the pump or pumps is thus taken direct from the piston. The 2
pump barrels may be either cast on the cylinder or bolted thereto, as
desired.
In order that my Invention may be the better understood I herewith

page_text: The steam is admitted through the steam pipe I into the steam
chest L, and from thence passes, according to the position of the valve K
or K', along the steam port E to the end A of the cylinder, the other end
being then open to the exhaust. The pressure thus actuates the double-
headed piston B with the intermediate slot. It is thus communicated
to the crank D, which is caused to revolve, the fly wheel F serving to
carry the engine over the dead centres. The crank carrying with it tho
eccentric cam M in case of the reciprocating slide valve K', in
Figs. 2 & 3, or carrying round the rotary valve K, causes the position
of the valve & ports to be reversed, making the end to which steam
had been admitted in free communication with the exhaust pipe J, by
means of the pocket H in cither of the valves, the other end of the
steam cylinder is at the same time in communication with the steam.
The pressure on the piston is thus reversed, and the action is continued
indefinitely.
In Sheet II. Fig. 1 represents a sectional clevation; Fig. 2, a trans-
verse section; Fig. 3, a half sectional plan; Fig. 4, a transverse section
through the feed pumps and valves; Fig. 5, an elevation of the valve face
on cylinder; Fig. 6, a plan of under side of lower slide valve; Fig. 7, a
plan of top of lower slide valve.
The action of the steam, the operation of the engine, & the descrip-
tion & lettering of parts is the same as in Sheet I., and need not there-
fore be repeated.
The difference in this arrangement consists in the application of an
expansion valve K", travelling on the back of the lower slide valve K',
& worked by the eccentric cam M', which is carried on a continuation
of the crank shaft passing through a suitable slot in the crown of the
lower valve. The positions also of the steam passages E and the central
exhaust pocket J' leading to the exhaust pipe J are more clearly shown
in Fig. 5.
Further, an arrangement of feed pump or pumps, as forming part
of many engines, is shown in Figs. 1 & 4, where the plunger or
plungers P, P, P, P, are bolted to the ends of the slotted part of the
piston, which thus communicates the motion in a very simple manner.
A simple arrangement of valve box is shown at Fig. 4.
In Sheet I., Fig. 1, is shown also a method of holding together the two
portions of the slotted piston by steady bolts N, N, under the nuts or

page_text: heads of which are placed a suitable spring washer Q or other elastic
body, so that the bearing faces of the slot will follow up any wear in
the brasses.
Having now described in full the nature of the said Invention, & the
manner in which the same is or may be used or carried into effect, I
would have it clearly understood that what I hereby claim is,―
First. The combination of a double-headed piston longer than the
stroke, working in two single-acting cylinders in the same line, &
operating a crank between the two ends by means of a vertical slot,
whereby a rotary motion may be communicated to the crank from the 1
double-headed piston without the use of a connecting rod or packing
glands.
Second. The arrangement. of a rotating circular valve working on &
driven by the crank shaft, but at the same time is free to move radially
from the centre under centrifugal force, causing it thereby to curtail the 1
steam admission & act as its own governor.
Third. The manner of operating the ordinary box slide, with also
expansion valve if desired, by means of cams keyed to the shaft, and
working direct on to the inside faces of the valves in their exhaust cavity
from underneath.
Fourth. The arrangement of the spring slot, whereby the bearing faces
of the slot are kept up on to the crank brasses, following up any wear,
preventing knock after the engine has been running some time.
2
Fifth. The method of arranging & working a feed pump or pumps as
part of the engine by taking their motion direct from the slot ends or 2
other part of the piston within the main framing of the cylinders.
In witness whereof; I, the said Norman Owthwaite, have to this
my Specification set my hand and seal, the Sixteenth day of June,
One thousand eight hundred and seventy-five.