IMPROVEMENTS IN STEAM ENGINES
Year: 1870

page_text: LETTERS PATENT to Alexander Baumanu, of Heilbroun, in the
Kingdom of Wurtemburg, Civil Engineer, for the Invention of
"IMPROVEMENTS IN STEAM ENGINES."
Scaled the 15th September 1870, and dated the 25th March 1870.
PROVISIONAL SPECIFICATION left by the said Alexander Baumann
at the Office of the Commissioners of Patents, with his Petition, on
the 25th March 1870.
I, ALEXANDER BAUMANN, of Heilbronn, in the Kingdom of Wurtem-
burg, Civil Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
This Invention consists in certain arrangements whereby the valvo
action of steam engines is greatly improved. By means of a slide valve
actuated by two pistons of unequal area working in special cylinders
provided for that purpose, or by a piston valve of corresponding con-
struction, full steam pressure is admitted during one stroke of the
engine, and the back stroke is effected by the expansion of the steam.
For this purpose the piston rod is constructed with a sectional arca

page_text: equal to half the area of the piston in cases in which the steam is to be
expanded to half its working pressure, and other suitable proportions
are adopted for corresponding degrees of expansion as will be well
understood. It being supposed that the steam is to be expanded to half
its working pressure the slide valve is actuated by two pistons, the area
of one being half the area of the other. During the full steam stroke
the slide valve is kept in its proper position by reason of the working
steam pressure acting simultaneously upon the reduced face of the
engine piston, and upon the reduced face of the piston which works the
slide valve. When the full steam stroke is nearly accomplished the
piston of the engine passes over a steamway and admits steam also on
to the face of the larger piston actuating the slide valve. The slide
valve is thus moved backwards, the exhaust is cut off, and the two ends of
the cylinder are set in communication. The steam in the cylinder acts by
its expansive force and effects the back stroke, keeping the slide valve in
its position until the expansion is so far advanced that the working
steam pressure, which continually acts upon the reduced face of the
piston actuating the slide valve, overcomes the pressure of the expanding
steam which acts upon the face of the larger piston actuating the slide
valve. The slide valve then moves backwards giving full steam and
exhaust. To prevent the pistons striking against the respective covers
steam cushions are provided, and in determining the areas of the pistons
the volumes of the steam passages and spaces taken up by these cushions
must be taken into consideration.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Baumann in the Great Seal Patent
Office on the 23rd September 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
BAUMANN, of Heilbronn, in the Kingdom of Wurtemburg, Civil Engi-
neer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of March, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Alexander Baumann, Her special licence

page_text: for
that I, the said Alexander Baumann, my executors, administrators,
and assigns, or such others as I, the said Alexander Baumann, 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,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention
"IMPROVEMENTS IN STEAM ENGINES," upon the condition (amongst others)
that I, the said Alexander Baumann, my executors or administrators,
by an instrument in writing under my, or their, or one of their hands
and seals, 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 Alexander Baumann, 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 Drawing hereunto
annexed, and to the letters marked thereon, that is to say:
-
My said Invention consists in certain arrangements whereby the valve
action of steam engines is greatly improved. By means of a slide valve
actuated by two pistons of unequal area working in special cylinders
provided for that purpose, or by a piston valve of corresponding con-
struction full steam pressure is admitted during one stroke of the engine,
and the back stroke is effected by the expansion of the steam. For this
purpose the piston rod is constructed with a sectional area equal to half
the area of the piston in cases in which the steam is to be expanded to
half its working pressure, and other suitable proportions are adopted for
corresponding degrees of expansion as will be well understood. It being
supposed that the steam is to be expanded to half its working pressure
the slide valve is actuated by two pistons, the area of one being half the
area of the other. During the full steam stroke the slide valve is kept
in its proper position by reason of the working steam pressure acting
simultaneously upon the reduced face of the engine piston and upon the
reduced face of the piston which works the slide valve. When the full
steam stroke is nearly accomplished the piston of the engine passes over
a steamway and admits steam also on to the face of the larger piston

page_text: actuating the slide valve. The slide valve is thus moved backwards,
the exhaust is cut off, and the two ends of the cylinder are set in
communication. The steam in the cylinder acts by its expansive force
and effects the back stroke, keeping the slide valve in its position until
the expansion is so far advanced that the working steam pressure,
which continually acts upon the reduced face of the piston actuating
the slide valve overcomes the pressure of the expanding steam which
acts upon the face of the larger piston actuating the slide valve. The
slide valve then moves backwards giving full steam and exhaust. To
prevent the pistons striking against the respective covers steam cushions
are provided, and in determining the areas of the pistons the volumes of
the steam passages and spaces taken up by these cushions must be taken
into consideration.
I will now proceed to refer to the annexed Drawing, which represents
a section of a steam engine connected to a pump; the pump itself is 1
of the ordinary construction, and it is only shewn in the Drawing
because this Invention is chiefly adapted for the construction of steam
pumps.
The distribution of the steam is effected by a piston valve which, as it
is shewn at A and B, offers to the steam unequal areas, the prolongation
of the valve passing through a stuffing box C at the end of its stroke
in either direction; this piston valve is stopped by a piece of india-
rubber D and E to avoid noise. The two faces of the main piston F and
Ghave to each other very nearly the same proportion as the faces A and B
of the piston valve. This is obtained by means of the piston rods H and I
passing through the stuffing boxes K and L. During the full steam
stroke the piston valve rests on the piece of india-rubber D, thereby
admitting steam from the steam entrance M through the steamway N
on to the face F of the main piston, and closing thereby the steamway O,
whilst the steamway P is set in communication with the exhaust port Q.
The main piston therefore moves from F to G during the steam stroke.
The piston valve is kept in its position by reason of the working steam
pressure acting simultaneously on the reduced face F of the main piston
and upon the reduced face A of the piston valve. When the steam
stroke is nearly accomplished the main piston passes over a steamway R
and admits steam also on to the larger face B of the piston valve. The
piston valve is thus moved into the position in which it is shewn in the
Drawing, the exhaust port Q is cut off, and the two ends of the cylinder

page_text: are set in communication through the steamways O and P; the steam
in the cylinder acts by its expansive force and effects the back stroke,
keeping the piston valve in its position until the expansion is so far
advanced that the working steam pressure (which continually acts upon
the reduced face A of the piston valve because it leaks at M. and
accumulates in the small space S) overcomes the pressure of the
expanding steam which acts upon the larger face B of the piston valve.
The piston valve then moves backwards, giving full steam on to the
face F and exhaust on the face G. To prevent the piston striking the
respective covers steam cushions are provided from O to N in the up
stroke, and from P to Win the down stroke and in determining the
areas A, B, F, G, of the pistons the volumes of the steam passages and
the spaces taken up by these cushions must be taken into consideration,
that is to say, in the present case the proportion between the face B and
the face A is slightly greater than that between the face G and the
face F so as to allow for the compression taking place between O and N.
For the down stroke there is scarcely any cushion left because in the
case of a steam pump the forcing stroke is likely to be made with
comparatively small speed.
Having thus declared and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I would observe in
conclusion that what I consider novel and original, and therefore claim
as the Invention secured to me by the said herein-before in part recited
Letters Patent is, the combination and arrangement of parts and
mechanism substantially as and for the purposes herein-before set forth
and described, or any mere modifications thereof.
In witness whereof, I, the said Alexander Baumann, have here-
unto set my hand and seal, this Twentieth day of September,
in the year of our Lord One thousand eight hundred and seventy.